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Pressure

mH₂OtoinH₂O

Convert metres of water column (mH₂O) to inches of water column (4 °C) (inH₂O).

Factor1 mH₂O = 39.37008 inH₂O

Converter

mH₂O

Accepts numbers or expressions, e.g. 150 + 14.7

Result
39.3701inH₂O

Rendered to 6 significant figures.

Formula

Formula
inH₂O = mH₂O × 39.37008

Multiply any value in metres of water column by 39.37008 to obtain the value in inches of water column (4 °C).

Worked example

Convert 1 mH₂O to inH₂O.

  1. 01Start with 1 mH₂O.
  2. 02Multiply by the conversion factor: 1 × 39.37008 = 39.3701 inH₂O.
Result1 mH₂O = 39.3701 inH₂O

Conversion table

mH₂OinH₂O
139.37
278.74
5196.85
10393.7
20787.4
501968.5
1003937
2007874
50019685
100039370

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from mH₂O to inH₂O?
1 mH₂O equals 39.37008 inH₂O. To convert, multiply the value in metres of water column by 39.37008.
How do I convert 1 mH₂O to inH₂O?
1 mH₂O = 39.3701 inH₂O. For any value, multiply by 39.37008.
How do I convert inH₂O back to mH₂O?
Divide by the same factor — or equivalently, multiply by 0.0254. So 1 inH₂O = 0.0254 mH₂O.
When would I need to convert metre of water column to inch of water column (4 °C)?
Pressure conversions between mH₂O 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).

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