Five percentage questions, each with its own tab — and every answer comes with the arithmetic that produced it, so you can check it or learn it.
Loaded with an example. Type over either field.
Answer
30
20% of 150 is 30
The working
Check this before you rely on it. A free everyday calculator, provided as a guide — not tax, accounting, financial or legal advice. The working is shown above so you can verify it against your own figures. See our terms of use.
Percentage of a number, what one number is as a percentage of another, an increase, a decrease, or the change between two figures.
The labels change to match the question, so you always know which number goes where. It recalculates as you type.
Every step is shown underneath the answer — divide by 100, multiply, subtract. Useful for homework, and for trusting the result.
Divide the percentage by 100, then multiply by the number. 20% of 150 is 0.2 × 150 = 30. The "% of a number" tab does this and shows both steps.
Because the second percentage is taken from a bigger number. £100 increased by 10% is £110, and 10% of £110 is £11 — so you come back to £99, not £100. This catches people out constantly, which is why the increase and decrease tabs are separate.
Percentage change has a direction: from 150 to 180 is a 20% increase. Percentage difference is usually used when neither number is the "starting" one. This calculator does change, because that is what people almost always mean.
Yes. For percentage change the calculation divides by the magnitude of the starting number, so going from −50 to −25 correctly reads as a 50% improvement rather than −50%.
Because there is no meaningful answer. Any increase from zero is infinitely large as a percentage, so the calculator says so rather than showing a misleading number.