Density altitude for drag racing
A normally aspirated engine makes less power in thin air, so racers compare passes made on different days by the density altitude at the track. Heat and humidity push it up, and so does a falling barometer. This table holds the dew point at 60 F and shows two altimeter settings side by side.
Not for flight planning. Use your aircraft's POH or flight manual and an official weather briefing.
Open these numbers in the calculator and change them to match your own conditions.
| Temperature | Altimeter 29.70 inHg | Altimeter 30.10 inHg |
|---|---|---|
| 60 F (16 C) | 1,182 ft | 725 ft |
| 70 F (21 C) | 1,826 ft | 1,371 ft |
| 80 F (27 C) | 2,456 ft | 2,003 ft |
| 90 F (32 C) | 3,071 ft | 2,620 ft |
| 100 F (38 C) | 3,673 ft | 3,223 ft |
Many racing weather stations report station pressure rather than an altimeter setting. The calculator takes either one: pick station pressure under Pressure input and enter the track elevation.
How these figures are worked out
Each figure uses the National Weather Service method: station pressure from the altimeter setting and elevation, vapour pressure from the dew point, then virtual temperature and density altitude. The calculator runs the same code. Figures are rounded to the nearest foot and are estimates.