Fish Weight Calculator
Estimate weight from length and girth (by species or precise)
Measurement
Estimated weight
0 kg
※ Adding girth captures body condition and is most accurate (weight=length×girth²÷28902). Length-only uses an average species coefficient and varies by season, sex and individual.
Result
⚠️ This calculator is a reference tool based on published fish length-weight relationships (W=a×L^b) and girth-based estimation formulas, plus other publicly available conversion data. Real products vary in diameter, strength (lb) and weight for the same gauge depending on material (nylon, fluorocarbon, PE braid), maker, number of braided strands (4/8) and coating, so results may differ from the product label. PE braid lb ratings in particular vary widely by maker, so treat them as a range and always check the product label for exact values. calcstool.com assumes no liability for tackle choices, equipment damage, accidents or fishing outcomes based on these results.
FAQ
How is fish weight estimated?
Two ways: (1) length+girth: weight(kg)=length×girth²÷28902, accurate regardless of species; (2) length+species: weight(g)=a×length^b using an average coefficient. Adding girth is most accurate.
Why measure girth?
At the same length, a plump vs lean fish weighs very differently. Girth reflects body volume directly, so it is far more accurate than length alone.
Is the estimate exact?
It is a reference estimate shown as a range, varying with season, sex and individual. Weigh on a scale for exact values. Enter actual weight to see body condition vs the estimate.
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