Calculator

About this tool

A plain calculator for everyday arithmetic — add, subtract, multiply, divide, and percentages — that works entirely in your browser with a mouse, touch, or the keyboard. For trigonometry, logarithms, exponents, roots, and a memory register, use the scientific calculator; to type a whole expression like (12 + 5) * 3 and evaluate it at once, use the expression calculator.

How input works. This is an immediate-execution calculator: it applies each operation as you press the next operator, the way a basic pocket calculator does. Pressing 2 + 3 × 4 gives 20, not 14, because the × acts on the running total of 5. If you need standard operator precedence (multiplication before addition), use the expression calculator instead, which parses the whole line.

Keyboard shortcuts. Digits and . + - * / type directly. Enter or = evaluates, Backspace deletes the last digit, and Esc clears everything. The ± button flips the sign of the current number, and % converts it to a fraction of the running total.

How the percent key behaves. On this style of calculator, % is context-sensitive. 200 + 10 % adds 10% of 200 and gives 220; 200 × 10 % gives 20. This matches most physical calculators but surprises people expecting % to simply mean "divide by 100." To work purely in percentages, the percentage calculator is clearer, and the percentages guide covers the four common cases.

Precision. Calculations use the browser's standard double-precision floating-point arithmetic. That's exact for everyday sums but can show tiny artefacts on some decimals — the classic 0.1 + 0.2 landing at 0.30000000000000004 internally. Results are rounded for display, so you'll rarely see this, but don't rely on the last digit for financial reconciliation.

Division by zero is undefined, so the calculator clears and shows a hint rather than displaying Infinity or a misleading number.

Nothing you type is transmitted or stored; the calculator runs fully offline once the page has loaded.

Frequently asked questions

Can I use my keyboard?

Yes. Type numbers and + - * / directly, press Enter or = to calculate, Backspace to delete the last digit, and Escape to clear.

Why does 2 + 3 × 4 give 20 instead of 14?

This calculator applies each operation immediately as you press the next operator, like a basic pocket calculator. For standard precedence (multiplication first), use the expression calculator.

What does the ± button do?

It switches the sign of the number currently shown between positive and negative.

How does the % key work?

It's relative to the current operation: 200 + 10% adds 10% of 200. It doesn't simply divide by 100. Use the percentage calculator for direct percentage work.

Why did dividing by zero clear the display?

Division by zero has no defined result, so the calculator shows a hint and resets instead of displaying an error value.

Is it accurate for money?

For everyday sums, yes. It uses floating-point arithmetic, which can carry minute rounding differences, so a dedicated ledger is better for exact financial totals.