DevTool Desk

Percentage Calculator

What is X% of Y?

15% of 200 is30

X is what percent of Y?

40 is what % of 16025%

Percentage change from X to Y

Change from 80 to 100+25%

X is P% of what number?

25 is 20% of125

Four common percentage problems in one place: find X% of a number, figure out what percent one number is of another, calculate the percentage increase or decrease between two values, or work backwards to find the original number a percentage came from.

Frequently asked questions

What's the difference between 'percentage change' and 'X is what percent of Y'?

'X is what percent of Y' expresses X as a share of Y (e.g. 40 is 25% of 160). 'Percentage change' measures how much a value grew or shrank relative to its starting point (e.g. going from 80 to 100 is a 25% increase) — the direction and starting value matter.

Why is percentage change negative sometimes?

A negative result means the 'to' value is smaller than the 'from' value — a decrease. For example, going from 100 to 80 is a -20% change.