Pressure
hPatoinH₂O
Convert hectopascals (hPa) to inches of water column (4 °C) (inH₂O).
Factor1 hPa = 0.4014631 inH₂O
Converter
hPa
Accepts numbers or expressions, e.g. 150 + 14.7
Result
inH₂O
Rendered to 6 significant figures.
Formula
Formula
inH₂O = hPa × 0.4014631
Multiply any value in hectopascals by 0.4014631 to obtain the value in inches of water column (4 °C).
Worked example
Convert 100 hPa to inH₂O.
- 01Start with 100 hPa.
- 02Multiply by the conversion factor: 100 × 0.4014631 = 40.1463 inH₂O.
Result100 hPa = 40.1463 inH₂O
Conversion table
| hPa | inH₂O |
|---|---|
| 1 | 0.40146 |
| 2 | 0.80293 |
| 5 | 2.0073 |
| 10 | 4.0146 |
| 20 | 8.0293 |
| 50 | 20.073 |
| 100 | 40.146 |
| 200 | 80.293 |
| 500 | 200.73 |
| 1000 | 401.46 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from hPa to inH₂O?
1 hPa equals 0.4014631 inH₂O. To convert, multiply the value in hectopascals by 0.4014631.
How do I convert 1 hPa to inH₂O?
1 hPa = 0.401463 inH₂O. For any value, multiply by 0.4014631.
How do I convert inH₂O back to hPa?
Divide by the same factor — or equivalently, multiply by 2.490889. So 1 inH₂O = 2.49089 hPa.
When would I need to convert hectopascal to inch of water column (4 °C)?
Pressure conversions between hPa and inH₂O 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).