The percentage of change can be calculated by using one of two formulas. The percentage of increase, or positive change, can be calculated as follows: increase ÷ original number × 100. The percentage of decrease, or negative change, can be calculated according to the following formula: decrease ÷ original number × 100.Continue Reading
Establish whether there has been a decrease or increase in the two figures being compared by subtracting the new figure from the original figure. A positive number represents an increase, and a negative number represents a decrease. For example, if the original figure was 70 and the new figure was 91, there has been an increase of 21.
Divide the increase or decrease by the original figure. If figures have increased by 21 and the original figure is 70, then 21 would be divided by 70. The answer would be 0.3.
Once you have determined the fraction by which the number has been changed, multiply it by 100 to get the percentage change. If, as in the previous example, there has been an increase by a factor of 0.3, multiply 0.3 by 100. This makes the percentage change 30%.