Pressure
Convert inch of mercury (inHg) to pound per square inch (psi). Pressure is force per unit area. Process engineers move constantly between SI (kPa, bar) and US (psi) units, and between absolute and gauge.
1 inHg = 0.4911542 psi
To convert inch of mercury to pound per square inch, multiply the inHg value by 0.4911542. To go the other way, divide by 0.4911542 (or multiply by 2.03602).
| inHg | psi |
|---|---|
| 1 | 0.4911542 |
| 2 | 0.9823084 |
| 5 | 2.455771 |
| 10 | 4.911542 |
| 25 | 12.27886 |
| 50 | 24.55771 |
| 100 | 49.11542 |
| 250 | 122.7886 |
| 500 | 245.5771 |
| 1000 | 491.1542 |
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 295.2998 inHg is 145.0377 psi.
Multiply the value in inHg by 0.4911542 to get psi. For example, 10 inHg = 4.911542 psi.
1 inHg equals 0.4911542 psi.
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.