Everyday maths
Percentage calculator
Work out a discount, a share or a percentage change. See the result and the calculation together.
Price after a discount
Use the same currency throughout. Prices are rounded to two decimal places.
- Original price
- 100
- Discount (%)
- 20%
- You save
- 20
100 × (1 − 20 ÷ 100)How is this calculated?
A percentage is a part per hundred. Multiply the amount by the percentage and divide by 100. To find a share, divide the part by the whole and multiply by 100. Percentage change compares the difference with the starting value.
Calculation assumptions
Discounts use a nonnegative price and a rate from 0% to 100%. Percentage change requires a starting value above zero; a share cannot use a zero total. Prices are displayed to two decimal places and other results to six. Use a decimal point or comma without thousands separators. This is a numerical calculation and does not add taxes or fees.
Math references & privacyFormulas checked 23 October 2026
Privacy
Calculations run in your browser. Entered financial values are neither sent to analytics nor saved.