Calculating percentages from ratios is a vital mathematical skill that’s useful in a variety of real-life situations, such as financial analyses, test scoring and tax preparation. A percentage, which means per 100 parts, is actually a ratio itself with 100 as the denominator, or bottom number in a fraction. Converting a ratio into a percentage is a simple process and a calculator may be helpful.
Covert the ratio into a fraction by taking away the words or symbols, such as the phrase “to” or a colon, and replacing them with a solidus, also known as a fraction bar or dividing line. For instance if the ratio is 3:5 or “3 to 5,” you would change this to 3/5.
Divide the numerator, or top term, by the denominator, or bottom term. For example, 3/5 is 0.6. Using a calculator may be helpful for this step.
Multiply the answer by 100. Continuing with the example, you would multiply 0.6 by 100, which comes to 60.
Add a % symbol to get your final answer. The ratio of “3 to 5” is 60%, or 60 percent, which means that 3 is 60 percent of 5.
With practice, you’ll be able to calculate many simple ratios quickly in your head. For instance, you’ll discover that 1 is always 20 percent of 5, so 2/5 would be twice this amount or 40 percent, and 4/5 would be 80 percent.