Activities Hobbies What Is PSI? Print Ian Lishman / Getty Images Hobbies Cars & Motorcycles Contests Couponing Freebies Frugal Living Fine Arts & Crafts Astrology Card Games & Gambling Playing Music Learn More By Christine & Scott Gable Christine & Scott Gable Automotive Writers B.S.E, Art Education, Millersville University Christine and Scott Gable are hybrid auto and alternative fuel experts who brewed biodiesel and traveled 125,000 miles on waste vegetable oil. Learn about our Editorial Process Updated on 05/09/19 The acronym PSI stands for "Pounds per Square Inch," and is the common unit of measurement for pressure. It can be understood as the amount of force that is exerted on an area of one square inch. Normal atmospheric pressure at sea level is 14.7 PSI. Pronunciation: Pronounce each letter individually: P - S - I. Example: Normal tire pressure is usually about 32 PSI.