A percentage change is a useful indicator to show the growth or decline of a particular phenomenon. You can compare between two factors using percentage change, also known as percent growth rate or rate of change. You can apply it for population, employment rate, economic factors, etc. You can calculate any number from any timeline and calculate it with another number from another timeline to determine the rate of growth. Percent change calculation is very easy, if you understand the basics of the calculation method and know how to apply the formula. The following formula should be employed: Percent Change in X = [ (Value at the end of period - Value at the beginning of period)/ Value at the beginning of period] x 100 For example: Percent Change in X = [ (12- 8)/ 8] x 100 Therefore, Percentage Change in X = [4/8] x 100                                            = 0.5 x 100                                            =50 % Therefore the answer is 50%. You can even further calculate percent change over time. Calculate Percent Change Over Time You can calculate year to year change to understand the rate of inflation or deflation from one period to the next. This is very useful to understand the worth of your investment in money. You need to use the following formula: Percent Change = {(Value Present/- Value Past)/ Value Past x 100}/ N Here, N stands for the number of years between the two values of past and present. For example , if there was a difference of 5 years between the values of past and present then, percent Change in X = [ (12- 8)/ 8] x 100 Therefore, Percentage Change in X = [4/8] x 100                                       = 0.5 x 100                                       = 50/ 5 Thus, percentage change over time = 10% Calculate Percent Change Between Two Numbers You can calculate percent change between two numbers on the basis that you are either considering a reduction in value or increase in value. The reduction in value will result a higher percentage change and increase in value will give a decreased percentage change. This is due to the higher base that results in a lower percentage for any given change in value. Just follow the given example to understand how to calculate percent change between two numbers. Percent Change = [(Value Present - Value Past)/Value Past] x 100 For example, Percent Change- [($25,000 - $ 20,000) /$ 20, 000] x 100                                    = $5,000 / $ 20,000 x100                                    = 0.25 x100                                    = 25% Therefore the percent change between two numbers is 25%. In Excel If you are working on an excel sheet and need to calculate percent change, you will not find any built-in function. In order to calculate percent change in excel you will need to use the following formula: Percent Change = (new_value-original_value)/ABS(original_value) You can even use an alternative formula to calculate percent change in excel: Percent Value = (new_value/original_value)-1 To get the answer in a percentage value, you will need to format the cell containing the formula with the percentage format. You can use this formula for Microsoft Excel 2000 standard edition, 2002 Standard Edition, 97 Standard Edition, Microsoft Excel 2001 for Mac and Microsoft Excel 98 for Macintosh. You just need to remember the formula and put in the correct values in the correct place. I hope this article has helped you in an easy way.