Online Calculator
Quick arithmetic, percentages, and parentheses — no app to install.
Short answer: A free everyday calculator for quick arithmetic — addition, subtraction, multiplication, division, percentages, and parentheses — with a full touch-friendly keypad that works with mouse or touch. It runs entirely in your browser with nothing to install and no account needed.
Last updated: October 13, 2026
How it works
Build an expression with the keys — digits, decimals, the four operations, parentheses, and a percent key — then tap Calculate. The calculator respects standard order of operations: parentheses first, then percent and negation, then multiplication and division, then addition and subtraction.
AC clears everything, ⌫ deletes the last character, and after a result appears you can keep calculating from it — type another operation and the answer becomes the start of the next expression.
A worked example
The calculator loads with a worked example already evaluated:
The expression stays on the screen so you can see exactly what produced the answer. Press AC and try your own — for instance, (12 + 8) × 15% evaluates to 3, because 15% is read as 0.15.
Frequently asked questions
How does the percent key work?
It divides the number before it by 100, so 20% behaves as 0.2. That makes discount math easy: 250 − 20% style expressions work the way you expect when written as 250 × 20% for the discount amount.
Does it follow order of operations?
Yes. Parentheses are evaluated first, multiplication and division before addition and subtraction — 2 + 3 × 4 gives 14, not 20.
What happens if I divide by zero?
The calculator stops and tells you division by zero is not possible, rather than showing a misleading result. Press AC or fix the expression with ⌫.
Can I keep calculating from a result?
Yes. After Calculate, the answer becomes the start of the expression, so you can press +, × and so on to continue without retyping it.
Is anything I calculate sent anywhere?
No. The calculator runs entirely in your browser; your numbers never leave the page.
Why does 0.1 + 0.2 give 0.30000000000000004?
Binary floating-point cannot represent most decimal fractions exactly, so tiny rounding errors appear. It affects virtually every computer and calculator app. For money, round the final answer to cents.
What is the correct order of operations?
Parentheses first, then exponents, then multiplication and division (left to right), then addition and subtraction (left to right). So 2 + 3 × 4 = 14. Parentheses remove all doubt.
How do I calculate a percentage on the calculator?
Write it as multiplication to avoid convention surprises: a 15% tip on $42 is 42 × 0.15 = 6.30, and adding 10% to 50 is 50 × 1.10 = 55.
Getting reliable answers from a calculator
Calculators are exact about arithmetic but literal about meaning — most "wrong answers" are really ambiguous questions. The biggest source of ambiguity is the order of operations: multiplication and division bind tighter than addition and subtraction, so 2 + 3 × 4 is 14, not 20. When in doubt, add parentheses to say exactly what you mean: (2 + 3) × 4 is unambiguously 20.
Percentages are the next trap. On many calculators, typing 50 + 10% adds 10% of 50 (giving 55), while others treat % as "divide by 100" (giving 50.1). Neither is wrong; they are different conventions. The unambiguous route is to write out the multiplication yourself — a 10% increase on 50 is 50 × 1.10 = 55, a 15% tip on a $42 bill is 42 × 0.15 = 6.30 — and reserve the % key for cases you have verified on that specific device.
Why 0.1 + 0.2 is not 0.3
Try 0.1 + 0.2 and you may see 0.30000000000000004. This is not a bug in the calculator — it is how binary floating-point arithmetic works in virtually every computer. Decimal fractions like 0.1 cannot be represented exactly in binary, so tiny rounding errors accumulate. For everyday math it is harmless; for money, always round the final result to cents rather than trusting the raw display.
Two more habits save trouble: division by zero is undefined, not zero — a calculator that errors on it is correct — and chained operations evaluate left to right within the same precedence level, so 100 − 20 − 10 is 70, while 100 − (20 − 10) is 90. Parentheses are free; use them generously.
Does this calculator follow the order of operations?
Yes. Parentheses are evaluated first, then percent and negation, then multiplication and division, then addition and subtraction — the standard mathematical order. So 2 + 3 × 4 gives 14, not 20.
Use the parenthesis keys to override the order explicitly: (2 + 3) × 4 gives 20. If a result ever surprises you, re-enter the expression with explicit parentheses to confirm exactly what was computed.
How is this different from my phone’s calculator?
The percent key here has one explicit behavior — it divides the number by 100 — instead of the context-dependent conventions that make phone calculators unpredictable (where 50 + 10% can mean different things on different devices). Parentheses are first-class keys rather than hidden behind a rotation gesture.
And because it’s a web page, there’s nothing to install, no app permissions, and the same calculator works identically on your phone, tablet, and desktop.