Science, Tech, Math › Science What Is PSI? Definition of Unit Print crescott / 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. 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. Learn about our Editorial Process Updated on January 13, 2020 PSI definition: PSI is a unit of pressure expressed in pounds of force per square inch of area. It stands for Pounds per Square Inch.1 PSI = 6894 Pascals = 0.070 atmospheres = 51.715 torr Cite this Article Format mla apa chicago Your Citation Helmenstine, Anne Marie, Ph.D. "What Is PSI? Definition of Unit." ThoughtCo, Aug. 29, 2020, thoughtco.com/what-does-psi-stand-for-605565. Helmenstine, Anne Marie, Ph.D. (2020, August 29). What Is PSI? Definition of Unit. Retrieved from https://www.thoughtco.com/what-does-psi-stand-for-605565 Helmenstine, Anne Marie, Ph.D. "What Is PSI? Definition of Unit." ThoughtCo. https://www.thoughtco.com/what-does-psi-stand-for-605565 (accessed April 25, 2024). copy citation