Open any European weather map and the swirling L over a storm reads something like 998 hPa, a number that means nothing to an American raised on inches of mercury. That number is millibars in disguise — the hectopascal and the millibar are numerically identical, so 998 hPa is 998 mbar — and it tells you exactly how deep the low-pressure system is. The anchor point for the whole scale is standard sea-level pressure: 1,013.25 mbar, which also equals 101,325 pascals, 760 millimeters of mercury, and 14.6959 PSI. This converter starts from Millibars (mbar) and fans out to Bar, Pascals (Pa), Kilopascals (kPa), PSI, and mmHg in a single glance, because weather nerds, divers checking their gauges, and chemistry students each need a different dialect. Type 1013.25 and you will see 1.01325 bar, 101,325 Pa, 101.325 kPa, 14.6959 PSI, and 760 mmHg all at once. The handy identity to carry in your head is that one millibar is exactly 100 pascals — the millibar was built that way when meteorologists moved to SI units, which is why converting mbar to Pa is the easiest multiplication on this page.

With the pre-filled defaults — Millibars (mbar) 1,013.25 — the Millibar Converter returns Bar 1.013250, Pascals (Pa) 101,325.00, Kilopascals (kPa) 101.3250, PSI 14.6959, mmHg 760.0003. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.