Pressure
Convert bar (bar) to standard atmosphere (atm). Pressure is force per unit area. Process engineers move constantly between SI (kPa, bar) and US (psi) units, and between absolute and gauge.
1 bar = 0.9869233 atm
To convert bar to standard atmosphere, multiply the bar value by 0.9869233. To go the other way, divide by 0.9869233 (or multiply by 1.01325).
| bar | atm |
|---|---|
| 1 | 0.9869233 |
| 2 | 1.973847 |
| 5 | 4.934616 |
| 10 | 9.869233 |
| 25 | 24.67308 |
| 50 | 49.34616 |
| 100 | 98.69233 |
| 250 | 246.7308 |
| 500 | 493.4616 |
| 1000 | 986.9233 |
Line and vessel ratings, pump discharge heads, and relief set points are all specified in pressure units — usually psi or barg in the field and kPa in calculations.
Always track whether a value is absolute or gauge: 0 barg equals about 101.3 kPa absolute, and mixing the two is a common and costly error.
Worked example. A pressure of 10 bar is 9.869233 atm.
Multiply the value in bar by 0.9869233 to get atm. For example, 10 bar = 9.869233 atm.
1 bar equals 0.9869233 atm.
Line and vessel ratings, pump discharge heads, and relief set points are all specified in pressure units — usually psi or barg in the field and kPa in calculations.