Percentage Calculator

Four percentage calculators in one

This percentage calculator answers the four questions people ask most about percentages. Type your numbers and the answer appears instantly.

Question	Formula	Example
What is X% of Y?	X ÷ 100 × Y	15% of 200 = 30
X is what % of Y?	X ÷ Y × 100	30 of 200 = 15%
Percentage increase / decrease	(New − Original) ÷ Original × 100	80 → 100 = +25%
Increase / decrease by %	Base × (1 ± % ÷ 100)	200 ± 10% = 220 / 180

How to calculate a percentage of a number

Divide the percentage by 100 and multiply by the number. 20% of 450 is 0.20 × 450 = 90. This is what you need for discounts, tips, tax and commission.

How to find what percent one number is of another

Divide the part by the whole and multiply by 100. If you scored 42 out of 50, that is 42 ÷ 50 × 100 = 84%.

How to calculate percentage change

Subtract the old value from the new value, divide by the old value and multiply by 100. A price that goes from 80 to 100 is a 25% increase; from 100 to 80 it is a 20% decrease. The calculator shows increases in green and decreases in red.

Add or subtract a percentage

Enter a base number and a percentage to see both results at once: the number increased by that percentage and the number decreased by it. Useful for adding VAT, applying a discount or planning a salary raise.

Common mistakes

• A 50% rise then a 50% fall is not zero. 100 → 150 → 75: you end 25% lower.
• Percentage points are not percent. Going from 10% to 12% is 2 percentage points, but a 20% increase.
• Always divide by the original value when calculating change, not the new one.

Frequently asked questions

How do I calculate a percentage on a calculator?

For “X% of Y” multiply Y by X and divide by 100. For “X out of Y as a percent” divide X by Y and multiply by 100.

How do I reverse a percentage?

If a price after a 20% increase is 120, divide by 1.20 to get the original 100. After a 20% discount, divide by 0.80.