Pressure
inHgtommHg
Convert inches of mercury (0 °C) (inHg) to millimetres of mercury (mmHg).
Factor1 inHg = 25.4 mmHg
Converter
inHg
Accepts numbers or expressions, e.g. 150 + 14.7
Result
mmHg
Rendered to 6 significant figures.
Formula
Formula
mmHg = inHg × 25.4
Multiply any value in inches of mercury (0 °C) by 25.4 to obtain the value in millimetres of mercury.
Worked example
Convert 30 inHg to mmHg.
- 01Start with 30 inHg.
- 02Multiply by the conversion factor: 30 × 25.4 = 762 mmHg.
Result30 inHg = 762 mmHg
Conversion table
| inHg | mmHg |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 50 | 1270 |
| 100 | 2540 |
| 200 | 5080 |
| 500 | 12700 |
| 1000 | 25400 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from inHg to mmHg?
1 inHg equals 25.4 mmHg. To convert, multiply the value in inches of mercury (0 °C) by 25.4.
How do I convert 1 inHg to mmHg?
1 inHg = 25.4 mmHg. For any value, multiply by 25.4.
How do I convert mmHg back to inHg?
Divide by the same factor — or equivalently, multiply by 0.03937007. So 1 mmHg = 0.0393701 inHg.
When would I need to convert inch of mercury (0 °C) to millimetre of mercury?
Pressure conversions between inHg and mmHg are common when working with mixed-vendor instrumentation, when piping codes use different units to process datasheets, or when converting field readings into SI for hydraulic calculations.
Is the conversion exact?
The factor shown is precise to at least 7 significant figures. For most process-engineering work this is far better than instrument accuracy. For metrology or trade applications, refer to the relevant national standard (NIST, BIPM, ISO 80000).