Pressure
inHgtomH₂O
Convert inches of mercury (0 °C) (inHg) to metres of water column (mH₂O).
Factor1 inHg = 0.3453156 mH₂O
Converter
inHg
Accepts numbers or expressions, e.g. 150 + 14.7
Result
mH₂O
Rendered to 6 significant figures.
Formula
Formula
mH₂O = inHg × 0.3453156
Multiply any value in inches of mercury (0 °C) by 0.3453156 to obtain the value in metres of water column.
Worked example
Convert 30 inHg to mH₂O.
- 01Start with 30 inHg.
- 02Multiply by the conversion factor: 30 × 0.3453156 = 10.3595 mH₂O.
Result30 inHg = 10.3595 mH₂O
Conversion table
| inHg | mH₂O |
|---|---|
| 1 | 0.34532 |
| 2 | 0.69063 |
| 5 | 1.7266 |
| 10 | 3.4532 |
| 20 | 6.9063 |
| 50 | 17.266 |
| 100 | 34.532 |
| 200 | 69.063 |
| 500 | 172.66 |
| 1000 | 345.32 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from inHg to mH₂O?
1 inHg equals 0.3453156 mH₂O. To convert, multiply the value in inches of mercury (0 °C) by 0.3453156.
How do I convert 1 inHg to mH₂O?
1 inHg = 0.345316 mH₂O. For any value, multiply by 0.3453156.
How do I convert mH₂O back to inHg?
Divide by the same factor — or equivalently, multiply by 2.895902. So 1 mH₂O = 2.8959 inHg.
When would I need to convert inch of mercury (0 °C) to metre of water column?
Pressure conversions between inHg and mH₂O 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).