Trout Weight Calculator
Estimate trout weight from length and girth for rainbow, brown, brook, and related stocked trout.
Quick answer: Standard trout formula: (length × girth²) ÷ 800. Compare your estimate to the 48 lb world record (Bell Island Hot Springs, Alaska, 1970).
Standard trout formula: (length × girth²) ÷ 800
of the 48 lb rainbow trout world record
Optional gear for measuring trout
A board gives a fast total-length reading, a scale verifies the estimate, and a fish-friendly net helps keep handling controlled. Compare sizes and current availability before buying.
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- Fish measuring boards Look for a readable scale, raised end stop, and enough length for your target species.
- Water-resistant fishing scales Use a scale when you need a measured weight instead of a length-based estimate.
- Rubberized landing nets A knotless rubberized basket can reduce tangles and help keep the fish supported.
Common questions
How do you calculate trout weight?
Standard trout formula: (length × girth²) ÷ 800. If girth is missing, a length-only formula is used. Estimates are approximate.
What is the trout world record?
The rainbow trout world record is 48 lb, caught at Bell Island Hot Springs, Alaska in 1970.
Related species guides: rainbow trout , brown trout , brook trout , cutthroat trout , lake trout , tiger trout , splake