Percentage Calculator

Calculate a percentage of a number, find what percentage one number is of another, and measure percentage increase or decrease.

Three percentage questions, one page. Type your numbers and the answers update as you go — nothing to submit and nothing to install.

What is X% of Y?

Result


X is what percentage of Y?

Result


Percentage increase or decrease

Change

How Does It Work?

  1. Pick the question you needThe page covers the three percentage questions people actually ask: a percentage of a number, a share expressed as a percentage, and a change between two values.
  2. Type your numbersEvery field accepts decimals and negative values. Results recalculate as you type, so there is no button to hunt for.
  3. Read or copy the answerEach block shows the result plus the working underneath, so you can check it or paste it into an email.

What Is It Used For?

Percentages sit behind most everyday number questions: a tip, a sale price, a tax line, a grade, a growth figure in a report. This calculator keeps all three common forms on one screen so you never have to remember which way round the division goes.

  • Working out a discount, a tip or a commission on a price.
  • Turning a score into a percentage — 45 correct answers out of 180 questions.
  • Measuring growth or decline between two figures, such as last month against this month.
  • Checking an invoice line, a payslip deduction or a bank fee.
  • Homework and exam practice where you need to see the working, not just the answer.

Examples

QuestionWorkingAnswer
20% of 250250 × 0.2050
15% of 89.9089.90 × 0.1513.49
45 out of 18045 ÷ 180 × 10025%
120 → 150(150 − 120) ÷ 120 × 100+25%
80 → 60(60 − 80) ÷ 80 × 100−25%

Frequently Asked Questions

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply by the number. For 20% of 250: 20 ÷ 100 = 0.2, then 0.2 × 250 = 50. The first block above does this for you.

How do I work out what percentage one number is of another?

Divide the part by the whole and multiply by 100. For example 45 out of 180 is 45 ÷ 180 = 0.25, which is 25%.

What is the formula for percentage increase?

Subtract the old value from the new value, divide by the old value, then multiply by 100. Going from 120 to 150 gives (150 − 120) ÷ 120 × 100 = +25%.

Why is a 20% decrease not cancelled out by a 20% increase?

Because each percentage applies to a different starting number. 100 reduced by 20% is 80; 80 increased by 20% is 96, not 100. The second percentage is calculated on the smaller amount.

Can I use decimals or negative numbers?

Yes. All three blocks accept decimals, and the percentage change block accepts negative values as well.

Is my data sent anywhere?

No. The calculation runs entirely in your browser with JavaScript. Nothing you type is uploaded or stored.

Free. No registration. This tool runs entirely in your browser, so the data you enter stays on your device.