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Everyday maths
Percentage Calculator
Calculate a percentage of any number or find the percentage change between two values.
How to calculate percentages and percentage change
Choose the right percentage formula
To find a percentage of a number, multiply the number by the percentage and divide by 100. To find percentage change, use (new value − original value) ÷ original value × 100. A positive change is an increase; a negative change is a decrease.
Worked examples: a share and an increase
15% of 200 is 200 × 15 ÷ 100 = 30. A value rising from 80 to 100 increases by 20, so its percentage change is 20 ÷ 80 × 100 = 25%. The original value is the reference point.
Check the starting value
Percentage-change mode requires a positive original value; a change from zero has no defined percentage under this formula. Results are rounded to two decimal places. A change between two percentages can also be expressed in percentage points, which is a different measure.