Top 5 Best 18-Inch Car Subwoofers (2021 Review)

Wanting to really make waves with your new subwoofer setup? 

Then you’re probably looking for the best 18 inch subwoofers for the money.

12s are just too small, and 15s don’t feel quite sufficient enough. We get you! 

Of course, when you’re investing in a larger subwoofer design like these, you need to know that you’re getting good value for the money. Plus, it’s important to make sure you’re getting good sound quality in addition to volume.

While all subwoofers can get the job done, choosing 18 inch subs means you’re looking for power. But you’re paying more for these larger subwoofers.

So, you want something dependable, that produces loud and deep bass, and is a reasonable price for its performance, which is where we come in. 

In this guide, you’ll learn:

  • What are the advantages of an 18-inch subwoofer for your car
  • How to pick the best 18-inch car subwoofers
  • And much more!

Below is a quick list of my favorite 18-inch car subwoofers. Keep scrolling to learn more of my top tips to choose and use the best 18-inch subwoofers for your car.

Skar Audio Single 18" 1200W Loaded SDR Series Vented Subwoofer Enclosure | SDR-1X18D2
  • Vented enclosure
  • 1 ohm final impedance
  • Pre-wired and pre-mounted
  • Vented enclosure
  • 1 ohm final impedance
  • Pre-wired and pre-mounted
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Eminence Professional Series Kilomax Pro 18A 18" Pro Audio Subwoofer Speaker, 1250 Watts at 8 Ohms
  • Made by brand with over 50 years of experience
  • 8 ohms make it easier to monitor output
  • Works well in sealed or ported enclosures
  • Made by brand with over 50 years of experience
  • 8 ohms make it easier to monitor output
  • Works well in sealed or ported enclosures
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Rockville RVP18W8 1200 Watt Raw Replacement DJ PA Subwoofer 4 Ohm Sub Woofer, 18 inch
  • Comes in 4 and 8 ohm options
  • Frequency response of up to 26hz
  • 500 watt RMS
  • Comes in 4 and 8 ohm options
  • Frequency response of up to 26hz
  • 500 watt RMS
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Harmony Audio HA-ML182 Monolith 18" Car Stereo Competition SPL Sub 3500W Dual 1 Ohm Subwoofer
  • Available in 1 ohm or 2 ohm options
  • RMS of up to 1750 watts
  • Won’t overheat
  • Available in 1 ohm or 2 ohm options
  • RMS of up to 1750 watts
  • Won’t overheat
View on Amazon
2 Rockville RVP18W8 2400w 18" Pro Subwoofers 8-Ohm Raw Subwoofers
  • Dual set for fuller sound
  • 1200 RMS
  • 26hz frequency response
  • Dual set for fuller sound
  • 1200 RMS
  • 26hz frequency response
View on Amazon

Our Overall Top #1 Pick: Skar Audio Single 18″ 1200W Loaded SDR Series Vented Subwoofer Enclosure | SDR-1X18D2

We love this 18-inch car subwoofer because it’s high quality and easy to install. Since it’s pre-mounted, pre-wired, and pre-enclosed, all you need to do is hook it up and place it. You’ll save money and time with this subwoofer. 

The best part about this subwoofer is its 1-ohm final impedance. In short, this means that you’ll get the biggest boom from your sub. The lower the ohm’s number, the stronger your bass will be.

Low impedance is great, but we do want to note that it can mean that you’ll need to spend a little extra on your amplifier. Even so, this subwoofer is still one of the best subwoofers for the money because of its superior performance.

Add to that the other cost savings in installation, wiring, and enclosures, and this subwoofer is a good deal even after amplifier costs.  

Plus, this speaker has a 18hz frequency response which is better than most subwoofers on the market. 

Top 5 Best 18-inch Car Subwoofers

In a hurry? Check out our top 5 picks below! Keep reading to learn more about these 18 inch subwoofers for the money. 

  1. Skar Audio Single 18″ 1200W Subwoofer (Our Top Pick)
  2. Eminence Professional Series Kilomax Subwoofer (Best High-End)
  3. Rockville 1200 Watt Raw Replacement Subwoofer, 18 inch (Runner Up)
  4. Harmony Audio HA-ML182 Monolith 18″ Subwoofer
  5. 2 Rockville RVP18W8 2400w 18″ Pro Subwoofers

What are the Advantages of a High Quality 18-Inch Car Subwoofer?

Most 18-inch car subwoofers are a pretty big investment in the sound quality in your car or truck. It’s important to know that you’re going to get good value for that investment, and one of the best ways to do that is to buy high quality. 

That’s a little counterintuitive, especially if you’re someone that likes to look for hidden gems that aren’t as expensive but offer premium performance. Don’t worry, we’ve included a few of those hidden gems in this article, but the longevity and performance of lower-quality subwoofers is still questionable. 

In general, since sound quality is difficult to optimize and require high-level engineering and design, it’s best to go for high-quality options instead of cheaper alternatives. 

That’s because a high quality design will provide high quality performance over the long run instead of just up front. These designs are also often more protective, which helps prevent your subwoofer from being damaged during normal use of your vehicle. 

Especially if you’re looking to improve the sound quality in your daily driver, a family vehicle, or a vehicle that goes on long drives, durability is critical to getting a good deal. 

That’s one of the reasons we’ve also chosen pre-enclosed subwoofers for some of the best options in this review. Pre-enclosed subwoofers are generally more durable because the enclosure is chosen specifically for how well it will work with the subwoofer inside. 

Overall, high quality subwoofers are also usually easier to install and need less modification. That’s great news if you’re looking for more of a plug and play experience instead of custom crafting your subwoofer’s enclosure and installation.

How to Pick the Best 18-Inch Car Subwoofers?

Magnet Size

A lot of people think that a large magnet is better for your subwoofer. That really isn’t true. Size doesn’t equal power when it comes to magnets.

Your sub’s magnet size doesn’t matter that much. What truly matters is the magnet’s material.

Keep in mind that magnets made from neodymium or ferrite are often best, even if they are smaller than other materials.

Many companies will list their larger magnet size to draw in customers because it sounds like it’s important. The only aspect you’ll want to pay attention to when it comes to the magnet is the material it’s made from. 


Larger subwoofers are more likely to produce distortion. That’s because they often have a stronger output. While a speaker may have an overall high wattage output, the RMS wattage dictates its true capabilities.

You’ll want to make sure your subwoofer isn’t too powerful for your amplifier. If you plan on both buying subwoofers and upgrading your amplifier, go by the sub’s RMS rate rather than its peak wattage number. 

Then, see what amplifier you can get to match that. Remember to do the math if you’re using more than one subwoofer. The RMS rating of one sub is not the same when you add another one into the picture.


There are two types of voice coils: single, and dual. Single coils can only be wired to their listed impedance. For example, a subwoofer that’s rated as 2-ohm can only be wired to 2-ohm. 

Dual coils allow for more possibilities through either parallel wiring, or series wiring. Parallel will give you more ohms. If you have two 8-ohm speakers, your final impedance will be 4 ohms in using parallel wiring. 

On the other hand, series wiring does the opposite. If you have two 8-ohm subs, your final impedance will be 16 ohms. This is less ideal, unless you’re trying to match a low-powered amplifier, in which case this is actually a good idea. 

Getting the right setup from your investment is important, so if you’re really looking at a good ideal I recommend a balancing act between the sound quality and performance of your subwoofer and the cost of a better amplifier. 

Frequency Response

Large subwoofers typically provide a deeper frequency response. This means that your bass will be deeper and more responsive. The lower your frequency, the deeper your sound spectrum. 

Similar to ohms, frequencies are best when their numbers are low. The average lowest frequency response for subwoofers is between 25 and 35hz. As you’ll see in our list, some 18 inch subwoofers can hit up to 18hz. 


Your ohm level is also important here. Most average sized subs (like 10s and 12s) produce up to 2 ohms, but many 18 inch subs are wired for a 1-ohm final impedance. This, in combination with a lower frequency means that these subs can create more rumble than smaller speakers. 

That said, there are 18-inch speakers that only produce 8 ohms (like our dual Rockville subs) but when paired and properly wired, these will have a final impedance of 4 ohms instead. Check out the video below to see more about how to wire up your subs. 

Our Reviews of the Best 18-Inch Car Subwoofers

  1. Skar Audio Single 18″ 1200W Subwoofer

If you choose this subwoofer, you’re picking the quickest and most effective 18 inch sub option. It’s pre-enclosed, pre-wired, and pre-mounted, meaning that all you’ll need to do is hook it up. 

Not only does that mean it’s faster to install, it also saves you money on the cost of additional accessories for your subwoofer. 

It’s wired to produce a 1 ohm final impedance. Its sound frequencies are among its most impressive specs, reaching 18hz which is much lower than the average lowest frequency rating. 

This means that you’ll hear bass that hits some of the lowest possible frequencies for a fuller “boom.” Lower bass also gives you a richer, harder-hitting sound.  

This is thanks to its wiring, and its high-surround roll. Everything in this subwoofer is designed to give you better performance and to work well together. 

 It’s a larger enclosure, though, so if you have a truck, this may not be ideal for you. This subwoofer takes up a fair amount of space and doesn’t work well in vehicles that don’t have some spare space. However, this subwoofer has a nice aesthetic appeal and looks great in car trunks or in the back of an SUV. 

Overall, the sound quality of this subwoofer combined with its impressive design efficiency makes it a great deal in addition to being a premium option. 

PROS (+) CONS (-)
+ You don’t have to do much work to install it
+ It has a 1 ohm final impedance 
+ High-surround roll enables lower frequencies
– Can’t fit in tighter spaces, like trucks

2. Eminence Professional Series Kilomax Subwoofer

As we stated earlier, size doesn’t matter when it comes to magnets. Material does. The Eminence Pro 18A subwoofer uses a ferrite magnet, which works just as well as Alnico magnets

Higher quality magnet choice means that this subwoofer has some extra space to give you better performance. That’s because better magnets give you better sound performance in less space. 

This subwoofer gets 32hz on the frequency scale, and has double spider suspension which protects your coil when hitting those lower frequencies.

That means that this option is more durable and won’t need replacement as often. That durability makes this subwoofer a much better deal for the money.

This sub has an 8 ohm impedance, which can be good or bad depending on what you’re looking for.

It’s good if you don’t want to invest in the expensive speakers you’d need to handle larger ohms (4 ohms, 2 ohms, and especially 1 ohm). 

However, better ohm performance creates a deeper bass sound and they help your sub to tap into those lower frequencies. That means that this subwoofer gives you great sound quality, but can’t go as deep as some alternatives.

If you want a high-end brand with impressive sound quality, this is a great sub. If you’re looking for something that hits super deep though, it may not be your first choice. 

PROS (+)CONS (-)
+ Uses a ferrite magnet
+ 32hz frequency resonance
+ Reliable, high tier brand
– 8 ohm impedance

3. Rockville 1200 Watt Raw Replacement Subwoofer, 18 inch

This subwoofer comes with both 4 ohm and 8 ohm impedance options. We recommend buying the 4 ohm option if you plan on making this a dual setup. 

This speaker only has one coil, so it can only be wired to have the impedance that’s listed with it.

Two 4’s will sound better than two 8’s, but two 8’s might be a better deal depending on the rest of your sound equipment.

These subs are under 100 dollars a piece, and Rockville is a well-known and dependable brand, so they’re definitely a great budget pick for 18 inch subwoofers.

If you’re looking for a more affordable but high performance option, these are a great choice.

These subs are not enclosed, though. You’ll have to do the wiring and the enclosing on your own if you get these. 

While these are 1 or 2 ohms, they still produce a deep, full bass with a frequency response of 25hz. 

PROS (+) CONS (-)
+ Available in 8 ohms if you are looking for less impedance
+ Great frequency response of 25hz
+ Affordable, easy to turn into a dual setup
– You have to purchase/build and set up your own enclosure

4. Harmony Audio HA-ML182 Monolith 18″ Subwoofer

This pick is a little pricier than some of our other picks, but it’s still one of the best subwoofers for the money. That’s because it’s one of the most powerful 18 inch subwoofers you can get for your vehicle. 

You’re definitely getting your money’s worth with a peak wattage of 3500 and an RMS of 1750, alongside its 1-ohm final impedance score. 

You can purchase a 2-ohm option for the same price as the 1-ohm sub, so you’re not paying extra for a harder thump. 

With all this power, overheating is definitely a possibility, but not in this case. Harmony Audio uses large, slotted vents to help this sub breath and stay cool. Just make sure you’re pairing it with a proper amp like we’ve explained above. 

This sub’s frequency response is 30hz, which is definitely impressive, but pales in comparison to lower frequencies common with 18 inch subs that range anywhere from 18hz to 25hz. Despite this, its final 1-ohm impedance makes up for this overall. 

Overall, this design is worth the extra cost and comes with a lot of benefits like easier installation and a well designed enclosure.

PROS (+)CONS (-)
+ Options for 1 or 2 ohms, priced the same
+ Has a high RMS of 1750 watts
+ Large, slotted vents prevent overheating despite high power level
– Frequency response isn’t as deep as other subs on our list

5. 2 Rockville RVP18W8 2400w 18″ Pro Subwoofers

These subs are good if you’re wanting a dual setup.

They have a high RMS rating of 1200, meaning it’ll be louder than the average 300-600 RMS rating.

They aren’t quite as powerful if you’re looking for a single subwoofer setup. It just doesn’t balance the sound very well as a single unit, despite overall good performance. 

It also can reach 25hz which further puts some bang into its “boom.”

Despite this, it is only an 8-ohm setup between the two. Since it’s a single coil system, it’s impossible to wire it for better impedance. That means you can save a bit on your amplifier, but comes with some downsides in terms of the quality of sound. 

However, you’ll still be getting a louder sub setup than if you were to get a set of 10 inch subs, etc. The high RMS rating and low frequency response still creates a heavy, loud bass sound. 

While this isn’t our top pick for this list by any means, it’s still a high-quality option that gives you a lot of bang for your buck with the right setup.

PROS (+)CONS (-)
+ Dual sub setup
+ High 1200 RMS rating
+ Hits lower frequencies well
– Single voice coil
– 8-ohm

Our Top Pick: Skar Audio Single 18″ 1200W Subwoofer

We are impressed by the Skar Audio subwoofer for many reasons. Between its accessibility, easy installation, and final impedance, choosing this sub is a no-brainer. For those who are new to the subwoofer scene, or who just don’t have the time to put all the extra work into a bass setup, we highly recommend this product. 

Further, this is the most aesthetically appealing subwoofer on our list. Subs aren’t only about sound. If they’re not hiding under a seat, it’s important that they look nice, too. Skar Audio knows this which is part of why we love their products. 

Of course, all of those benefits get even sweeter when you remember that Skar Audio is able to offer this subwoofer at a great price too! It’s easily one of the best 18 inch subwoofers for the money. 

Final Thoughts On The Best 18-Inch Car Subwoofer

18 inch subwoofers are not for the weak. While smaller subs can still produce a great, heavy bass sound, large subs are still louder overall. 

An 18 inch sub’s larger cone is what really helps it reach those lower bass frequencies. If you like the type of bass that makes your car shake, that you can feel in your chest, large subs are almost guaranteed to give you that. 

We especially recommend these subs to people who have larger vehicles. They’ll require more space, especially if you choose a ported enclosure. But because of their size, the bass will cover your entire vehicle like a blanket of sound. 

That sound will make you glad you decided to get a bigger subwoofer. Smaller options just really can’t compete, even though they have their own benefits. 

With the selections on this list, you not only know what some of the best subwoofers are, but also know that you’re getting your money’s worth from all the subwoofers on this list!

Hopefully you now have an idea of what are the best 18-inch car subwoofers! Now, go out and get to thumpin’! 



Heather has developed an interest in cars after having to maintain and fix her own car over the years. She's here to help you answer your car questions.

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