Science, Tech, Math › Science Unit Definition in Science What is a unit in science? Share Flipboard Email Print The meter, yard, inch, and centimeter are all units of length. wwing / Getty Images Science Chemistry Chemical Laws Basics 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 October 14, 2019 A unit is any standard used for making comparisons in measurements. Unit conversions allow for measurements of a property that have been recorded using different units—for instance, centimeters to inches. Examples The meter is one standard of length. A liter is a standard of volume. Each of these standards can be used to compare with other measurements made using the same units.