How to convert bar to atmospheres
- Take the value in bar.
- Use the formula atmospheres = bar ÷ 1.01325.
- For example, 5 bar is 4.93 atm.
About bar and atmospheres
A bar is exactly 100,000 Pa and a standard atmosphere is exactly 101,325 Pa, so 1 bar is 0.986923 atm. Multiply bar by 0.98692 to get atm. The units are close enough that for rough work you can treat them as equal, at a cost of about 1.3%.
Bar is the everyday unit on European gauges, espresso machines, watches and dive gear, while chemistry, gas laws and older textbooks work in atmospheres. Converting matters when a formula or table expects atm, for example the ideal gas law with R in L·atm.
Examples
- 5 bar (a watch rated to 5 bar) is 4.93 atm
- 9 bar (the classic espresso brewing pressure) is 8.88 atm
- 1.01 bar (standard atmospheric pressure) is 1 atm
- 200 bar (a common scuba cylinder fill) is 197.38 atm
Bar to atmospheres chart
| Bar | Atmospheres |
|---|---|
| 0.1 | 0.0987 |
| 0.25 | 0.247 |
| 0.5 | 0.493 |
| 0.75 | 0.74 |
| 1 | 0.987 |
| 1.01 | 1 |
| 1.5 | 1.48 |
| 2 | 1.97 |
| 2.5 | 2.47 |
| 3 | 2.96 |
| 4 | 3.95 |
| 5 | 4.93 |
| Bar | Atmospheres |
|---|---|
| 6 | 5.92 |
| 8 | 7.9 |
| 9 | 8.88 |
| 10 | 9.87 |
| 15 | 14.8 |
| 20 | 19.74 |
| 50 | 49.35 |
| 100 | 98.69 |
| 200 | 197.38 |
| 232 | 228.97 |
| 300 | 296.08 |