Convert Millibars to Inches of Water
Convert Millibars (mbar) to Inches of Water (inH₂O) instantly and accurately.
Conversion Formula
inH₂O = mbar × 0.401463076
About Millibars
A millibar (mbar) = 100 Pa = 1 hPa - the historically dominant meteorological pressure unit. Standard sea-level pressure is 1013.25 mbar. Hurricane intensity is characterised by central pressure: Category 5 storms typically below 920 mbar (US record: 892 mbar, 1935). Upper-air analysis levels - 850, 700, 500, 300, 200 mbar - appear throughout decades of archived meteorological data. Aircraft cabins are pressurised to ~750-800 mbar at cruise altitude. 'Weather bombs' see pressure fall 24+ mbar in 24 hours. 1 mbar = 100 Pa.
About Inches of Water
One inch of water column (inH₂O or in WC) = pressure from 1 inch of fresh water at standard gravity ≈ 249.09 Pa. The standard unit for low-pressure measurement in US HVAC and plumbing: ductwork static pressure, fan performance, filter ratings, and gas appliance manifold pressures are all specified in inches WC. Household natural gas supply pressure is typically 7 in WC (0.25 psi). Blower door tests for building air-tightness use 50 Pa ≈ 0.2 in WC test pressure. 1 inH₂O = 249.089 Pa.
Quick Reference Table
| Millibars (mbar) | Inches of Water (inH₂O) |
|---|---|
| 1 mbar | 0.401463 inH₂O |
| 2 mbar | 0.802926 inH₂O |
| 5 mbar | 2.00732 inH₂O |
| 10 mbar | 4.01463 inH₂O |
| 25 mbar | 10.0366 inH₂O |
| 50 mbar | 20.0732 inH₂O |
| 100 mbar | 40.1463 inH₂O |