Science, Tech, Math › Science How to Calculate Percent Share Flipboard Email Print Glow Images / Getty Images Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated February 06, 2020 Calculating percent is a fundamental math skill, whether you're taking a class or just living life! Percentages are used to make car and house payments, calculate tips and pay taxes on goods. Percent calculations are fundamental to many classes, especially science courses. Here's a step-by-step tutorial on how to calculate percent. What Is Percent? Percentage or percent means 'per one hundred' and expresses the fraction of a number out of 100% or the total amount. A percent sign (%) or the abbreviation "pct" is used to denote percentage. How To Calculate Percent Determine the total or whole amount.Divide the number to be expressed as a percent by the total.In most cases, you'll divide the smaller number by the larger number.Multiple the resulting value by 100. Example Percent Calculation Say you have 30 marbles. If 12 of them are blue, what percent of the marbles are blue? What percent are not blue? Use the total number of marbles. This is 30.Divide the number of blue marbles into the total: 12/30 = 0.4Multiple this value by 100 to get the percent: 0.4 x 100 = 40% are blueYou have two ways to determine what percent are not blue. The easiest is to take the total percent minus the percent that are blue: 100% - 40% = 60% not blue. You could calculate it, just like you did the initial blue marble problem. You know the total number of marbles. The number that is not blue is the total minus the blue marbles: 30 - 12 = 18 non-blue marbles.The percent that is not blue is 18/30 x 100 = 60%As a check, you can make sure the total of blue and non-blue marbles adds up to 100%: 40% + 60% = 100% Learn More Now that you understand the basic principle, explore practical applications of the percent calculation: How to Calculate Mass Percent: Mass percent is used to express the abundance of elements in a sample.How to Calculate Percent Composition by MassPercent Error Calculation: Percent error is a common calculation in scientific disciplines.Volume Percent Concentration: Aside from mass percent, another common method of expressing concentration is using volume. This is often uses with liquids.