Converting Pascals to Atmospheres

This example problem demonstrates how to convert the pressure units pascals (Pa) to atmospheres (atm). Pascal is a SI pressure unit that refers to newtons per square meter. Atmosphere originally was a unit related to the air pressure at sea level. It was later defined as 1.01325 x 10⁵ Pa.

Problem:

The air pressure outside a cruising jet liner is approximately 2.3 x 10⁴ Pa. What is this pressure in atmospheres?

Solution:

1 atm = 1.01325 x 10⁵ Pa

Set up the conversion so the desired unit will be cancelled out. In this case, we want Pa to be the remaining unit.

pressure in atm = (pressure in Pa) x (1 atm/1.01325 x 10⁵ Pa)
pressure in atm = (2.3 x 10⁴/1.01325 x 10⁵) Pa
pressure in atm = 0.203 atm

Answer:

The air pressure at cruising altitude is 0.203 atm.