Use the form below to calculate how much a fish weighs based on its length and its girth. If you do not know the fish's girth, leave it blank and it will be approximated for you.
Fish Weight Calculations
The fish weights are calculated with the formulas below. If a fish girth is not specified, the default value Fish Girth = 0.58 * Length is used.
Trout, steelhead, mackerel, snook, redfish, bonefish
Fish Weight = Length * Girth * Girth / 900
Salmon, bass
Fish Weight = Length * Girth * Girth / 800
Walleye
Fish Weight = Length * Length * Length / 3500
Pike, gar
Fish Weight = Length * Length * Length / 2700
Sunfish, bluegill
Fish Weight = Length * Girth * Girth / 1200
