How to convert millibars to inches of mercury
- Take the value in millibars.
- Use the formula inches of mercury = millibars × 0.02952998016.
- For example, 1,013.25 mbar is 29.92 inHg.
About millibars and inches of mercury
A millibar is 100 pascals, the same as a hectopascal (hPa), and an inch of mercury is 3,386.39 pascals. So 1 mbar is 0.02953 inHg: multiply millibars by 0.02953, or divide by 33.864. Standard sea-level pressure, 1,013.25 mbar, is 29.92 inHg.
Most weather services and pilots outside North America give air pressure in hPa or mbar, while US weather reports, home barometers sold in the US and North American altimeter settings use inches of mercury. A handy anchor: about 34 mbar make 1 inHg, so a fall from 1,013 to 979 mbar is a drop of about an inch.
Examples
- 1,013.25 mbar (standard sea-level pressure) is 29.92 inHg
- 1,000 mbar (the 1000 mbar line on a weather map) is 29.53 inHg
- 970 mbar (a deep low, an illustrative storm value) is 28.64 inHg
- 870 mbar (Typhoon Tip in 1979, the lowest pressure measured in a tropical cyclone) is 25.69 inHg
Millibars to inches of mercury chart
| Millibars (mbar) | Inches of mercury (inHg) |
|---|---|
| 870 | 25.69 |
| 900 | 26.58 |
| 920 | 27.17 |
| 940 | 27.76 |
| 950 | 28.05 |
| 960 | 28.35 |
| 970 | 28.64 |
| 980 | 28.94 |
| 990 | 29.23 |
| 995 | 29.38 |
| 1,000 | 29.53 |
| Millibars (mbar) | Inches of mercury (inHg) |
|---|---|
| 1,005 | 29.68 |
| 1,010 | 29.83 |
| 1,013.25 | 29.92 |
| 1,015 | 29.97 |
| 1,020 | 30.12 |
| 1,025 | 30.27 |
| 1,030 | 30.42 |
| 1,035 | 30.56 |
| 1,040 | 30.71 |
| 1,050 | 31.01 |