Percentage Increase Calculator
How much something grew — or shrink. Click any i for detail.
Values
Mode
i
Mode
Find the percent, or apply a percent to a start value. |
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|---|---|
Starting value
i
Old value
The before number. |
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New value
i
New value
Used in find-% mode. |
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Percent
i
Percent
Used in apply mode. Negative = decrease. |
How to use this calculator
- Pick find % or apply %.
- Enter the starting number.
- Enter the new number or the percent.
- Negative percent change is a decrease.
Results explained
Percent change = (new − old) / |old|. Apply mode: new = old × (1 + %). Distinct from percent-off (sale price) math.
Quick reference: percent change
Going 100 → 80 is −20%, not the inverse of +20%.
| Item | Detail |
|---|---|
| 80 → 100 | +25% |
| 100 → 80 | −20% |
| Apply +10% to 80 | 88 |
| Percent off page | Sale / discount context |
For compound growth over years, use ROI or compound interest.
How the estimate is built
%Δ = (new − old) / |old| × 100.
Example scenario
80 to 100 is +25%.
FAQ
Why absolute value in the denominator?
So a sign on the start value does not flip the meaning of up vs down in odd cases. For typical positive prices it matches (new−old)/old.
Markup vs this?
Markup is a pricing identity. This is a general % change.
Inflation?
See the inflation calculator if you have a rate over years.