What Does RMS mean and Why It’s So Important

Building the perfect audio system is a fun (and expensive) hobby that has kept audiophiles busy for decades, and with the advancement of technology, the hobby is getting more and more addictive as the years go by. However, a technical term that most people doesn't seem to understand is RMS. What is it and should you care about it? The short answer is: Yes!


Audio technology is not the easiest thing to grasp, especially for beginners who are new to the game. Building the ideal system requires a solid understanding of several terms that are important to know in order to not only make the system work in the first place but also to perform at its best.

One of the most important terms that you may come across when purchasing new speakers and amplifiers is RMS. For experienced speaker buyers (at least those who know what they are doing), RMS is probably the most important metric that you need to take into consideration when buying new equipment.

Let’s dive into this term and break down what it means, why it’s important and everything else you need to know in order to understand how RMS fits into the system over all.

What Exactly Does RMS Mean?

Literally speaking, RMS stands for Root Mean Square, and it’s a mathematical term that is used in several forms of audio technology to represent the average power output over a prolonged period of time.

RMS is used to represent the average power output that speakers can handle, as well as the average power output that amplifiers can provide continuously, without any issues.

To give you an example, a speaker with a 50w RMS rating may be able to handle 150w of power in short bursts (a loud bass kick, or any other loud expression that happens intermittently throughout a song), but for prolonged periods of usage, the average power output should be around 50w for continuous play.

Literally speaking, RMS stands for Root Mean Square, and it’s a mathematical term that is used in several forms of audio technology to represent the average power output over a prolonged period of time.

RMS ratings are not completely accurate, as most figures aren’t when it comes to voltage and current, but it is still by far the best indicator of the average range of a speaker’s power output that you should respect and always aim to expect.

RMS ratings are without a doubt the most important metric that you should be looking at when comparing new car audio equipment. It is the only representation of a piece of equipment’s true power output. However, if that is the case then why don’t the speaker manufacturers reflect that in their marketing and product advertisements? We will discuss that in the next section.

Why Don’t Manufacturers Push RMS as an Important Metric?

The goal of a product manufacturer is to sell as many products as possible. I am not saying that the car speaker manufacturers are churning out bad quality products in hopes of making as much money as possible, that’ not the case at all, but let’s be honest, the bigger numbers excite you more than the small ones, right?

Lots of consumers still don’t fully understand what the different metrics and numbers mean when they are looking to buy some new speakers, so to the uninformed, a higher power output usually means a more powerful speaker.

Because of this, the manufacturers are more likely to push the peak power output as the main metric in their product descriptions and marketing efforts, because this is what the majority of consumers are excited by.

Peak power output is an important figure to know when purchasing a set of speakers because it allows you to align the numbers with the power output of your amplifier. However, the peak power output is not the figure that represents the true power of speakers that you are interested in purchasing, so it shouldn’t be the one that you gravitate towards.

RMS Queen Mary - This is not the type of RMS that we are talking about here!

So, What Does All Of This Mean For Me?

Now that you understand the meaning and the importance of RMS, you should use this information when you decide to upgrade or install a new car audio system. Configuring your system around the peak power outputs of the individual pieces (speakers, subwoofers, head units etc.) is just asking for trouble, as these numbers are not a true representation of what the products can handle on a continuous, day-to-day basis.

It is often thought that some manufacturers have been known to exaggerate their RMS and peak power numbers in order to make them more appealing to consumers, but that’s genuinely not the case. All products that are CEA tested are tested using the same equipment and are put under the same testing methods, so the RMS rating is generally very accurate.

With that being said, the speakers that you purchase are only as good as the amplifier that is feeding them. You should already know that it’s important to match up your amplifiers power output with the power rating of your speakers and subwoofers, but what most manufacturers don’t tell you is that most speakers can actually handle a slightly higher RMS than they advertise. As long as your amplifier matches the anywhere between 75% – 150% of the advertised RMS of your speakers, you will have no problems with them.

If you had to take away one key piece of advice from this article it would be to make sure that your amplifier is configured to output the same wattage as the RMS of the speakers and subwoofers that it is feeding. Doing so will drastically reduce the chance of your equipment failing, and will give you the peace of mind knowing that your system is working efficiently and can cruise along for long periods of time without any issues.

Don’t let the peak power numbers fool you. Stick with RMS and you will be fine.

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