Pressure
inH₂Otombar
Convert inches of water column (4 °C) (inH₂O) to millibars (mbar).
Factor1 inH₂O = 2.490889 mbar
Converter
inH₂O
Accepts numbers or expressions, e.g. 150 + 14.7
Result
mbar
Rendered to 6 significant figures.
Formula
Formula
mbar = inH₂O × 2.490889
Multiply any value in inches of water column (4 °C) by 2.490889 to obtain the value in millibars.
Worked example
Convert 10 inH₂O to mbar.
- 01Start with 10 inH₂O.
- 02Multiply by the conversion factor: 10 × 2.490889 = 24.9089 mbar.
Result10 inH₂O = 24.9089 mbar
Conversion table
| inH₂O | mbar |
|---|---|
| 1 | 2.4909 |
| 2 | 4.9818 |
| 5 | 12.454 |
| 10 | 24.909 |
| 20 | 49.818 |
| 50 | 124.54 |
| 100 | 249.09 |
| 200 | 498.18 |
| 500 | 1245.4 |
| 1000 | 2490.9 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from inH₂O to mbar?
1 inH₂O equals 2.490889 mbar. To convert, multiply the value in inches of water column (4 °C) by 2.490889.
How do I convert 1 inH₂O to mbar?
1 inH₂O = 2.49089 mbar. For any value, multiply by 2.490889.
How do I convert mbar back to inH₂O?
Divide by the same factor — or equivalently, multiply by 0.4014631. So 1 mbar = 0.401463 inH₂O.
When would I need to convert inch of water column (4 °C) to millibar?
Pressure conversions between inH₂O and mbar 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).