Reverse percentage calculator
Enter the final value, the percentage and whether it went up or down to recover the starting value. Simply subtracting the percentage from the final value gives the wrong answer.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter final value, percentage and change type.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Original = final ÷ (1 + percentage ÷ 100) after an increase, or final ÷ (1 - percentage ÷ 100) after a decrease
Example
Inputs: Final value = 115, Percentage = 15 %, Change type = After an increase. Result: Original value: 100; Amount added or removed: 15.
Limits and caveats
- Assumes a single change at one rate. For several changes in a row, use the successive percentage change calculator.
Questions about this tool
I paid 115 including a 15% increase. What was the original price?
Divide 115 by 1.15. The original price was 100 and the increase was 15.
Why not just take 15% off 115?
The 15% was calculated on the original price, not the final one. Taking 15% off 115 gives 97.75, which is wrong.
How do I find the price before a 20% discount if I paid 80?
Choose after a decrease and divide 80 by 0.8. The price before the discount was 100.