Calculator

A browser calculator for everyday arithmetic and common scientific functions when you need a quick answer without opening a spreadsheet.

Who this is for

Anyone who wants an answer without opening a spreadsheet or hunting for the calculator app: a quick percentage on an invoice, a square root in the middle of writing something, trigonometry for a homework question or a workshop measurement. It sits in a browser tab you already have open, keeps a visible history of what you worked out, and does not need installing on a machine you do not control.

How to use Calculator

1. Enter numbers with buttons or the keyboard.
2. Apply operators and parentheses as needed.
3. Use scientific functions from the keypad when shown.
4. Check history if the tool lists previous results.
5. Clear when you start a new problem to avoid leftover state.

Worked examples

Example 1. Tip: 48.50 × 0.15 for a 15% tip on a bill.

Example 2. Order of operations: (3 + 5) × 2 should equal 16.

Example 3. Percentage off: 120 × 0.8 for a 20% discount on 120.

Floating-point maths

Computers use binary floating point. You may occasionally see a tiny rounding artefact on long decimals. For money, round to cents using the rules your finance process requires.

How the maths is evaluated

Expressions are parsed properly rather than evaluated left to right as a cheap pocket calculator would. The whole expression is read into tokens, converted with the shunting-yard algorithm and then computed, which is what gives you correct operator precedence, nested brackets and functions applied to sub-expressions. It also means the expression stays editable as text until you press equals, so a typo near the start does not force you to begin again.

Nothing is passed to the browser's own code evaluator, which matters more than it sounds: a calculator built the lazy way runs whatever you type as JavaScript, and this one cannot, because it only understands numbers, operators and the functions on its own keypad. Everything is computed locally in the page — no expression you enter is ever sent to a server.

Common mistakes

Leaving the calculator in the wrong angle mode. DEG and RAD give completely different answers for the same sine, and the mode is the single most common reason a trigonometry result looks wrong. Trusting operator precedence you have not checked is the second — this calculator follows the normal order of operations, so 2 + 3 x 4 is 14, not 20, and brackets are the way to force the other reading. Mistaking ln for log is the third: ln is base e, log is base 10.

Tips

Type rather than click — the keyboard works throughout, including Enter for equals and Backspace for the delete key, and it is far quicker than aiming at buttons. Use the history panel instead of re-entering a figure you already calculated; each entry shows the expression alongside its result, so you can check your working rather than just the answer. Reach for brackets more often than you think you need to, particularly around anything negative, where the difference between -3² and (-3)² catches everyone eventually.

Accessibility notes

Every key is a real button, so the whole calculator is reachable by keyboard and by a screen reader, and full keyboard entry means you never have to use the on-screen keypad at all. The expression and the result are separate text elements that update as you work, so the running expression can be re-read without recalculating. The history list is plain text and can be selected and copied.

Limitations (honest)

• Floating-point rounding can appear on long decimals.
• Not a computer-algebra system — no symbolic simplify.
• Not a full statistics package.
• Requires JavaScript in a modern browser.

Privacy

Everything you enter is evaluated in the page. No expression, result or history entry is sent to a server, and the history lives only in the open tab — closing it clears the lot. Advertising cookies and the choices available to you are covered in the Privacy Policy and in the consent notice shown on your first visit.

Related tools on ToolsAre.Us

For converting between units rather than calculating with them, the Unit Converter covers length, weight, temperature and more. The Colour Picker handles the arithmetic between HEX, RGB and HSL, and the World Clock does the same for times across zones. The full tool list is on the home page.

FAQ

More help: Calculator FAQ · All tools · Contact · About