PSI — What It Is and Why It Matters
PSI (pounds per square inch) is an imperial unit of pressure used primarily in North American diving for tank pressure readings. A standard aluminum 80 cubic foot tank is filled to approximately 3000 PSI (about 207 bar). Most dive computers and gauges can display pressure in either bar or PSI based on user settings.
While bar has become the international standard in diving, PSI remains common on North American-manufactured equipment and in U.S. dive training. Converting between the two is straightforward: divide PSI by 14.5 to get bar, or multiply bar by 14.5 to get PSI.
Frequently Asked Questions
Should I set my dive computer to bar or PSI?
Use whichever system you learned with and are comfortable reading quickly. If you dive internationally, bar is more universal. If you dive primarily in North America, PSI is familiar. Consistency matters more than the unit itself.
What is the minimum PSI to end a dive?
A common guideline is 500 to 700 PSI (35 to 50 bar) reserve. This provides enough air for a controlled ascent with a safety stop, plus a margin for unexpected situations. Some dive operators have specific minimum-return-pressure policies, typically 500 or 700 PSI.
Affiliate Disclosure: DiveComputers is a participant in the Amazon Services LLC Associates Program and eBay Partner Network. Links on this page may earn us a commission at no extra cost to you.