It's great that you are returning wild trout, salmon and pike in order to ensure their survival to add to the spawning stock. Of course, it's also very nice to know how big your catch is, and in the UK at least it has been the tradition to record weight rather than weight. Now there is no need to put a fish through extra stress and delay, because you can get a pretty good estimate of the weight of a trout, salmon or pike from its measured length.

The formulae used in the calculator below is:

Trout Weight (in pounds) = (Length x Girth^2)/800 where Length and Girth are expressed in inches.

Pike Weight (in pounds) = (Length x Girth^2)/900 where Length and Girth are expressed in inches.

If you have recorded only the length measurement, the calculator will automatically insert the typical girth measurement (58% of the length) expected for a fish of that size. (Hen fish tend to have bigger girth measurements than cock fish of the same length; also, lake trout are often deeper-bodied than river trout, so measuring girth is definitely worthwhile if you need a very accurate result).

Download our Flyfishing Courses Brochure here:

First Nature
Bwlchgwyn, Rhydlewis, Llandysul SA44 5RE
Telephone: 01239 851952
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