Best weight calculator for flathead catfish
The fish in my profile picture weighed in at 30 lbs on my rapala digital scale. The scale has not been super consitent. I came to believe that it was 30lbs and never questioned it. That scale is now gone and I haven't bought the new one form Coffey mareting yet, so for the last carp I caught I used a length and girth calculator to get the weight. A 28in carp with 16 in girth weighed 12lbs, just out of curiosity I tryped in the only measurements I had on the flathead. It was 42inches long. The auto girth it produced was around 24 inches and estimated it at 42lbs. I know mine was not that big. But it had a bigger girth than the 16inch gith of the smaller carp. Question is, what weight calculator is best, and what is the formula, since they are usually more accurate than the weight generators. I don't know what the average weight for a 42in flat is, it was my first flat ever, caught last march. Sorry for rambling, any info would be appreciated.
Brad, the 42" flat you caught could have been 40 pounds. I have done a lot of work with flatheads and thier length can be a good indicator of weight if the fish is in the 40 to 55 inch range. Granted this rule doesnt always apply but is pretty accurated for 45-55 inch flatheads (+/-a few pounds). Anyway great fish and Good luck.
- John A
I have tested the old (L x G x G)/800 rule and it works pretty well for flatheads, but it seems to overestimate their weight a bit.
I know, you don't have a measured girth for your fish. The thing is that flathead weights are very variable depending on how fat they are. Your fish may very well have been 40 pounds, but it also could have been 30, depending on how fat it was. If you still had the scale, you could test it and adjust from there.
I guess you'll just have to get fishing and catch another one!
I am pretty sure it wasn't near 40 lbs, it was thinner than some I have seen on here. I figure it is between 30 and 35 so I am calling it 30, so my goal of a 40 from that pond is still motivation. I never bothered with girth when I had a scale, but I am recording it now. Thanks for the input.
the fish in your avitar looks to be 30+ to me. i cant say about the formula thing. nice fish there by the way.
From my experience flatheads can be highly variable in weight depending on the girth of the fish. I have caught a 36in. long, 26in. girth fish that went 27lbs. I have seen a 41in. long fish that went 22lbs. The girth on that fish was unknown but I would probably guess at somewhere between 20-24in. girth. The florida state record flathead was 42.5in. long with a 36in. girth and went 49.39 lbs! Fat fish for sure. I think girth makes a huge difference between one fish and another and length alone will give a very rough estimate.
Without a girth, it is all guessing. 40+" fish can vary from 25lb to 60lbs. It's all about the girth.
Here is a 41x23 that weighed 29lbs:
Here's a 43x27 that weighed 35lbs
Here is a 46" fish that weighed 54lbs (no girth measurement)
In relation to this topic I have a Bass Pro Shops tape measure (Sticker) That is stuck to the inside of my boat, and underneath the measurement part it has a little chart off a few different species of fish and their estimated weight based on there length.....it doesn't have any catfish species on this chart but rather bass, crappie and walleye And for everyone of these types of fish that I have caught I have actually measured it and compared its weight to what the chart says it should weigh....and it is not even close! Everything is highly over estimated. It doesn't say the formula used to come up with the figure but it is way off. And after thinking about this for awhile it just goes to show that there probably is no exact formula to use that will be close to accurate....to many variables would come into play. It is very frustrating...I think the best thing to do is to invest in a very good scale and start documenting your catches with length, girth and weight for each type of species and you should be able to get a good general idea for your part of the country on basic measurements and there respected weights in relation. Be careful...to much math may hurt the cat man's brain.