API for Calculating Flight Miles
 

Does anyone know what service/API sites use to calculate the flight miles between two airports?

Usually based off great circle routing

gcmap.com is an example site

However, some airlines (such as DL) don't seem to follow any of the standard sources and you need to check the miles on their own website. Differences compared to the great circle routing calculations are not unusual, although the deviations are usually small. Also, the distances according to DL occasionally change, so you can't necessarily go by previous experience.

Thanks good sir. Do you know what the service behind that site is? I'm looking to query the service directly instead of going through this or another website.

No idea. Sorry!

The formula for doing the math is actually pretty easy and well documented. You need a database of IATA codes, latitude & longitude to feed in to the formula but once you have that then getting the maths part done is easy. Doing a ton of calculations can slow down the server a bit but if it is just a couple per page load that shouldn't be an issue. I have the code in vb.net if you want that. I'll even give you a dump of the airports table from my DB if you want that, too.

I suppose I could set up an API-ish service to just return the distances if you want that rather than doing the calculations on your own server.

how much you charge to do that