cmH₂O Conversion Tool - Convert Centimeters of Water to Any Unit
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cmH₂O Conversion Table
This comprehensive cmH₂O conversion table shows how various units relate to centimeters of water column, a unit often used in medical and engineering applications. Use this reference for quick conversions between cmH₂O and other common pressure units.
| Conversion | To Unit | Multiplier |
|---|---|---|
| cmH₂O to pascals | Pascals | 98.0665 |
| cmH₂O to kilopascals | Kilopascals | 0.0980665 |
| cmH₂O to bar | Bar | 0.000980665 |
| cmH₂O to millibar | Millibar | 0.980665 |
| cmH₂O to atmospheres | Atmospheres | 0.000967841 |
| cmH₂O to torr | Torr | 0.735559 |
| cmH₂O to psi | PSI | 0.0142233 |
| cmH₂O to inHg | Inches of Mercury | 0.028959 |
| cmH₂O to mmHg | Millimeters of Mercury | 0.735559 |
This cmH₂O conversion reference table provides accurate conversion factors for both SI and imperial units. All values are based on internationally recognized standards for maximum precision in scientific and engineering applications. One cmH₂O is defined as the pressure exerted by a column of water 1 cm high at 4°C.
What is cmH₂O?
Centimeters of water (cmH₂O) is a unit of pressure that represents the pressure exerted by a column of water 1 centimeter high at 4°C (the temperature at which water reaches its maximum density). This unit is commonly used in medical applications, particularly in respiratory therapy and ventilator settings, to measure pressure differences in airways and breathing circuits. Our cmH₂O conversion tool helps you easily convert between cmH₂O and other pressure units. For example, 1 cmH₂O equals approximately 0.0142 psi or 98.0665 pascals.
What is the SI of cmH₂O?
While cmH₂O is not an SI unit itself, it can be converted to the SI unit for pressure, the pascal (Pa). The pascal is defined as one newton per square meter (N/m²). In the SI system, pressure measurements are typically expressed in pascals or its multiples like kilopascals (kPa). When working with pressure unit conversions, cmH₂O relates to SI units as follows:
- 1 cmH₂O = 98.0665 pascals
- 1 cmH₂O = 0.0980665 kilopascals
- 1 pascal = 0.0101972 cmH₂O
What is cmH₂O Used For?
Centimeters of water is used in specific applications where relatively low pressures are measured. As a non-SI unit, cmH₂O is particularly common in medical and biological contexts where water-based pressure measurements are relevant. For pressure conversions, cmH₂O has these key applications:
Medical Ventilation
Measuring pressure settings in mechanical ventilators and continuous positive airway pressure (CPAP) machines. For example, a typical CPAP setting might be 10 cmH₂O, which equals approximately 1.42 psi.
Respiratory Therapy
Quantifying pressure differences in breathing circuits and measuring lung function parameters. For example, measuring inspiratory pressure that might be set at 20 cmH₂O (approximately 2.84 psi).
Hydrostatic Systems
Measuring low-pressure differences in water-based systems and fluid mechanics experiments. For example, measuring pressure drop across filters or in small piping systems.
Biological Research
Measuring pressure in biological systems such as blood pressure in small vessels or pressure in plant xylem. For example, measuring transpiration pull in plants which might be measured in cmH₂O.
Etymology and History
The unit "cmH₂O" represents centimeters of water column, a measurement based on the height of a water column that produces a specific pressure. This method of pressure measurement has its roots in early fluid mechanics studies and was particularly important in the development of steam engines and hydraulic systems. The "H₂O" subscript indicates that water is the reference fluid, and "cm" specifies that the height is measured in centimeters. In the context of pressure measurement systems, cmH₂O became a standard unit in medical applications due to its relevance for breathing pressure measurements. The definition is based on water at 4°C, when it has maximum density (approximately 999.972 kg/m³).
The unit continues to be used in modern medical equipment despite the prevalence of SI units, as it provides an intuitive understanding of pressure for healthcare professionals working with respiratory systems. This practical approach to pressure units conversion reflects the specialized needs of medical applications where water-based pressure measurements are most relevant.
Frequently Asked Questions
Why is cmH₂O used in medical settings?
cmH₂O is used in medical settings because it provides a practical and intuitive measure of respiratory pressures. Healthcare professionals can easily understand the pressure equivalent to a specific height of water column, which is particularly relevant for breathing mechanics. This unit is especially common in ventilator settings, CPAP machines, and pulmonary function tests where pressures are relatively low and water-based measurements make physiological sense.
How accurate is the cmH₂O definition?
The definition of cmH₂O is based on the density of water at 4°C, which is precisely 999.972 kg/m³. Using this value and the standard acceleration due to gravity (9.80665 m/s²), 1 cmH₂O equals exactly 98.0665 pascals. This makes cmH₂O a well-defined unit that can be accurately converted to SI units. The precision is sufficient for medical and engineering applications where this unit is commonly used.
What's the difference between cmH₂O and mmHg?
Both cmH₂O and mmHg are units of pressure based on fluid columns, but they use different reference fluids. cmH₂O uses water while mmHg (millimeters of mercury) uses mercury. Since mercury is much denser than water (about 13.6 times), 1 cmH₂O equals approximately 0.735 mmHg. mmHg is more commonly used in blood pressure measurements, while cmH₂O is more common in respiratory applications.
How do I convert cmH₂O to other units?
Use our cmH₂O conversion calculators above, or multiply by the appropriate conversion factor. For example, to convert cmH₂O to pascals, multiply by 98.0665; to convert cmH₂O to psi, multiply by 0.0142233. For detailed instructions on converting cmH₂O to pascals, visit our cmH₂O to Pa converter. Our tool also handles conversions to other pressure units with high precision.
What are common uses for cmH₂O conversion?
cmH₂O conversion is essential in medical ventilation (ventilator settings), respiratory therapy (CPAP/BiPAP machines), pulmonary function testing, and biological research. Whether setting pressure support on a ventilator or measuring breathing pressures in research, our cmH₂O converter tool simplifies these specialized tasks that require water-based pressure measurements.
How does cmH₂O conversion differ from other pressure units?
cmH₂O is unique in using water as its reference fluid and is primarily used in medical and biological applications. Unlike SI units like pascals which are based on force per unit area, cmH₂O is based on a fluid column height, making it more intuitive for applications involving liquid pressures. This relationship makes cmH₂O conversion particularly straightforward for healthcare professionals who understand the physiological relevance of water column measurements.
Can I convert very small or very large measurements in cmH₂O?
Yes, our cmH₂O converter handles both extremely small and large measurements with precision. For very low pressures, you can convert fractions of cmH₂O to pascals. For higher pressures, the tool can convert large cmH₂O values to other units. Our smart rounding feature ensures readable results for all scales, making it suitable for both delicate medical measurements and industrial applications.
Is your cmH₂O conversion tool free to use?
Yes, our cmH₂O conversion calculator is completely free with no registration required. Simply enter your value, select your target unit, and get instant, accurate results. We believe precise pressure conversion should be accessible to everyone, from medical professionals working with ventilators to researchers conducting fluid mechanics experiments.