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Pressure

inH₂OtocmH₂O

Convert inches of water column (4 °C) (inH₂O) to centimetres of water column (cmH₂O).

Factor1 inH₂O = 2.54 cmH₂O

Converter

inH₂O

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

Result
25.4cmH₂O

Rendered to 6 significant figures.

Formula

Formula
cmH₂O = inH₂O × 2.54

Multiply any value in inches of water column (4 °C) by 2.54 to obtain the value in centimetres of water column.

Worked example

Convert 10 inH₂O to cmH₂O.

  1. 01Start with 10 inH₂O.
  2. 02Multiply by the conversion factor: 10 × 2.54 = 25.4 cmH₂O.
Result10 inH₂O = 25.4 cmH₂O

Conversion table

inH₂OcmH₂O
12.54
25.08
512.7
1025.4
2050.8
50127
100254
200508
5001270
10002540

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from inH₂O to cmH₂O?
1 inH₂O equals 2.54 cmH₂O. To convert, multiply the value in inches of water column (4 °C) by 2.54.
How do I convert 1 inH₂O to cmH₂O?
1 inH₂O = 2.54 cmH₂O. For any value, multiply by 2.54.
How do I convert cmH₂O back to inH₂O?
Divide by the same factor — or equivalently, multiply by 0.3937008. So 1 cmH₂O = 0.393701 inH₂O.
When would I need to convert inch of water column (4 °C) to centimetre of water column?
Pressure conversions between inH₂O and cmH₂O 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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