Pressure units used in weather
Meteorologists commonly use hectopascals (hPa) or millibars (mbar); these units are numerically identical. Aviation reports in the United States often use inches of mercury (inHg), while scientific and engineering work may use pascals, kilopascals or bars.
Common atmospheric pressure conversions
- 1 hPa = 1 mbar = 100 Pa
- 1 standard atmosphere = 1013.25 hPa
- 1013.25 hPa = 29.9213 inHg
- 1013.25 hPa = 760 mmHg
Station pressure vs sea-level pressure
A pressure conversion changes only the unit. It does not adjust a station reading for elevation. Weather maps normally show pressure reduced to mean sea level so locations at different elevations can be compared. Converting a mountain station's raw pressure to inHg will not turn it into sea-level pressure.
Small differences can appear because apps round to different decimal places. This converter keeps a high-precision value internally and formats each unit to a useful number of digits.
Frequently asked questions
Are hPa and mbar the same?
Yes. One hectopascal is exactly equal to one millibar, so weather values are numerically identical in both units.
What is normal atmospheric pressure?
The defined standard atmosphere is 1013.25 hPa, 29.9213 inHg or 760 mmHg. Actual local pressure changes with weather and elevation.
Does this converter correct pressure for altitude?
No. It converts units only. Altitude correction requires elevation, temperature and a defined reduction method.
Method and sources
Last reviewed: July 11, 2026.
