Estimating Fish Weight
You can get a fairly accurate estimate of the weight of a fish (in pounds) without having to remove it from the water. Take the following measurements in inches. Measure the length of the fish from the lower jaw to the fork of the tail (Shown as L). Measure the girth by going all the way around the fattest part of the fish (Shown as G). If you can only measure the fish from one side, take the full measurement from top to bottom and double it.
Use the following formula to determine the weight of the fish.
(Girth X Girth) X Length) / 800 = weight in pounds
For example, let’s say you just caught a red drum that measured 36 inches fork length. The girth measured 19 inches.
19 X 19 = 361 X 36 = 12996 / 800 = 16.245 lbs