No one actually knows how to lculate what speaker cable they need

Any cable; interconnects, speaker, power, etc. will work in ones system. It is up to the end user to experiment & determine what cable they like best in their system and how much they want to pay for it. It really is quite simple, just treat it as you would another component.

Thanks, but sorry...NO.
I'm talking here on speaker's cables only. So lets leave the other cables out ot this discussion. 
The only insite I have from your answer, is that
You say "try and error with a budget".
I say, "Tell me what brand and model your amp. and speakers are, what is the distance between them - and I'll calculate for you what cable is required".
The optimum cable for the money. First time - and also the last.

Why would I get lost over and over agin, waist my time and money, rather that use a GPS nav device or a map, and get there first time on spot?
For the un of it...
As for the optimum, as I assume you already own an amplifier and a set of speakers, they are given. so is placment that requires the length.
You may never know if your preference is right, till you get to hear the optimum (the one) and compar.
Other cables: if I use XLR's and an ordinary catle power cord, I'm good. 
It won't get any better than that.

On top, it dosn't alter my opening line:
No one actually knows how to lculate what speaker cable they need

What you say, when I'll here it, I'll know it is. Till than, just going in circles, spending money and enjoy the journy. Hope you are not on the same page on other subjects, as health.

What does "iculate" mean?  Do you mean "articulate"?

Hmmm, I thought it was calculate, but see your point.  Always glad to see your posts, BTW.

I would edit the title of your post if possible. It makes no sense at all.

I do believe the word in question is calculate. As I read the comments by the OP and see the obvious errors in spelling/typing, I’m not sure if I could trust the calculations.

b4icu

It goes back to cable manufaturars, mostly provide no relevant data! to sales and the users. None will answer this!

What data do you seek?

What a coincidence. I just came across this site that was recommended by another site:http://www.sengpielaudio.com/calculator-cable.htm

Maybe this can help the OP is determining what he needs.

All the best,
Nonoise

Ok.
Sorry for the speling. English is my 3rd laguage. This site does not allow to copy from word (speler). So you need to be pasined. Thanks.
To exampls:
A PASS LAB 250W power amp, with B&W802 diamond - 3m long:
4 AWG.
An EMOTIVA 250W power amp, with Vienna acoustics beethiven - 2.5m
0 AWG.
The point is that no other is up to the task. The link:  http://www.sengpielaudio.com/calculator-cable.htm deals with interconnect. Not with speakers cables. Ther the parasatic capacitance of the line has a tall on the highs. Balnced lines solve the issue.

I have owned, and in some cases still own, Synergistic Research, Audioquest, Tara Labs, Mapleshade, AntiCables, Van den Hul and (yikes) Monster speaker cables.

And for under $30 I just bought from Blue Jeans Cable Co. 16 feet of Belden 12-gauge 5000UE and 4 pair of gold plated, compression style banana plugs. I cut the wire in half and installed the plugs, installed the shrink tubing, and then hooked them up to my speakers and to my amp in my system paying no attention to "directionality."

These speaker cables sound AS GOOD as any I have owned or listened to previously!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! No break in needed.

Steve

Hi Steve
What amplifier and speakers do they connect?

What makes you think that you got the right cable now? 
This is a blind shot in the dark as all other cables before. 
You still may have a cable that is not getting the best out of your speakers. You just don't know that.

" What makes you think that you got the right cable now?"
-No, I have the left cable now ... ;-)

" This is a blind shot in the dark as all other cables before."
-No, it isn’t having tried many cables over 40 years in the hobby.

" You still may have a cable that is not getting the best out of your speakers."
-Oh no, the humanity !!!

" You just don’t know that. "
-I know my system sounds very good with the speaker cables that I have installed now, after making that decision based upon my experience through experimentation. There is no shortcut.

0 AWG ?? What car are you using this battery cable on ? 

"0 AWG"

Call in the crane!

http://www.wireandsupply.com/4_0_WELDING_CABLE_1000_FT_REEL_SPOOL_FREE_SHIPPING_p/wc-4-0-03-dir-1000ft.htm

We want to listen to the speakers not jump start them.

A one foot length would make for a great blackjack. 🤪

"0 AWG"

Really?

It might be a good idea to push the bong aside for a few days so you can get back in touch with reality.

This is the oddest thread. 

Amps: Manley NEO 250 monoblocks
Speakers: Thiel CS2.4

I have correct speaker cables, for me, when I hear more than I've heard before and didn't spend an arm and a leg to do so. Plus, the overall balance and stage are "just right." 

Berning Quadrature, TAD Ref1, MIT Oracle 2M. How’d I do?

I needed a 24-foot run from my Bryston 4BSST2 amplifier to my Thiel 2.7 speakers. (4 ohm,  down to 2.6 ohm @ 160 cps.)

I chose Belden 5T00UP 10 gage cables. (1.03 ohm resistance /1000  feet; 26pF capacitance per foot)

Blue Jeans Cable made them up for me, with ultrasonic welded spades for termination. 

Couldn't be happier. Excellent bass, midrange and treble for my classical music CDs. 

Disclaimer: I'm a retired electrical engineer. 

Remember guys, don't feed the Trolls.......

Any MULTI strand 99.5% pure copper (NOT clad) wire will work.
The thicker the better.  12 gauge and thicker will easily 
handle up to 1000 watts/channel rms with no problems.

Simple rule, the thicker the better, the purer the copper the better.
12/10 gauge & thicker will easily handle up to 1000 watts rms amps 
with no problems.

Simple math. Take into account the power demands of the speakers to achieve the desired SPL. Then the power output of your amplifier, and subtract the two. This gives you the margin that can be lost to resistance in the speaker cable, P=I^2*R. You know the power needed to drive your speakers, and you know the speaker average impedance, which gives you the amount of current by plugging in the power and approximating resistance with average impedance. Take the power margin from above, and thus current value and use the same equation to solve for resistance of the cable. Divide this resistance by the distance in feet to obtain maximum ohms per foot of cable, and go shopping!

ff

Opera Consonance  Cyber 800 monoblocks to Focal 936 Electras connected with Jena lab Trio speaker cables A really nice pure all copper cable.

For the gut with the Bryston 4BSST2 and 24’ long cables:
You are not doing well. The Bryston 4BSST2 http://www.bryston.com/PDF/Manuals/300006[3B4B].pdf have a DF of 500. You need a 3x0 AWG! it may be expensive...
You better get closer, as 8’ and use a single 0 AWG. An other option, is to used two monoblocks and a shoer (3’) of a 4 AWG cable.

For the guy with the  Opera Consonance Cyber 800, even thou you have monoblks, because it is tube (very bad DF) and no data on DF! you may use any cable over 24 AWG thick (home phone line).

Mr. sleepwalker65 your math is wrong. The cable is fighting the power (P) or the current (I). I used Klipsh speakers (8 ohms) with 99dB/w/m SPL with a Caver 250W amp. that played at
0.001W-1W as loud as it should and still a thicker cable improved sound! 
The coin been lost under the Damping Factor (DF) parameter. The higher that is, the thicker the cable you need. It is about controling the speaker, not doing a welding, towing a truck or any other idea you were throwing as you thought it is funny.  

Mr. cakyol
All cooper for electrical use is 99.5% pure. Try to get one with less!
Most cables are using wires as thick as 12-14 AWG because that’s the thicker they can fit into their banana plug (Not a very sintific one).
All qualities they say they give the cables: Cooper purity, use of silver, cryogenic treatment, Bi Wire, Burn In etc’ - has nothing to do with the spec. of a speaker cable. It’s all snake oil mambo jumbo, to cover their and customers ignorance.

Mr.  sleepwalker65
The answer is with the Damping Factor (DF) of your amplifier. There are some exceptions, if he speakers are not coil loaded (ribbon, electrostatic etc'.) or if the Amp. is a class-D type. But most, use a A-B class amp with ordinary speakers.
DF is defined as the ratio between the Amp's. output resistance (Ro, in Ohms) vs. an 8 ohms speaker, @ 1kHz.
As so, an Amp. with a DF of 500 has a Ro of 8/500=0.016 ohms.
The DF is given and you get it as you buy your Amp. It is used to be the higher the DF, the better is the Amp. Some use very stiff feedback to achive it - Not so good.
Others, may have tube amps. that have very low DF as low as 8! 
The DF is actually the way the Amp. is getting control over the speaker's coil. A coil, especially a moving one in a magnetic field, generates an electric current that is equal to the one made it move, but in the opposite direction. It is called the "Lentz" law.
Speaker cables are in a way two resistors (Rc) that connect the power Amp. to the speaker. Why two? becuse the cables go to the speaker (red) and goes back (black) to the amplifier. 
As so, the speaker's impedace has no significance in this electrical circuit.
The speaker cables resistance, just need to be significantly lower than the DF.
Other wise, the DF would decrease. So if the Rc = DF you actually have a 1/2 of the DF you paid for. This guy with his  Bryston 4BSST2, with a DF of 500 is now enjoying an Amplifier equals to a poor reciever of the 70's with a DF of about 40!
In other words, he is maybe listening to less than 10% of his equipment's full potential.
The long (24') that would count as 2xRc, is actually equals to the resistance of a 48' long cable. A few more feet and you need transportation to go visit them! :-) Why so long?
A thick cable (4 AWG and thicker) is hard to make and would cost a lot. Rather than go that long with cables, it is better to get the amplifier closer, maybe use two monoblocks and guid a blanced interconnect (XLR) that can run up to 100m with no sound degradation, while cost's little. 

0 guage (AWG) wires are difficult to work with. They are thick. Too thick to solder, as by the time the tin melts, the isolator also gets burned. It is no longer as good for isloating, it exposes the cooper to oxidize and look bad. The cable itself can not fit into any banana plug on the market. An agent must be connected between the two.
A 0 AWG cable is more costly than a 14 AWG, more heavy and less flexible. However, all can be overcome with some technology. Even up to 4 times 0 AWG!
Most cables on the market (regardless of price factor) are not getting thicker than 14 AWG. For this reason.
Some would look thick, but hey are looking so because a thick isolating tube over a regular 12-14 AWG cooper core.
Some make thick cable, but charge a lot for them. This might not be a problem, for others who spend that much on a power cable, that really makes no sense at all.
The market, as for what it is, is tricky. None tels you what their cable is good for (DF, Rc, or other), a lot of urban legends are sticked to them (cryogenic, cooper purity, high end banana plugs!) and a nylone sleve that looks nice, to cover the poor materials beneath.
Price: What would you think a 0 AWG, 2.5m (8’) long speaker cable set should cost? (if guage goes thicker or cable longer, it would naturally cost more).

Did you make it to the ICU?

DeKay

"When are you gonna come down
 When are you going to land"

b4icu

All qualities they say they give the cables: Cooper purity, use of silver, cryogenic treatment, Bi Wire, Burn In etc’ - has nothing to do with the spec. of a speaker cable. It’s all snake oil mambo jumbo, to cover their and customers ignorance.

I'll ask you a second time: If you don't care for the data being provided by cable manufacturers, what data is it that you seek?

I don't know why you want to use 0 AWG wire unles it's in an automobile setup. 

"I hope this doesn't damp ones enthusiasm ... ;-)"

dill, how do you actually gauge ones enthusiasm?

What about a double run of 0 AWG wire?
Should be twice as good ....

" dill, how do you actually gauge ones enthusiasm?"
- A polygraph? ...... ;-)

Hi
I would aspect cables maker to specify:

1. The actual cooper gauge.
2. The cable length (feet or meter).
3. It’s actual resistance (for a single and for a pair (Red+Balck) in Ohms.

I already made cables of 4 AWG (3m) and 0 AWG (2.5m).
Also has the technical solution to make 2x0 AWG and 4x0 AWG cables.
So far, all cables were made for free, only cost of material.

Can this site (forum) hold pictures? I can attach some.

For all who think it is a joke, you better check it out. First thing, you can get your speakers closer to the amplifier (as a start) and use some jump start cables between the amp. and speaker. Be carfull not to do any short circuit on amp’s outputs!
You may be surprised (for the good) from the sonic change! after that you may come back and share that with us. At the end, ask your self what is the right gauge you need and how to get one. You realize that the jump start cables can not to stay for long.

It is better to understand the relations between amplifiers, speaker cables and speakers, do a knowladgble calculation, and by that make a custom cable to fit - rather than gues and try, with no particular direction or insight.