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Free calculator tool
Percentage Calculator
Calculate a percentage of a number, find what percentage one value is of another, measure percentage change or increase and decrease a value.
Browser-side processing No sign-up Free to use
25% of 200
Formula: (25 ÷ 100) × 200
How it works
A direct path from input to result.
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Use clear controls to choose exactly how the result should be produced.
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Take the finished result with you. No account or saved project required.
About this tool
Use Percentage calculator with confidence.
Percentages describe a value relative to 100, but everyday questions use that idea in several different ways. This calculator separates the most common formulas so you can find a percentage of a number, identify what percentage one value represents, measure change or adjust a starting value.
The calculation appears with its formula so you can check which values were treated as the part, whole, original and new value. Results update locally as you type and no calculation history is sent to UsefulGrid.
Common uses
Find a discount amount or calculate the new value after a percentage increase or decrease.
Measure the percentage change between an original result and a newer result.
Find what percentage a count, cost or measurement represents of a larger whole.
Practical tips
“What is 20% of 80?” and “20 is what percent of 80?” are different calculations with different answers.
Percentage change divides by the magnitude of the starting value, not the ending value.
A 20% increase followed by a 20% decrease does not return to the starting value because the second change uses a different base.
Questions about Percentage calculator
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 200 is 0.15 × 200, which equals 30.
Why is percentage change undefined from zero?
The formula divides by the original value. Division by zero is undefined, so a change from zero should be described as an absolute change instead.
Is percentage change the same as percentage-point change?
No. Moving from 20% to 25% is an increase of 5 percentage points but a relative increase of 25%.