Convert Feet of Water to Inches of Water
Convert Feet of Water (ftH₂O) to Inches of Water (inH₂O) instantly and accurately.
Conversion Formula
inH₂O = ftH₂O × 12
About Feet of Water
One foot of water column (ftH₂O) ≈ 2,989 Pa - the US customary equivalent of cmH₂O used in civil and hydraulic engineering. Municipal water supply systems are designed for 40-80 psi head ≈ 92-184 ft; fire suppression sprinkler systems require minimum 7 psi ≈ 16 ft. Well pump specifications, sump pump head ratings, irrigation mainline pressure, and drainage calculations all use feet of head. 1 ft of water = 12 in WC = 0.4335 psi ≈ 2,989 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
| Feet of Water (ftH₂O) | Inches of Water (inH₂O) |
|---|---|
| 1 ftH₂O | 12 inH₂O |
| 2 ftH₂O | 24 inH₂O |
| 5 ftH₂O | 60 inH₂O |
| 10 ftH₂O | 120 inH₂O |
| 25 ftH₂O | 300 inH₂O |
| 50 ftH₂O | 600 inH₂O |
| 100 ftH₂O | 1200 inH₂O |