Percentage Change Calculator: From One Value to Another
Calculate the percentage change between two numbers — how much a value has risen or fallen relative to where it started.
Adjust the inputs and select Calculate for a full breakdown.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Percentage change | Difference |
|---|---|---|
| 80 to 100 | 25.00% | 20 |
| 200 to 150 | -25.00% | -50 |
| 1,000 to 1,250 | 25.00% | 250 |
| 45 to 30 | -33.33% | -15 |
How This Calculator Works
Enter the starting value and the ending value. The calculator finds the difference between them, then divides that difference by the starting value to express the move as a percentage. A positive result is an increase; a negative result is a decrease.
The Formula
Percentage Change
Old is the starting value, New is the ending value
Worked Example
A value that moves from 80 to 100 has changed by 20 in absolute terms. Measured against the starting value of 80, that is a 25% increase. The same change of 20 from a start of 200 would be only a 10% change.
Key Insight
Percentage change always depends on the starting point, not just the size of the move. This is why the same dollar gain looks dramatic on a small base and trivial on a large one — the base is half the story.
Frequently Asked Questions
How is percentage change calculated?
Subtract the starting value from the ending value, divide by the starting value, and multiply by 100. The result is the change as a percentage of where you began.
What does a negative percentage change mean?
A negative result means the ending value is lower than the starting value — a decrease. The calculator labels the direction so the sign is never ambiguous.
Why does the starting value matter so much?
Percentage change is measured relative to the start. The same absolute move is a larger percentage from a small starting value and a smaller percentage from a large one.
Can I use this for any kind of number?
Yes — prices, counts, measurements, scores. As long as the starting value is above zero, the percentage change is well defined.
What if the starting value is zero?
Percentage change from zero is undefined, because any move would be an infinite percentage. The calculator asks for a starting value above zero.
Related Calculators
Data Sources & Benchmarks
This calculator draws on 1 independent, dated source.
Methodology & Review
Percentage change is the difference between the two values divided by the starting value. The calculator requires a starting value above zero, since change from zero is mathematically undefined.
Written by Ugo Candido · Last updated May 17, 2026.