Convert Inches of Mercury to Millibars

Convert Inches of Mercury (inHg) to Millibars (mbar) instantly and accurately.

Conversion Formula

mbar = inHg × 33.8638864

About Inches of Mercury

One inch of mercury (inHg) ≈ 3,386 Pa - the primary barometric pressure unit in US aviation and meteorology. ASOS weather stations, METARs, and altimeter settings in the US report in inHg. Standard sea-level pressure is 29.92 inHg. Altimeters are set to local QNH in inHg to maintain altitude reference. US barometers for home weather stations display inHg. Typical pressure range: 28.5-31.0 inHg in continental weather systems. Record low: ~25.70 inHg (Typhoon Tip, 1979). 1 inHg = 3,386.39 Pa.

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.

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