Reverse percentage calculator
Enter the value after the change and the percent to find the original value.
Calculated in your browser. Nothing you enter is sent or saved.
Short answer
Divide the final value by 1 plus the percent over 100 for an increase, or by 1 minus the percent over 100 for a decrease. For example, 120 after a 20% increase was 120 / 1.2 = 100.
Why not just subtract the percent
A 20% increase is 20% of the original value, not 20% of the final value. Subtracting 20% from 120 gives 96, which is wrong. The correct original is 120 / 1.2 = 100.
Examples
- 120 after a 20% increase: original 100.
- 80 after a 20% decrease: original 100.
- 59.5 after a 15% decrease: original 70.
- A price with 20% sales tax of 24: the price before tax is 24 / 1.2 = 20.
A 100% decrease always ends at zero, so the original value cannot be recovered.
Frequently asked questions
How do I remove tax from a price?
Choose "increase", enter the price with tax as the final value and the tax rate as the percent. The result is the price before tax.