Pressure
ftH₂Otopsi
Convert feet of water column (4 °C) (ftH₂O) to pounds-force per square inch (psi).
Factor1 ftH₂O = 0.4335275 psi
Converter
ftH₂O
Accepts numbers or expressions, e.g. 150 + 14.7
Result
psi
Rendered to 6 significant figures.
Formula
Formula
psi = ftH₂O × 0.4335275
Multiply any value in feet of water column (4 °C) by 0.4335275 to obtain the value in pounds-force per square inch.
Worked example
Convert 100 ftH₂O to psi.
- 01Start with 100 ftH₂O.
- 02Multiply by the conversion factor: 100 × 0.4335275 = 43.3528 psi.
Result100 ftH₂O = 43.3528 psi
Conversion table
| ftH₂O | psi |
|---|---|
| 1 | 0.43353 |
| 2 | 0.86706 |
| 5 | 2.1676 |
| 10 | 4.3353 |
| 20 | 8.6706 |
| 50 | 21.676 |
| 100 | 43.353 |
| 200 | 86.706 |
| 500 | 216.76 |
| 1000 | 433.53 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from ftH₂O to psi?
1 ftH₂O equals 0.4335275 psi. To convert, multiply the value in feet of water column (4 °C) by 0.4335275.
How do I convert 1 ftH₂O to psi?
1 ftH₂O = 0.433528 psi. For any value, multiply by 0.4335275.
How do I convert psi back to ftH₂O?
Divide by the same factor — or equivalently, multiply by 2.306659. So 1 psi = 2.30666 ftH₂O.
When would I need to convert foot of water column (4 °C) to pound-force per square inch?
Pressure conversions between ftH₂O and psi 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).