Convert Inch of water to Millimeter of Water (inH2O to Millimeter of Water)

Inch of water (inH2O) and Millimeter of Water (Millimeter of Water) are both units of pressure. With the conversion form below, you can effortlessly and accurately convert inch of water to millimeter of water. This free online calculator tool makes it simple and easy to perform the conversion from inH2O unit to the Millimeter of Water unit.

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 inch of water (symbol: inH₂O or inH2O) is a non-SI unit of pressure based on the pressure exerted by a one-inch column of water under standard gravity. It is commonly used in HVAC systems, ventilation, gas distribution, and fluid mechanics to measure low-pressure differences. Although the pascal is the SI unit of pressure, the inch of water remains widely used because it provides a convenient scale for low-pressure applications. More information is available in the inch of water reference.

One inch of water is equal to 249.089 pascals, 2.54 centimeters of water, 0.00249089 bar, 0.0361263 psi, and 0.249089 kilopascals. The inch of water is one of the most commonly used units for measuring low gas and air pressures.

The millimeter of water (symbol: mmH₂O or mmH2O) is a non-SI unit of pressure defined as the pressure exerted by a one-millimeter column of water under standard gravity. It is commonly used in ventilation systems, clean rooms, HVAC engineering, and laboratory instruments to measure small pressure differences. Although the pascal is the SI unit of pressure, the millimeter of water remains a practical unit for low-pressure applications. It is based on the concept of a water column.

One millimeter of water is equal to 9.80665 pascals, 0.1 centimeter of water, 0.0000980665 bar, 0.00142233 pounds per square inch, and 0.00980665 kilopascal. The millimeter of water is widely used for measuring very low gas and liquid pressures.