How to calculate a percentage
To find a percentage of a number, divide the percentage by 100 and multiply by the number. For example, 20% of 150 is 30 because 20 ÷ 100 × 150 = 30.
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Enter two numbers to calculate.
Increase or decrease by a percentage
For an increase, multiply the starting number by 1 plus the percentage as a decimal. For a decrease, multiply by 1 minus the percentage as a decimal. Use the tabs above and the calculator does the working for you.
Percentage calculator guide
Percentages are a quick way to describe a part of a whole as an amount out of 100. This calculator handles three common percentage calculations: finding a percentage of a number, increasing a number by a percentage, and decreasing a number by a percentage.
Find X% of Y
Formula: (X ÷ 100) × Y
Example: 15% of 80 = 12.
Increase by X%
Formula: Y × (1 + X ÷ 100)
Example: 80 increased by 15% = 92.
Decrease by X%
Formula: Y × (1 − X ÷ 100)
Example: 80 decreased by 15% = 68.
Percentage calculator FAQs
How do I work out 20% of a number?
Multiply the number by 0.20. For example, 20% of 250 is 50.
How do I add a percentage to a number?
Convert the percentage to a decimal, add 1, then multiply by the starting number. To add 10%, multiply by 1.10.
How do I subtract a percentage from a number?
Convert the percentage to a decimal and subtract it from 1. To reduce a number by 25%, multiply it by 0.75.
Is a percentage decrease the same as percentage change?
Not quite. Decreasing a number by a chosen percentage gives a new value. Percentage change measures the relative difference between an original value and a new value.
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