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 10^{5} Pa.

### Pa to Atm Problem

The air pressure outside a cruising jet liner is approximately 2.3 x 10^{4} Pa. What is this pressure in atmospheres?

**Solution:**

1 atm = 1.01325 x 10^{5} 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 10^{5} Pa)

pressure in atm = (2.3 x 10^{4}/1.01325 x 10^{5}) Pa

pressure in atm = 0.203 atm**Answer:**

The air pressure at cruising altitude is 0.203 atm.

Check Your Work

One quick check you should do to make sure your answer is reasonable is to compare the answer in atmospheres to the value in pascals. The atm value should be about 10,000 times smaller than the number in pascals.