When to use this calculator
Measure the percentage increase or decrease between two positive values. A negative result means a decrease; zero original values do not have a defined percentage change.
Explore the percentage & ratio calculators for other questions in this topic. For a related calculation, use the Percentage Composition Calculator: Find one component’s percentage of the sum of three components.
An increase and its reversal use different bases
A price rising from 80 to 100 increases by 25%. Falling from 100 back to 80 is a 20% decrease. The differences are both 20, but the denominators differ. A zero starting value has no defined relative percentage change.
PUTTING IT INTO PRACTICE
Percentage Change: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Original value | 80 |
| New value | 100 |
| Result | 25 % |
- Check the input labels and enter the example values above.
- Apply the relationship: Change (%) = (new − original) ÷ original × 100.
- The result is 25 %, rounded for display.
How to interpret your result
A negative result means a decrease; zero original values do not have a defined percentage change.
Choose the base before calculating. Percentage points compare two rates by subtraction, while percentage change divides a difference by an original value. Successive discounts apply one after another rather than adding together.
Frequently asked questions
Should I use this to compare two interest rates?
For a rate changing from 4% to 5%, the increase is 25% relative to the old rate, or one percentage point. Choose the measure that matches the statement you want to make.
Should I use percentage change or percentage points?
Use percentage change for relative movement from a baseline. Use percentage points for the direct difference between two percentage rates.
How do I use the percentage change calculator?
Enter original value, new value. The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Change (%) = (new − original) ÷ original × 100.
What should I check before using the result?
A negative result means a decrease; zero original values do not have a defined percentage change.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see OpenStax: financial percentage relationships ↗. This is a topic reference, not an external review or endorsement of this tool.
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