10 Aug 2016 Ultimately, it can be a great calculation to understand growth rates of things over a long period of time. The formula for CAGR is defined as: CAGR How to Calculate an Annual Percentage Growth Rate - Calculating Annual Growth over Multiple Years Get the starting value. Get the final value. Determine the number of years. Calculate the annual growth rate. The formula is: Plugging in the above values we get [(125 / 100)^(1/2) - 1] for a CAGR of 11.8%. Despite the fact that the stock's price increased at different rates each year, its overall growth rate can be defined as 11.8%.