Tool 3 of 10
Reverse percentage calculator.
If Y is X% of some number, what is that number? Work backwards from any percentage.
Frequently asked questions.
What is a reverse percentage?
A reverse percentage finds the original value before a percentage was applied. For example, if 80 is 40% of X, reverse percentage finds X = 200.
What is the reverse percentage formula?
Original Value = Final Value ÷ (Percentage ÷ 100). Example: Original = 80 ÷ (40 ÷ 100) = 80 ÷ 0.4 = 200.
When would I use a reverse percentage?
Common uses: finding the original price before a discount, calculating pre-tax price, or working out a full amount when you only know a portion.
If something costs $75 after a 25% discount, what was the original price?
$75 is 75% of the original price (100% − 25%). So: Original = 75 ÷ 0.75 = $100.
What if the percentage is more than 100%?
If a value is 150% of the original (i.e., it grew), the formula still works: Original = Final ÷ 1.5.
Is this the same as "what percent of X is Y"?
No. "What percent of X is Y" finds the percentage. Reverse percentage finds the original whole when you know the part and the percentage.