How to Estimate a Fish's Weight Weigh a fish without a scale | The Old Farmer's Almanac

How to Estimate the Weight of a Fish

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Fishing the Salmon River, Polaski, NY

Photo Credit
Mary Jaeger
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No more fishing stories! When it comes to fishing, the best part is talking about how big your fish is! However, if you are a catch-and-release fisherman, sometimes you cannot accurately portray its size. Now you can! Here’s how to estimate the weight of a fish.

  • Measure the fish from the tip of its nose to the tip of its tail.
  • Then measure its girth at the thickest portion of its midsection.

Weight of a fat-bodied fish
(bass, salmon)
(length x girth x girth)/800

Weight of a slender fish
(trout, northern pike)
(length x girth x girth)/900

If a fish is 20 inches long and has a 12–inch girth, its estimated weight is
(20 x 12 x 12)/900
2,880/900=3.2 pounds

What is the biggest fish you have ever caught? Tell us all about it in the comments below!

About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann

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