About the Percentage Change Calculator
A percentage increase, decrease, and reverse percentage calculator, in your browser.
What it is
The Percentage Change Calculator finds the percentage increase or decrease between two values, or works backward from a known result and percentage to find the original value. It's built for anyone comparing prices, salaries, measurements, or any before-and-after values.
Features
Two modes
Calculate % change between two values, or reverse a known % change to find the original.
Handles negatives
Correctly computes percentage change even when values cross or start below zero.
Step-by-step working
See the exact formula and substitution used to reach the result.
Instant validation
Undefined cases, like a zero original value, are flagged clearly.