Atmospheres to bar
Multiply atmospheres by 1.0133 to get bar.
5 atm = 5.0663 bar
How to convert atmospheres to bar
The bar is exactly 100 000 pascals (100 kPa), close to one atmosphere. The atmosphere is the standard atmosphere, exactly 101 325 pascals.
Worked example — 5 atm: 5 × 1.0133 = 5.0663 bar.
Atmospheres to bar table
| Atmospheres | Bar |
|---|---|
| 0.5 atm | 0.506625 bar |
| 1 atm | 1.0133 bar |
| 2 atm | 2.0265 bar |
| 3 atm | 3.0398 bar |
| 5 atm | 5.0663 bar |
| 10 atm | 10.1325 bar |
| 20 atm | 20.265 bar |
| 50 atm | 50.6625 bar |
| 100 atm | 101.325 bar |
Reverse and related
About atmospheres and bar
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)
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)
Where people use this
Atmospheres: diving, chemistry, altitude. Bar: tyre pressure outside the US, diving, weather. 1 atm is about 1.013 bar.
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 bar is 1 atm?
One atmosphere is about 1.013 bar.
Is a bar the same as an atmosphere?
Almost — one atmosphere is 1.013 bar, so a bar is just under one atm.
How many bar is 2 atm?
2 atm is about 2.03 bar.