Almost everyone encounters reverse percentage problems: seeing a discounted price on a tag and wanting to know the retail price, or looking at an invoice total and needing to deduce the pre-tax amount. A reverse percentage calculator solves this immediately.
What is a Reverse Percentage Problem?
Standard percentage math moves forward: Original × Rate = Portion. Reverse percentage problems move backward: you are given the final result and the percentage rate, and you must deduce the original base value.
Formula 1: Original Price After a Discount
Reverse Discount Equation
Original Value = Final Price ÷ (1 - Discount Rate ÷ 100)
If a laptop is on sale for $720 after a 25% discount: $720 ÷ (1 - 0.25) = $720 ÷ 0.75 = $960 original price.
Formula 2: Original Price After an Increase or Tax
Reverse Increase / Tax Equation
Original Value = Final Price ÷ (1 + Tax Rate ÷ 100)
Verify your base calculations on our free Percentage Calculator.