Inches of Mercury to Atmospheres Converter
Common Conversions
| inHg | atm |
|---|---|
| 0.1 | 0.003342 |
| 1 | 0.033421 |
| 5 | 0.167106 |
| 10 | 0.334211 |
| 15 | 0.501316 |
| 20 | 0.668421 |
| 25 | 0.835527 |
| 29.921 | 1 |
| 30 | 1.003 |
| 50 | 1.671 |
| 100 | 3.342 |
| 1000 | 33.421 |
Why this conversion matters in chemistry
US weather reports quote barometric pressure in inches of mercury — sea-level standard is 29.92 inHg, equivalent to 1 atm. Chemistry calculations want atm. The factor between them is 0.033421 atm per inHg, which falls out of 29.9213 inHg per atm. Local barometric readings are what feed into a boiling-point correction or a gas-volume calculation at actual conditions. A 30.15 inHg reading on a high-pressure morning is 1.008 atm, which is to use in correcting an experimental boiling point against the literature value at exactly 1 atm.
Formula
Worked Examples
Standard atmospheric pressure expressed in both unit conventions — the calibration anchor.
A typical sea-level barometric reading, slightly above standard pressure.
The factor itself — useful as a quick mental check on a barometer reading.
About half an atmosphere — the kind of pressure a moderate vacuum-distillation operation might hold.