Percentage calculator

Choose the question that looks like yours, type the numbers, and get a clear answer.

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Formula and steps included

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Optional learning Learn how this math works See the formula, definitions, and step-by-step method.

Formula

Percentage formulas for four common questions

Percent of a number: result = (percent / 100) × number; What percent: percent = (part / whole) × 100; Percent change: change = ((new − original) / |original|) × 100; Reverse percentage: original = final / (1 ± percent/100), using + for an increase and − for a decrease

Percent means per hundred. Converting a percentage to a decimal by dividing by 100 lets you multiply, divide, and compare values consistently.

The correct formula depends on which value is unknown. The calculator separates the four common forms so the labels match the question you are trying to answer.

How to use the formula

Find a part or a percent
To find a part, divide the percent by 100 and multiply by the number. To find a percent, divide the part by the whole and multiply by 100.
Measure a change
Subtract the starting number from the new number, divide by the starting number, and multiply by 100.
Work backward from a change
Divide the final value by 1 + percent / 100 after an increase, or by 1 − percent / 100 after a decrease.

Worked examples

Percentage calculator examples

Calculate a sale discount

Twenty-five percent of 80 is (25 / 100) × 80 = 20, so subtracting the discount gives a sale price of 60.

Recover a value before an increase

If a value is 90 after a 20% increase, the original is 90 / (1 + 20 / 100) = 90 / 1.2 = 75.

Common questions

Percentage calculator FAQ

Which percentage calculator should I use?

Use percent of a number for questions like 15% of 60. Use what percent when comparing a part with a whole, percent change when comparing an old value with a new one, and reverse percentage when a final value and its increase or decrease are known.

What is the difference between percent change and percentage-point change?

Percent change measures the change relative to the original value. Percentage-point change is simple subtraction between two percentages, such as 40% to 45% being a 5-point increase.

Why can some percentage calculations not use zero?

What-percent and percent-change formulas divide by the whole or original value, so that value cannot be zero. A 100% decrease cannot be reversed to one unique original value because its change factor is zero.

Are my percentage values uploaded or saved?

Your values stay in your browser and are not saved by default or uploaded. Use Save on this device to keep them here, or download a backup file.