Matchcover sizes are normally spoken of in terms of how many matches that matchbook carries. Hence, a "20-stick" is a matchbook that carries 20 matches. There are some special cases that will be referred to later, however. Foreign sizes don't conform to our domestic standards and have always presented the American collector with a perplexing quagmire!
The 'bread & butter' sizes for matchcovers in this country have been 10s, 20s, 30s, and 40s, and I don't believe anyone makes 10s anymore. All other sizes are peripheral. The 20s and 30s are the most common, with 20s being the leading size, by far.
10-STICK: The standard here was the "Ten-Strike" (trademark) by Universal Match Co. However, Lion Match Co. made a wide-strike Feature that only held 10 matches. The cover, itself, was 30-strike size. A regular 10-strike is half the size of a 20-stick.
11-STICK: Lion Match Co.'s "Giant" held 11 matches, but these, just like the cover, were giant-sized. These covers are 9 1/16"x3 3/8").
12-STICK: Arrow Match Co. had the industry standard here with its "12-Up." Slightly wider than a 10-strike.
14-STICK: Lion's famous "Midget" set the pattern for this size. Ohio Match Co. soon copied it with its "Junior." Opposite composite of the Giant; everything here was miniaturized. (3 3/16"x1 1/8")
15-STICK: Lion "Features" comprise this category. Cover measurement is same as 20-strike cover.
16-STICK: Well, there was a 16-strike, but I've never been able to find out who produced it or what the trademark name was.
18-STICK: This was Universal's "Jupiter One-Eight," a short-lived experiment of making matchbooks in Belgium and then importing them here. 1 1/2"x4 7/16.
20-STICK: Universal's popular "Jewelite" carried 20 matches; later, Columbia Match Co. came out with its "Eagle 20," but, as noted above, 20-strikes were made by everyone! 1 1/2" x4 1/2." The Jewelite measures 1 7/8"x5 1/16."
21-STICK: Lion's extra-nice "21 Features" make up this category. These are 30-strike sized covers.
22-STICK: Here we find Lion's "22 Features." These are also 30-strike sized covers.
24-STICK: United Match Co. came out with a 24-strike, as did Columbia, with its "Eagle 24," and Universal's terrible flop, "Classique," also had 24 matches. Columbia's entry measured 1 1/2"x4 4/16" while Universal's Classique was 2"x5 1/8."
28-STICK: Universal's "Aristocrat" (actually, a 30-sized cover) had 28 matches, as did its famous "Jewel," which measured 1 7/8"x5 1/16."
30-STICK: All the modern companies made 30s, as did many of the older companies. Examples in this size are Columbia's "Eagle 30," Diamond's "Ambassador," Universal's "Action," Lion's "Diplomat," etc. 2"x4 6/16. Britain's "Major" even carried 30, but tends to be a little wider.
36-STICK: Diamond Match Co.'s "Perfect 36" is the only one I know of in this size. 4 3/8"x 2 1/2."