Percent Change Calculator
Percent change calculator: percentage increase or decrease between an old value and a new value.
Editorial review: Farrow (pseudonym; identity and professional credentials are not disclosed). This page is for educational purposes, not professional advice.
Your inputs
Results update as you type. Nothing you enter leaves your device.
Results
- Difference
- 20
Example with the starting values
These results use the calculator's initial inputs. Change the values above to calculate your own estimate.
Inputs
- Old value
- 80
- New value
- 100
Results
- Percent change
- 25%
- Difference
- 20
How does the Percent Change Calculator work?
Percent change is the relative difference between an old value and a new value, expressed as a percent of the old value. The formula is (new − old) / |old| × 100.
A positive result is an increase and a negative result is a decrease. For example, going from 80 to 100 is (100 − 80) / 80 × 100 = a 25% increase. The result is undefined when the old value is 0.
Frequently asked questions
How do I calculate percent increase?
Subtract the old value from the new value, divide by the old value, and multiply by 100. Rent going from $1,200 to $1,320 is a 120 / 1,200 = 10% increase.
How do I calculate percent decrease?
Use the same formula; the result is negative. A price falling from $50 to $40 is (40 − 50) / 50 × 100 = −20%, a 20% decrease.
Why doesn't a 50% gain undo a 50% drop?
Each percent is based on a different starting value. $100 down 50% is $50, and $50 up 50% is only $75. You would need a 100% gain to get back to $100.
Is percent change the same as percentage points?
No. A rate going from 4% to 5% is a 1 percentage point increase, but a 25% percent change.