Air Pressure Converter: hPa, mb, inHg and mmHg
Weather maps and most forecasts use hectopascals (the same size as millibars), while US and aviation reports often use inches of mercury. Enter a reading in any unit.
Formula
- 1 hPa = 1 mb = 100 Pa
- 1 mmHg = 133.322387415 Pa (conventional millimetre of mercury)
- 1 inHg = 25.4 mmHg ≈ 3386.389 Pa, so inHg = hPa ÷ 33.86389
hPa, mb and mmHg are shown to 2 decimal places, inches of mercury to 3.
Reference table
| Hectopascals (hPa) | Millibars (mb) | Inches of mercury (inHg) | Millimetres of mercury (mmHg) |
|---|---|---|---|
| 950 | 950 | 28.053 | 712.56 |
| 960 | 960 | 28.349 | 720.06 |
| 970 | 970 | 28.644 | 727.56 |
| 980 | 980 | 28.939 | 735.06 |
| 990 | 990 | 29.235 | 742.56 |
| 1000 | 1000 | 29.53 | 750.06 |
| 1010 | 1010 | 29.825 | 757.56 |
| 1013.25 | 1013.25 | 29.921 | 760 |
| 1020 | 1020 | 30.121 | 765.06 |
| 1030 | 1030 | 30.416 | 772.56 |
| 1040 | 1040 | 30.711 | 780.06 |
| 1050 | 1050 | 31.006 | 787.56 |
Good to know
- 1013.25 hPa is the standard atmosphere, the reference pressure at sea level.
- Weather reports normally give pressure reduced to sea level, so readings from places at different altitudes can be compared directly. A raw reading taken on a mountain will be much lower.