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Help Figuring Weight

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  • Super User

For you guys that catch double digit largemouth on a regular basis I am trying to figure out how much a 29" bass in healthy conditions might weigh. A person I know went out last weekend with no camera, scale, or measuring tape. He laid the bass down next to his rod and marked it off. When he got home it was 29" between the marks.

Ive never caught a DD bass, but I have weighed in a 10.2 that was only 23.5in and have also weighed in a 7.8 that was 27in. It really can vary dramatically, but id say if it was 29in and healthy it was easily over 10.

  • Super User

I'd be curious as well. About a week ago I caught a LM while testing out a spinnerbait I just made. It was 23.25" long x 21" girth.

I went on a few sites and I got the following formulas to measure weight:

Length x Length x Length/1600 = 7.85 lbs

Length x Length x Girth/1200 = 9.45 lbs

Length x Girth x Girth/1050 = 9.76 lbs

Not that I want to sell myself short, but I tend to believe it was 7.85 lbs or in that range.

Good post. :)

After catching a definite personal best (by a bunch) today, with no scale. I will be saving myself the trouble and picking up a scale this week. It sucks not really knowing.

I'd be curious as well. About a week ago I caught a LM while testing out a spinnerbait I just made. It was 23.25" long x 21" girth.

I went on a few sites and I got the following formulas to measure weight:

Length x Length x Length/1600 = 7.85 lbs

Length x Length x Girth/1200 = 9.45 lbs

Length x Girth x Girth/1050 = 9.76 lbs

Not that I want to sell myself short, but I tend to believe it was 7.85 lbs or in that range.

Good post. :)

Call it eight my friend.

Highly variable. It could go anywhere from 10 to 20+ lbs. Without hearing at least that it was of thin, medium, or fat / thick build, I wouldn't even want to try to narrow that range. I caught an emaciated 28 1/2"er once that weighed 6 1/2 lbs. My PB which went 29 1/2" weighed 18.4 lbs. A year later when my buddy caught her, she was 30" in length, but only 17.2 lbs. Probably starting her old age decline.

This fish was only 26" in length, but with a girth of nearly 25", it weighed 15.8 lbs.

fe86ea10.jpg

fe76ea10.jpg

Peace,

Fish

  • Super User

The key to calculating accurate weights is accurate measurement.

The bass should be laid on a wet towel, flat surface with held mouth closed.

The length measurement is from the tip of the closed mouth to the center of the tail. The girth measurement is around the widest area with the dorsal fin down.

I use the formula length times length times girth divided by 1200,

L X L X G / 1200 = weight in lbs, for LMB up to 15 lbs, with a 10% error factor.

The IGFA formula is based on round bodied fish like tuna, not accurate for LMB.

The average girth for a LMB is 75% to 80% of the length. LMB can be heavy bodied with girths at 90% to 100%.

I have weighed lots of giant bass, none over 30". Consider the new world record LMB from Japan was 29" long X 28.5 girth and weighed 22 lbs 5 oz.

Tom

  • Super User

After catching a definite personal best (by a bunch) today, with no scale. I will be saving myself the trouble and picking up a scale this week. It sucks not really knowing.

You can certainly bet I'll be doing the same thing... ;) I have one that needs to go to confession every sunday. :D

  • Super User

I use the formula length times length times girth divided by 1200,

L X L X G / 1200 = weight in lbs, for LMB up to 15 lbs, with a 10% error factor

X2

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