Atmospheres to bar – and bar to atmospheres
1 atm = 1.01325 bar
All units in this category
- 101,325Pa
- 1,013.25hPa
- 101.325kPa
- 1.01325bar
- 1atm
- 14.695949psi
- 759.99989mmHg
Formula
Multiply the value in atmospheres by 1.01325 to get bar.bar = atm × 1.01325
Multiply the value in bar by 0.98692327 to get atmospheres.atm = bar × 0.98692327
How to convert atmospheres to bar
Type a value in the field above and the result is calculated instantly. Use the arrow button to swap direction, or pick other units from the lists.
Doing it in your head
A rough conversion for when the calculator is not to hand. The error comes last, and it holds in both directions at that order of magnitude.
- Atmospheres to bar: × 7 ÷ 8 + 15%. That gives 1.006 instead of 1.01325, an error of 0.69%.
Atmospheres to bar – common values
| Atmospheres (atm) | Bar (bar) |
|---|---|
| 0.5 | 0.506625 |
| 1 | 1.01325 |
| 1.5 | 1.51988 |
| 2 | 2.0265 |
| 2.5 | 2.53313 |
| 3 | 3.03975 |
| 5 | 5.06625 |
| 10 | 10.1325 |
| 50 | 50.6625 |
| 100 | 101.325 |
Bar to atmospheres – common values
| Bar (bar) | Atmospheres (atm) |
|---|---|
| 0.5 | 0.493462 |
| 1 | 0.986923 |
| 1.5 | 1.48038 |
| 2 | 1.97385 |
| 2.5 | 2.46731 |
| 3 | 2.96077 |
| 5 | 4.93462 |
| 10 | 9.86923 |
| 50 | 49.3462 |
| 100 | 98.6923 |
About the units
Atmospheres. One standard atmosphere is exactly 101,325 pascals, fixed for general use by the General Conference on Weights and Measures in 1954. That is 1.01325 bar or 14.7 psi, and the value comes from the mercury barometer and its 760 millimetres. The atmosphere serves as a reference pressure in chemistry, diving and materials testing, but it is absent from the EU units directive and is not a legal trade unit. The technical atmosphere is a different unit, 98,066.5 pascals, some three per cent lower.
Bar. One bar is exactly 100,000 pascals. The unit was taken up by the General Conference on Weights and Measures in 1948 and appears in the EU units directive, so it is legal across the union. It is used for tyre pressure, plumbing, diving and process industry in Europe, and in weather reports as the hectopascal, which is the same thing as the millibar. One bar is 14.5 psi. Normal sea-level pressure is 1.01325 bar, so not quite one bar, and tyre pressure is gauge pressure.