Fish formula for weight
 

(Girth x Girth x Lenght)divide by 800=Weight

(15 x15 X 37)/800=10.4 pounds

Only works for the trout and salmon family............not pike or walleye.

I use these: pike--length x length x length divide by 3500 = lbs

walleye--length x length x length divide by 2700 = lbs

trout-- Girth x girth x length divide by 800 = lbs

I have another for metric but havn't used it yet.

Thx BigRed..........didn't know those other two.........how close do they come to being 'on'?