bar to atm - Converting Bars to Atmospheres Pressure

Worked Pressure Unit Conversion Problem

These example problems demonstrate how to convert the pressure unit 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 10 5 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.

Helpful Tip Convert bar to atm

When converting bar to atm, the answer in atmospheres should be slightly lower than the original value in bars.

bar to atm Pressure Conversion Problem #1

The air pressure outside a cruising jet liner is approximately 0.23 bar. What is this pressure in atmospheres?

pressure in atm = (0.23/1.01325) atm

pressure in atm = 0.227 atm

Check your answer. The answer in atmospheres should be slightly less than the answer in bars.

0.23 bar > 0.227 atm

bar to atm Pressure Conversion Problem #2

Convert 55.6 bars into atmosphere.

Use the conversion factor:

1 atm = 1.01325 bar

Again, set up the problem so the bar units cancel out, leaving atm:

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

pressure in atm = (55.6/1.01325) atm

pressure in atm =54.87 atm

bar > atm (numerically)

55.6 bar > 54.87 atm

bar to atm Pressure Conversion Problem #3

You can also use the bar to atm conversion factor:

1 bar = 0.986923267 atm

Convert 3.77 bar into atmospheres.

pressure in atm = (pressure in bar) x (0.9869 atm/bar)

pressure in atm = 3.77 bar x 0.9869 atm/bar

pressure in atm = 3.72 atm

Do you need to work the conversion the other way? Here is how to convert atm to bar.

Notes About Units

The atmosphere is considered to be an established constant. This does not mean that the actual pressure at any point at sea level actually will be identical to 1 atm. Similarly, STP or Standard Temperature and Pressure is a standard or defined value, not necessarily equal to actual values. STP is 1 atm at 273 K.

When looking at pressure units and their abbreviations, be careful not to confuse bar with barye. Barye is the centimeter-gram-second of CGS unit of pressure, equal to 0.1 Pa or 1x10 -6 bar. The abbreviation for the barye unit is Ba.

Another potentially confusing unit is Bar(g) or barg. This is a unit of gauge pressure or pressure in bars above atmospheric pressure.