CALCULATOR · Math
Percentage Change Calculator
Measure increase or decrease between two values as a signed percentage.
Show formula
Δ% = (to − from) ÷ |from| × 100
Inputs
Result
Your result appears here
Enter From (old value) / To (new value) and the result fills in as you type.
How it works
- Enter the old value.
- Enter the new value.
- Read the signed percentage and direction.
Frequently asked questions
Why is the change from zero undefined?
Percentage change divides by the original value; dividing by zero has no meaning, so the tool reports the absolute difference instead.
How are negative starting values handled?
The absolute value of the start is used as the base, keeping the sign of the reported change meaningful.
Examples
- A price moved from 80 to 100 — what is the change?
- +25%, an absolute rise of 20.
- And back down from 100 to 80?
- −20%. The pair is not symmetric: the fall is measured against a base of 100, the rise against 80.
- What if the starting value is 0?
- There is no base to compare against, so the tool says the change is undefined and points you to the absolute difference instead of inventing a percentage.