How to convert inches of mercury to millibars
- Take the value in inches of mercury.
- Use the formula millibars = inches of mercury × 33.86389.
- For example, 29.92 inHg is 1,013.21 mbar.
About inches of mercury and millibars
One inch of mercury is 3,386.39 pascals, which is 33.8639 millibars or hectopascals. Multiply inHg by 33.864 to get mbar. 30.00 inHg is 1,015.92 mbar and 29.00 inHg is 982.05 mbar.
The unit comes from mercury barometers, where air pressure holds up a column of mercury about 30 inches tall. US weather reports, home barometers and North American altimeter settings still use it, while forecasts and aviation elsewhere use hPa (mbar). The value here is for mercury at 0 °C, the standard reference.
Examples
- 29.92 inHg (standard pressure, the altimeter setting used above 18,000 ft in the US) is 1,013.21 mbar
- 30.2 inHg (a fair-weather high, an illustrative value) is 1,022.69 mbar
- 28.5 inHg (a strong storm, an illustrative value) is 965.12 mbar
- 26.05 inHg (Hurricane Wilma in 2005, the lowest Atlantic pressure on record) is 882.15 mbar
Inches of mercury to millibars chart
| Inches of mercury (inHg) | Millibars (mbar) |
|---|---|
| 26 | 880.46 |
| 27 | 914.33 |
| 27.5 | 931.26 |
| 28 | 948.19 |
| 28.5 | 965.12 |
| 29 | 982.05 |
| 29.2 | 988.83 |
| 29.4 | 995.6 |
| 29.5 | 998.98 |
| 29.6 | 1,002.37 |
| 29.7 | 1,005.76 |
| Inches of mercury (inHg) | Millibars (mbar) |
|---|---|
| 29.8 | 1,009.14 |
| 29.9 | 1,012.53 |
| 29.92 | 1,013.21 |
| 30 | 1,015.92 |
| 30.1 | 1,019.3 |
| 30.2 | 1,022.69 |
| 30.3 | 1,026.08 |
| 30.4 | 1,029.46 |
| 30.5 | 1,032.85 |
| 30.6 | 1,036.24 |
| 31 | 1,049.78 |