How to Calculate Percentage Increase and Decrease

Percentage change tells you how much a value has gone up or down compared with where it started. It is useful for prices, sales figures, measurements, grades, business data, and many everyday comparisons.

Percentage Increase Formula

Subtract the original value from the new value, divide by the original value, and multiply by 100.

Percentage Increase = ((New Value − Original Value) ÷ Original Value) × 100

Example of an Increase

Suppose a price changes from 80 units to 100 units. The increase is 20 units. Divide 20 by 80 and multiply by 100 to get a 25% increase.

Percentage Decrease Formula

For a decrease, subtract the new value from the original value, divide by the original value, and multiply by 100.

Percentage Decrease = ((Original Value − New Value) ÷ Original Value) × 100

Example of a Decrease

If a value falls from 100 units to 75 units, the decrease is 25 units. Since 25 divided by 100 equals 0.25, the percentage decrease is 25%.

Use the Original Value as the Base

The original value is the reference point for standard percentage-change calculations. Using the new value instead can produce a different figure, so always identify the starting value before calculating.

Quick Calculation

An online percentage calculator is useful when you need to compare several changes or want to reduce the chance of making a manual arithmetic error.