Convert Millimeters of Water to Centimeters of Mercury
Convert Millimeters of Water (mmH₂O) to Centimeters of Mercury (cmHg) instantly and accurately.
Conversion Formula
cmHg = mmH₂O × 0.007355591353
About Millimeters of Water
One millimetre of water column (mmH₂O) = pressure from 1 mm of fresh water at standard gravity = exactly 9.80665 Pa. Preferred for very low differential pressures in HVAC: ductwork static pressures, fan curves, filter resistance, and building pressurisation are in mm WC. Gas valve operating pressures are typically 0.5-3 mm WC; clean-room cascade differentials 12-25 mm WC. A domestic gas hob manifold operates at ~20 mm WC on natural gas. Also used in spirometer calibration and hospital oxygen delivery systems. 1 mmH₂O = 9.80665 Pa.
About Centimeters of Mercury
One centimetre of mercury (cmHg) = 10 mmHg ≈ 1,333.22 Pa. Historical medical and physiological literature used cmHg for intracardiac and intravascular pressures before mmHg became universal. Left ventricular systolic pressure ~12 cmHg; pulmonary artery systolic 2-3 cmHg. Some older European cardiological textbooks and pre-1970s surgical literature report pressures in cmHg. Central venous pressure, cerebral perfusion pressure, and intra-abdominal pressure are occasionally cited in cmHg in legacy datasets. 1 cmHg = 1,333.22 Pa.
Quick Reference Table
| Millimeters of Water (mmH₂O) | Centimeters of Mercury (cmHg) |
|---|---|
| 1 mmH₂O | 0.00735559 cmHg |
| 2 mmH₂O | 0.0147112 cmHg |
| 5 mmH₂O | 0.036778 cmHg |
| 10 mmH₂O | 0.0735559 cmHg |
| 25 mmH₂O | 0.18389 cmHg |
| 50 mmH₂O | 0.36778 cmHg |
| 100 mmH₂O | 0.735559 cmHg |