Percent Change Formula

How to Calculate Percent Increase or Decrease

Percent change is a useful measure of how much a quantity has either increased or decreased over a period of time. For example, if a business's profits were $124,000 in 1992 and $307,000 in 1997, then the percent increase over that 5-year period is 147%. If the crime rate in a small town was 25 incidents per year in 2002, and the crime rate was 17 incidents per year in 2004, then the percent decrease is 32% over that 2-year period.

In order to calculate percent change, you only need to know the value at the beginning of the period and the value at the end of the period.

Computing Percent Increase

If the end value is larger than the beginning value, then the percent increase is given by the formula

%INCR = [ 100*(E-B)/B ]%,

where E is the end value and B is the beginning value. For example, if we use B = 124,000 and E = 307,000, then the percent increase is

[100*(307000-124000)/124000]% = 147.58%

Computing Percent Decrease

If the beginning value is larger than the end value, then the percent decrease is given by the formula

%DECR = [ 100*(B-E)/B ]%,

For example, if we use B = 25 and E = 17, then the percent decrease is

[100*(25-17)/25]% = 32%

When the beginning and end values are equal, the percent change is 0%.

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