Calculators

Percentage calculator

Three common percentage problems in one page: percentage of a number, one number as a percentage of another, and increase or decrease by a percentage. Each answer shows the working.

Runs locally in your browser

How it works

Percentage of a number multiplies the value by the percentage and divides by 100. “X is what percent of Y” divides X by Y and multiplies by 100, and is refused when Y is zero because division by zero has no answer. Increase and decrease apply the percentage to the original value first, then add or subtract it, so a 20% increase followed by a 20% decrease lands 4% below where you started — the two percentages do not cancel each other out.

Worked example

15% of 240 = 0.15 × 240 = 36. The number 36 is 15% of 240. Increasing 240 by 15% gives 276; decreasing 276 by 15% gives 234.60 — not back at 240, which is the trap this page shows in full.

Questions and answers

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