CalcTape Web - User Manual

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 data stays local on your device.

Contents

1. The Concept: How CalcTape Works
2. Interface Overview
3. The Editor: Writing Calculations
4. The Keyboard: All Keys Explained
5. Customizing User Keys (VAT)
6. The Menu
7. The Status Bar
8. Sharing Calculations
9. Saving and Automatic Backup
10. Keyboard Shortcuts
11. Error Messages
12. Limits & Notes
13. Privacy
14. CalcTape for Other Platforms

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:

The Header

The header spans the very top of the window (the dark blue 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).

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:

• 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.
• 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 picks the palette that suits your region (derived from the browser language); 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 and हिन्दी (Hindi); 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

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.

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.

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 in blue and marked with a blue bar on the left; all lines that are part of a calculation (values, variables, sum lines) have a continuous sand-colored stripe on the left. Totals are displayed in bold, so the result of every calculation is easy to spot at a glance.

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.
• 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

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.

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 (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.

The three most common cases:

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.

Comments

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

Variables (Named Values)

CalcTape lets you name values and reuse them later. Variable names must start with a letter and must not contain special characters. 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 =.

Further background on variables and advanced calculation rules can be found at calctape.com.

Offer when a value repeats. When the same value 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.

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; the mobile keyboard (landscape bottom sheet) omits them for space. The keys are color-coded by function:

Number Keys

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

Operator Keys

Function Keys

Memory Keys

The four memory keys exist only on the desktop keyboard:

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.

Control Keys

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

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 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, and Comments 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. On your very first visit, the first tutorial opens automatically on an empty tape; if you start a tutorial later 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 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, without any server involvement. The entire content is compressed and written directly into the URL.

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 Excel/PDF: Exports the calculation as a file - the replacement for the screenshot you would otherwise take.

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.

• System share … (if supported by the browser, mainly on mobile devices): opens the native share menu of the operating system.

Opening a Shared Link

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

• Confirmation prompt: If the editor already contains something, CalcTape asks before loading, because the existing content will be replaced by the calculation from the link. 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. No data is ever transmitted to a server: the content sits after the # in the address and never leaves the browser.

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.

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

On a Mac, use ⌘ (Command) instead of Ctrl.

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%.

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:

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: The on-screen keyboard in the mobile browser can interfere with input - there, our CalcTape apps for iOS and Android, designed specifically for mobile, are the better choice.

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.

Anonymous usage statistics: So we can keep improving CalcTape Web, we count in anonymous, aggregated form how often individual features are used (e.g. share links, themes, settings). We also count app starts and, in coarse steps, how intensively the app is used. Only event counters with no personal reference are stored - no cookies, no IP addresses, no identifiers, and no calculation content. Individual people cannot be identified from this. What exactly is collected, and on what legal basis, 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. 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.