How to Calculate Percentage Change: Formula and Examples

Percentage change tells you how much a value increased or decreased relative to its starting point. It is widely used in finance, analytics, and everyday comparisons.

Percentage change formula

Percentage change = ((new value - old value) / old value) x 100

If the result is positive, it is a percentage increase. If it is negative, it is a percentage decrease.

Example: percentage increase

Old value: 50. New value: 65.

((65 - 50) / 50) x 100 = (15 / 50) x 100 = 30%

Example: percentage decrease

Old value: 80. New value: 60.

((60 - 80) / 80) x 100 = (-20 / 80) x 100 = -25%

Common mistakes

• Using the new value as the baseline. The baseline is usually the old value.
• Forgetting to convert to percent by multiplying by 100.
• Not handling old value = 0. Percentage change is undefined when the old value is zero.

Quick tip

Use the percentage calculator on this site to check your math in seconds.