Free reference
Altimeter Setting to Station Pressure
Turn the barometer in a weather report into the true station pressure density altitude needs.
What is the difference between altimeter setting and station pressure?
Station pressure is the real air pressure where you stand. A Kestrel, a track weather station and the app's weather all report it. Altimeter setting is that pressure corrected to sea level, so weather reports from different elevations can be compared. It is the "barometer" on most weather apps.
At sea level they are the same. Up high they are far apart: on a standard day at 2,000 ft the altimeter setting reads 29.92″ while station pressure is about 27.82″. Density altitude needs station pressure. Put an altimeter setting into a DA formula and the answer comes out far too low.
How do I convert altimeter setting to station pressure?
The conversion is the standard-atmosphere reduction the National Weather Service uses: station pressure = altimeter × (1 − 0.0065 × elevation in meters ÷ 288.15)5.255. The DA calculator has an altimeter box that does this for you.
What is station pressure at my elevation?
Station pressure in inches of mercury for common altimeter settings and track elevations.
| Elevation | 29.60″ | 29.80″ | 29.92″ | 30.00″ | 30.20″ | 30.40″ |
|---|---|---|---|---|---|---|
| 0 ft | 29.60 | 29.80 | 29.92 | 30.00 | 30.20 | 30.40 |
| 1,000 ft | 28.55 | 28.74 | 28.85 | 28.93 | 29.12 | 29.32 |
| 2,000 ft | 27.52 | 27.71 | 27.82 | 27.89 | 28.08 | 28.27 |
| 3,000 ft | 26.53 | 26.71 | 26.82 | 26.89 | 27.07 | 27.25 |
| 4,000 ft | 25.57 | 25.74 | 25.84 | 25.91 | 26.08 | 26.26 |
| 5,000 ft | 24.63 | 24.80 | 24.90 | 24.96 | 25.13 | 25.30 |
| 6,000 ft | 23.72 | 23.88 | 23.98 | 24.04 | 24.20 | 24.36 |
| 7,000 ft | 22.84 | 23.00 | 23.09 | 23.15 | 23.30 | 23.46 |
Then look up your DA on the density altitude chart.
Can the app do this for every pass?
Yes. The free logbook saves true station pressure and DA from the closest weather station each time you log a pass. Photograph your meter and it reads that instead.