Convert Millimeters of Water to Kilopascals
Convert Millimeters of Water (mmH₂O) to Kilopascals (kPa) instantly and accurately.
Conversion Formula
kPa = mmH₂O × 0.00980665
About Millimeters of Water
One millimetre of water column (mmH₂O) = pressure from 1 mm of fresh water at standard gravity = exactly 9.80665 Pa. Preferred for very low differential pressures in HVAC: ductwork static pressures, fan curves, filter resistance, and building pressurisation are in mm WC. Gas valve operating pressures are typically 0.5-3 mm WC; clean-room cascade differentials 12-25 mm WC. A domestic gas hob manifold operates at ~20 mm WC on natural gas. Also used in spirometer calibration and hospital oxygen delivery systems. 1 mmH₂O = 9.80665 Pa.
About Kilopascals
A kilopascal (kPa) = 1,000 Pa - the practical everyday SI pressure unit for moderate pressures. Car tyre inflation: 200-250 kPa (29-36 psi); truck tyres 550-830 kPa. Blood pressure in SI countries: 16/10.7 kPa (= 120/80 mmHg). Systolic blood pressure 16 kPa. Carbonated beverages are packaged at 200-500 kPa CO₂. Medical oxygen cylinders at 15,000 kPa; scuba cylinders 200-300 bar = 20,000-30,000 kPa. 1 kPa = 1,000 Pa = 0.01 bar = 0.145 psi.
Quick Reference Table
| Millimeters of Water (mmH₂O) | Kilopascals (kPa) |
|---|---|
| 1 mmH₂O | 0.00980665 kPa |
| 2 mmH₂O | 0.0196133 kPa |
| 5 mmH₂O | 0.0490333 kPa |
| 10 mmH₂O | 0.0980665 kPa |
| 25 mmH₂O | 0.245166 kPa |
| 50 mmH₂O | 0.490333 kPa |
| 100 mmH₂O | 0.980665 kPa |