Inches of Mercury to Millimeters of Mercury Converter
1 inch of mercury = 25.4 millimeters of mercury
Almost identical to the torr, but defined separately. This uses conventional mmHg, not a temperature-specific mercury-column realization.
1 inch of mercury equals 25.4 millimeters of mercury
How to convert inches of mercury to millimeters of mercury
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.
mmHg = inHg × 127/5One inch of mercury is 127/5 millimeters of mercury, so a single multiplication converts any value.
254 mmHg = 10 × 127/5Almost identical to the torr, but defined separately. This uses conventional mmHg, not a temperature-specific mercury-column realization.
Inches of mercury to millimeters of mercury conversion table
Common values in inches of mercury, converted to millimeters of mercury.
| Inches of mercury (inHg) | Millimeters of mercury (mmHg) |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 3 | 76.2 |
| 4 | 101.6 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 25 | 635 |
| 50 | 1,270 |
| 100 | 2,540 |
| 250 | 6,350 |
| 500 | 12,700 |
| 1,000 | 25,400 |
About these units
inch of mercuryinHg
Exactly 25.4 mmHg. The US aviation and weather-report pressure unit.
millimeter of mercurymmHg
The conventional millimetre of mercury: 133.3224 Pa, following the NIST SP 811 convention.
Reference: NIST Special Publication 811.
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.