PSI to Inches Of Water (psi to inH₂O)
1 pound per square inch equals 27.67990471 inches of water (rounded).
How to convert pounds per square inch to inches of water
To convert pounds per square inch to inches of water, multiply the number of pounds per square inch by 27.67990471. The factor is rounded to 10 significant digits. To go the other way, multiply inches of water by 0.036127292 (rounded).
inches of water = pounds per square inch × 27.67990471
Example: 10 pounds per square inch = 276.7990471 inches of water.
About these units
Pound Per Square Inch (psi)
About 6,894.757 pascals. The common unit for tire pressure, hydraulics and gas pipelines in the US.
Unlike most pressure units, psi has no namesake: it simply spells out its own definition, one pound-force acting on one square inch, and it is based on avoirdupois units. Used mainly in the United States, it is about 6.895 kilopascals.
The letters after the unit matter. Psia is measured against a vacuum, while psig is measured against the surrounding air, so at sea level, where the atmosphere is about 14.7 psi, you add that amount to a gauge reading to get an absolute one. A bicycle tire at 65 psig is therefore at 79.7 psia, and the label psid means a difference between two pressures rather than a reference to ambient air.
Typical automobile tires are listed at about 32 psig, and road racing bicycle tires at about 120 psig. One standard atmosphere is 14.696 psi, which gives a feel for how many multiples of sea-level air those tire pressures represent.
1 pound per square inch = 6,894.757293 pascals (approximately).
Sources: Wikipedia: Pounds per square inch; Wikipedia: Standard atmosphere (unit)
Inch Of Water (inH₂O)
About 249.089 pascals (the conventional value, 25.4 mm × 9.80665 Pa). Used for air pressure in HVAC and gas appliances.
Building services and gas fitting rely on this unit. Manometers filled with water read small differences in air or gas pressure, and in North America the result is stated in inches of water column. Natural gas supplied to appliances is typically 6 to 7 inches WC, and HVAC technicians use it for pressure across coils, filters and ducts. A pipe organ's wind pressure is quoted the same way.
Which water is meant matters a little. Wikipedia gives about 249.082 Pa for water at 4 degrees Celsius, equal to 39.2 degrees Fahrenheit, and also the conventional 249.08891 Pa, which is 25.4 mm times 9.80665 and is the figure used here. NIST lists 249.082 Pa at 39.2 degrees Fahrenheit and 248.84 Pa at 60 degrees Fahrenheit, and some industry standards use 60 or 68 degrees Fahrenheit. About 27.7 inches of water equal 1 psi.
1 inch of water = 249.08891 pascals (exactly).
Sources: Wikipedia: Inch of water; NIST SP 811, Appendix B.8
Related conversions
- Inches of water to PSI (reverse)
- PSI to pascals
- PSI to kilopascals
- PSI to bars
- PSI to standard atmospheres
- PSI to hectopascals
- PSI to megapascals
- PSI to millibars
- PSI to torr
- PSI to millimeters of mercury
- PSI to inches of mercury
- PSI to gigapascals
- PSI to kilopounds per square inch
- Pascals to inches of water
- Kilopascals to inches of water
- Bars to inches of water
- Standard atmospheres to inches of water
See all pressure units.