[MathGeek]

Originally Posted by swamp snorkler

Next time measure the girth, that will get you a little closer.

Here's a calcultor http://www.fishdreams.com/calculator.all_species.html

40" fish with a 25" girth puts you at 31 lbs
40" fish with a 27" girth puts you at 36.5 lbs

It is important to note that the calculator uses fork length rather than total length. If you measure the fish from the mouth to the END of the tail, you have a total length. Plugging that number into a calculator that uses fork length (the length from the mouth to the fork in the tail) significantly overestimates the weight of the fish. In bull reds, the fork length is usually about 3" SHORTER than the total length, so a fish 40" long will have a fork length closer to 37".