Over the years, looking at various reels and their line capacities, I've always wondered... Why are line capacities so different from eachother even when the diameters are the same.

Let's look at a random reel. The Zillion SV TW.

It has a mono capacity of around 14/100 or 16/85.

But it's braid capacity is rated at 30/100 and 40/80.

On average, 40lb test braid is around the same diameter as 10lb mono, and 16lb test mono is around the same diameter as 65lb braid. If that is the case, why then does the braided line's capacity seem so "short" when you look at the diameters.

Maybe it's the way the line behaves on the spool? Does the braid "fluff" out more on a reel?

Three things. 1- “on average” when it comes to size equivalence doesn’t take into account manufacturer ratings and actual diameter. 2- not all braid is created equal. For instance, 832 is a little thicker than listed (if I recall correctly). And some braid is very round and some is flat. It stacks differently on the reel. 3- Not all mono is rated equally. US mono is typically thicken for a given rating than JDM mono. The Zillion matches JDM mono (sunline for instance).

19 minutes ago, casts_by_fly said:

Three things. 1- “on average” when it comes to size equivalence doesn’t take into account manufacturer ratings and actual diameter. 2- not all braid is created equal. For instance, 832 is a little thicker than listed (if I recall correctly). And some braid is very round and some is flat. It stacks differently on the reel. 3- Not all mono is rated equally. US mono is typically thicken for a given rating than JDM mono. The Zillion matches JDM mono (sunline for instance).

Interesting!! That's good to know! Thabk you.

Do you know how shimano rates their reel line capacities?

I don’t. I’m pretty sure that Daiwa uses JDM mono as my zillions bear that out. And I’ve been buying JDM reels so it’s pretty accurate (I also use sunline). But I’m mostly shimano for my reels (also JDM reel and line) and I haven’t checked them for capacity since it’s never a limiting factor. The zillion is the only reel that has pushed my limits (with big USD mono on a long casting rod).

I think @bulldog1935 posted a spool calculator recently that might help to guide you.

Topic was covered pretty well on this thread.

@casts_by_fly is referring to Pattaya calculator:

https://www.pattayafishing.net/fishing-reel-line-capacity-estimator/

2 hours ago, Rocky998 said:

Over the years, looking at various reels and their line capacities, I've always wondered... Why are line capacities so different from eachother even when the diameters are the same.

It's reasonable to wonder why, and you've gotten good answers, but for me it's irrelevant. 150 Meter or 300 Meter filler spools break down nicely into a number of batches of 165', so that's what I use as the length for my mainline with a backer to fill out the rest. I happen to have a mountain of inexpensive 50lb 8 strand braid, so that's what I choose to use as a backer.

For bass fishing with typical 6'10"-7'3" bass rods and the typical baits associated with bass fishing, a 165' cast is quite far and not easily achieved with stock low profile casting reels. Aside with from a 1 ounce dark sleeper, 3.5" poop bait, or certain heavy frogs, few will exhaust the top shot/mainline down to the connection knot whether it's braid or plastic mainline. I'm not worried about hitting the backer knot. In the rare case that I do, so what?

21 hours ago, casts_by_fly said:

I don’t. I’m pretty sure that Daiwa uses JDM mono as my zillions bear that out. And I’ve been buying JDM reels so it’s pretty accurate (I also use sunline). But I’m mostly shimano for my reels (also JDM reel and line) and I haven’t checked them for capacity since it’s never a limiting factor. The zillion is the only reel that has pushed my limits (with big USD mono on a long casting rod).

I think @bulldog1935 posted a spool calculator recently that might help to guide you.

21 hours ago, bulldog1935 said:

Topic was covered pretty well on this thread.

@casts_by_fly is referring to Pattaya calculator:

https://www.pattayafishing.net/fishing-reel-line-capacity-estimator/

I checked out that calculator! It would be really helpful, except for the fact I need the line diameter and length that the company publishes. And I don't know. Shimano and daiwa, at least to my knowledge, does not show that information for their casting reels.

I'm looking at putting 18lb daiwa samurai fluorocarbon (.353mm diameter) on a shimano metanium 150 for jigs. Would this be too thick, or should i bump it down to 16lb test? (.337mm)

Line compression. (or lack thereof...)

@Rocky998 Every one of their spools is listed in Japan aftermarket with that information.

https://www.hedgehog-studio.com/page/628

Here's the chart that gives diameter for JDM braid and mono.

https://www.jpfishingtacklenews.com/japanese-line-size/

26 minutes ago, bulldog1935 said:

@Rocky998 Every one of their spools is listed in Japan aftermarket with that information.

https://www.hedgehog-studio.com/page/628

Sadly I could not find where it lists that specific information. I looked for a while.

26 minutes ago, bulldog1935 said:

Here's the chart that gives diameter for JDM braid and mono.

https://www.jpfishingtacklenews.com/japanese-line-size/

Appreciate that, thank you!!

@Rocky998 - I use 18 lb shooter (same diameter you’re looking at) on a bantam 100. More than enough capacity. A 150 sized reel will be just fine with that line. FWIW, I have 20 lb big game on another Bantam 100 and it’s 30% bigger diameter and also just fine.

6 hours ago, casts_by_fly said:

@Rocky998 - I use 18 lb shooter (same diameter you’re looking at) on a bantam 100. More than enough capacity. A 150 sized reel will be just fine with that line. FWIW, I have 20 lb big game on another Bantam 100 and it’s 30% bigger diameter and also just fine.

Thank you! Thats great to hear!

You don't feel restricted by casting distance at all with the shooter line?

Rule #1: Casting distance is not a factor for bass fishing; casting accuracy and presentation is.

Rule #2: If you feel long casting distance is important for bass fishing, refer to rule #1.

6 hours ago, Rocky998 said:

Thank you! Thats great to hear!

You don't feel restricted by casting distance at all with the shooter line?

Nope. I have it on my 7’4” jig and ‘other’ rod. I can pitch short casts with a jig/texas rig or I can bomb some lures almost out to 50 yards (was just doing it 2 hours ago).

9 hours ago, Glenn said:

Rule #1: Casting distance is not a factor for bass fishing; casting accuracy and presentation is.

Rule #2: If you feel long casting distance is important for bass fishing, refer to rule #1.

Yup, I understand that, but since I do not own a boat, it's a lot more important to me than some others. Further I can cast = more presentation time and more water I can cover from shore.

7 hours ago, casts_by_fly said:

Nope. I have it on my 7’4” jig and ‘other’ rod. I can pitch short casts with a jig/texas rig or I can bomb some lures almost out to 50 yards (was just doing it 2 hours ago).

Awesome! That's great to hear, then! Thank you!

You will never cast it down to the spool. On my Metaniums, I start with 50 yards or so of backing and top it off with Invisx or, if I catch a sale, Tatsu. There's no need to hit them in the head with the bait. One thing FFS has shown what a lot of us already knew, is that they will come a long way to get a bait they want.

Also if you're not proficient with a baitcaster yet I would hold off on the expensive line .

9 hours ago, rangerjockey said:

You will never cast it down to the spool. On my Metaniums, I start with 50 yards or so of backing and top it off with Invisx or, if I catch a sale, Tatsu. There's no need to hit them in the head with the bait. One thing FFS has shown what a lot of us already knew, is that they will come a long way to get a bait they want.

Also if you're not proficient with a baitcaster yet I would hold off on the expensive line .

After a long while of using multiple baitcasters now, I feel pretty proficient at it. I can cast far and accurately with low braking. Although backlashes happen to anyone and everyone, so I do worry about it happening with the fluorocarbon and having to replace the whole spool. Because if I remember right, if fluoro backlashes, it ruins the line, right?

Not necessarily, but there is a better chance of it. Fluoro doesn't like a kink so if you get a good backlash and one of those loops pulls hard on the running line it's going to make a kink somewhere very inconvenient.

7 hours ago, casts_by_fly said:

I don’t. I’m pretty sure that Daiwa uses JDM mono as my zillions bear that out. And I’ve been buying JDM reels so it’s pretty accurate (I also use sunline). But I’m mostly shimano for my reels (also JDM reel and line) and I haven’t checked them for capacity since it’s never a limiting factor. The zillion is the only reel that has pushed my limits (with big USD mono on a long casting rod).

I think @bulldog1935 posted a spool calculator recently that might help to guide you.

6 hours ago, bulldog1935 said:

Topic was covered pretty well on this thread.

@casts_by_fly is referring to Pattaya calculator:

https://www.pattayafishing.net/fishing-reel-line-capacity-estimator/

59 minutes ago, casts_by_fly said:

Not necessarily, but there is a better chance of it. Fluoro doesn't like a kink so if you get a good backlash and one of those loops pulls hard on the running line it's going to make a kink somewhere very inconvenient.

Ah, gotcha. Thanks for the explanation!

What's even more baffling is my ss air lists 6lb capacity as 50yds, but the 8lb capacity as...umm 50yds