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Unit converters

Percentage calculator — percent of, change & discounts

Calculate a percentage of a number, what percent one value is of another, percentage change, increases and discounts. Clear formulas and examples. Free and private.

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Use a dot or comma as the decimal separator, without thousands separators, currency signs or %. Arabic and Persian digits are supported. Example: 12.5 or 12,5.

Enter both values, or try the example.

Formula

P × number ÷ 100

How to use this tool

Choose the question you want to solve, enter the two labeled values, then select Calculate. Use the example for the selected mode. Choose the number of significant digits and copy the result with its inputs and formula.

Good to know

Nonnegative inputs only. Percentage change needs an original value greater than zero; “what percent” needs a total greater than zero. Decreases are limited to 100%. Up to 30 digits per input and scientific exponents from -30 to 30. Exact rational arithmetic rounds only the display. Inputs are not saved or uploaded.

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Percentage questions

How do I find a percentage of a number?

Divide the percentage by 100 and multiply by the number. For example, 15% of 200 is 30. Choose the first mode to calculate it.

How is percentage change calculated?

Subtract the original from the new value, divide by the original, and multiply by 100. From 80 to 100 is a 25% increase. From 100 to 80 is a 20% decrease. The starting value matters.

What is the difference between percent and percentage points?

Moving from 20% to 25% is an increase of 5 percentage points, but a relative increase of 25%. The change mode calculates relative percentage change, not percentage points or symmetric percentage difference.

Does decreasing by 20% undo an increase of 20%?

No. Increasing 100 by 20% gives 120; decreasing 120 by 20% gives 96. Each operation uses its current starting value.

How are decimal numbers rounded?

The calculation uses exact rational values. Only the displayed answer is rounded to 6, 10 or 15 significant digits; the page labels rounded results. A comma is always decimal, never a thousands separator.