Percentage Calculator

Percent of, percent change, increase and decrease, and the price before a discount

calendar_today Last updated: October 9, 2026

What is a percentage of a number?

Percent %

Number

30

What percent is one number of another?

Part

Whole

25%

Percent change between two numbers

From

To

+25%

An increase.

Increase or decrease a number by a percent

Number

Percent %

120

The original number before a rise or discount

Number after the change

Percent %

100

Percent difference between two numbers

First

Second

100%

Taking a percentage off is not the reverse of adding it: a price of 115 after a 15% rise was 100 before it, not 97.75. Arabic digits (٠–٩) work too. Calculated in your browser.

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Sahel's percentage calculator answers the three most common percentage questions and shows the formula, running in your browser with nothing sent anywhere.

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How does this tool work?

1

Pick the kind of question

What is X% of Y, what percent is X of Y, or the percentage change.

2

Enter the two numbers

The answer appears as you type, with no calculate button.

3

Read the result and formula

The working is shown so you can check it or reuse it.

Frequently asked questions

How do I find a percentage of a number? expand_more

Multiply the number by the percentage and divide by 100. So 15% of 200 is 200 × 15 ÷ 100 = 30.

How do I calculate percentage change? expand_more

Subtract the old value from the new one, divide by the old value, then multiply by 100. A negative result is a decrease.

Why does a discount followed by the same increase not return to the start? expand_more

Because each percentage is taken from a different base. 20% off 100 gives 80, and 20% on top of 80 gives 96, not 100.

What happens when the base is zero? expand_more

The tool says the percentage is undefined rather than showing a misleading number.

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