Air Density Online

weather calculations for racers

Free Weather Calculations based on weather data you input
Real-time information based on current weather observations at various race tracks.
Jet your car from anywhere with an internet connection

Sep 20, 16 - Historical Weather Data

We've gotten a few questions recently asking about weather data from a past date. We do not store historical data on our site. But all hope is not lost! There is still a way to get air density or adjusted altitude from a previous date.

  1. Type in the date and location at Weather Underground History & Data Archive.
  2. Once you've found your date and location, scroll to the bottom to find the closest time in the Hourly Weather History & Observations section.
  3. You will need to get the elevation for your location. You can find that either on the track page or using the altitude calculator near the bottom of the free calcs page.
  4. Then using the temperature, humidity, and barometer from Weather Underground as well as the elevation, use the top calculator on the free calcs page to get the air density, density altitude, corrected barometer, and other information.

Hopefully this will help when looking for weather from past dates!

Sep 1, 16 - The latest race tracks added

We added a few more tracks in August:

Want to see your track in the list also? Send it to us and we'll add it ASAP!

Aug 26, 16 - Price changes are coming to Pro-Calc

Several years ago we set a special introductory price of Pro-Calc thinking we would change it eventually. Well... it took a few years but that time has come! Starting November 1 the price for Pro-Calc will be going up to $89.99/year.

We have added many new features to Pro-Calc including an expanded help section and more frequently updated weather in the tracks section for registered users. We plan on adding more new features in the upcoming months.


We want to show our appreciation for our users who have used Pro-Calc over the last few years. Therefore, anyone who signs up at the current price will be locked into that price going forward for at least the next 3 years. This means that anyone who has signed up before November 1, 2016 will continue to receive the $59.99/year price through 2019!

Have you been on the fence regarding Pro-Calc? Try a free 14 day trial or sign up for Pro-Calc to lock in the current low price!

Aug 22, 16 - Measuring the Atmosphere Around a Track

Imagine a cubic foot of air near the ground level at the race track. It may seem empty but there are molecules moving around within that area. Depending on various environmental factors, that cubic foot of air can contain oxygen, other elements such as nitrogen and carbon dioxide, moisture, and particles of pollution. Each of these vary depending on the location, elevation, and current weather environment.

We need oxygen for combustion in our engines. However, as we can see, the amount of oxygen in the atmosphere fluctuates. This is why, for instance, you might notice a great engine performance at certain times of day and bad performance at others. Tracking the weather can help us determine jetting changes in order to compensate for the changing atmosphere. Using the information we provide on the tracks pages of this site can help you do that.

This article will explain those variables. Hopefully it will help you to better understand the atmosphere and better tune your engine for optimum performance.

(read more...)
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