How to Work Out a Percentage
Work out a percentage of an amount
Use amount × percentage ÷ 100. To find 15% of £240, calculate 240 × 15 ÷ 100 = £36.
Work out what percentage one number is of another
Use part ÷ total × 100. If 30 out of 120 responses choose an option, 30 ÷ 120 × 100 = 25%.
Calculate a percentage increase or decrease
Subtract the original value from the new value, divide the difference by the original value, then multiply by 100. If a price rises from £80 to £100, the increase is £20, and £20 ÷ £80 × 100 = 25%.
Percentage points are different from percent change
If a rate moves from 20% to 25%, it has risen by 5 percentage points. Relative to the original 20%, that movement is a 25% increase. Keeping these two ideas separate avoids a common reporting mistake.
Reverse a percentage
If £120 is the value after a 20% increase, divide by 1.20 to recover the original amount: £120 ÷ 1.20 = £100. After a 20% decrease, divide the final value by 0.80.
Use the UK percentage calculator
Source & methodology
The ONS style guidance directly explains percentages and the distinction between percentages and percentage points.