Convert Centimeters of Water to Millimeters of Mercury
1 centimeter of water (cmH₂O) equals 0.7355591353 millimeters of mercury (mmHg).
1 cmH₂O = 0.7355591353 mmHg
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk centimeter of water to millimeter of mercury converter to paste a column from Excel.
How to Convert Centimeter of Water to Millimeter of Mercury
- 1 cmH₂O = 0.7355591353 mmHg
- 1 mmHg = 1.35951 cmH₂O
- Example: convert 15 cmH₂O to mmHg: 15 cmH₂O = 15 × 0.7355591353 mmHg = 11.03338703 mmHg
Reference conditions. cmH₂O: Conventional water column: ρ = 1000 kg/m³ and gₙ = 9.80665 m/s² (≈ water at 4 °C). mmHg: Conventional mercury column: ρ = 13 595.1 kg/m³ and gₙ = 9.80665 m/s² (≈ mercury at 0 °C / 32 °F).
Formula
mmHg = cmH₂O × 0.7355591352767
or mmHg = cmH₂O ÷ 1.35951
Derivation from SI units:
- 1 cmH₂O = 1000 kg/m³ × 9.80665 m/s² × 0.01 m = 98.0665 Pa
- 1 mmHg = 13 595.1 kg/m³ × 9.80665 m/s² × 0.001 m = 133.322387415 Pa
- 1 cmH₂O = 98.0665 Pa ÷ 133.322387415 Pa per mmHg = 0.7355591352767 mmHg
Both units are defined exactly, so the factor is exact. Centimeter of Water definition: centimeter of water; Millimeter of Mercury definition: millimeter of mercury.
Worked examples
- A pressure of 10 cmH₂O equals 7.355591353 mmHg.
10 cmH₂O × 0.7355591353 = 7.355591353 mmHg - Because mercury is about 13.6 times denser than water, 13.6 cmH₂O is close to 10.00360424 mmHg.
13.6 cmH₂O × 0.7355591353 = 10.00360424 mmHg
Centimeter of Water to Millimeter of Mercury conversion table
| Centimeters of Water (cmH₂O) | Millimeters of Mercury (mmHg) |
|---|---|
| 0.5 cmH₂O | 0.3677795676 mmHg |
| 1 cmH₂O | 0.7355591353 mmHg |
| 2 cmH₂O | 1.471118271 mmHg |
| 3 cmH₂O | 2.206677406 mmHg |
| 4 cmH₂O | 2.942236541 mmHg |
| 5 cmH₂O | 3.677795676 mmHg |
| 6 cmH₂O | 4.413354812 mmHg |
| 8 cmH₂O | 5.884473082 mmHg |
| 10 cmH₂O | 7.355591353 mmHg |
| 12 cmH₂O | 8.826709623 mmHg |
| 15 cmH₂O | 11.03338703 mmHg |
| 20 cmH₂O | 14.71118271 mmHg |
| 25 cmH₂O | 18.38897838 mmHg |
| 30 cmH₂O | 22.06677406 mmHg |
| 35 cmH₂O | 25.74456973 mmHg |
| 40 cmH₂O | 29.42236541 mmHg |
| 50 cmH₂O | 36.77795676 mmHg |
| 60 cmH₂O | 44.13354812 mmHg |
| 80 cmH₂O | 58.84473082 mmHg |
| 100 cmH₂O | 73.55591353 mmHg |
Where it's used
Clinicians compare cmH₂O (airway, cerebrospinal fluid, venous pressures) with mmHg (blood pressure). One cmH₂O is about 0.736 mmHg.
Centimeter of Water to other pressure units
| Conversion | 1 cmH₂O equals |
|---|---|
| centimeter of water to pascal | 98.0665 Pa |
| centimeter of water to kilopascal | 0.0980665 kPa |
| centimeter of water to megapascal | 0.0000980665 MPa |
| centimeter of water to psi | 0.01422334331 psi |
| centimeter of water to bar | 0.000980665 bar |
| centimeter of water to millibar | 0.980665 mbar |
| centimeter of water to decibar | 0.00980665 dbar |
| centimeter of water to torr | 0.7355592401 Torr |
| centimeter of water to millimeter of mercury | 0.7355591353 mmHg |
| centimeter of water to millimeter of water | 10 mmH₂O |
| centimeter of water to inch of water | 0.3937007874 inH₂O |
| centimeter of water to inch of water (60 °F) | 0.3940945989 inH₂O (60 °F) |
| centimeter of water to inch of mercury | 0.02895902107 inHg |
| centimeter of water to atmosphere | 0.0009678411054 atm |
| centimeter of water to barye | 980.665 Ba |
Frequently asked questions
How many mmHg is 1 cmH₂O?
1 cmH₂O = 0.7355591353 mmHg.
How many millimeters of mercury are in 1 centimeter of water?
1 cmH₂O = 0.7355591353 mmHg.
How do I convert centimeters of water to millimeters of mercury?
Multiply the value in cmH₂O by 0.7355591353, or divide it by 1.35951. For example, 15 cmH₂O × 0.7355591353 = 11.03338703 mmHg.
Is the cmH₂O to mmHg conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "centimeter of water, conventional (cmH2O)".
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "millimeter of mercury, conventional (mmHg)".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Centimeters of Water to Millimeters of Mercury. Retrieved October 17, 2026, from https://scientificconverters.com/pressure/centimeter-of-water-to-millimeter-of-mercury/
IEEE
Scientific Converters, "Convert Centimeters of Water to Millimeters of Mercury," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/pressure/centimeter-of-water-to-millimeter-of-mercury/