CalcTape CalcTape Web - User Manual

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 calculations are stored locally in your browser.

CalcTape Web in your browser
CalcTape Web in your browser

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


2. Interface overview

The app is divided into the following areas:

AreaPositionFunction
Headervery top (dark bar)Menu icon ☰, logo & product name, theme menu, dark mode switch, language selector (globe icon), "Share" button
Toolbarabove the editorUndo/Redo, lines, typeface, digit grouping, zoom, help, contact link (see below)
Editor (tape)center, full heightInput area for your calculations (lined "paper")
Status barbelow the editorClickable chips: Zoom, cursor position; errors; "Automatically saved"
Result paneltop rightCurrent block result, grand total and memory - each click to copy
Keyboardright (mobile: bottom)Virtual calculator keyboard
Apps panelbottom rightLinks to the CalcTape apps (Mac, Windows, Android, iPhone, Business)
Footervery bottomCopyright, 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 header
The header

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:

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:

The toolbar
The toolbar

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
The result panel

Adapting to window size

The interface is responsive:

CalcTape can also be added to the home screen on mobile devices as a PWA (Progressive Web App) and launched like a native app. For everyday work on a phone, the CalcTape apps for Android and iOS are the better choice (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
A calculation, line by line

Line structure

 <Operator> <Number> <optional comment text>

Example: + 1,234.50 income March

Calculation rules at a glance

InputMeaning
+, -Addition, subtraction
*, /Multiplication, division
^Power - ^ 0.5 is the square root (9 becomes 3)
%Percentage of the running subtotal
= / EnterClose the block, draw a subtotal
Empty lineNew, independent calculation
( behind the operatoropens a bracket across lines (see "Brackets across lines")
)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
Percentages are calculated automatically

The three most common cases:

TaskInputResult
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 / 1.19100.00

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.

Brackets across lines

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

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.

Working with named values
Working with named values

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

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
The on-screen keyboard

Number keys

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

Operator keys

KeyMeaning
+Addition
Subtraction
×Multiplication
÷Division

Function keys

KeyMeaning
= ⁄↲ (Enter)Close block → calculate result, draw subtotal, new line
%Percentage calculation

Memory keys

The four memory keys exist only on the desktop keyboard:

KeyMeaning
MRMemory Recall: retrieve/insert the stored value
M+Add the current value to memory
M−Subtract the current value from memory
MCClear 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:

KeyMeaning
One line up
One line down
One character left
One character right

Control keys

KeyMeaning
ACAll 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

ElementFunction
LabelText displayed on the key (max. 16 characters)
Formula / textWhat is inserted when the key is pressed, e.g. + 19% or * 0.8
Calculate / Enter [= ↵]Toggle switch (see below)
DefaultResets 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:

"\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


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
The menu
EntryShortcutFunction
UndoCtrl+ZUndo the last change
RedoCtrl+YRedo the undone change
Show linesCtrl+Shift+LToggle the lined "paper" on/off (on by default)
Proportional typefaceSets 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 pastingAdapts 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 inCtrl+Shift++Increase text/key size (zoom)
Zoom outCtrl+Shift+−Decrease text/key size (zoom)
TutorialsOpens a list of eight short interactive tutorials (also reachable via the help icon in the toolbar)
Show NewsRe-opens the latest release news message (desktop layout only)
ManualOpens this manual (new tab)
CalcTape Apps for Desktop & MobileOverview 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
The status bar
ChipMeaning
<%>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 savedConfirmation 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:

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.

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

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 that has brackets across lines.

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

ShortcutFunction
Ctrl + SSave calculation (download file)
Ctrl + ZUndo
Ctrl + YRedo
Ctrl + Shift + LToggle show lines on/off
Ctrl + Shift + +Zoom in
Ctrl + Shift + −Zoom out
Ctrl + Shift + 0Reset zoom to 100%
Alt + plus / minus / asterisk / slashType an operator as text, e.g. in the comment behind a number (see below)
Enter / =Close block, calculate result/subtotal
BackspaceDelete character to the left
DeleteDelete 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:

MessageCause / Remedy
Division by zeroA division by 0 was attempted.
Too many operatorsMultiple operators without a value in between.
Invalid calculationGeneral calculation error in the line.
Syntax errorThe line is not formally valid.
Calculations must start with a number or a signStart the line with a valid input (number, +, ).
Percentage needs a subtotalInsert a subtotal after the percentage value (operator precedence).
Percentage only with a simple valueThe % sign must immediately follow a number.
Percentage not at the startA percentage value cannot be the first entry in a calculation.
Unknown functionFunction name in a formula not recognized (section 3, "Formulas").
The number is too largeA value or a result has more than 32 digits before the decimal point.
Invalid variable nameNames must start with a letter and contain no special characters.
Variable name already in useThe name has been assigned more than once.
Invalid variable definitionThe right side of a definition cannot be calculated.
Variable undefinedThe name's definition was deleted; lines that still use it report this.
Value of variable is undefinedThe definition has no valid value, such as x = without a number, or calculates with such a variable.
Circular reference - the value depends on itselfA 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 linesThis definition form is only allowed in sum lines; otherwise put the name to the left of =.
This closing bracket has no opening bracketAbove 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 closedThere is a separator line under an open bracket. Enter at the end of the calculation closes open brackets before the total.

12. Limits & notes


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:

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.