Pressure
ftH₂OtommHg
Convert feet of water column (4 °C) (ftH₂O) to millimetres of mercury (mmHg).
Factor1 ftH₂O = 22.41984 mmHg
Converter
ftH₂O
Accepts numbers or expressions, e.g. 150 + 14.7
Result
mmHg
Rendered to 6 significant figures.
Formula
Formula
mmHg = ftH₂O × 22.41984
Multiply any value in feet of water column (4 °C) by 22.41984 to obtain the value in millimetres of mercury.
Worked example
Convert 1 ftH₂O to mmHg.
- 01Start with 1 ftH₂O.
- 02Multiply by the conversion factor: 1 × 22.41984 = 22.4198 mmHg.
Result1 ftH₂O = 22.4198 mmHg
Conversion table
| ftH₂O | mmHg |
|---|---|
| 1 | 22.42 |
| 2 | 44.84 |
| 5 | 112.1 |
| 10 | 224.2 |
| 20 | 448.4 |
| 50 | 1121 |
| 100 | 2242 |
| 200 | 4484 |
| 500 | 11210 |
| 1000 | 22420 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from ftH₂O to mmHg?
1 ftH₂O equals 22.41984 mmHg. To convert, multiply the value in feet of water column (4 °C) by 22.41984.
How do I convert 1 ftH₂O to mmHg?
1 ftH₂O = 22.4198 mmHg. For any value, multiply by 22.41984.
How do I convert mmHg back to ftH₂O?
Divide by the same factor — or equivalently, multiply by 0.04460335. So 1 mmHg = 0.0446033 ftH₂O.
When would I need to convert foot of water column (4 °C) to millimetre of mercury?
Pressure conversions between ftH₂O 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).