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What Size of Speaker Wire Should I Use For My Speakers & Subwoofer

There are a ton of things to think about when you’re building a car audio system. Amps, subwoofers, and speakers steal the spotlight, but, that doesn’t mean that speaker wires don’t matter.

Speaker wires play a crucial role in the performance of a car audio system. Although these wires can’t make your audio system sound better than it really is, they can and should ensure that every last drop of power makes its way from your amplifier to your speakers.

Conversely, poor-quality or mismatched speaker wires can definitely hold the system back from sounding its best and reaching its full potential, which can turn it into an expensive disappointment.

The most important thing to think about when buying speaker wires is AWG (American Wire Gauge). Getting the wrong AWG for your speakers or subs can end up giving you horrible sound quality. But AWG isn’t the only thing to take into account, let’s take a look at what makes good quality speaker wires.

What Size Speaker Wire Do I Need?

Before discussing what gauge speaker wire is appropriate for your speakers and/or subwoofer(s), you first need to understand what wire gauge is.

Wire gauge (AWG) refers to the thickness of the wire, rated with a numerical designation that runs opposite to the diameter of the conductors — that is to say, the lower the wire gauge number, the thicker the wire diameter & the higher the wire gauge number, the thinner the wire. For example, a 12 AWG is thicker than an 18 AWG wire.

So, why does the thickness of the wire matter for speakers? Well, the short answer has to do with resistance (measure of restriction of conductivity in a circuit). A thicker wire presents less resistance to current flow. This means that a thicker wire will generally transmit a more cleaner signal to the speaker. 14-gauge speaker wire, for example, is much thicker than 18-gauge speaker wire and most importantly, it offers slightly less than half the resistance to audio signals.

Lower-gauge speaker wire is usually recommended for long wire runs, high-power applications, and low-impedance speakers (4 or 6 ohms). So, naturally, thicker wire will cost more than thinner wire.

For relatively short runs (less than 50 feet) to high-impedance speakers (8ohm, 16ohm…etc), you may be able to get by with thinner wire; 16 gauge wire for instance will usually do just fine. It’s also cost-effective and easy to work with.

Keep in mind that the length of the speaker wire will also have a major impact on the gauge of wire you need to get an optimal performance out of your speaker.

The proper wire size for your speakers, as indicated by AWG, is determined by several factors, including the planned load on the circuit (impedance), the length of the cable runs, and the material the wire is made out of.

The best way to find the right wire gauge for your speakers is to figure out the exact length of the cable runs, speaker loads, then compare them to this handy chart:

Speaker Wire Gauge2 Ohm Speakers4 Ohm Speakers6 Ohm Speakers8 Ohm Speakers
18 AWG9 ft18 ft28 ft37 ft
16 AWG12 ft23 ft35 ft47 ft
14 AWG20 ft40 ft61 ft81 ft
12 AWG31 ft62 ft93 ft124 ft
10 AWG48 ft96 ft144 ft191 ft

These tabulated values are the recommended cable distances one should use for various speaker cable gauges and speaker loads.

There are a few exceptions, but generally speaking, here are safe gauges to use (in AWG):

  • For Subwoofers: 12 AWG
  • For Longer Speaker wire runs: 12 AWG
  • For Shorter Speaker wire runs: 16 AWG

If you have some power-hungry subwoofers hooked up to a beefy amplifier, you’ll probably want to bump that speaker wire gauge down to 10 or even 8 AWG speaker wire.

How Does Resistance Affect Performance?

Speaker wire has three fundamental electrical properties: resistance, capacitance and inductance.

Resistance is by far the most important property of speaker wire to look at. It goes hand in hand with the wire thickness and ­length. A longer thinner wire has much more resistance than a shorter thicker wire of the same structure.

For this reason, an ideal speaker wire should have the lowest resistance possible. To get the best and most efficient energy transfer a thicker wire such as a 12-gauge wire would be preferred over an 18-gauge thinner wire.

Metaphorically speaking you can think of a speaker wire as as a water pipe with water flowing through it. The narrower the pipe, the more resistance it has, as less water can flow through the pipe in a certain length. Furthermore, in a longer pipe, water will take longer to flow through it.

I mean, think about it, the farther an audio signal travels down a wire, the more resistance – and power loss – it encounters. Because thicker wires offer the least resistance to the flow of signal, they have the best capacity for carrying audio signals over long distances. Not only that, but low-resistance wire also allows more of the source’s power through to the speaker coil. This translates to more power and more sound.

Why Does Speaker Impedance Matter?

Impedance refers to the load a speaker places on an amplifier. It’s measured in ohms, and symbolized by the Greek letter omega (Ω).

Most speakers have impedance ratings of 2, 4, 8, or 16 ohms. But that number is more like an average taken over a wide range of audible frequencies. In other words, nominal speaker impedance is constantly changing, thus it can wander above or below the stated average.

Keep in mind that wire thickness affects impedance, or how smooth audio signal runs through the wire, over a distance.

I mean, think about it, when your speakers are hooked up to an amplifier, the speakers with a lower impedance will draw more current (higher amperes) than higher impedance speakers. This can make a difference in the wire gauge size you need based on the length and power carried to the speakers.

Obviously, the higher the amperage rating of the circuit, the larger the wire needs to be in order to avoid exceeding its temperature rating and thereby overheating, which could melt the wire and cause fire.

Not to mention the fact that the thicker the wire the less resistance there is and therefore less power loss across it at high power levels or in long cable run.

How Much Wire Do You Need?

Your decision in choosing the correct wires for your subwoofers and speakers should also be based on the length of the cable run and the impedance load of your speakers.

The easiest way to figure out how much speaker wire you’ll need is to run a string from your head unit or amplifier mounting location to each of the speaker locations. Measure the string and add a fair amount of extra length (approximately 4 to 6 feet of extra cable). This will provide some slack for easier connection to your equipment.

You can also use a tape to measure how much wire you’ll need. However, we found that using string is much more convenient because it allows you to get a much better idea visually. Plus, you can just measure the string with your tape measure once you’re done.

Once the total required wire length is determined, check the nominal impedance of your speakers, then you can choose the wire gauge size accordingly.

For example, if the nominal impedance of your speaker(s) is 4 ohms or lower, and that your speakers are power-hungry, it’s highly recommended to choose a 14 or 12-gauge wire, no matter the distance.

For most high impedance speakers (8ohm, 16ohm…etc) with a shorter run (less than 50 feet), a 16-gauge wire would be an ideal choice.

For long wire runs of 75 feet or more, it’s a good idea to opt for at least 16 gauge, if not a 14 or 12-gauge wire in case the speaker(s) have a low impedance rating.

It goes without saying that the resistance is directly proportional to the length of the wire, the longer the wire the greater the resistance.

That being the case, at longer distances, you will always want to keep the resistance of the wire as low as possible with a thicker gauge wire.

What Type of Wire Do You Need?

Beyond the physical size of the wire and its length, you also want to know what the wire is made of.

The material the wire is made out of will also affect the resistance. Different materials have different resistivities.(the ability of the material to resist electric current).

Copper is recognized as one of Earth’s finest conductive metals. In fact, it is the standard benchmark for electrical conductivity. That is to say conductivity ratings are expressed as a relative measurement to copper. The downside, however, is that copper costs an arm and a leg compared to other materials such as aluminum, zinc, and nickel, which are way less conductive.

So, if you are a serious audiophile who cares about reproducing music in its purest form, opt for speaker wire that’s based on pure copper. Pure copper speaker wire might be more expensive, but it is definitely worth it in the long run.

One might say that silver is slightly more conductive than copper, so it’s better to use silver speaker wire for finely nuanced sound reproduction, right? Well, yes, silver is more conductive but it is considerably more expensive and not as strong.

Copper-Clad Aluminum Vs. Copper Speaker Wire

If you’re on a tight-budget or if you don’t want to splurge on the most expensive speaker wire, copper-plated or copper-clad aluminum wire is a decent substitute, and there isn’t much of noticeable difference in sound quality.

To cut down on cost, manufacturers started using aluminum wire dipped in a thin coating of copper. This technique created an aluminum core cable coated with a thin layer of copper. This is known as copper-clad aluminum.

Aluminum is lightweight and doesn’t cost much compared to copper, so at first it may seem like a great way to replace the more expensive copper based wire options. However, there’s a problem.

Aluminum has 61% of the conductivity of copper. In other words, it has 39% more resistance. This means it’ll take larger aluminum wires to get the same power handling, capacity, and resistance value.

Some marketing gimmicks, low price tag, combined with consumer ignorance have allowed copper clad aluminum speaker wire to become more common in the marketplace.

Stranded Vs. Solid Conductors

Almost all speaker wire sold is stranded. This is because stranded wire is extremely flexible, easier to route into cramped spaces, can withstand vibration and flexing without fatiguing and eventually breaking compared to solid wire; therefore, it is more commonly used in audio industry.

Nevertheless, stranded wires are far from being perfect. Their diameter is slightly larger yet they provide a similar carrying capacity as solid wires. This is not to mention their initial cost that’s considerably higher than solid cables. These costs are higher due to the more complex manufacturing process required to make these intricate wires.

Additionally, stranded cables are not ideal when it comes to preventing electronic interference as the air channels in between each strand amplify the “skin effect” created by the magnetic fields along the the outer edge, or skin, of a wire. So, always make sure to choose well-insulated stranded speaker wire, and most importantly, route your speaker wires away from any source of interference.

Is Oxygen Free Speaker Wire Worth It?

Some people swear by oxygen free copper (OFC). They claim it has better conductivity, and therefore “sound” better than standard copper wire. However, the problem is that this is hard to prove unequivocally.

After some research and testing, we’ve found that OFC doesn’t really make any noticeable difference. We believe it’s that OFC is most likely hype, and it’s safe to say that it’s really just expensive audiophile snake oil. It’s not worth spending more money on it.

Speaker Wire Gauge Chart

speaker wire size chart

Alex Brown

Hey There, my name is Alex Brown, I'm an LA-based sound engineer with over 10 years experience installing, troubleshooting, and repairing commercial, automotive, and household sound equipment. I've installed highly competitive car audio systems, and everything from navigation systems to full car stereo systems, remote starters, alarms and beyond. I enjoy creating solutions and simplifying everyday needs. I also love helping people get great sounding gear, thereby, saving the world from bad sound one customer at a time.

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