Science, Tech, Math › Science How to Find Mass of a Liquid From Density Share Flipboard Email Print Ryan McVay/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 January 04, 2019 Review how to calculate the mass of a liquid from its volume and density. Density is mass per unit volume: density = mass / volume You can rewrite the equation to solve for mass: mass = volume x density Density of liquids usually is expressed in units of g/ml. If you know the density of a liquid and the volume of the liquid, you can calculate its mass. Similarly, if you know the mass and volume of a liquid, you can calculate its density. Example Problem Calculate the mass of 30.0 ml of methanol, given the density of methanol is 0.790 g/ml. mass = volume x densitymass = 30 ml x 0.790 g/mlmass = 23.7 g In real life, you can usually look up the density of commons liquids in reference books or online. While the calculation is simple, it's important to cite answer using the correct number of significant digits.