Percentage Change Calculator
The percentage increase or decrease from one value to another.
- Difference20.00
- Percentage change25%
Inputs used
- From (starting value)80
- To (final value)100
About this calculator
Percentage change is the difference between two values expressed as a share of the starting value: from 80 to 100 is a change of 20, which is 25% of 80 — a 25% increase. A negative result means a decrease.
Note the asymmetry: going up from 80 to 100 is +25%, but coming back down from 100 to 80 is only −20%, because the base changes. That is why a 50% loss needs a 100% gain to recover, and why "up X%, down X%" never quite returns to where you started.
The starting value must not be zero — percentage change from zero is undefined.
Quick reference
Percentage change from one value to another
Percentage change from the starting value (row) to the final value (column). Positive is an increase, negative a decrease.
| From (starting value) | 50 | 80 | 100 | 120 | 150 | 200 |
|---|---|---|---|---|---|---|
| 50 | 0% | 60% | 100% | 140% | 200% | 300% |
| 80 | -37.5% | 0% | 25% | 50% | 87.5% | 150% |
| 100 | -50% | -20% | 0% | 20% | 50% | 100% |
| 120 | -58.33% | -33.33% | -16.67% | 0% | 25% | 66.67% |
| 150 | -66.67% | -46.67% | -33.33% | -20% | 0% | 33.33% |
| 200 | -75% | -60% | -50% | -40% | -25% | 0% |
Frequently asked questions
How do I calculate percentage change?
Subtract the starting value from the final value, divide by the starting value, and multiply by 100. From 80 to 100 the difference is 20, and 20 ÷ 80 = 0.25, so it's a 25% increase.
What is the percentage increase from 80 to 100?
A 25% increase, because the rise of 20 is a quarter of the starting value of 80. Note that going back from 100 to 80 is only a 20% decrease, since the base is now larger.
Why doesn't an increase then an equal-sized decrease return to the start?
Because each percentage is taken from a different base. Up 25% from 80 gives 100, but down 25% from 100 gives 75, not 80 — which is why a 50% loss needs a 100% gain to recover.
Can percentage change be negative?
Yes — a negative result means the value went down. From 200 to 150 is a change of −50 over 200, a 25% decrease.
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Results are informational only — not financial, medical or legal advice.