I am not allowed to print out copies of the soft-hackle gauge in Sylvester Neme's book, "The Soft-Hackle Fly Addict. (Copyright Infringements)
But I can give you the dimensions of the hackle for the different sized hooks.
I will give you the hook size, with the length and width of the feather. Make a box and insert a oval shape within the box for the hook size, and you will have a accurate gauge for sizing the hackle....
SIZE 6 HOOK: Length 1-3/8 inch, Width 1 inch.
SIZE 8 HOOK: Length 1-1/8 inch, Width 3/4 inch.
SIZE 10 HOOK: Length 15/16 inch, Width 5/8 inch.
SIZE 12 HOOK: Length 3/4 inch, Width 1/2 inch.
SIZE 14 HOOK: Length 5/8 inch, Width 7/16 inch.
SIZE 16 HOOK: Length 1/2 inch, Width 5/16 inch.
~Parnelli