Art Lingren talks about the length minus 20 rule to come up with approximent weight. 29 inch steelie minus 20 inches gives approx. 9lb steelie. The other more accurate method is called sturdy's formula. Weight in pounds = 0.00133 x (girth)squared x length (girth and length in inches. A 40 inch fish with a girth of 24 should be 30.6 lbs.