# Percentage Decrease Calculator

LAST UPDATE: September 24th, 2020

## Definition – What is a percentage?

A percentage is a number expressed as a fraction of 100.
If a number is 100% (100 percent), then it is a “whole” – the same as one.
If a number is 50%, then it is a half – the same as 0.5 or 1/2.
If a number is 400%, then it is 4 times, the same as 4.

## Formula – How to Calculate Percentage Decrease

Percentage decrease is found by dividing the decrease by the starting number, then multiplying that result by 100%.

Percent Change = (Decrease ÷ First Value) x 100%

Note: the percent decrease measures FROM the first value. A decrease from 50 of 25 is a change of 50% (25 is the difference between the two numbers, and 25 is 50% of 50)). If that decease were looked at the other way around, it would be a different percentage change (25 increase by 25 to 50 is an increase of 100%).

### Example

Decrease from 50 by 25: (25 ÷ 50) x 100% = 0.5 x 100% = 50%

Decrease from 75 by 25: (25 ÷ 75) x 100% = 0.333 x 100% = 33.3%

Decrease from 0.0443 by 0.0001: (0.0001 ÷ 0.0443) x 100% = 0.002257 x 100% = 0.2257%