Convert Centimeters of Water to Standard Atmospheres
Convert Centimeters of Water (cmH₂O) to Standard Atmospheres (atm) instantly and accurately.
Conversion Formula
atm = cmH₂O × 0.0009678411054
About Centimeters of Water
One centimetre of water column (cmH₂O) ≈ 98.07 Pa - the clinical pressure unit for respiratory and intravascular measurements. Mechanical ventilator settings are in cmH₂O: peak inspiratory pressure (PIP) 15-30 cmH₂O; PEEP 5-15 cmH₂O; plateau pressure should stay below 30 cmH₂O to avoid lung injury. Lumbar puncture CSF opening pressure is normally 8-20 cmH₂O. CPAP/BiPAP therapy for sleep apnea: 4-20 cmH₂O. Central venous pressure is also reported in cmH₂O. 1 cmH₂O = 98.0665 Pa.
About Standard Atmospheres
The standard atmosphere (atm) = exactly 101,325 Pa - defined by the 10th CGPM (1954) as the reference air pressure at sea level. Used to define STP (0°C and 1 atm) for gas law and thermochemistry. Chemical equilibrium constants (Kp), Henry's law solubility, and thermodynamic tables are tabulated at 1 atm. ISA aviation standard: sea-level 1 atm / 15°C, pressure halving every ~5.5 km. Diving physics: +1 atm per 10 m depth (fresh water) so 30 m = 4 atm absolute. Diamond formation in Earth's mantle: ~50,000 atm. 1 atm = 101,325 Pa.
Quick Reference Table
| Centimeters of Water (cmH₂O) | Standard Atmospheres (atm) |
|---|---|
| 1 cmH₂O | 0.000967841 atm |
| 2 cmH₂O | 0.00193568 atm |
| 5 cmH₂O | 0.00483921 atm |
| 10 cmH₂O | 0.00967841 atm |
| 25 cmH₂O | 0.024196 atm |
| 50 cmH₂O | 0.0483921 atm |
| 100 cmH₂O | 0.0967841 atm |