# 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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