Find how much a value has increased or decreased relative to where it started. Enter the two values below. The result panel shows the calculation used, and the examples explain how to interpret it.
How to use the percentage change calculator
- Identify the values required by the input labels.
- Enter percentages as whole-number rates: 15 means 15%.
- Select Calculate and read the result together with its formula.
- Check the assumptions below before applying the answer to a real situation.
Formula and method
Worked example
A price moves from 64 to 80. First subtract the original: 80 − 64 = 16. Divide the 16 increase by the original 64 to get 0.25. Multiply by 100 and the percentage increase is 25%. The new value is therefore 125% of the original.
In the opposite direction, 80 to 64, divide the 16 reduction by 80. The decrease is 20%. This is why changing the direction changes the percentage, even though the numerical gap stays the same.
Example calculations
| Original | New | Change |
|---|---|---|
| 80 | 100 | 25% increase |
| 100 | 80 | 20% decrease |
| 250 | 250 | 0% |
| 50 | 0 | 100% decrease |
Input rules and limitations
The original value must be greater than zero. A change from zero has no finite relative percentage. Negative baselines require a context-specific interpretation and are not supported here.
Display precision can be changed from two to eight decimal places. Intermediate values are not rounded, but the calculation uses standard browser floating-point arithmetic. Currency figures should be rounded according to the rules relevant to your actual transaction.
Common questions
Does the result include units?
The calculator works with numbers. Keep the same units for comparable quantities and add the appropriate unit when reporting the result.
Why does the calculator reject some inputs?
The original value must be greater than zero. A change from zero has no finite relative percentage. Negative baselines require a context-specific interpretation and are not supported here.
Is my information sent to a server?
Calculator values stay in your browser. They are not submitted to the website’s server for calculation.
Where can I learn the related formulas?
Use the main percentage calculator for basic shares and wholes, or browse our guides for worked examples and common mistakes.
Choose the right comparison
Use the percentage change calculator for an original-to-new comparison, the percentage difference calculator when neither value is the baseline, and the percentage points calculator to subtract rates. You can also return to the main percentage calculator.