Estimating weight only by length? 2024

12poundbass reply :

I was watching Bill Dance's show the other night and he was talking about a way to estimate a fish's weight only by length. Here's what he explained...the fish is 20" multiply 20x20x20 then divide by 1600. Always divide by 1600. I was wondering if anyone has tried this and if it's fairly accurate. I caught a nice one last year and went to weigh it and my batteries were dead in my scale! If this is fairly accurate it would be pretty handy since most fisherman have a ruler. I don't carry a tape to do the length/girth formula (although I guess I should if I want a replica mount). I haven't tried it yet (iced out in Michigan) and wondering if anyone has?

riverbasser reply :

Its about as accurate as me asking your height and then guessing your weight based on the average of people that are the same height. I made be dead on or way off.

Too me there is no substitute for a scale. I've caught 23" bass that weighed 4lbs. By his formula I should have a new PB

roadwarrior reply :

http://www.bassresource.com/bassfishing/fishcalculator.html

J Francho reply :

The only time I use length is when I'm fishing an online kayak tournament, where length is how contestants are scored. Otherwise, it's always mass. If you want to know the fish's mass, weigh it.

WRB reply :

Most bass weight calculators that only use length assume the girth is 75% of the length*.

* length being bass laid flat measure from end of closed mouth to end of tail.

If I use the BR site calculator and add girth my PB** weighs 23.08 lbs!....would a world record!

Length X Length X Girth /1200 is more accurate, still no substitute for a certified scale weight.

Tom

** 29" L X 28" G, actual weight 19.3 lbs.

12poundbass reply :

This is exactly why I asked. Conclusion...carry extra batteries!

MIbassyaker reply :

On 12/20/2016 at 11:50 PM, 12poundbass said:

I was watching Bill Dance's show the other night and he was talking about a way to estimate a fish's weight only by length. Here's what he explained...the fish is 20" multiply 20x20x20 then divide by 1600. Always divide by 1600. I was wondering if anyone has tried this and if it's fairly accurate. I caught a nice one last year and went to weigh it and my batteries were dead in my scale! If this is fairly accurate it would be pretty handy since most fisherman have a ruler. I don't carry a tape to do the length/girth formula (although I guess I should if I want a replica mount). I haven't tried it yet (iced out in Michigan) and wondering if anyone has?

I have checked this against the largemouth I catch in lakes around our area, and I have found it overestimates the weight for the vast majority. for instance, the formula estimates 16" bass to be about 2.5 lb. The ones I catch are more like 2.25. 20" by the formula is a 5lber, but my 20" bass are closer to 4.5.

12poundbass reply :

That's not too far off unless the difference gets bigger the longer the fish. Maybe it's a little more accurate for northern bass since their growing season is shorter, or maybe I'm looking too far into it. Either way I'm packing an extra set of batteries just in case they die on me again. Then again since fisherman always "lie" you could use it to your advantage and tell your buddy I caught a 10 pounder just do the math! Lol!

Red Bear reply :

keep extra scale batteries, or keep a $5 backup spring scale with you.

12poundbass reply :

On 12/21/2016 at 1:25 AM, Red Bear said:

keep extra scale batteries, or keep a $5 backup spring scale with you.

I wasn't a big fan of the spring scale. I noticed that you could fudge it fairly easily. That's why it's now a toy for my son and I'm packing extra batteries as soon as I get home before I forget.

J Francho reply :

My Chatillon spring scale is more accurate and consistent than any digi-scale. There was a review recently of a baggage scale from Amazon or something that was very accurate, and inexpensive.

Team9nine reply :

I do it frequently on bass when I just want a good general idea of fish weight. However, I don't follow the generic formulas listed above. Instead, I use a standard weight table that runs in 1/4 inch increments as calculated by local and regional biologists. Not good enough for big bass or PBs, but plenty good enough for everything else. Contact you local DNR to see if they have a specific std wt table for your local waters.

RHuff reply :

Just go with 20 inches is roughly 5lbs..... You can adjust the ratio accordingly.

Catt reply :

On 12/21/2016 at 12:20 AM, WRB said:

Most bass weight calculators that only use length assume the girth is 75% of the length*.

* length being bass laid flat measure from end of closed mouth to end of tail.

If I use the BR site calculator and add girth my PB** weighs 23.08 lbs!....would a world record!

Length X Length X Girth /1200 is more accurate, still no substitute for a certified scale weight.

Tom

** 29" L X 28" G, actual weight 19.3 lbs.

Exactly!

It also depends on the individual bass, some are short/fat & some are long/slim.

This bass was over 30" in length which is longer than WRB's be didn't have his girth so it only weighted 11 lb 3 oz.

J Francho reply :

On 12/21/2016 at 4:55 AM, Catt said:

only weighted 11 lb 3 oz.

Pffft! Nice dink, Catt.

IndianaFinesse reply :

Just don't use the weight calculator here on bassresource, that way overestimates the weight. I've tested it against my scale, and it showed that for the length and girth of a bass that I knew weighed 2.4 pounds, it said it weighed 4.1 pounds! I've also tested it against several other fish, and each time it guessed the weight to be nearly double the actual weight of the fish. I used that calculator on what I thought to be my pb a couple years ago before I bought a scale, and it showed it to be 10.3 pounds. Looking back on it, it probably only weighed around 6 pounds, so I guess I should change my "pb" to an 8.2 pounder that I caught and weighed on a scale.

Dogmatic reply :

I think I posted this before, but this is put out by the PAFBC, and this past season we checked it against our fish and found it "relatively" accurate. Take in account this is for Northern strain, and season.

Red Bear reply :

On 12/21/2016 at 2:38 AM, 12poundbass said:

I wasn't a big fan of the spring scale. I noticed that you could fudge it fairly easily. That's why it's now a toy for my son and I'm packing extra batteries as soon as I get home before I forget.

what do you mean by fudge it exactly? just make sure it is set to zero before you weigh the fish, its not hard at all. id probably trust my spring scale more in the long run than i trust a digital. too many things could go wrong with a digital and the electronics in it. even a low battery could possibly give you wrong weights. not saying digital scales are garbage or even frequently wrong by any means, just that i would put more faith in my spring scale. just because something costs more and/or is more advanced technologically doesnt mean its better...

the reel ess reply :

On 12/21/2016 at 1:25 AM, Red Bear said:

keep extra scale batteries, or keep a $5 backup spring scale with you.

I'd trust the length-only method more.

Red Bear reply :

On 12/22/2016 at 1:12 AM, the reel ess said:

I'd trust the length-only method more.

too unreliable. you have short fat bass, long skinny bass, short skinny bass, long fat bass...too many variations to trust only length. there is nothing wrong with spring scales at all. i know i said 5 dollar in my post, but thats as a back up plan to digital, but you cant deny boga grips have quite a good reputation

the reel ess reply :

On 12/22/2016 at 1:16 AM, Red Bear said:

too unreliable. you have short fat bass, long skinny bass, short skinny bass, long fat bass...too many variations to trust only length. there is nothing wrong with spring scales at all. i know i said 5 dollar in my post, but thats as a back up plan to digital, but you cant deny boga grips have quite a good reputation

Spring scales are almost always wrong and that will be in one direction so that everything you weigh will weigh either lighter or heavier than it really is. At least the length average is dead in the middle of the bell curve.

J Francho reply :

On 12/22/2016 at 1:18 AM, the reel ess said:

Spring scales are almost always wrong and that will be in one direction so that everything you weigh will be either lighter or heavier than it really is. At least the length average is dead in the middle of the bell curve.

Depends on what spring scale you're using. Boga's are pretty accurate. Chatillon are the standard that any scale is held to. I trust my Chitillon over any "digital" scale any day. The only issue is reading an analog scale - you have to watch out for parallax. I think many confuse accuracy with resolution. Just because a scale carries out and rounds to 1/100 oz. doesn't mean it's more accurate.

the reel ess reply :

On 12/22/2016 at 1:23 AM, J Francho said:

Depends on what spring scale you're using. Boga's are pretty accurate. Chatillon are the standard that any scale is held to. I trust my Chitillon over any "digital" scale any day. The only issue is reading an analog scale - you have to watch out for parallax. I think many confuse accuracy with resolution. Just because a scale carries out and rounds to 1/100 oz. doesn't mean it's more accurate.

He said the $5 spring scale

J Francho reply :

On 12/22/2016 at 1:25 AM, the reel ess said:

He said the $5 spring scale

I quoted you. You said "spring scales."

Here's a link to Chatillon: http://www.chatillon-scales.com/weighing-solutions/fish-and-game-scales/in-series.aspx

This model work for most, though you might want to go to a higher max load, depending where you live:

https://www.amazon.com/ScalesGalore-Chatilllon-IN-12-Fishing-Scale/dp/B000235XFC/ref=sr_1_9_a_it?ie=UTF8&qid=1482341428&sr=8-9&keywords=chatillon+scale

the reel ess reply :

On 12/22/2016 at 1:27 AM, J Francho said:

I quoted you. You said "spring scales."

Here's a link to Chatillon: http://www.chatillon-scales.com/weighing-solutions/fish-and-game-scales/in-series.aspx

This model work for most, though you might want to go to a higher max load, depending where you live:

https://www.amazon.com/ScalesGalore-Chatilllon-IN-12-Fishing-Scale/dp/B000235XFC/ref=sr_1_9_a_it?ie=UTF8&qid=1482341428&sr=8-9&keywords=chatillon+scale

And I quoted him. He was referring to a backup $5 scale

J Francho reply :

Enough dude. There's nothing wrong with spring scales. Cheap digital scales will let you down more often. I still have a 20 year old 5$ Rapala spring scale I use for setting drags. It's as accurate as the day I bought it. Test it when you buy it. If it's right, it will always be right.

Now....those dial type scales from BPS......that's another story....

Red Bear reply :

On 12/22/2016 at 1:35 AM, the reel ess said:

And I quoted him. He was referring to a backup $5 scale

exactly, a BACKUP, if youve invested in a digital scale you like i dont see the point in buying an expensive backup scale. a 5 dollar back up spring scale will get you by for the day, and its not way off inaccurate as you surmise, its close enough to be satisfactory. if you want a longterm every day spring scale then i wouldve suggested a better alternative, but im talking a cheap inexpensive back up that will get you by. not everything has to cost a million dollars for it to work, sheesh

On 12/22/2016 at 1:41 AM, J Francho said:

Enough dude. There's nothing wrong with spring scales. Cheap digital scales will let you down more often. I still have a 20 year old 5$ Rapala spring scale I use for setting drags. It's as accurate as the day I bought it. Test it when you buy it. If it's right, it will always be right.

Now....those dial type scales from BPS......that's another story....

thanks, i wasnt sure if anyone would agree with me or not, but i feel the same way about scales. i work in bulk mail and use a digital postage scale all the time, its not uncommon for it to go bad out of the blue and have numbers jumping all over the place and such. some people seem to forget there was once life without all these electronics at are fingertips, yet people still got the job done with their "old fashioned" tools and methods...

12poundbass reply :

On 12/22/2016 at 12:46 AM, Red Bear said:

what do you mean by fudge it exactly? just make sure it is set to zero before you weigh the fish, its not hard at all. id probably trust my spring scale more in the long run than i trust a digital. too many things could go wrong with a digital and the electronics in it. even a low battery could possibly give you wrong weights. not saying digital scales are garbage or even frequently wrong by any means, just that i would put more faith in my spring scale. just because something costs more and/or is more advanced technologically doesnt mean its better...

What I meant by fudge it (with mine at least) is when I weighed a bass it would go to say 5 pounds if I moved just right it would move up or down by several ounces. This wasn't an isolated incident either. Maybe it was junk, I would like to think not considering I spent $25 on it and I didn't use it that often. As far as digital and technology goes I'm old school I don't dive in head first over technology I stick with what works. I don't care if things are the latest and greatest if what I have works I stick with it.

the reel ess reply :

On 12/22/2016 at 1:41 AM, J Francho said:

Enough dude. There's nothing wrong with spring scales. Cheap digital scales will let you down more often. I still have a 20 year old 5$ Rapala spring scale I use for setting drags. It's as accurate as the day I bought it. Test it when you buy it. If it's right, it will always be right.

Now....those dial type scales from BPS......that's another story....

Merry Christmas!

Red Bear reply :

J Francho reply :

On 12/22/2016 at 1:45 AM, Red Bear said:

thanks, i wasnt sure if anyone would agree with me or not, but i feel the same way about scales. i work in bulk mail and use a digital postage scale all the time, its not uncommon for it to go bad out of the blue and have numbers jumping all over the place and such.

Interesting that you mention that. The club I was in had a two identical digital scales for weigh-ins. It had a large, remote display so that everyone could witness the weights coming in in real time. Those scales cost a fortune. They had to be sent in every year to be calibrated, tested, and confirmed. The warranty included a replacement scale would be overnighted should it go haywire. It's happened a couple times, and we had to use the second scale.

WRB reply :

I used a laboratory grade Chatillion spring scale for decades. Spring scales are as accurate as your ability to read it. Spring scales read in a particular increment depending on the scale, most 25 lb scales have 2 oz graduations, all have issues with parallax. Parallax is how the indicator aliens to the value from your perspective. Spring scsle accuracy is dependent on how linear it is and temperature used in. Most spring scales are accurate within 2%.

Didgital scales display numbers that don't need to be interpreted. Didgital scales are dependant on linear accuracy of the force gage and voltage operating the scale, battery strength. Most Didgital scales are accurate within 1% with a new battery.

Measurements using a tape are dependant on many factors; how the bass in laying, how snag the mouth is held tight, how tight the tape is pulled and where the tape is located.

Length measurement vary greatly, most should be within 1/2".

No panaceas for measuring, calculating or weighing bass.

Tom

J Francho reply :

I vote for displacement as the standard!

Red Bear reply :

On 12/22/2016 at 2:08 AM, J Francho said:

Interesting that you mention that. The club I was in had a two identical digital scales for weigh-ins. It had a large, remote display so that everyone could witness the weights coming in in real time. Those scales cost a fortune. They had to be sent in every year to be calibrated, tested, and confirmed. The warranty included a replacement scale would be overnighted should it go haywire. It's happened a couple times, and we had to use the second scale.

seems to me the more you use them the less reliable they come, of course the same can be said about many things. i cant speak for everyone, but i dont weigh every bass i catch anyways or even a majority, just dont care to, i weigh the ones that look worthy enough to weigh. ive weighed enough bass that i can pretty much say to myself "looks to be about two pounds", toss it back and not really care if it was 1.75 or 2.5 lbs. but i do know that we've been through a few digital postage scales here at work, i also know that the old school letter hanging scales always work...

Choporoz reply :

On 12/22/2016 at 2:20 AM, WRB said:

Spring scales are as accurate as your ability to read it.

Bingo.

Aliens aside, digital scales are 'easier' to read for most....for a couple/few reasons -- no parallax, digital numerals will 'fix' on most after a period of 'stillness'; while springs will continue to move as long as your hand/arm and/or the fish move...at all

J Francho reply :

What a cool, and simple device. I like it.

12poundbass reply :

On 12/22/2016 at 2:00 AM, Red Bear said:

Lol I was thinking the same thing.

J Francho reply :

If you say so, then.

11256

Estimating weight only by length? 2024

related General Bass Fishing Forum topic

previous topic

next topic

most viewed General Bass Fishing Forum topic