Note: Updated Jan 2011 with the new larger BSA neckerchief size. Updated again Sep 2018 with new URLs and the 2015 edition of the ANSI standard.
The BSA’s Insignia Guide says this about the size and shape of the neckerchief, “Official neckerchiefs are triangular in shape.” There is a more info about how to wear it, who chooses the neckerchief (the troop), who approves special neckerchiefs (the council), and so on. It does say that special neckerchiefs are “the same size as official ones”. Oddly, they don’t say what size that is.
So I researched it. One reason to have a bigger neckerchief is so it can be used as a triangular bandage, so I also checked the common sizes for those, including the ANSI-standard size.
| Source | Shape | Side | Diag. |
|---|---|---|---|
| BSA 1926-1931 [1] | Square | 32 | 45 |
| BSA 1938 [2] | Square | 30 | 42 |
| BSA through 2010 [3] | Triangle | 29 | 41 |
| BSA 2011 | Triangle | 35 | 49.5 |
| Scouts UK, modern (Wood Badge) [3] | Triangle | 30.5 | 43 |
| Chief Neckerchief (reg.) | Triangle | 31 | 44 |
| Chief Neckerchief (large) | Triangle | 34 | 48 |
| Moritz Standard | Triangle | 35 | 49.5 |
| Moritz Cub Scout | Triangle | 25 | 37 |
| Scoutneckers, UK (child) | Triangle | 27.5 | 39 |
| Scoutneckers, UK (adult) | Triangle | 34 | 48 |
| Just Neckers (Zone West), Canada (small) | Triangle | 18 | 36 |
| Just Neckers (Zone West), Canada (med.) | Triangle | 23 | 46 |
| Just Neckers (Zone West), Canada (large) | Triangle | 27 | 57 |
| Just Neckers (Zone West), Canada (X-large) | Triangle | 30 | 60 |
| Stadri | Triangle | 30 | 42 |
| Traditional Scouting | Square | 32 | 45 |
| Troop 151, Georgetown, TX | Triangle | 31 | 44 |
| Triangular bandage | Triangle | 36 | 51 |
| Large triangular bandage (ANSI Z308.1-2015) | Triangle | 40 | 56 |
- U.S. Scouting Collectibles, George Cuhaj, 2001, p 79. Neckerchiefs are describes as “Full Square, 28 x 32”. I am assuming that the cloth has shrunk along one axis of the weave. Other neckerchiefs are described as “Full Square 32 x 32”.
- Handbook for Scoutmasters, 1938, p 292. “of cotton, 30 inches square (or triangular in shape, cut diagonally from such a square), in plain or combination colors, as selected by the Troop, District, or Council.”
- Personal neckerchiefs, I made the measurements.
Most Casual Observer 
Pingback: BSA neckerchiefs are finally big enough | Most Casual Observer