Pressure
mmHgtoftH₂O
Convert millimetres of mercury (mmHg) to feet of water column (4 °C) (ftH₂O).
Factor1 mmHg = 0.04460335 ftH₂O
Converter
mmHg
Accepts numbers or expressions, e.g. 150 + 14.7
Result
ftH₂O
Rendered to 6 significant figures.
Formula
Formula
ftH₂O = mmHg × 0.04460335
Multiply any value in millimetres of mercury by 0.04460335 to obtain the value in feet of water column (4 °C).
Worked example
Convert 760 mmHg to ftH₂O.
- 01Start with 760 mmHg.
- 02Multiply by the conversion factor: 760 × 0.04460335 = 33.8985 ftH₂O.
Result760 mmHg = 33.8985 ftH₂O
Conversion table
| mmHg | ftH₂O |
|---|---|
| 1 | 0.044603 |
| 2 | 0.089207 |
| 5 | 0.22302 |
| 10 | 0.44603 |
| 20 | 0.89207 |
| 50 | 2.2302 |
| 100 | 4.4603 |
| 200 | 8.9207 |
| 500 | 22.302 |
| 1000 | 44.603 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from mmHg to ftH₂O?
1 mmHg equals 0.04460335 ftH₂O. To convert, multiply the value in millimetres of mercury by 0.04460335.
How do I convert 1 mmHg to ftH₂O?
1 mmHg = 0.0446033 ftH₂O. For any value, multiply by 0.04460335.
How do I convert ftH₂O back to mmHg?
Divide by the same factor — or equivalently, multiply by 22.41984. So 1 ftH₂O = 22.4198 mmHg.
When would I need to convert millimetre of mercury to foot of water column (4 °C)?
Pressure conversions between mmHg and ftH₂O 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).