What this calculator does
Fish weight estimate works out estimated live weight of a fish from its length and girth, without using a scale. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaWeight (lb) = length (in) × girth (in)² ÷ species constant; girth ≈ length × 0.58 if not measured
The inputs explained
| Field | What to enter |
|---|---|
| Length (nose to tail fork) (in) | A number, measured in in. Starts at 20. |
| Girth (0 to estimate from length) (in) | A number, measured in in. Starts at 0. |
| Species group | Choose from Bass, panfish, walleye, general, Trout, salmon, Pike, muskie. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with length (nose to tail fork)
Every other input is held at the calculator’s starting values while length (nose to tail fork) varies. Select any row to load that scenario into the calculator.
How the answer changes with length (nose to tail fork)