Reverse percentage calculations help you find the original number before a percentage increase or decrease. This is useful for sale prices, tax, tips, markups, discounts, and price changes.
Use the Percentage Calculator for quick percentage results, then use the formulas below when you need to work backward.
Find original price after a discount
If an item is $80 after a 20% discount, the sale price is 80% of the original price. Divide $80 by 0.80. The original price was $100.
Find original price after an increase
If a price is $120 after a 20% increase, the new price is 120% of the original. Divide $120 by 1.20. The original price was $100.
Reverse percentage formulas
- After discount: original = sale price / (1 – discount rate)
- After increase: original = new price / (1 + increase rate)
Related tools
For sale prices, read the discount percentage guide. For tax after a discount, use the Sales Tax Calculator.