Inches Of Water to Kilopascals (inH₂O to kPa)
1 inch of water equals 0.24908891 kilopascals exactly.
How to convert inches of water to kilopascals
To convert inches of water to kilopascals, multiply the number of inches of water by 0.24908891. This factor is exact. To go the other way, multiply kilopascals by 4.01463076 (rounded).
kilopascals = inches of water × 0.24908891
Example: 10 inches of water = 2.4908891 kilopascals.
About these units
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
Kilopascal (kPa)
1,000 pascals. Used for tire pressures, weather reports in many countries and engineering.
Kilopascal is the form of the pascal that most people actually use. The pascal itself is very small, so outside meteorology the kilopascal became the common choice in most fields, and it equals one centibar. Medical elastography reports tissue stiffness in kPa, and Canada reports atmospheric pressure in kPa rather than hectopascals.
A standard atmosphere is 101.325 kPa. In 1982 IUPAC recommended a different reference for chemistry, a standard pressure of exactly 100 kPa, which split the older convention of 1 atm into two competing standards.
Blood pressure shows how the units line up. One mmHg is 0.13332 kPa, and a normal reading is below about 16.0 kPa systolic and 10.7 kPa diastolic, the same thing as the familiar 120 over 80 in millimeters of mercury.
1 kilopascal = 1,000 pascals (exactly).
Sources: Wikipedia: Pascal (unit); Wikipedia: Standard atmosphere (unit); Wikipedia: Millimetre of mercury
Related conversions
- Kilopascals to inches of water (reverse)
- Inches of water to pascals
- Inches of water to bars
- Inches of water to standard atmospheres
- Inches of water to PSI
- Pascals to kilopascals
- Bars to kilopascals
- Standard atmospheres to kilopascals
- PSI to kilopascals
- Hectopascals to kilopascals
- Megapascals to kilopascals
- Millibars to kilopascals
- Torr to kilopascals
- Millimeters of mercury to kilopascals
- Inches of mercury to kilopascals
- Gigapascals to kilopascals
- Kilopounds per square inch to kilopascals
See all pressure units.