Air Density Online

About this site

This site was created to provide weather calculations for land and water racing. It uses data from various third party sources including the National Weather Service. This is useful for racers who tune using air-fuel ratio or anyone who could benefit from weather data such as air density and density altitude while tuning their engines.

Currently, the tracks weather pages list tracks worldwide including in the United States, Canada, and Australia. If you have a track that's not on the list, contact us and we will work to add it to the site.

FAQ: ProCalc & ProTune | FAQ: DA Calc & Tracks | Articles | Disclaimer | The Developers | Credits

FAQ: Tracks and DA Calculator

I'm a racer. How do I use this site?
This site is designed to enable racers to track various weather data for the purposes of engine tuning. It is important to track the amount of oxygen in the air in order to get the best combination of oxygen and fuel for combustion within an engine. Many factors can influence the amount of oxygen in the air including temperature, humidity, barometric pressure, and track elevation. This site helps to track that information.

The list of US race tracks and the list of international race tracks provides current weather data, a 36 hour forecast, and historical weather for past dates. If you do not see your track in the list, let us know and we will add it.

What math are you using? What industry standards are you using?
This site uses the motorsports standard of 60 deg f, 29.92 inHg (at sea level), and dry air (0% relative humidity). Please note that this site does not support the aerospace or automotive standards of ambient weather conditions.

What do you mean by corrected and uncorrected barometer?
The barometer reading you see when you check the weather report is a corrected value. It is adjusted to provide a standard measurement across different elevations. The calculations in this site require the uncorrected value in order to provide accurate results. Please note:

  • If you are getting your barometer value from the local weather report, chances are it is the corrected value and needs to be adjusted. On this website, that means that you will need to provide the elevation of the location you will be at.
  • If you are getting your barometer value from a barometer measuring device, it is most likely the uncorrected value and needs no adjustment. If this is the case, do not enter the elevation of your location when using the calculators on this site.

We wrote a blog post about this if you would like further information: Understanding the difference between corrected and uncorrected barometer.

How accurate is the weather data for each track?
Basic weather data comes from either the National Weather Service or Visual Crossing Weather and, as such, is very accurate. However, the closest weather station to each track can vary in distance from a mile or two up to 20-30 miles. Additionaly, the weather data is updated hourly (sometimes less in certain locations). Please note, however, that the track elevation, latitude, and longitude are always taken from the track's location and not from the weather station's location. If you need to calculate density altitude with custom weather variables, there is a free air density calculator you can use instead.

Why is the forecast section considered experimental?
This section uses forecasted data that may or may not be accurate. Particularly, forecasting barometer can be tricky. Our weather provider, Visual Crossing Weather, is very good but you should consider all this data as being for informational purposes only.

This page is meant as a general reference. If you would like a more precise density altitude or air density, you can enter the values into the free DA calculator.

How do I interpret the wind direction?
The standard for reading wind direction is to interpret it as the direction it is coming from. If the direction lists N (north), that means it is coming from the north and blowing south. If SE (southeast) is listed, that means the wind is coming from the southeast and blowing to the northwest.

The number, in degrees, listed is the actual degree from due north (0 degrees) that the wind direction is blowing from. 0 to 90 degrees is northeast. 91 to 180 is south east. 181 to 270 is south west. 271 to 360 is north west.

I do not see my track in the list. Will you be adding it any time soon?
We are slowly building and extensive list but want your feedback. Please send your track name and location and we will add it to the list as soon as possible.

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FAQ: ProCalc & ProTune

How much do these cost and what do I get access to?
ProCalc is an annual subscription for $89.99. This will get access to all 3 jetting calculators and the air-fuel ratio calculator. You can store up to 3 baselines for different engine setups and can access your account from anywhere with internet access, especially internet-enabled smartphones. You can export your data as a csv file for keeping extended records. New features are constantly being added. Learn more about ProCalc here.

ProTune features a one time payment for $159.99. This is a program we developed to assist racers in setting up their ideal baseline. Users will fill out a questionnaire regarding their current setup and our engine expert, Bob Szabo, will create an ideal baseline for you including information about how to tune for your specific setup. This will be permanently stored in your account for your reference. You must have a ProCalc subscription in order to utilize Protune.

The ProTuning Package includes ProTune along with 1 year of access to ProCalc for $249.98. For the first year. Renewing your ProCalc subscription will be charged at the current ProCalc price of $89.99.

Recently we added ProTune Advanced. This package is similar to ProTune but we will also provice a custom analysis using current data, a dyno report, or assist in setting up a new combination. ProTune Advanced is available for $599.98.

Please note that the tracks pages and DA calculators will always be free for use by anyone who wishes to use them.

How do I sign up?
You can sign up by going to the ProCalc page and clicking on the buy now button for the option you would like to purchase. From there you will be taken to Paypal's website where your payment will be processed. Upon successful completion of payment, you will be redirected to the registration page where you will create your login name and password.

How long does it take for me to get access to ProCalc and/or ProTune?
ProCalc access is granted as soon as payment is received. You will be emailed instructions to complete your signup as soon as your order is processed. If you do not receive an email from us, check your spam folder. If you still have not received an email, contact us and we will assist you.

ProTune and Protune Advanced access takes a bit longer to get setup. As soon as your payment is received, you will be emailed a questionnaire to fill out and you will be given immediate access to the ProTune area of ProCalc. However, the full setup cannot be made available until we have received your questionnaire and have had time to process your setup. Please allow up to 5 business days once your questionnaire has been received to finish your ProTune setup. Also, please be aware that Bob may contact you by email for further information regarding your setup. While we will work to provide your details as quickly as possible, we will not proceed until we receive all the information requested. If you have not received you questionnaire or have further instructions regarding ProTune, contact us for further information.

What is your refund policy?
ProCalc customers have 30 days from date of payment to request a refund. We will remove your access and refund the full amount of your payment. To request a refund, contact us here.

ProTune and ProTune Advanced customers can request a refund if they have not yet submitted their questionnaire for processing. Once we have received your questionnaire, we will begin configuring your setup in our system. A 50% refund may be granted after submitting your questionnaire if Bob has not yet completed your setup. To request a refund for ProTune or ProTune Advanced, contact us here.

Read more about our refund policy on our Terms and Conditions page.

Any questions regarding our refund policy can be made by filling out our contact form here.

What types of fuel are supported?
Methanol is the main fuel that is supported on this site. E85 is also supported. We have ProCalc procedures for other ethanol blends as well as racing gasoline. Contact us with questions regarding your application.

Nitro is supported as well. When using the calculators, an option to enter a percentage of nitro up to 100% is available. Percentages are calculated either by weight or by volume. This option allows you to test your setup using methanol while also by adding percentages of nitro to your setup.

What kinds of engines are you supporting?
Currently normally aspirated and supercharged fuel injected engines are supported. This should accommodate a majority of racers. We also have procedures for turbocharged racing engines, 2 cycle, and rotary engines as well. (contact us for info about these engines) We are not supporting carbureted engines at this time. If you are unsure if our site will work with your engine, please contact us for further assistance.

What are the advantages of using air/fuel ratio?
Air/fuel ratio is a proven method of maintaining the optimum combination of air and fuel for the purposes of combustion within your engine. By maintaining this ratio with changing weather or elevation, you will be able to maintain your engine's peak performance despite environmental changes. Air to fuel ratio is the fundamental value used in EFI. ProCalc provides that information to mechanical fuel injection as well.

I'm not familiar with tuning using Air/fuel ratio. Will I be able to easily understand your site?
The first time you log in to ProCalc, you will be prompted to create a baseline using easily accessible information about your engine setup. An air/fuel ratio will be created from that and can be used as a starting point for fine-tuning your setup and for learning about air/fuel ratio. In addition there is an extensive help, example, and troubleshooting section along with detailed help videos available to ProCalc members.

If you are still unsure about going it on your own, we have created ProTune to further assist you in getting setup. We will get details about your engine setup and create you first baseline for you. In addition, we will provide detailed information about your specific setup. Click here to learn more about ProTune. If you have dyno data or an extensively customized setup, we offer ProTune Advanced.

Do you have any plans for developing this site further?
There are many plans in development for the site. If you have ideas for features, please contact us.

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Helpful Articles

We have written several articles for our website and for various publications. These may assist you with weather data and engine tuning. Hopefully they will help you get more use out of this site. Check this page often for the latest articles.

Visit articles page

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Please note: This site is a reference for racers to check their jetting. It is not intended as a diagnostic tool for complete engine function. Checking results against another source is recommended. Many engine setup & tuning needs go beyond the intent & capability of this site. Ultimately the racer, crew chief, or car owner has final say in which engine modifications are made.

Full details of our legal policy can be found on our legal page. Any questions or comments regarding this policy can be made on our contact form.

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Meet the developers

Bob Szabo is a welding engineer, long-time drag racer, and author at He has published materials about engine tuning for racers using air-fuel-ratio and advocates using afr tuning for greater control and repeatability in engine tuning. You can learn more about Bob's background in his bio on

Jennifer Szabo is Bob's daughter and a professional web developer. Jennifer grew up around drag racing and helped edit her dad's books. However her main contribution to this site is as the programmer who keeps the site running on the web.

Bob and Jennifer enjoy interacting with racers. If you have any questions regarding the use of this site or racing in general, send them a question and they will do their best to answer it.

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Information and math related to air density and engine calibration came from information provided by

Weather and geographical info used on this site is provided by:

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