Mercury barometers used to measure air pressure. Credit: Edal Anton Lefterov/Creative Commons

Pressure is a measurement of force per unit area. Unfortunately, there are many different units associated with pressure and these units are still used in a variety of applications. Atmospheres (atm) and pounds (force) per square inch (PSI) appear on many pressure gauges on even scientific instruments. This example problem shows how to convert atm to PSI units.

Example Problem: The pressure at sea level is generally considered to be 1 atm. Pressure increases the deeper you dive in the ocean by roughly 1 atm every 10 meters. At a depth of 2 km (2000 m), the pressure will be 200 atm. What is this pressure in PSI?

Solution: The relationship between atm and psi is:

1 atm = 14.223 PSI

Multiply 200 atm by the conversion factor to calculate PSI.

? PSI = 2846.6 PSI

Answer: The pressure at a depth of 2 km is 2846.6 PSI.