Calculating a discount: formulas and basics
Final price, reverse calculation and discount rate explained simply
A discount is a percentage price reduction applied to an original price. The calculation follows standard percentage arithmetic: the discount rate is deducted from the original price, and the result is the final price. The formula is: final price = original price × (1 − discount rate ÷ 100). The discount amount itself is the difference between the original and the final price.
The reverse calculation is often needed too: if only the reduced price and the discount rate are known, the original price can be found with original price = final price ÷ (1 − discount rate ÷ 100). This is useful for checking the regular price before a discount offer.
If the original and final price are known instead, the actual discount rate applied can be calculated: discount rate = (original price − final price) ÷ original price × 100. Use this mode, for example, to make offers from different retailers comparable.