Pressure
Convert standard atmosphere (atm) to bar (bar). Pressure is force per unit area. Process engineers move constantly between SI (kPa, bar) and US (psi) units, and between absolute and gauge.
1 atm = 1.01325 bar
To convert standard atmosphere to bar, multiply the atm value by 1.01325. To go the other way, divide by 1.01325 (or multiply by 0.9869233).
| atm | bar |
|---|---|
| 1 | 1.01325 |
| 2 | 2.0265 |
| 5 | 5.06625 |
| 10 | 10.1325 |
| 25 | 25.33125 |
| 50 | 50.6625 |
| 100 | 101.325 |
| 250 | 253.3125 |
| 500 | 506.625 |
| 1000 | 1013.25 |
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 9.869233 atm is 10 bar.
Multiply the value in atm by 1.01325 to get bar. For example, 10 atm = 10.1325 bar.
1 atm equals 1.01325 bar.
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.