％ Percentage Calculator
Four everyday percentage questions answered instantly, each with the formula so you can check the math.
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What is X% of Y?
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X is what percent of Y?
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Percentage change from X to Y
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Increase or decrease a value by a percentage
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How to use the Percentage Calculator tool
- Pick the calculation that matches your question.
- Type the numbers – results update as you type.
- Copy the answer or read the formula underneath.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. 20% of 50 = 0.20 × 50 = 10.
How is percentage change calculated?
(new − old) ÷ |old| × 100. Going from 80 to 100 is a 25% increase; going from 100 to 80 is a 20% decrease – the base is always the starting value.
Why doesn't a 20% increase then a 20% decrease get me back?
The second percentage applies to a bigger base. 100 + 20% = 120, and 120 − 20% = 96. To reverse a 20% increase you need a 16.67% decrease.