What is the width of seat tracks on airliners? I've been scouring the internet for the track width of seats in airlines, and can't find anything on it. Does anyone know around what that dimension might be?

I'm not looking for the dimensions of the seats themselves, but the width of the tracks that the seats attach to.
The attachment rail/track width (gauge) is not fixed. It differs from plane to plane, and the chosen seat manufacturer obliges.

21" or 55 cm seems the average though.



Source: stanford.edu

Above image shows B717 cross section, you can notice the 3-abreast and 2-abreast both are on two rails. No high-res available.

Different plane models:



Some are wall mounted.