Frequently Asked Questions

1) What equations are used to calculate the Density Altitude?

All of the equations and algorithms are given on my Density Altitude web page. Click here to go to the Density Altitude page.

2) How is the Dyno Correction Factor calculated?

All of the equations and algorithms are given on my Correction Factor web page. Click here to go to the Corrected Horsepower page.

3) Why don't these calculated density altitude values agree with the density altitude reported by my local ASOS/AWOS-3?

It appears that the ASOS/AWOS-3 stations (automated weather observation stations located primarily at airports all around the US) do not include the moisture content of the air in their density altitude calculations. You can approximate their calculations by setting the dew point (or relative humidity) to a very low value.

4) Can you send me an Excel spreadsheet with these calculations?

No, I have only created the calculators as Javascripts, so either use them as Javascripts, or go to the pages of calculator equations (as described in items 1 and 2 above) and write your own spreadsheet program using the equations and algorithms that I've carefully described.
 

5) Can I use the calculator when I'm not connected to the internet?

Sure... it's very easy to save the calculator on your computer. In fact, virtually any web page from any web site can be saved on your computer.
 
If you're using Microsoft Internet Explorer:

Go to the web page that you want to save.. then in the web browser menu bar, click on File, then click on Save As.

Then the Save Webpage dialog box will then pop open... Choose a file name and location that suit you, select Save as type: Web Page, Complete. Then select Encoding: Western European (Windows).. then click Save.

If you're using Firefox:

Go to the web page that you want to save.. then in the web browser menu bar, click on File, then click on Save Page As.

Then the Save As dialog box will then pop open... Choose a file name and location that suit you, select Save as type: Web Page, Complete.. then click Save.

Presto.. the web page is now stored on your computer and can be run anywhere, anytime.

6) Can I run the calculators on my iPhone, 'Droid or Blackberry?

Yes, any of the calculators can be run on any smart phone, or any other digital appliance, which has a JavaScript-enabled web browser.

You can either run the calculator in your web browser using an internet connection, or you can run the calculators "off-line" by saving the complete web page to your mobile device as described in item 4 above.

Additionally, there is an iPhone/iPod Touch/iPad app called DenAlt, created by Marcus Staloff, available for free in the "Navigation" section of the Apple Apps store which uses these same density altitude equations, and presents an attractive graphic display.

7) Can I put the calculators on another web site?

No... Please don't. From time to time I make changes and improvements in the calculators, and I want all users to be able to come to this web site in order to use the very latest, most accurate versions of these copyrighted calculators.

As alternatives to putting my calculators on your web site: you can open a new browser window and display my web page in that new window, or you can just give your users a link to my web page.

All of the calculators are copyrighted, and are made available for use on this web site for an individual's own personal usage.

8) General copyright statement for all of the calculators

Copyright 1998-2010.
All Rights Reserved, Richard Shelquist, January 1998 - Apr 2010.
The calculators on this web site, including all programming code, are the copyrighted intellectual property of Richard Shelquist and Shelquist Engineering. The calculators may be freely used for an individual's own personal use via my web site, or by means of one copy on an individual's own computer for personal use, but no portion of the calculator may copied or republished in any form on any web site, bulletin board, computer network, or any other means.

updated 18-Sep-2007