Converting Atmospheres to Bars

This example problem demonstrates how to convert the pressure units bar (bar) to atmospheres (atm). Atmosphere originally was a unit related to the air pressure at sea level. It was later defined as 1.01325 x 10⁵ pascals. The bar is a pressure unit defined as 100 kilopascals. This makes one atmosphere nearly equal to one bar, specifically: 1 atm = 1.01325 bar.

Problem:

The pressure under the ocean increases roughly 0.1 atm per meter. At 1 km, the water pressure is 99.136 atmospheres. What is this pressure in bars?

Solution:

1 atm = 1.01325 bar

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

pressure in bar = (pressure in atm) x (1.01325 bar/1 atm)
pressure in bar = (99.136 x 1.01325) bar
pressure in bar = 100.45 bar

Answer:

The water pressure at a depth of 1 km is 100.45 bar.