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Reverse percentage calculator
Work backward from a final price, salary, population, score, or other value after a known percentage change.
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Original value100
80 ÷ (1 − 20%)
From question to answer in three moves.
01
Enter the final value you already know.
02
Enter the percentage and choose increase or decrease.
03
See the value before the change.
CLEAR ANSWERS
Math without mystery.
How do you reverse a percentage decrease?+
Divide the final value by 1 minus the percentage as a decimal. After a 20% decrease, divide the result by 0.8.
How do you reverse a percentage increase?+
Divide the final value by 1 plus the percentage as a decimal. After a 20% increase, divide the result by 1.2.
Why is reversing 20% not the same as adding 20%?+
The forward and reverse calculations use different base values, so equal percentage moves do not cancel each other by simple addition.