Percentage calculator

Six calculations in one: a percentage of an amount, what percentage one number is of another, increases, decreases, change and the original amount.

How it works

A percentage is a fraction of 100: 15% of something is 15 parts in every 100. To calculate it, multiply the amount by the percentage and divide by 100.

Percentage change compares a new value with the old one: if a price goes from 80 to 92, it has risen by 15%. Watch out: going up 20% and then down 20% doesn’t bring you back to where you started (100 → 120 → 96).

X% of Y = Y × X / 100
What % A is of B = A / B × 100
Change = (new − old) / old × 100

Frequently asked questions

How do I calculate 20% of 150?

Multiply 150 by 20 and divide by 100: 150 × 20 / 100 = 30. Shortcut: 150 × 0.20 = 30.

How do I find 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 × 100 = 25%.

If something costs 80 after a 20% discount, what was the original price?

Divide the final price by what’s left after the discount: 80 / 0.80 = 100. That’s the “original amount” mode.

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