Atmospheres to Inches of Mercury Converter
Common Conversions
| atm | inHg |
|---|---|
| 0.01 | 0.299 |
| 0.1 | 2.992 |
| 0.25 | 7.48 |
| 0.5 | 14.961 |
| 1 | 29.921 |
| 2 | 59.843 |
| 5 | 149.607 |
| 10 | 299.213 |
| 25 | 748.033 |
| 50 | 1496.07 |
| 100 | 2992.13 |
| 1000 | 29921.3 |
Why this conversion matters in chemistry
Inches of mercury is the unit a US weather report uses for barometric pressure (sea-level standard is 29.92 inHg) and the one HVAC engineers reach for when sizing duct pressures. In a chemistry lab the practical use case is barometric corrections to boiling-point work. A barometer reading of 28.5 inHg, equivalent to 0.952 atm, drops water's observed boiling point to about 98.6 °C — a noticeable shift when calibrating a thermometer against the steam point. Multiplying by 29.9213 is the conversion that lets a chemistry-textbook atm value land on the inHg gauge that's actually in front of you.
Formula
Worked Examples
Standard sea-level atmospheric pressure — the value behind every barometric correction in a calorimetry or distillation calibration.
Half an atmosphere — about ambient pressure at 5,500 m elevation, also a moderate vacuum-distillation setting.
About the pressure inside a pressurized reaction vessel during a small-scale hydrogenation charge.
A modest vacuum, the kind a sealed desiccator might hold with a freshly charged anhydrous calcium sulfate desiccant.