Percentage Change Calculator
Enter two values to instantly calculate the percentage change, or find what percent one number is of another.
Percentage change measures how much a value has increased or decreased relative to its original value. This calculator handles both percentage increase and decrease, and can also find what percentage one number is of another — or calculate a specific percent of a value.
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Last reviewed: April 2026Report an error
% Change
+25%
80 to 100 is a 25% increase.
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The Formula
% Change = ((New − Old) / |Old|) × 100
- New = The new value
- Old = The original value
Source: Khan Academy — Percent Change ↗
How to Use This Percent Change Calculator
- Select the mode: % Change, X% of Y, or X is what % of Y.
- Enter the two values.
- Read the result and the plain-English explanation.
Frequently Asked Questions
- % Change = ((New Value − Old Value) / |Old Value|) × 100. A positive result is an increase; negative is a decrease.
- Percent change compares a new value to an original (directional: which came first matters). Percent difference compares two values without a defined "original" — it uses the average as the denominator.
- Division by zero is undefined. If the original value is zero, percent change is mathematically undefined. Use the actual change (the difference) instead.
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