Künzli uses a lot of different boot-trees because people have different feet and because fashion asks for different shapes. That is how everyone should find his or her best shape and favourite look.
For allrounders, already the width is a help: S, M, L.
For the professional Künzli "Ortho®" and Künzli "Protect" offer the choice of E to L.
For the expert Künzli offers measuring tables, that help measure the individual foot and associate it to the appropriate size
| Indication | Width (allround) |
Width (expert) |
Description |
| FL | S | F | slim, tailored boot-tree, the "medial section" for sneakers |
| GO | M | G | classical pointed shape with comfortable width at the ball of the foot |
| SL | M | G | modern Sneakerlast, fitted shape in "medial section" with closed heelcup for more heelgrip |
| TF | M | G | sporty, with slim and high point |
| BA | S | E | delicate, slightly pointed female boot-tree |
| JO | M | G | comfortable width from tip to heel, close grip at the heel |
| J | M | G | for boots, higher arch and tailored heel |
| VZ | M-L | H | wide |
| SA | L | J | natural shape, very wide, especially at the arch |
| STA | M | G | middle width, for safety models |