Finding the Percent of Change

100% on blackboard

Finding the percent of change is using the ratio of the amount of change to the original amount. The increased amount is really the percent of increase. If the amount decreases then the percent of the change is the percent of the decrease which will be a negative.

The first question to ask yourself when finding the percent of change is:
Is it an increase or a decrease?

Let's Try a Problem with an Increase

175 to 200 -- We have an increase of 25 and subtracted to find out the amount of change.

Next, we will divide the amount of change by our original amount.

25 ÷ 200 = 0.125

Now we need to change the decimal to a percent by multiplying 1.125 by 100:


We now know that the percentage of change which in this case is an increase from 175 to 200 is 12.5%

Let's Try One That Is a Decrease

Let's say I weigh 150 pounds and I lost 25 pounds and want to know my percentage of weight loss.

I know the change is 25.

I then divide the amount of change by the original amount:

25 ÷ 150 = 0.166

Now I will multiply 0.166 by 100 to obtain my percentage of change:

0.166 x 100 = 16.6%

Therefore, I have lost 16.6% of my body weight.

The Importance of Percent of Change

Understanding the percentage of change concept is important for crowd attendance, points, scores, money, weight, depreciation and appreciation concepts etc.

Tools of the Trade

Calculators are a terrific tool to quickly and capably calculate percent increases and decreases.

Remember that most phones have calculators as well, which enables you to calculate on the go as the need arises.