Here ya go...
View attachment 132285
I wrote this up a couple years or so back... It's posted on here somewhere, but never hurts to toss it out again in a new post from time to time...
Basically the tubes are listed from smallest to largest. This is essentially all LPR/MPR tubes. Some new ones have probably come out (say for the big new Estes kits) but I haven't bought any of them and haven't added them to the list. It's a good start anyway if someone wants to add to it, have at it...
I didn't put "Estes" as a mfg. on the list-- basically anything with a "BT-" designator is an Estes tube... (not that they offer all of them for sale, hence the Semroc and Totally Tubular references). Quest uses metric-sized tubes where the tube number is the outer diameter in millimeters IIRC.
As for the naming conventions, it's a long story, but basically they started with the BT-20 size tube (which an 18 mm motor fits nicely into) and then as they added new sizes, they assigned an arbitrary number from there, like old code jumping in tens to leave room between the numbers in case they came out with a size "in between" two already available sizes later on... For instance, when they came out with a tube between the size of BT-50 and BT-60, they called it a BT-55. Centuri used a tube a hair bigger than BT-55, and when Estes bought Centuri they ended up with them, and ultimately used that tube size on some of their rockets (like the Astrocam 110) and thus called it a BT-56. There's more to it than that and someone could really explain the history of it if they wanted to...
Later and good luck! OL JR