Calculators & Time
A calculator that shows its working
Type an expression rather than pressing keys one at a time. The answer updates as you type, the whole calculation stays visible and editable, and the history keeps what you worked out.
The answer appears here as you type.
Type an expression and the answer updates as you go. Enter records it in the history, Escape clears. Use ^ for powers and ! for factorial; the scientific calculator adds trigonometry and logarithms.
- Runs in your browser
- No account required
- Free to use
How it works
Nothing is evaluated as code
The quick way to build a calculator on the web is to hand the input to the JavaScript engine and let it run. That turns a calculator into a way to execute whatever was typed — harmless when you type it yourself, less so when the expression arrives in a link somebody sent you. This tokenises the input, converts it to postfix and evaluates that, so nothing is ever run as code.
Calculator semantics, not JavaScript ones
In JavaScript `2^3` is 1, because ^ is bitwise XOR. On a calculator it has to be 8. Exponentiation is also right-associative, so `2^3^2` is 2⁹ rather than 8², and unary minus binds below it, so `-2^2` is -4. Those are the differences that make a hand-rolled evaluator quietly wrong.
Errors instead of NaN
Dividing by zero gives Infinity in JavaScript and NaN propagates silently through everything after it. Both are named here instead — "Division by zero" tells you what happened, where NaN tells you nothing.
What it does
Live answer
Updated as you type, so a mistyped bracket shows immediately rather than after you press equals.
History you can reuse
The last dozen calculations, each one click away from going back into the input.
Floating point tidied up
0.1 + 0.2 shows as 0.3 rather than 0.30000000000000004 — the representation error is hidden without hiding real precision.
Runs in your browser
No account and no upload — what you type is never sent anywhere. Analytics records that the tool was opened, never what you put into it.
Practical advice
Getting a better result
- Enter records the result in the history; Escape clears the input.
- Use ^ for powers and ! for factorial. Brackets work as you would expect.
- For trigonometry and logarithms, the scientific calculator adds those functions.
Questions
Things people ask
Is it safe to paste an expression from somewhere else?
Yes. The input is parsed as arithmetic and nothing is ever executed, so an expression containing code does not run — it simply reports that it is not something the calculator understands.
Why does 0.1 + 0.2 not show as 0.30000000000000004?
Because that is a property of binary floating point rather than of the arithmetic, and showing it is not useful. The result is rounded to twelve significant figures, which removes the representation error while keeping any precision you actually put in.
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Open toolWho builds these
Free tools by day. Websites that earn their keep by trade.
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