Percentage Calculator
Solve the three everyday percent problems: what is X% of Y, X is what percent of Y, and increase or decrease a number by a percent.
How it works
X% of Y = Y × X ÷ 100 · X as % of Y = X ÷ Y × 100 · Y changed by X% = Y × (1 ± X ÷ 100)
A percent is just a fraction with 100 on the bottom, so every percent question is a multiply or a divide. Finding X% of Y multiplies by the decimal form of the percent; asking what percent X is of Y divides the part by the whole; increasing or decreasing by X% multiplies by (1 + X÷100) or (1 − X÷100).
Worked example
What is 25% of 200? Convert 25% to the decimal 0.25 and multiply: 200 × 0.25 = 50. Flipping it around, 50 ÷ 200 × 100 confirms that 50 is 25% of 200.
Frequently asked questions
How do I convert a percent to a decimal?
Divide by 100, which moves the decimal point two places left: 25% = 0.25, 7.5% = 0.075, 150% = 1.5. To go the other way, multiply by 100.
Can a percentage be more than 100%?
Yes. 250% of 40 is 100 — percentages over 100 simply mean more than the whole. They show up constantly in growth figures and markups.
Why is 20% of 50 the same as 50% of 20?
Multiplication is commutative: 0.20 × 50 and 0.50 × 20 are both 10. Swapping the numbers like this often makes mental math much easier.
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This calculator is for educational purposes. Double-check important results before acting on them.