To use the Percent Change Calculator, enter an amount in the first field, tab or click out of it, and then do the same in the second field. The answer will display automatically.
The percent of increase or decrease is the measure of percent change. It is commonly calculated to find how much something has changed, like finding a pay increase or discovering how grocery bills have climbed from one trip to the next. The calculations are relatively straight forward but easily forgotten. That and the frequency of use is one of the reasons we offer the Percent Change Calculator here, as well as one the top tools on the home page of Percent Calculators.
Finding Percent Changes
Okay, so how do you calculate percent increases or decreases? Let’s cover a couple of examples. In our first one, we’ll walk through the steps in finding a pay raise in percentage.
Calculating Percent Increase
Example 1: Jackson’s intern job at a software company paid $15.42 an hour. He graduated from college and accepted a full-time position from the same company for a larger wage of $35.52 an hour. What is Jackson’s percent increase in pay?
Solution: Using the handy-dandy Percent Change Calculator, dropping the two amounts into it quickly returns a percent pay increase of 130.35%. Here’s how the calculator found the percent increase.
Formula: [(New Value – Old Value)/Old Value] x 100 = Answer. Or, in variable format: [(B-A)/A] x 100 = Answer
Answer: We assign the older value to variable A and the newer value to variable B. Units, in this case the dollars, are always stripped or canceled out in percent change problems since we’re looking for increases or decreases in percentage. So in the first part of the equation we take 35.52 and subtract 15.42 from it and get 20.10. Then we divide that amount by the original older value and get 1.3035. Now we must convert that number to a percent by multiplying it by 100. That gives us a percent increase answer of 130.35%.
Formula Completed: [(35.52-15.42)/15.42) x 100] = 130.35%
Calculating Percent Decrease
Example 2: Arnold bought a new car that gets better gas mileage. Arnold drove his old car to visit family two months ago and spent $160.89 for gas. Arnold made the same trip last month in his new car. Even though gasoline prices were unchanged, the total he spent for gas went down to $105.20. What percent decrease in gas prices did Arnold enjoy because of his new car’s efficiency?
Solution: Placing the two amounts into the Percent Change Calculator returns a percent decrease of 34.61%. The formula is identical to the previous example. Here’s how the calculator found the percent change.
Formula: [(New Value – Old Value)/Old Value] x 100 = Answer. Or, in variable format: [(B-A)/A] x 100 = Answer
Answer: We assign the older value of 160.89 to variable A and the newer value of 105.20 to variable B. Using the formula, we take the new value 105.20 and subtract the older value of 160.89 to get -55.69. Then we divide that amount by the older value and get -0.34614. Now we must convert that number to a percent by multiplying it by 100. That gives our percent decrease answer of 34.61%.
Formula Completed: [(105.20-160.89)/160.89) x 100] = -34.61%
Lessons
The website Math Goodies™ offers an excellent series of interactive lessons by Gisele Glosser on percent increases and decreases. We have no affiliation with the site. We just like it.