How to calculate percentages and discounts
Percentage calculations answer different questions. A percentage of a value, a percentage change and a discounted price use related but distinct formulas.
Calculate a percentageGet an instant result with your own values.Percentage formulas
To find x% of a number, multiply by x and divide by 100. For percentage change, divide the difference by the original value. For a discount, multiply the original price by (1 − rate ÷ 100).
Worked example
20% of 500 is 100. A 20% discount on 500 leaves a final price of 400. A second 10% discount applies to 400, not the original 500.
Check the result before using it
Keep every input in the unit shown by the calculator and compare the result with a second source when it affects a purchase, contract or financial decision. Market prices, tax rates and provider terms may change. The worked example explains the arithmetic, while the linked calculator lets you replace every example value with figures that match your situation.
Percentage questions
Can successive discounts be added?
No. Each discount applies to the remaining price, so 20% then 10% equals a total reduction of 28%.
What is the percentage increase formula?
New value minus old value, divided by old value, multiplied by 100.