▸ processconvert
Pressure

inH₂OtommHg

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

Factor1 inH₂O = 1.86832 mmHg

Converter

inH₂O

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

Result
186.832mmHg

Rendered to 6 significant figures.

Formula

Formula
mmHg = inH₂O × 1.86832

Multiply any value in inches of water column (4 °C) by 1.86832 to obtain the value in millimetres of mercury.

Worked example

Convert 100 inH₂O to mmHg.

  1. 01Start with 100 inH₂O.
  2. 02Multiply by the conversion factor: 100 × 1.86832 = 186.832 mmHg.
Result100 inH₂O = 186.832 mmHg

Conversion table

inH₂OmmHg
11.8683
23.7366
59.3416
1018.683
2037.366
5093.416
100186.83
200373.66
500934.16
10001868.3

Reference values rounded to 5 significant figures for display.

FAQ

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

Related conversions