Example
After a 25% price increase, a laptop now costs $375. What was the original price?
Vi = 375 / (1 + 25/100) = 375 / 1.25 = 300
The original price was $300.
Example
After a 20% discount, a jacket costs $80. What was the original price?
Vi = 80 / (1 - 20/100) = 80 / 0.8 = 100
The original price was $100. (Note: for a decrease, use a negative percentage, e.g. enter -20.)
Example
After an 8% decline, a town's population is 4,600. What was the population before the decline?
Vi = 4600 / (1 - 8/100) = 4600 / 0.92 = 5000
The population before the decline was 5,000.
When to use this calculator
Use this when you know the result of a percentage change and need to find the original value — for example, working out a pre-tax price from a tax-inclusive one, or a pre-discount price from a sale price. To go forward instead (from an original value to a new one), use the percentage increase or percentage decrease calculator.
Frequently asked questions
How do I enter a decrease?
Enter the percentage as a negative number, e.g. -20 for a 20% decrease.
What if the percentage entered is -100%?
This case is undefined, since it would mean dividing by zero — a -100% change would mean the final value is zero, which has no single original value.
Is this the exact opposite of the increase/decrease calculators?
Yes. Where those calculators go from original value to new value, this one goes from new value back to original. Related: percentage increase calculator and full formula guide.