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Pressure

inH₂OtoinHg

Convert inches of water column (4 °C) (inH₂O) to inches of mercury (0 °C) (inHg).

Factor1 inH₂O = 0.07355591 inHg

Converter

inH₂O

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

Result
7.35559inHg

Rendered to 6 significant figures.

Formula

Formula
inHg = inH₂O × 0.07355591

Multiply any value in inches of water column (4 °C) by 0.07355591 to obtain the value in inches of mercury (0 °C).

Worked example

Convert 100 inH₂O to inHg.

  1. 01Start with 100 inH₂O.
  2. 02Multiply by the conversion factor: 100 × 0.07355591 = 7.35559 inHg.
Result100 inH₂O = 7.35559 inHg

Conversion table

inH₂OinHg
10.073556
20.14711
50.36778
100.73556
201.4711
503.6778
1007.3556
20014.711
50036.778
100073.556

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from inH₂O to inHg?
1 inH₂O equals 0.07355591 inHg. To convert, multiply the value in inches of water column (4 °C) by 0.07355591.
How do I convert 1 inH₂O to inHg?
1 inH₂O = 0.0735559 inHg. For any value, multiply by 0.07355591.
How do I convert inHg back to inH₂O?
Divide by the same factor — or equivalently, multiply by 13.5951. So 1 inHg = 13.5951 inH₂O.
When would I need to convert inch of water column (4 °C) to inch of mercury (0 °C)?
Pressure conversions between inH₂O and inHg 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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