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Pressure

mmHgtoinH₂O

Convert millimetres of mercury (mmHg) to inches of water column (4 °C) (inH₂O).

Factor1 mmHg = 0.5352402 inH₂O

Converter

mmHg

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

Result
406.783inH₂O

Rendered to 6 significant figures.

Formula

Formula
inH₂O = mmHg × 0.5352402

Multiply any value in millimetres of mercury by 0.5352402 to obtain the value in inches of water column (4 °C).

Worked example

Convert 760 mmHg to inH₂O.

  1. 01Start with 760 mmHg.
  2. 02Multiply by the conversion factor: 760 × 0.5352402 = 406.783 inH₂O.
Result760 mmHg = 406.783 inH₂O

Conversion table

mmHginH₂O
10.53524
21.0705
52.6762
105.3524
2010.705
5026.762
10053.524
200107.05
500267.62
1000535.24

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from mmHg to inH₂O?
1 mmHg equals 0.5352402 inH₂O. To convert, multiply the value in millimetres of mercury by 0.5352402.
How do I convert 1 mmHg to inH₂O?
1 mmHg = 0.53524 inH₂O. For any value, multiply by 0.5352402.
How do I convert inH₂O back to mmHg?
Divide by the same factor — or equivalently, multiply by 1.86832. So 1 inH₂O = 1.86832 mmHg.
When would I need to convert millimetre of mercury to inch of water column (4 °C)?
Pressure conversions between mmHg 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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