Percentage Change Calculator

Use this percentage change calculator to measure how much a value increased or decreased from an original value to a new value.

Original Value
New Value

How to Use the Percentage Change Calculator

Enter the original value and the new value to measure the relative increase or decrease.

Practical Example

If a value rises from 80 to 100, the percentage change is 25%.

Factors That Affect the Result

The original value is the reference point, so reversing the inputs changes the result. A zero starting value cannot produce a standard percentage-change calculation.

Frequently Asked Questions

Can percentage change be negative?

Yes. A negative result indicates a decrease.

Why does direction matter?

Because the original value is used as the denominator.

What if the original value is zero?

Standard percentage change is undefined.

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How Percentage Change Is Calculated

Percentage change compares a new value with an original value. The standard formula is (new − original) / original × 100. A positive result represents an increase and a negative result represents a decrease. For example, moving from 80 to 100 is a 25% increase.

Direction Matters

Percentage change is not symmetric. Moving from 80 to 100 is +25%, but moving from 100 back to 80 is -20% because the denominator is different. This is why the starting value must be identified correctly.

If the original value is zero, the ordinary percentage-change formula involves division by zero and is not defined. For comparisons where neither value should be treated as the baseline, percentage difference may be more appropriate. Use consistent units and distinguish percentage points from percent change when comparing rates such as 10% and 15%.

Percentage Change vs. Percentage Difference

Percentage change is directional because one value is the baseline. Percentage difference treats two values symmetrically and uses their average as the reference. Use percentage change for before-and-after comparisons; use percentage difference when neither measurement should be treated as the original value.