Percentage Calculator
Work out percentages quickly: a percentage of a number, what percentage one number is of another, and percentage increase, decrease or difference.
Calculation
20.00% of 150.00 is
30.00
How to calculate a percentage
A percentage is simply a fraction of 100. To find a percentage of a number, divide the percentage by 100 and multiply by the number, so 20% of 150 is 0.2 × 150 = 30. This calculator handles that and the reverse question of what percentage one number is of another.
Percentage increase and decrease compare a starting value with an end value. Percentage difference compares two values without treating either as the starting point, which is useful when neither is obviously the baseline.
Worked examples
What is 15% of 80? That is 0.15 × 80 = 12. And 12 is what percentage of 80? It is 12 ÷ 80 × 100 = 15%.
If a price rises from £40 to £50, that is a 25% increase. If it falls from £50 to £40, that is a 20% decrease, the same amount, but a different percentage because the starting point changed.
Frequently asked questions
What is the difference between increase and difference?
Percentage increase measures change from a specific starting value. Percentage difference compares two values relative to their average, without picking a baseline.
Why is a rise and fall between the same numbers a different percentage?
Because the starting value changes. Going from 40 to 50 is a 25% rise; going from 50 to 40 is a 20% fall, since the base is larger.
Can I use decimals?
Yes. The calculator accepts decimal inputs such as 12.5% or 33.33.
How do I add a percentage to a number?
Use the percentage increase mode, or work out the percentage of the number and add it on. For VAT specifically, use the VAT calculator.
Figures last reviewed on 13 August 2025.
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