– free air density forecast for USA racetracks:
– free air density calculator for anywhere:

From this site, the racer can determine air density, density altitude, and grains of water; all commonly used in tuning race engines. Currently for racetracks throughout the USA, the racer can locate the track from an extensive list of tracks. Click on the track, and the current air density values appear instantly. A forecast is provided from the page as well. Click on “view forecasted data” near the center of the web page.

Locations outside the USA are currently not set up on this track locator page. For these, the racer can look up free calcs and enter temperature and humidity. If the racer has the uncorrected air pressure, that value can be entered. If the racer has the corrected air pressure, he needs the altitude of that location. The free calculator will determine the air density, density altitude, and grains of water.