Length
Tip of the nose → tip of the tail
Quick catch-and-release estimate
Fish Weight Calculator
Estimate a fish’s weight from its length and girth.
Useful when you want to release the fish without putting it on a scale.
How to Measure Your Fish
Measure quickly and keep the fish supported.
Girth
Around the widest part of the body
How does the fish weight calculator work?
Fish weight is usually estimated from body measurements such as length and girth. Because fish of the same length can have different body shapes, girth generally makes the estimate more useful. This fish weight calculator uses published formulas when available and a published general formula as a fallback.
Why estimate instead of weigh?
If you’re planning to release a fish, measuring it quickly can be more convenient than handling it longer to use a scale. The result is still an estimate, not a record-certified weight.
Formula notes and sources
Bass estimates use the Wisconsin DNR bass formula. Trout uses the DNR trout formula. Other species use the Texas Parks and Wildlife general length-and-girth formula unless a dedicated formula is added. Length-only results are intentionally limited. Read the Wisconsin DNR formula guide and the Texas Parks and Wildlife fishing FAQ.
Calculations are performed locally in your browser. Your measurements are not uploaded or saved.