# CalcTape Web – Manual & Guide

> Manual for CalcTape Web: interface, calculating with comments, user keys, sharing via link and privacy — right in your browser.

- Language: English
- This page as HTML: https://www.calctape.com/en/manual-web
- Updated: 2026-10-20

CalcTape Web is the browser-based version of the **CalcTape** calculator. Instead
of showing only a single intermediate result like a conventional calculator,
CalcTape works like a **paper tape with a notepad function**: you write your
calculation line by line, can add a comment to every value, and edit anything at
any time. Everything is recalculated instantly.

> *Calculate, Comment, Correct:* in your browser, no installation required.
> Your calculations are stored locally in your browser.

![CalcTape Web in your browser](https://www.calctape.com/img/manuals/web-overview-en-light.webp)

## 1. The concept: how CalcTape works

CalcTape differs from a conventional calculator in four ways:

### Quick start: 60 seconds
Type these two lines and close the block with **=**:

```
 +      1,000.00 Net price
 +         19.00% VAT
 ---------------
 +      1,190.00
```

That is all there is to it. Four moves come up in daily use:

1. **Change a value** - click into the first line and make it 1,500; everything
   below recalculates instantly.
2. **Comment** - behind every number you may write what it is about.
3. **Copy the result** - one click on the large value at the top right puts it
   on the clipboard.
4. **Pass it on** - **Share** creates a link that carries the calculation
   itself, or saves it as a file (sections 8 and 9).

The rest of this manual covers the details - you do not need it to get
started.

### Line-by-line calculation
Each line contains an operator and a value, e.g. `+ 1,350.00`. CalcTape
accumulates the lines continuously, like a receipt.

### Automatic subtotals
When you close a block (using the **= / Enter** key), CalcTape automatically
draws a separator line and writes the running **subtotal** below it:

```
 +      3,230.00 Salary
 -      1,350.00 Rent
 -        780.00 Groceries
 ---------------
 +      1,100.00 Available
```

### Comments right next to the numbers
You can write any text after a value (in the example above "Salary", "Rent" …).
CalcTape ignores the text when calculating but displays it alongside the numbers,
so every calculation stays easy to follow.

### Edit anything at any time
You can change any value in any line at any time.
**The entire calculation is recalculated instantly.** That is what makes
CalcTape so flexible.

### Multiple calculations side by side
- **Without a blank line** between two blocks you get a convenient **subtotal**.
- **With a blank line** you start a **completely new, independent calculation**
  in the same document.

## 2. Interface overview

The app is divided into the following areas:

| Area | Position | Function |
|---|---|---|
| **Header** | very top (dark bar) | Menu icon ☰, logo & product name, theme menu, dark mode switch, language selector (globe icon), **"Share"** button |
| **Toolbar** | above the editor | Undo/Redo, lines, typeface, digit grouping, zoom, help, contact link (see below) |
| **Editor (tape)** | center, full height | Input area for your calculations (lined "paper") |
| **Status bar** | below the editor | Clickable chips: Zoom, cursor position; errors; "Automatically saved" |
| **Result panel** | top right | Current block result, grand total and memory - each click to copy |
| **Keyboard** | right (mobile: bottom) | Virtual calculator keyboard |
| **Apps panel** | bottom right | Links to the CalcTape apps (Mac, Windows, Android, iPhone, Business) |
| **Footer** | very bottom | Copyright, version, legal links |

### The header
The **header** spans the very top of the window (the dark bar) and gathers
the app's global controls. From left to right it holds:

- the **menu icon (☰)** - opens the main menu with all commands (section 6);
- the **logo and product name** "CalcTape Web";
- the **theme menu** - pick a color palette (see below);
- the **dark-mode switch** (moon/sun icon);
- the **language selector** (globe icon);
- the **"Share"** button - create a share link or save the calculation
  (section 8).

![The header](https://www.calctape.com/img/manuals/web-header-en-light.webp)

**Color theme.** The **theme button** in the header (a small color tile with
the theme's key colors, the active theme's name and a small arrow) opens a
menu with several color palettes. Each palette is shown as a **preview
tile** - a miniature of the tape and the keypad in that palette's colors,
matching the light or dark mode you are in. The active palette is framed and
carries a check mark. Available palettes:

- **Crisp Azure** - the default: near-white surfaces, with CalcTape blue used
  only as an accent on the result, variables and custom keys, plus an amber
  AC key as the sole warning signal.
- **Classic Copper** - the classic CalcTape look (navy/blue).
- **Vivid Indigo** - a bold indigo/slate scheme with colored key accents.
- **Subtle Slate** - a calm, muted steel-blue for relaxed work.
- **Ledger Green** - the accountant's look: green journal paper, a red pencil
  for negatives, ledger green for the results.
- **Sunlit Amber** - built for bright light: warm paper instead of glaring
  white, strong contrast and cool operator keys.
- **Neutral Graphite** - entirely grey, with no colour accent at all: keys
  are distinguished only by brightness, with colour reserved for negative
  numbers and the AC key. For anyone who wants the interface to stay as
  quiet as possible.
- **High Contrast** - for washed-out or reflective displays in bright light:
  pure white and pure black instead of fine gradations, keys separated by
  colour as well (blue operators, yellow custom keys, red AC), heavier type in
  the tape and on the keys, and visible borders around tape, keypad and panels.
- **High Contrast Warm** - the same contrast level on cream instead of pure
  white paper: glossy displays turn a white sheet into a mirror, and maximum
  brightness is tiring over time. The first choice for long sessions in
  bright surroundings.

On your first visit CalcTape starts everyone off with the same palette
("Crisp Azure"); as soon as you choose one yourself, your choice applies.

The palette is **independent** of light/dark mode: any palette can be combined
with the light or dark theme.

**Dark mode.** The **moon/sun icon** switches between light and dark themes. On
the first visit CalcTape follows your device's system setting; your choice is
then saved.

**Language.** The **globe icon** switches between **Deutsch**, **English**,
**Español**, **Français**, **Italiano**, **Português**, **हिन्दी** (Hindi) and
**Bahasa Melayu** (Malay);
the active language is marked with ✓ and is saved. Without an explicit choice
CalcTape follows your browser's language. This manual is available in all of
these languages too.

Your palette, dark-mode and language choices are all stored locally and restored
on your next visit.

### The toolbar
The most important actions are available as icon buttons directly above the tape,
organized in groups:

- **Edit:** Undo, Redo (grayed out when not available)
- **View:** lines on/off, proportional typeface, Indian digit grouping, zoom out,
  zoom display (click = reset), zoom in
- **Help:** opens the help menu with the Tutorials, links to this
  manual and the CalcTape apps, and the About dialog.
  At the far right, the **Problems or ideas?** link opens the contact form on
  calctape.com in a new tab, with "Web" already selected as the platform.
  In a narrow window (mobile) the link is hidden; in a wide one it is the
  first thing to go when the toolbar gets too tight.

![The toolbar](https://www.calctape.com/img/manuals/web-toolbar-en-light.webp)

**Save calculation** lives in the **Share** popover (section 8), not in the
toolbar.

Each icon shows a tooltip with a plain-text label **and** keyboard shortcut on
hover (e.g. "Undo (Ctrl+Z)").

### The result panel
The **result of the current block** is displayed large and clearly in the top
right. **Clicking the value copies it to the clipboard** (brief confirmation
"Result copied"). Below it, two rows show the **grand total** (the sum of the
final totals of all completed blocks) and the **memory value**; each can be
copied with a click. The small **copy icon** next to a value indicates this.

![The result panel](https://www.calctape.com/img/manuals/web-result-panel-en-light.webp)

### Adapting to window size
The interface is **responsive**:

- **Wide window (desktop):** Editor on the left, result panel and keyboard on
  the right; everything uses the full window height, and the tape scrolls
  internally.
- **Narrow window (mobile):** The keyboard becomes a **bottom sheet** at the
  bottom of the screen, with a drag handle and a mini result in the header.
  Tapping the drag handle collapses and expands the keyboard.
- At very low window heights, the keys are automatically made more compact.

CalcTape can also be added to the home screen on mobile devices as a **PWA**
(Progressive Web App) and launched like a native app. If you calculate on
your phone a lot, there are also native CalcTape apps for Android and iOS
(section 12).

## 3. The editor: writing calculations

The editor is the heart of the app. You can type freely using a **physical
keyboard** or use the on-screen keyboard buttons; both work equally well.

The tape looks like a **lined notepad** (the lines can be turned off via the
toolbar or Ctrl+Shift+L). For orientation, the **line containing the cursor** is
subtly highlighted and marked on the left with a bar in the accent color (blue
by default); all **lines that are part of a calculation** (values, variables,
sum lines) have a continuous stripe on the left in the color of the user keys.
**Totals** are displayed in bold, so the result of every calculation is easy to
spot at a glance.

![A calculation, line by line](https://www.calctape.com/img/manuals/web-editor-en-light.webp)

### Line structure
```
 <Operator> <Number> <optional comment text>
```
Example: `+ 1,234.50 income March`

- Every calculation must start with a **number** or a **sign** (`+` / `−`).
- Available operators are addition, subtraction, multiplication, division, and
  exponentiation.
- An **operator behind a number** starts the next calculation line, even in the
  middle of the comment. To put it into the comment, type it with **Alt**, on a
  Mac with **⌥** (see section 10).
- The **decimal and thousands separators** are set automatically according to
  your browser's language (in English: period as decimal separator, comma as
  thousands separator). The menu also offers **Indian digit grouping**
  (lakh/crore, e.g. `10,00,000.00`; see section 6).

### Calculation rules at a glance

| Input | Meaning |
|---|---|
| `+`, `-` | Addition, subtraction |
| `*`, `/` | Multiplication, division |
| `^` | Power - `^ 0.5` is the square root (9 becomes 3) |
| `%` | Percentage of the running subtotal |
| `=` / Enter | Close the block, draw a subtotal |
| Empty line | New, independent calculation |
| `(` behind the operator | opens a bracket (see "Calculations with brackets") |
| `)` | closes the bracket and shows its value |

**Multiplication binds before addition, across lines too.** `+ 10`, `+ 2`,
`* 3` gives **16**, not 36: the multiplication is calculated first, even though it comes
later. If the lines are to be worked through in their own order, close the
block with **=** before the multiplication.

**Precision.** Internally CalcTape calculates far more precisely than it
displays: `1 / 3` times `3` gives exactly `1.00`. Two decimal places are shown,
so very small results appear as `0.00` (e.g. `1 / 100,000`). Up to 32 digits
before the decimal separator are possible; longer numbers cannot be shown.
The two decimal places apply as long as CalcTape rounds (menu, **Rounding**).
With **Round nothing**, CalcTape keeps calculating with all 34 digits and shows
results with up to 30 of them: `1 / 100,000` then appears as `0.00001`, and
`1 / 3` times `3` stays `1.00`. Where a sum goes on beyond the 30 digits, the
tape shows `…` behind it.

**Pasted numbers** must match your separators: `1.234,56` from a German
spreadsheet is read as **1.23** in an English environment - the rest is dropped,
without an error message. So check pasted values before you rely on them.

### Percentage calculations
A percentage value is placed **after a number**, e.g. `- 40.00%`. It refers to
the current running subtotal. Example:

```
 +        910.50 Available budget
 -         40.00% | -364.20  Reserves
 ---------------
 +        546.30 Available
```

CalcTape automatically displays the amount calculated from the percentage right after it. On the tape it appears slightly smaller with an arrow in front of it (`→ -364.20`); in the line containing the cursor and when copying, it appears as in the text, with `|` (in the example `| -364.20`).

> Note: The operator immediately following a percentage value must not have a
> higher precedence than the percentage operator. If a corresponding error
> message appears, insert a subtotal after the percentage value.

![Percentages are calculated automatically](https://www.calctape.com/img/manuals/web-getting-started-en-light.webp)

**The three most common cases:**

| Task | Input | Result |
|---|---|---|
| Add 19% VAT | `+ 100.00`, then `+ 19.00%` | 119.00 |
| Deduct a 20% discount | `+ 100.00`, then `- 20.00%` | 80.00 |
| Extract the 19% VAT contained | `+ 119.00`, then `/ 1.19` | 100.00 |

> **Careful when extracting:** `- 19.00%` is **wrong** for this. It turns 119.00
> into 96.39, because the 19% are deducted from the **gross** amount, not from
> the net one. Contained VAT is always extracted by dividing by `1.19`.

### Calculations with brackets
Just as in a formula, you can put lines of a calculation in brackets. Type
`(` directly behind an operator: the line becomes the opening line
` + (`, and the bracket's first line begins below it. `)` closes the
bracket on its own line and shows its value. `12+14+(25-13)*11` and
Enter gives:

```
 +         12.00
 +         14.00
 + (
 +         25.00
 -         13.00
 ) | 12.00
 *         11.00
 ---------------
 +        158.00
```

- On the tape, a bracket's lines are indented, with a thin line in front of
  them and a subtly tinted area behind them. The value behind the closing
  bracket appears like a percentage amount, as `→ 12.00`.
- Brackets can be nested: `10+(44-12+(3+4)*3)*3` gives 169.00. Each level
  indents further and has its own line; the line of the bracket containing
  the cursor is colored.
- The operator on the opening line applies to the whole bracket: `- (`
  subtracts its value, `* (` multiplies by it. Multiplication binds before
  addition inside a bracket just as it does outside one.
- **Enter** or **=** at the end of the calculation closes any brackets
  still open and then draws the total. As long as a bracket is open, its
  line is dashed.
- Clicking the value behind the closing bracket highlights the whole
  bracket (see "Highlighting & Copying a Calculation").
- You type brackets using your device's keyboard; the on-screen keyboard
  has no bracket keys.
- A bracket in a note (`(3 nights, see receipt`) stays text. Pasted
  text only calculates a bracket if an operator precedes the `(` and the
  bracket is closed within the same block.

### Comments
Everything after the number is treated as a comment and does not affect the
calculation. This lets you document what a value represents.

A line made of text alone is a pure comment line. Starting it with a hash
(`# Travel expenses, March`) makes it a heading, shown in bold; several hashes
(`##`, `###`) work the same way. On top of that, `**bold**` and `*italic*` apply
in text lines and in the comment behind a number, and the underscore spelling
`__bold__` / `_italic_` does the same, except inside a word, so names like
`net_total` are left alone. The characters themselves disappear from view while
the caret is in another line; they are in the document either way, and selecting
or copying takes them along.

### Variables (named values)
CalcTape lets you name values and reuse them later. Variable names **start
with a letter** and consist of letters, digits and the underscore (`net_2`);
other **special characters** are not allowed. Upper and lower case make no
difference: `Rent` and `rent` are the same name. There are two ways to define
a variable:

**1. Direct assignment: `var = 123`**
The variable name goes **to the left** of the equals sign, the value to the right:

```
 vat = 19
 +      1,000.00 Net
 +           vat% | 190.00  VAT
```

**2. Naming a sum line: `... = var`**
In a **sum line** (subtotal), the name goes **to the right** of the equals sign
and takes on the result of that line:

```
 +      3,230.00 Salary
 -      1,350.00 Rent
 ---------------
 +      1,880.00 = budget

 +        budget
 -         25.00% | -470.00  Savings rate
 ---------------
 +      1,410.00 Available
```

The defined variable (`budget`) can be reused afterwards. In the example, a
new calculation starts after the blank line, takes over the budget and subtracts
a 25 % savings rate. This second form is **only allowed in sum lines**; in all
other lines the variable name must go to the left of `=`.

**Formulas.** The right side of a definition may hold a whole calculation:
with multiplication before addition, brackets, other named values and
functions such as `sqrt(x)` (square root), `round(x; places)` (commercial
rounding), `abs(x)` or `mod(x; y)` (remainder of a division):

```
 price = 12.50
 quantity = 3
 vat = 19
 gross = round(price * quantity * (1 + vat / 100); 2)
```

A semicolon separates the arguments of a function. Brackets and functions
work only in such definitions; on an ordinary calculation line CalcTape does
not calculate with them.

**Where a name applies.** A named value applies throughout the document,
including the lines above its definition: `+ rent` at the very top calculates
with `rent = 750` further down. Above the definition, however, a line that
starts with the name stays text, so a heading `Rent` above `rent = 750`
remains a heading. Behind an operator and in definitions the name always
applies. A value must not depend on itself: `a = a + 1`, or two definitions
that use each other, report a **circular reference** (section 11).

Further background on variables and advanced calculation rules can be found at
[calctape.com](https://calctape.com/en/).

![Working with named values](https://www.calctape.com/img/manuals/web-variables-en-light.webp)

**Offer when a value repeats.** When the same amount of 100 or more appears
three times on the tape, CalcTape asks whether it should become a named value.
After **OK**, `var = <value>` sits at the very top and every occurrence is
replaced by `var`; change the value up there and everything below
recalculates. **Undo** takes
the whole step back in one go. Decline twice and CalcTape stops asking.

### Highlighting & copying a calculation
Click a **sum** (shown in bold) to highlight the whole calculation it
belongs to with a subtle background, and reveal a copy icon top-right.
Click the icon to copy the complete calculation — including all computed
values — to the clipboard. The highlight disappears automatically after 10
seconds, or as soon as you type or click elsewhere. Scrolling keeps it — so
you can go through a long calculation without losing the highlight.

Likewise, clicking the **value of a bracket** (`→ 12.00` behind the closing
bracket) highlights the whole bracket, from the opening to the closing
line, with the same copy icon.

In addition, every subtotal and final total has its own small copy icon
right next to it: a quick tap copies just that value, a long press opens a
menu to copy it or add/subtract it to/from memory (M+/M−).

### Editing, inserting, deleting
- Click anywhere and overwrite the value;
  CalcTape recalculates immediately.
- **Paste from clipboard** (Ctrl+V) is supported; if the content no longer
  fits completely, CalcTape offers to insert only the part that still fits
  (line limit, see Section 12).
- **Delete** using the ⌫ (Backspace) or Delete key.

### Error display
If a line contains an error, it is marked directly on the tape (red left border,
reddish tint, wavy underline); the plain-text description appears as a tooltip on
the line and as a red chip in the status bar (see Section 11).

## 4. The keyboard: all keys explained

There are two slightly different layouts: the **desktop keyboard** (portrait,
right side) additionally has the four memory keys and a row of arrow keys; the
**mobile keyboard** (landscape bottom sheet) omits them for space. The keys are
color-coded by function:

![The on-screen keyboard](https://www.calctape.com/img/manuals/web-keypad-en-light.webp)

### Number keys
`0`-`9`, the double zero `00`, and the **decimal separator** (period). Use
these to enter values.

### Operator keys
| Key | Meaning |
|---|---|
| `+` | Addition |
| `−` | Subtraction |
| `×` | Multiplication |
| `÷` | Division |

### Function keys
| Key | Meaning |
|---|---|
| `= ⁄↲` (Enter) | Close block → calculate result, draw subtotal, new line |
| `%` | Percentage calculation |

### Memory keys
The four memory keys exist only on the desktop keyboard:

| Key | Meaning |
|---|---|
| `MR` | Memory Recall: retrieve/insert the stored value |
| `M+` | **Add** the current value to memory |
| `M−` | **Subtract** the current value from memory |
| `MC` | Clear memory |

The `MR`, `M+`, and `M−` keys also show a small preview of the affected memory
value, so you can see what the key will do before pressing it.

### Arrow keys
Above the two user keys, the **desktop keyboard** has a row of four arrow
keys. They move the cursor:

| Key | Meaning |
|---|---|
| `▲` | One line up |
| `▼` | One line down |
| `◀` | One character left |
| `▶` | One character right |

### Control keys
| Key | Meaning |
|---|---|
| `AC` | **All Clear**: discard the entire calculation and start over |
| `⌫` | Backspace: delete the last character |

> **Tip:** Accidentally pressed `AC`? Use **Undo** (the icon in the toolbar or
> Ctrl+Z) to restore the previous content, as long as the tab stays open and
> is not reloaded.

### User keys (VAT)
On the right there are two **customizable keys** for VAT, labeled `+VAT` and
`−VAT` by default. They insert a pre-configured calculation step; the VAT rate
is set automatically based on your locale (in Germany 19 %). These keys can be
freely reconfigured (see the next section).

## 5. Customizing user keys (VAT)

Each of the two VAT keys has a **gear icon ⚙** in its bottom right corner, which
appears when you hover over the key with your mouse (on touch devices it is
always visible). Clicking it opens the **"Edit user key"** dialog.

### Fields in the dialog

| Element | Function |
|---|---|
| **Label** | Text displayed on the key (max. 16 characters) |
| **Formula / text** | What is inserted when the key is pressed, e.g. `+ 19%` or `* 0.8` |
| **Calculate / Enter [= ↵]** | Toggle switch (see below) |
| **Default** | Resets all fields to the factory defaults; the button also names the country whose values apply (if country-specific VAT values exist) |

### The "Calculate / Enter" toggle
This switch controls whether a **line break** (equivalent to the `=`/Enter key)
is triggered automatically after the content is inserted:

- **On (default):** The result is calculated immediately after insertion and a
  subtotal is drawn.
- **Off:** Only the formula is inserted; the line stays open so you can keep
  typing.

### "\n" for a line break in the formula
You can write the character sequence `\n` in the **Formula / text** field; it
will be replaced by a real **line break** when inserted. This lets you store
multi-line snippets on a single key.

### Saving & resetting
- **OK** applies the changes; the new label appears on the key immediately. The
  setting is saved locally and persists.
- **Cancel** discards the changes.
- **Default** refills the fields with the factory values; if country-specific
  VAT values exist for your region, the button also names that country. This
  only takes effect after clicking **OK**; nothing is permanently deleted until
  then.

## 6. The menu

Click the **hamburger icon ☰** (top left) to open the main menu. It shows the
corresponding keyboard shortcut next to each entry and contains:

![The menu](https://www.calctape.com/img/manuals/web-menu-en-light.webp)

| Entry | Shortcut | Function |
|---|---|---|
| **Undo** | Ctrl+Z | Undo the last change |
| **Redo** | Ctrl+Y | Redo the undone change |
| **Show lines** | Ctrl+Shift+L | Toggle the lined "paper" on/off (on by default) |
| **Proportional typeface** | — | Sets text lines and comments in a proportional typeface; numbers keep a fixed width so the columns line up (on by default) |
| **Indian digit grouping (lakh/crore)** | — | Thousands grouping in Indian style (e.g. `10,00,000.00`) instead of groups of three; applies immediately to all values |
| **Detect number format when pasting** | — | Adapts pasted numbers to your number format, e.g. `1.234,50` becomes `1234.50`; ambiguous cases such as a lone `1,234` stay as they are. The first conversion is pointed out by a hint (on by default) |
| **Rounding** | - | Sets how CalcTape rounds. The entry shows the active choice and expands the four options: **Round nothing** (the calculation keeps all 34 digits of its precision and results show up to 30 of them, so a rest in the last places stays out of sight: `1 / 3` times `3` gives `1.00`; where a sum or a note behind a number goes on beyond that, the tape shows 30 digits and `…`, e.g. `10 / 1.5` as `6.66666666666666666666666666666…`), **Round final sums only** (subtotals that are carried on stay exact and show two more decimal places, "…" hints at further ones, and the notes behind numbers show the same; only the final sum is rounded), **Round results** (every sum is rounded and carried on as rounded; default), **Round everything** (the value of every line as well). Applies immediately to all sums |
| **Zoom in** | Ctrl+Shift++ | Increase text/key size (zoom) |
| **Zoom out** | Ctrl+Shift+− | Decrease text/key size (zoom) |
| **Tutorials** | — | Opens a list of eight short interactive tutorials (also reachable via the help icon in the toolbar) |
| **Show News** | — | Re-opens the latest release news message (desktop layout only) |
| **Manual** | — | Opens this manual (new tab) |
| **CalcTape Apps for Desktop & Mobile** | — | Overview of all CalcTape apps (new tab) |
| **About CalcTape…** | — | Opens a dialog with version information (app and calculation engine), a link to calctape.com and a button showing the third-party software licenses |

The **Undo** and **Redo** entries appear grayed out when there is nothing to undo
or redo. **Save calculation** is found in the **Share** popover (section 8);
Ctrl+S keeps working everywhere. The memory value and result are no longer shown
in the menu. They have moved to the **result panel** (top right), where they can
be copied with a click.

> The **Tutorials** are the fastest way to get to know CalcTape: **Getting
> started**, **Named values (variables)**, **Percentages**, **Subtotals and
> totals**, **Comments**, **Rounding**, **Order of operations** and **Formulas in named
> values** each explain one feature using a small example calculation. Highlighted numbers ("pills") can be tapped and edited
> directly to see live how the result adjusts. **Rounding** is about the setting:
> **Open setting** in the tutorial bar opens the rounding choices in the menu.
> On your very first visit,
> CalcTape starts with a short welcome calculation; the tutorials are in the
> menu. If you start a tutorial from the menu, the existing tape content is
> preserved and restored when you finish.

## 7. The status bar

Directly below the editor, the status bar continuously shows the current state
as clickable **chips**:

![The status bar](https://www.calctape.com/img/manuals/web-status-bar-en-light.webp)

| Chip | Meaning |
|---|---|
| **\<%\>** | Current zoom level (100 % = default). Click to reset the zoom. |
| **L \<line\>:\<col\>** | Position of the input cursor |
| **Error** (red) | When there is an error in the current line, the plain-text description appears here |
| **✓ Automatically saved** | Confirmation that the calculation is continuously saved locally |

The **grand total** (sum of all completed blocks) now lives in the result panel
(top right), not in the status bar.

A **warning banner** also appears above the chips when the calculation approaches
the maximum length of 500 lines: from about 95 % it shows a counter
("… of 500 lines"); when the limit is reached it turns red. If a new line is
then rejected, the banner briefly shakes as feedback (details in Section 12).

## 8. Sharing calculations

CalcTape can share a complete calculation **as a link**. The entire content is
compressed and written into the link itself; nothing is stored on a server.

### The Share button
The **"Share"** button is in the top right of the header. It opens a small menu:

- **Save calculation:** Saves the current calculation to a file that can be
  opened with the CalcTape apps (see section 9).
- **Copy link:** Copies a link to the **clipboard** that contains both the web
  address and the complete current calculation (brief confirmation "Link copied!").
  Paste it into an email, for example.
- **Copy as text:** Copies the tape the way it reads on screen - values,
  comments and the total line. For mail and chat, where a link would feel out
  of place.
- **QR code:** Shows the share link as a scannable code - the quickest way from
  the desktop to your phone. The code is generated locally; the calculation is
  not handed to any service.
- **Save as PDF:** Exports the calculation as a PDF file - the replacement for
  the screenshot you would otherwise take.
- **System share …** (if supported by the browser, mainly on mobile devices):
  opens the **native share menu** of the operating system.

When someone opens your link, they see the calculation right away and can keep
calculating in it: it is **their own copy** from then on, your version stays
untouched. Once a calculation has several commented items and a total, a
**"Share this calculation"** hint also appears below the result - the same menu,
just where one usually thinks of passing something on.

### Opening a shared link

Anyone who opens the link sees your calculation exactly as it was. The following
rules apply:

- **Number format:** Amounts appear in the recipient's notation. `1,250.00`
  becomes `1.250,00` in a German-language browser; the value stays the same.
- **Replace or append:** If the editor already contains something, CalcTape
  asks what should happen to it before loading: **Replace** puts the
  calculation from the link in its place, **Append** adds it below, separated
  by an empty line so both calculations keep their own totals. Clicking
  "Cancel" leaves the existing content unchanged.
- **The address bar is cleaned up:** After loading, CalcTape removes the data
  from the URL. Reloading the page (F5) does **not** re-import the calculation.
  If you want to keep the link, save it somewhere (for example in a note), not
  as a bookmark of the already-opened tab.
- **Checksum:** Every link contains a checksum. If the link was damaged in
  transit (for example, broken across lines or truncated by an email client),
  CalcTape detects this and shows an error message instead of loading a corrupted
  calculation.

> **Note:** There is no length limit when sharing: any calculation that the
> editor allows (max. 500 lines, Section 12) can also be shared as a link. The
> calculation is stored on no server: it sits after the `#` in the address,
> and browsers do not send that part when the link is opened. Anyone who has
> the link can read the calculation, though (Section 13).

## 9. Saving and automatic backup

### Automatic local backup
Your current calculation is **continuously and automatically** saved in your
browser's local storage. Close the tab and come back later; your content will
still be there. Settings (zoom, lines, user keys) are also retained.

### Save as a file
**Save calculation** (Share popover or Ctrl+S) downloads the calculation as a
CalcTape file. You can open this file with the **CalcTape apps**
(Windows, macOS, Android, iOS) and continue working on it there. Older
app versions cannot read a calculation with brackets.

The file carries the extension **`.calc`**. **The web version cannot open it
again** - that needs one of the apps. To pass a calculation on within the
browser, or move it to another device, use the share link (section 8).

## 10. Keyboard shortcuts

| Shortcut | Function |
|---|---|
| **Ctrl + S** | Save calculation (download file) |
| **Ctrl + Z** | Undo |
| **Ctrl + Y** | Redo |
| **Ctrl + Shift + L** | Toggle show lines on/off |
| **Ctrl + Shift + +** | Zoom in |
| **Ctrl + Shift + −** | Zoom out |
| **Ctrl + Shift + 0** | Reset zoom to 100% |
| **Alt + plus / minus / asterisk / slash** | Type an operator as text, e.g. in the comment behind a number (see below) |
| **Enter** / **=** | Close block, calculate result/subtotal |
| **Backspace** ⌫ | Delete character to the left |
| **Delete** | Delete character to the right |

> On a Mac, use **⌘ (Command)** instead of **Ctrl** and **⌥ (Option)** instead of **Alt**.

**When do the shortcuts work?** They work anywhere in the app - the tape does
*not* need to have the focus. All that is required is that the **page itself**
receives the keyboard (not the browser's address bar) and that the cursor is not
sitting in an input field. While a dialog is open they are switched off, so that
Tab, Esc and Enter belong to the dialog.

**Browsers come first.** Some combinations are caught by the browser before the
page ever sees them - in Chrome, Edge and Firefox, for example, **Ctrl+L**
(address bar) and **Ctrl+1** to **Ctrl+8** (switch tabs). That is why CalcTape
uses combinations with **Shift** for "show lines" and zoom. In the installed app
(PWA), which has neither address bar nor tabs, all shortcuts work anyway.

**Zoom: app or page?** **Ctrl + Shift + +/-** only enlarges CalcTape's text and
keys. The browser's familiar **Ctrl + +/-** is unaffected and still zooms the
whole page. **Ctrl + Shift + 0** restores 100%.

**Operators as text.** An operator typed behind a number starts the next
calculation line, even with the cursor in the middle of the comment. To put it
into the comment (`+ 100.00 Rent + heating`), type it with **Alt**, on a Mac
with **⌥ (Option)**. That works on the numeric keypad everywhere and on the
main keyboard under Windows and Linux; on a Mac the browser reports the special
character ⌥ types on a key, so there it is the keypad.

> Every one of these functions is also available in the toolbar and the menu. If
> your browser or an extension does intercept a shortcut, that is the reliable
> route.

You can also type freely in the editor at any time using a **physical keyboard**
including digits, operators, and text.

## 11. Error messages

When CalcTape detects an error in a line, it is marked on the line and explained
in the status bar. The most important messages:

| Message | Cause / Remedy |
|---|---|
| **Division by zero** | A division by 0 was attempted. |
| **Too many operators** | Multiple operators without a value in between. |
| **Invalid calculation** | General calculation error in the line. |
| **Syntax error** | The line is not formally valid. |
| **Calculations must start with a number or a sign** | Start the line with a valid input (number, `+`, `−`). |
| **Percentage needs a subtotal** | Insert a subtotal after the percentage value (operator precedence). |
| **Percentage only with a simple value** | The `%` sign must immediately follow a number. |
| **Percentage not at the start** | A percentage value cannot be the first entry in a calculation. |
| **Unknown function** | Function name in a formula not recognized (section 3, "Formulas"). |
| **The number is too large** | A value or a result has more than 32 digits before the decimal point. |
| **Invalid variable name** | Names must start with a letter and contain no special characters. |
| **Variable name already in use** | The name has been assigned more than once. |
| **Invalid variable definition** | The right side of a definition cannot be calculated. |
| **Variable undefined** | The name's definition was deleted; lines that still use it report this. |
| **Value of variable is undefined** | The definition has no valid value, such as `x =` without a number, or calculates with such a variable. |
| **Circular reference - the value depends on itself** | A definition uses itself, directly (`a = a + 1`) or through other definitions. Once the loop is broken, every affected line calculates again. |
| **Variable definitions only in sum lines** | This definition form is only allowed in sum lines; otherwise put the name to the left of `=`. |
| **This closing bracket has no opening bracket** | Above the line with `)`, the opening line is missing in the same block, or the bracket's first line does not have a value yet. |
| **The bracket is not closed** | There is a separator line under an open bracket. Enter at the end of the calculation closes open brackets before the total. |

## 12. Limits & notes

- **Maximum 500 lines** per calculation. From about 95 % a banner above the
  status bar shows how many lines are used; at 500 lines it turns red.
- **At the limit** only **new lines** are rejected (Enter, keys with an
  automatic line break) - the banner then shakes briefly. Typing within
  existing lines, deleting and undo keep working.
- **Paste from clipboard:** if the content no longer fits completely, a dialog
  asks whether to insert only the beginning that still fits - with a note that
  a truncated calculation may yield different results.
- **Longer calculations from earlier versions** are loaded in full and never
  truncated; they just cannot grow further. For more extensive calculations,
  the CalcTape apps are recommended.
- **Undo** only works as long as the tab is open and has not been reloaded.
  The undo history is also limited to a fixed amount of memory; with very
  large calculations the oldest steps are dropped first.
- **Internal error:** should the calculation engine unexpectedly stop (e.g.
  due to memory exhaustion), a dialog with a **Reload page** button appears.
  After reloading, the calculation is restored from the last automatic save
  (section 9).
- CalcTape Web uses **WebAssembly**; in very old browsers without WebAssembly
  support, a fallback version is used automatically.
- **On a phone or tablet:** CalcTape Web also runs in the mobile browser. If you calculate on the go a lot, the CalcTape apps for iOS and Android, designed specifically for mobile, are available too.

## 13. Privacy

CalcTape Web stores your **settings and calculations exclusively locally** on
your device. **The content of your calculation is not transmitted to our
servers** - not even when sharing: the link contains the calculation itself, it
is not held on a server.

But that also means: **whoever has the link can read the calculation.** And as
soon as you send it by e-mail, messenger or through a cloud service, the content
passes through that service and may be processed or stored there. So treat a
share link like the document itself.

The flip side of purely local storage: calculations are lost when **browser
data is cleared** or in **private/incognito mode**. A one-time notice on first
start points this out - save important calculations **as a file** or **share
them as a link** from time to time (Sections 8 and 9). No liability is
accepted for lost data.

**Usage statistics:** CalcTape Web sends no usage data. How the app is used is
determined from the web server's access log, which is created whenever a website
is visited. For the statistics we keep only **daily counters**, among them: visits and loads,
time of day, type of referring page, device class, operating system, browser,
country (rare countries only as the continent), views of the manual and the info
page, app version, error responses, link previews, and bots. The country is determined with a
database on our own web space, without asking any third-party service. We do not
store IP addresses, browser identifiers, or other device identifiers, and the
server never receives **calculation content** anyway. What the log contains and
how long it is kept is set out in the **privacy policy**.

The privacy policy, legal notice, and contact information are available via the
links in the **footer**.

## 14. CalcTape for other platforms

CalcTape is also available as a full-featured app with additional functionality
for:

- **Windows**
- **macOS**
- **Android**
- **iOS / iPhone**
- **CalcTape for Business (Enterprise)**

You can find the links in the **Apps panel** below the keyboard, in the menu,
and at [calctape.com](https://calctape.com/en/). Files saved from CalcTape Web
can be opened and edited in these apps as well.

*© schoettler Software GmbH - CalcTape Web. This manual describes the
user interface of the web version. Everything else about CalcTape can be found
at [calctape.com](https://calctape.com/en/).*