Percentage change measures how much a value has grown or shrunk relative to its starting value. The formula is: ((new − original) ÷ original) × 100.
Increase example
A price rises from $80 to $100. Subtract 80 from 100 to get 20, divide by 80 to get 0.25, then multiply by 100. That is a 25% increase.
Decrease example
A price falls from $100 to $80. Subtract 100 from 80 to get −20, divide by 100 to get −0.20, then multiply by 100. That is a 20% decrease.
Step by step
- Subtract the original value from the new value.
- Divide the difference by the original value.
- Multiply by 100.
- A positive result is an increase; a negative result is a decrease.
Increase vs decrease at a glance
| Original | New | Change | Result |
|---|---|---|---|
| 50 | 75 | +25 | +50% |
| 100 | 80 | −20 | −20% |
| 200 | 250 | +50 | +25% |
The denominators matter: the same +25 change is +50% from 50 but only +12.5% from 200. Always divide by the original value.
Use Mode 3 of our percentage calculator to get the change instantly.