# mbar to atm - Converting Millibars to Atmospheres

## Worked Pressure Unit Conversion Problem

This example problem demonstrates how to convert the pressure units millibar (mbar) 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. A bar is a pressure unit defined as 100 kilopascals and 1 millibar is 1/1000 bar. Combining these factors gives a conversion factor of 1 atm = 1013.25 mbar.

### mbar to atm Conversion Problem #1

The air pressure outside a cruising jetliner is approximately 230 mbar.

What is this pressure in atmospheres?

Solution:

1 atm = 1013.25 mbar

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

pressure in atm = (pressure in mbar) x (1 atm/1013.25 mbar)
pressure in atm = (230/1013.25) atm
pressure in atm = 0.227 atm

The air pressure at cruising altitude is 0.227 atm.

### mbar to atm Conversion Problem #2

A gauge reads 4500 mbar. Convert this pressure into atm.

Solution:

Again, use the conversion:

1 atm = 1013.25 mbar

Set up the equation to cancel out the mbar units, leaving atm:

pressure in atm = (pressure in mbar) x (1 atm/1013.25 mbar)
pressure in atm = (4500/1013.25) atm
pressure = 4.44 atm

### mbar to atm Conversion Problem #3

Of course, you can use the millibar to atmosphere conversion, too:

1 mbar = 0.000986923267 atm

This may also be written using scientific notation:

1 mbar = 9.869 x 10-4 atm

Convert 3.98 x 105 mbar into atm.

Solution:

Set up the problem to cancel out the millibar units, leaving the answer in atmospheres:

pressure in atm = pressure in mbar x 9.869 x 10-4 atm/mbar
pressure in atm = 3.98 x 105 mbar x 9.869 x 10-4 atm/mbar
pressure in atm = 3.9279 x 102 atm
pressure in atm = 39.28 atm

or

pressure in atm = pressure in mbar x 0.000986923267 atm/mbar
pressure in atm = 398000 x 0.000986923267 atm/mbar
pressure in atm = 39.28 atm

Need to work the conversion the other way? Here is how to convert atm to mbar

More Worked Pressure Conversion Problems