Howdy Fishon..

Welcome to the board!

I use a calculator off of a guide's site. All you need is length and girth (measured just in front of the dorsal) and you can get a fairly accurate weight.

I have made comparisons of the weights from the calculator to my digital postal scale (accurate to within 1/10 oz.) and found it to be pretty darn close....within 1/4 lb. in most cases.

http://www.johns-guide-service.com/Fishing.html

The calculator is about half-way down the page.

Mike B