What is percent change?
Percent change shows how much a value moved relative to its starting amount.
Percent Change Calculator
See how much a value changed relative to its starting point—positive for gains, negative for losses.
Enter old and new values
Provide the starting value and the ending value to measure percent change.
About this calculator
How to use Percent Change Calculator, plus the formulas and logic behind the results.
Tool description
Percent change measures relative change from an original baseline. The sign shows whether the value rose or fell.
How to use
- Enter the old (starting) value.
- Enter the new (ending) value.
- Select Calculate to view percent change.
- Check the direction and absolute difference.
Formulas & reference
Percent change = (new − old) ÷ |old| × 100
Change examples
- 50 → 65 is a +30% change
- 100 → 80 is a −20% change
- Direction comes from the sign
- Old = 0 is undefined
Calculation logic
The difference new − old is divided by the absolute old value and scaled by 100. A zero old value is rejected.
Positive results are increases; negative results are decreases; zero means no change.
Percent Change Calculator FAQ
Common questions about this calculator and how to use the results.
How do you calculate it?
Subtract old from new, divide by the absolute old value, and multiply by 100.
What does a negative result mean?
The new value is smaller than the old value—a decrease.
Is this the same as percentage difference?
No. Percent change uses a baseline; percentage difference uses the average of both values.
Why use absolute old value?
It keeps the denominator positive so the sign of the result reflects the direction of change.
Can old and new be equal?
Yes. The percent change is 0%.