Atmospheres to Millibars Converter

To convert a measurement in atmospheres to millibars, multiply the value by 1,013.25. The conversion factor comes from the relationship between both units and the pascal.

For example, to convert 5 atm to millibars: 5 × 1,013.25 = 5,066.25 mbar.

A standard atmosphere (atm) is a unit of pressure defined as exactly 101,325 pascals, approximating average sea-level air pressure. Defined by the International Union of Pure and Applied Chemistry as a reference pressure, the atmosphere is widely used in chemistry and physics to describe conditions relative to sea level.

Common uses of atmospheres include: Chemistry reference conditions (STP); Diving and hyperbaric medicine; Physics gas-law calculations; Describing high-pressure environments.

A millibar equals one thousandth of a bar, or 100 pascals, and is equivalent to the hectopascal used in modern meteorology. The millibar dominated weather reporting for much of the 20th century. It is numerically identical to the hectopascal (hPa) that officially replaced it, so 1013 mbar and 1013 hPa describe the same sea-level pressure.

Common uses of millibars include: Atmospheric pressure in weather forecasts; Barometer and altimeter readings; Aviation weather reporting; Storm and hurricane intensity tracking.

Here are some common values converted:

1 atm = 1,013.25 mbar 5 atm = 5,066.25 mbar 10 atm = 10,132.5 mbar 50 atm = 50,662.5 mbar 100 atm = 101,325 mbar