Inches of Mercury to Standard Atmospheres Converter
1 inch of mercury ≈ 0.0334210605 standard atmospheres
1 inch of mercury equals 0.0334211 standard atmospheres
How to convert inches of mercury to standard atmospheres
Unit conversion preserves the pressure reference. Gauge pressure and absolute pressure are different readings; changing between them also needs the ambient pressure. Mercury and water-column units use the conventions stated in their unit notes.
atm = inHg × 0.03342106055One inch of mercury is 0.03342106055 standard atmospheres, so a single multiplication converts any value.
0.334211 atm ≈ 10 × 0.03342106055Inches of mercury to standard atmospheres conversion table
Common values in inches of mercury, converted to standard atmospheres.
| Inches of mercury (inHg) | Standard atmospheres (atm) |
|---|---|
| 1 | 0.033421061 |
| 2 | 0.066842121 |
| 3 | 0.10026318 |
| 4 | 0.13368424 |
| 5 | 0.1671053 |
| 10 | 0.33421061 |
| 20 | 0.66842121 |
| 25 | 0.83552651 |
| 50 | 1.671053 |
| 100 | 3.3421061 |
| 250 | 8.3552651 |
| 500 | 16.71053 |
| 1,000 | 33.421061 |
About these units
inch of mercuryinHg
Exactly 25.4 mmHg. The US aviation and weather-report pressure unit.
standard atmosphereatm
Exactly 101,325 pascals, the defined standard sea-level pressure.
Reference: CGPM 1954.
Sources and precision
Table results are rounded to 8 significant digits; formula constants may be rounded to 10. Worked example answers use 6 significant digits. The converter starts at 6 significant digits and lets you change display precision. Calculations use the stored factors without intermediate rounding. Exact unit definitions do not make an input measurement more precise; conventional and measured factors follow the assumptions stated here.