Percentage Change Calculator

Percentage change measures how much a value has increased or decreased relative to its original value, expressed as a percentage. A positive result means an increase; a negative result means a decrease. It is widely used in finance, science, and everyday comparisons.

Use the formula: Percentage Change = ((V2 − V1) / |V1|) × 100, where V1 is the initial value and V2 is the final value. The absolute value of V1 is used in the denominator so the sign of the result correctly reflects increase or decrease regardless of whether V1 is positive or negative.

Percentage change is directional — it measures how much a value has moved from a specific starting point to an ending point. Percentage difference, on the other hand, compares two values symmetrically without a defined starting point, using their average as the denominator.

The formula still works: divide (V2 − V1) by the absolute value of V1, then multiply by 100. Using the absolute value of V1 ensures the sign of the result correctly indicates increase or decrease even when V1 is negative.

The percentage change from 5 to 20 is ((20 − 5) / |5|) × 100 = (15 / 5) × 100 = 300%. This is a 300% increase.

The percentage change from 20 to 10 is ((10 − 20) / |20|) × 100 = (−10 / 20) × 100 = −50%. This is a 50% decrease.

No. If the initial value (V1) is zero, division by zero occurs and the percentage change is mathematically undefined. In such cases, you cannot express the change as a percentage — only as an absolute difference.

Use percentage change when the order of values matters — you have a clear starting point and an ending point. Common uses include tracking price changes, population growth, revenue growth, test score improvements, or any before-and-after comparison.