How it works
Recover a value before a percentage increase. Enter a negative rate to reverse a reduction smaller than 100%.
original = final / (1 + r/100)
Worked example
Show example inputs and result
Final value: 120 · Increase: 20.
- Result
- 100
Questions and answers
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method reviewed: October 8, 2026 · Methods & accuracy