Reverse Percentage Calculator
Find the original amount before a percentage change.
Work backwards from the result
Often you know the final number and the percentage change, but need the original — the price before a discount, or the amount before tax. That is a reverse percentage, and it trips people up.
If a price is 80 after 20% off, the original was 100, because 80 is 80% of the original. This tool undoes an added or removed percentage to recover the starting value.
Useful and private
The calculation runs in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
What does it solve?
The original value, given the final value and the percentage that was added or taken off.
When do I need this?
To find a pre-discount price, a pre-tax amount, or an original figure before a known percentage rise.
How does it work?
It divides the final value by one plus or minus the percentage, depending on whether it was added or removed.
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