Convert Feet of Water to Inches of Mercury
Convert Feet of Water (ftH₂O) to Inches of Mercury (inHg) instantly and accurately.
Conversion Formula
inHg = ftH₂O × 0.8826709623
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 Mercury
One inch of mercury (inHg) ≈ 3,386 Pa - the primary barometric pressure unit in US aviation and meteorology. ASOS weather stations, METARs, and altimeter settings in the US report in inHg. Standard sea-level pressure is 29.92 inHg. Altimeters are set to local QNH in inHg to maintain altitude reference. US barometers for home weather stations display inHg. Typical pressure range: 28.5-31.0 inHg in continental weather systems. Record low: ~25.70 inHg (Typhoon Tip, 1979). 1 inHg = 3,386.39 Pa.
Quick Reference Table
| Feet of Water (ftH₂O) | Inches of Mercury (inHg) |
|---|---|
| 1 ftH₂O | 0.882671 inHg |
| 2 ftH₂O | 1.76534 inHg |
| 5 ftH₂O | 4.41335 inHg |
| 10 ftH₂O | 8.82671 inHg |
| 25 ftH₂O | 22.0668 inHg |
| 50 ftH₂O | 44.1335 inHg |
| 100 ftH₂O | 88.2671 inHg |