Percentage Calculator
Calculate percentages — find % of a number, what % one number is of another, and percentage increase/decrease.
Last updated: 2026-07-25
e.g. What is 20% of 100?
20% of 100 = 20.00
20.00
20% × 100 = 20.00
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Three percentage calculations in one tool: (1) What is X% of Y? — for tips, discounts, and VAT; (2) X is what percent of Y? — for test scores and proportions; (3) Percentage change from X to Y — for price changes, growth, and comparisons.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 20% of 150 = 150 × 20 ÷ 100 = 30. Use "What is X% of Y?" mode.
How do I calculate percentage change?
Subtract the original value from the new value, divide by the original, and multiply by 100. For example, increase from 100 to 125 = (125−100) ÷ 100 × 100 = +25%. Use "Percentage change" mode.
How do I reverse-calculate a percentage?
If you know a discounted price and the discount percent, divide by (1 − percentage/100). For example, £80 after 20% off = £80 ÷ 0.8 = £100 original price.