What Is PSI? Definition of Unit

Close-up of the meter on a pressure gauge

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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.
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Anne Marie Helmenstine, Ph.D.
Updated 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

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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 October 18, 2021).