Convert Feet of water to Inch of mercury (ftH2O to inHg)

Pressure is the force applied perpendicular to a surface per unit area: P = F / A. The SI unit is the pascal (Pa), equal to one newton per square metre (1 Pa = 1 N/m²). Practical applications use larger units: the bar (1 bar = 100,000 Pa, close to standard atmospheric pressure), atmosphere (atm) (1 atm = 101,325 Pa), and psi (pounds per square inch, used in the US for tire and gas pressures). Blood pressure is measured in mmHg (millimetres of mercury), also called torr.

The foot of water (symbol: ftH₂O or ftH2O) is a non-SI unit of pressure based on the pressure exerted by a one-foot column of water under standard gravity. It is commonly used in plumbing, HVAC systems, fluid mechanics, and water distribution networks to measure relatively low pressures. Although the pascal is the SI unit of pressure, the foot of water remains widely used in engineering applications involving liquids. More information can be found in the water column reference.

One foot of water is equal to 2,989.07 pascals, 12 inches of water, 0.0298907 bar, 0.433527 psi, and 0.029503 standard atmosphere. The foot of water is widely used for measuring hydrostatic and fluid system pressures.

The inch of mercury (symbol: inHg) is a non-SI unit of pressure based on the height of a mercury column one inch high under standard gravity. It is widely used in aviation, meteorology, and vacuum measurement, particularly in the United States and Canada. Although the pascal is the SI unit of pressure, the inch of mercury remains an important unit in many industries. More information is available in the inch of mercury reference.

One inch of mercury is equal to 3,386.39 pascals, 3.38639 kilopascals, 0.0338639 bar, 0.491154 psi, and 25.4 millimeters of mercury. The inch of mercury is commonly used for barometric pressure and vacuum measurements.