Reverse Percentage Calculator
Enter a value after a percent change below to instantly find the original value.
The Reverse Percentage Formula
Original = value after change ÷ (1 + percent change ÷ 100).
The most common mistake here is subtracting the percent from 100 and multiplying by that instead of dividing. For a price of $76 after a 20% decrease, multiplying by 80% again (76 × 0.80 = $60.80) doesn't undo anything — it applies the decrease a second time. The correct move is to divide by 0.80, which gives the true original price of $95.
Worked example
A price is $120 after a 20% increase.
120 ÷ (1 + 0.20) = 120 ÷ 1.20
Original price: $100
A second example: a price is $76 after a 20% decrease.
76 ÷ (1 − 0.20) = 76 ÷ 0.80
Original price: $95
Keep going
- Reverse percentage undoes a percentage increase, working backward from the new value to the original; the percentage increase calculator runs that same math forward instead. Percentage Increase Calculator
Frequently Asked Questions
How do you reverse a percentage change?
Divide the value after the change by (1 + the percent change as a decimal). Use a negative percent for a decrease.
If a price is $120 after a 20% increase, what was it before?
120 ÷ 1.20 = $100.
Why can't you just subtract the percentage back off the final value?
Because the percentage was originally calculated from the smaller starting value, not the larger final one — subtracting 20% of $120 (getting $96) doesn't undo a 20% increase from $100, since 20% of $100 and 20% of $120 aren't the same amount.
How do you reverse a percentage decrease?
The same idea works in reverse: divide the value after the decrease by (1 − the percent decrease as a decimal). A price of $76 after a 20% decrease started at 76 ÷ (1 − 0.20) = 76 ÷ 0.80 = $95.
Related Calculators
- Percentage Increase Calculator — Percentages & Money
- Percentage Decrease Calculator — Percentages & Money
- Discount Calculator — Percentages & Money
- Markup Calculator — Percentages & Money