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Pressure

mH₂Otoatm

Convert metres of water column (mH₂O) to standard atmospheres (atm).

Factor1 mH₂O = 0.09678411 atm

Converter

mH₂O

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

Result
0.967841atm

Rendered to 6 significant figures.

Formula

Formula
atm = mH₂O × 0.09678411

Multiply any value in metres of water column by 0.09678411 to obtain the value in standard atmospheres.

Worked example

Convert 10 mH₂O to atm.

  1. 01Start with 10 mH₂O.
  2. 02Multiply by the conversion factor: 10 × 0.09678411 = 0.967841 atm.
Result10 mH₂O = 0.967841 atm

Conversion table

mH₂Oatm
10.096784
20.19357
50.48392
100.96784
201.9357
504.8392
1009.6784
20019.357
50048.392
100096.784

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from mH₂O to atm?
1 mH₂O equals 0.09678411 atm. To convert, multiply the value in metres of water column by 0.09678411.
How do I convert 1 mH₂O to atm?
1 mH₂O = 0.0967841 atm. For any value, multiply by 0.09678411.
How do I convert atm back to mH₂O?
Divide by the same factor — or equivalently, multiply by 10.33227. So 1 atm = 10.3323 mH₂O.
When would I need to convert metre of water column to standard atmosphere?
Pressure conversions between mH₂O and atm 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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