Bar to atmospheres
Multiply bar by 0.986923 to get atmospheres.
5 bar = 4.9346 atm
How to convert bar to atmospheres
The atmosphere is the standard atmosphere, exactly 101 325 pascals. The bar is exactly 100 000 pascals (100 kPa), close to one atmosphere.
Worked example — 5 bar: 5 × 0.986923 = 4.9346 atm.
Bar to atmospheres table
| Bar | Atmospheres |
|---|---|
| 0.5 bar | 0.493462 atm |
| 1 bar | 0.986923 atm |
| 2 bar | 1.9738 atm |
| 3 bar | 2.9608 atm |
| 5 bar | 4.9346 atm |
| 10 bar | 9.8692 atm |
| 20 bar | 19.7385 atm |
| 50 bar | 49.3462 atm |
| 100 bar | 98.6923 atm |
Reverse and related
About bar and atmospheres
Bar (bar)
1 bar = 0.986923 atmDefinition. Exactly 100 000 pascals (100 kPa), close to one atmosphere
History and origin
The bar was introduced in the early twentieth century by the meteorologist Vilhelm Bjerknes, defined as exactly 100 000 pascals, close to average sea-level air pressure. Its name comes from the Greek for weight.
Current use
The bar is common outside the United States for tyre pressure, diving and weather, where the closely related millibar is also used.
Source: NIST SP 811, App. B; ISO 80000-4. Exact SI values are definitional (bar = 10⁵ Pa, atm = 101 325 Pa) or derived from the pound (NIST HB 44) and standard gravity 9.80665 m/s² (psi)
Atmosphere (atm)
1 atm = 1.0133 barDefinition. The standard atmosphere, exactly 101 325 pascals
History and origin
The standard atmosphere was defined as a reference pressure of exactly 101 325 pascals, close to average pressure at sea level. It gave a convenient benchmark before the pascal became standard.
Current use
Atmospheres are used in diving, chemistry and when describing pressure at altitude.
Source: NIST SP 811, App. B; ISO 80000-4. Exact SI values are definitional (bar = 10⁵ Pa, atm = 101 325 Pa) or derived from the pound (NIST HB 44) and standard gravity 9.80665 m/s² (psi)
Where people use this
Bar: tyre pressure outside the US, diving, weather. Atmospheres: diving, chemistry, altitude. 1 bar is about 0.987 atm.
Every value is carried to full double precision; the display is rounded.
Both units are defined in NIST SP 811, App. B; ISO 80000-4. Exact SI values are definitional (bar = 10⁵ Pa, atm = 101 325 Pa) or derived from the pound (NIST HB 44) and standard gravity 9.80665 m/s² (psi).
Questions people ask
How many atm is 1 bar?
One bar is about 0.987 atm.
How many atm is 2 bar?
2 bar is about 1.97 atm.
Is 1 bar one atmosphere?
Close — 1 bar is 0.987 atm, a fraction below atmospheric pressure.