Percentage Change Calculator
Compare an old value and a new value to get the percentage increase or decrease, the absolute difference and the ratio between them.
- Category
- Calculators
- Updated
- Cost
- Free · no sign-up
Increase
25%
30 higher than the original value.
Reversing a change needs a different percentage, because it is applied to a different starting number.
Increase, decrease, and why they aren't symmetric
Percentage change measures movement relative to a starting point. The formula is always the same:
(new − original) ÷ original × 100
The part people get wrong is that the base changes. A value that falls 50% then rises 50% does not return to where it started:
| Step | Value | Change |
|---|---|---|
| Start | 100 | — |
| Fall 50% | 50 | −50 |
| Rise 50% | 75 | +25 |
The 50% rise is applied to 50, not to 100. To get back to 100 from 50 you need a 100% increase. This asymmetry is why investment losses are harder to recover from than they look.
Percentage change versus percentage difference
They answer different questions:
- Change has a direction — from an old value to a new one. The original value is the denominator.
- Difference is symmetric — how far apart are two values with no ordering? The average of the two is usually the denominator.
Use change for anything over time. Use difference when comparing two things that happen to be different sizes.
When the original value is zero
Percentage change from zero is undefined — you can't divide by it, and any increase is infinite in percentage terms. Report the absolute change instead: "went from 0 to 40 sign-ups" is honest; "up 4,000%" is not.
How to use the Percentage Change Calculator
Three steps, no sign-up.
Enter the original value
The earlier or baseline number.
Enter the new value
The later number you're comparing against.
Read the direction as well as the size
The panel labels the result as an increase or a decrease so the sign is never ambiguous.