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To do a simple growth rate calculation, start with two data points that show a change in quantity over time. For instance, if your blog had 25 subscribers last month and now it has 100, you’d set 25 as your starting value and 100 as the ending value for your calculation. To find the growth rate, subtract the starting value from the ending value and divide the difference by the starting value. In our example, (100-25)/25 gives you 75/25, or 3. Multiply the growth rate by 100% to convert it to a percent value. 3 times 100% is 300%, which means the ending value is 300% bigger than the starting value. If you want to calculate an average growth rate over a longer period of time, such as several years, start by organizing your data points in chronological order from oldest to newest. Then, use the formula growth rate = (present/past)^1/n – 1, where n is the number of time periods represented by your data. So, for instance, if your starting value was 17 and your ending value was 36, and this growth took place after a period of 7 years, use the formula growth rate = (36/17)^1/7 – 1, which equals approximately 0.11, or 11%. Keep in mind that this formula assumes that there’s a steady rate of growth, so it only takes the start and end values into account. To learn how to calculate the average growth rate over regular time intervals, scroll down!
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