Percentage Calculator
Percent simply means "per hundred", so every percentage question reduces to multiplying or dividing by 100. Pick a mode, enter two numbers, and this calculator shows the answer along with the arithmetic that produced it.
- Accurate
- Real-time
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- 100% free
A% of B
50.0000
B increased by A%
250.0000
Details
Updates as you typeA percentage in every mode except "A is what percent of B?", where it is a plain amount.
The base amount the percentage is applied to or measured against.
Summary
Result
50.0000
- Remainder (B − result)
- 150.0000
- B increased by A%
- 250.0000
- B decreased by A%
- 150.0000
How this is calculated
- Percentage A
- 25.0000%
- Base B
- 200.0000
- A ÷ 100
- 0.250000
- (A ÷ 100) × B
- 50.0000
Compare scenarios
See how one change moves the result
- CurrentYour inputs as they stand50.0000Current
- Value A3162.0000
- Value B25062.5000
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For 25% of 200: 25 ÷ 100 = 0.25, and 0.25 × 200 = 50. That is exactly what the "What is A% of B?" mode does.
How do I work out what percent one number is of another?
Divide the part by the whole, then multiply by 100. If 30 people out of 120 replied, 30 ÷ 120 = 0.25, which is 25%. The whole cannot be zero, because nothing can be a share of nothing.
Why does a 10% rise followed by a 10% fall not return to the start?
Each percentage is taken from a different base. Raising 100 by 10% gives 110, but the 10% cut is then 11 rather than 10, leaving 99. Percentage changes multiply rather than add, so order and base always matter.
Can I use negative numbers in this calculator?
Yes. Negative percentages and negative bases are handled arithmetically, so a -20% increase is the same as a 20% decrease. Only a base of zero in the "A is what percent of B?" mode is rejected, since that division is undefined.