cmH2O - Centimetres of Water Column at 4 deg C Pressure Unit

Centimeters of Water Column is a manometric unit used to relate a pressure reading to the height of fresh water at a temperature of 4 degC. 1 Centimeter of Water Gauge equals 98.0665 Pascals.

The cmH2O pressure unit is mostly used to measure breathing on respirators and ventilators which are used in medical and physiological applications such as controlling respiratory conditions or monitoring athletic performance.

There are many ways of writing centimeters of water, but the cause of most confusion are Water Column (WC) and Water Gauge (WG), which both mean exactly the same thing.

For more details on metric water gauge pressure units please see our mWG page.

Please refer to the table below to find the value of 1 cmWC in another pressure unit.

To find the amount of cmWC in a different pressure unit please click on the approriate unit hyperlink in the table below.

Use our website pressure converter to convert multiple values of cmH2o.

Examine how cmH2O is calculated from SI units or check the the different ways of writing mmH2O.

cmH2O Pressure Conversion Factors

0.000980665	bar
0.0142233	psi
0.980665	mbar
98.0665	N/m²
98.0665	Pa
0.980665	hPa
0.0980665	kPa
0.0000980665	MPa
0.001	kg/cm²
10	mmH2O 4°C (39.2°F)
1	cmH2O 4°C (39.2°F)
0.01	mH2O 4°C (39.2°F)
0.393701	inH2O 4°C (39.2°F)
0.0328084	ftH2O 4°C (39.2°F)
0.735559	mmHg 0°C (32°F)
0.0735559	cmHg 0°C (32°F)
0.0289590	inHg 0°C (32°F)
0.735559	Torr
735.559	mTorr
0.000967841	atm
0.001	at
980.665	dyn/cm²
0.227573	oz/in²
735.559	µHg 0°C (32°F)
0.00000634971	tsi (uk, long)
0.00000711167	tsi (usa, short)
0.00102408	tsf (usa, short)
2.04816	psf
1	g/cm²

Please note that the conversion factors above are accurate to 6 significant figures.

cmH2O Derivation

The calculation below shows how the pressure unit Centimetres of Water Column (cmH2O) is derived from SI Units.

Formula

Pressure = Force / Area
Force = Mass x Acceleration
Mass = Density x Volume
Volume = Area x Height
Acceleration = Distance / (Second x Second)

SI Units

Mass: Kilogram (kg)
Length: Metre (m)
Time: Second (s)
Force: Newton (N)
Pressure: Pascal (Pa)

Input Values

Density = Water Density at 4degC = 1000 kg/m³
Area = 1 m²
Height = 1 cm = 0.01 m
Acceleration = Standard Gravity = 9.80665 m/s²

Calculation

1 cmH2O Mass = 1000 kg/m³ x 1 m² x 0.01 m = 10 kg
1 cmH2O Force = 10 kg x 9.80665 m/s² = 98.0665 N
1 cmH2O Pressure = 98.0665 N / 1 m² = 98.0665 Pa

cmH2O Alternate Descriptions

These are the different versions used for identifying cmH2O that you may find elsewhere.

Centimetres of H2O
Centimeters of H2O
Centimetres of Water Column
Centimeters of Water Column
Centimetres of Water Gauge
Centimeters of Water Gauge
cmH2O
cmWC
cmWG
cmWS
cmAq
cm H2O
cm WC
cm WG
cm WS
cm Aq
cmsH2O
cmsAq
cms H2O
cms Aq