Convert Centimeters of Water to Inches of Water
Convert Centimeters of Water (cmH₂O) to Inches of Water (inH₂O) instantly and accurately.
Conversion Formula
inH₂O = cmH₂O × 0.3937007874
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 Inches of Water
One inch of water column (inH₂O or in WC) = pressure from 1 inch of fresh water at standard gravity ≈ 249.09 Pa. The standard unit for low-pressure measurement in US HVAC and plumbing: ductwork static pressure, fan performance, filter ratings, and gas appliance manifold pressures are all specified in inches WC. Household natural gas supply pressure is typically 7 in WC (0.25 psi). Blower door tests for building air-tightness use 50 Pa ≈ 0.2 in WC test pressure. 1 inH₂O = 249.089 Pa.
Quick Reference Table
| Centimeters of Water (cmH₂O) | Inches of Water (inH₂O) |
|---|---|
| 1 cmH₂O | 0.393701 inH₂O |
| 2 cmH₂O | 0.787402 inH₂O |
| 5 cmH₂O | 1.9685 inH₂O |
| 10 cmH₂O | 3.93701 inH₂O |
| 25 cmH₂O | 9.84252 inH₂O |
| 50 cmH₂O | 19.685 inH₂O |
| 100 cmH₂O | 39.3701 inH₂O |