Enter your Fish Length, choose your Length Units and Fish Species Type, and this Fish Length-Weight Relationship Calculator will estimate your Estimated Fish Weight along with a Min/Max Weight Range — add an optional Fish Girth measurement for a sharper estimate, or let the tool calculate a typical Girth for your species automatically.
Estimated Fish Weight
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Weight Range (Min)
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Weight Range (Max)
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Calculated Girth
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Fish weight calculations are estimates based on allometric relationships and can vary by ±15-25% from actual weight. Factors like fish condition, season, and individual variation affect accuracy.
If girth is not provided, the calculator estimates it using the standard formula: Girth = 0.58 × Length. This provides a reasonable approximation for most fish species.
Yes, different species have unique body shapes and density, requiring species-specific formulas. For example, pike use Length³/2700 while sunfish use Length×Girth²/1200.
Most formulas use total length (tip of nose to end of tail). For Pacific halibut and some species, fork length (nose to fork of tail) may be specified.
Calculated weights are statistical averages. Individual fish can vary significantly based on feeding conditions, spawning status, age, and overall health.
Yes, the calculator includes formulas for both saltwater species (like Pacific halibut, snook) and freshwater species (like bass, walleye, pike).
Round weight is the whole fish weight, while net weight excludes head, guts, and sometimes fins. Commercial fisheries often use net weight for processing.