How Many Watts Is Good for a Car Stereo?


The factory stereo installed in my car is not powerful enough to cancel the road noise. So, I decided to upgrade it, and the first question that came into my mind is, how many watts is good for a car stereo?

In general, for a good audio experience, the car stereo should have more than 20 Watts RMS per channel. This wattage level is enough to power most standard car speakers and provide a satisfying sound experience.

Many factory-installed car stereos produce 5 – 15 Watt RMS per channel, and because of that, they do not provide an impressive on-road stereo experience.

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Tip: If you want to buy a new car stereo, always ask for RMS wattage per channel. 

Car stereo manufacturers label unimportant characteristics to show off higher wattage of their product, but the main rating that matters while selecting car stereo is RMS, not the peak wattage.

In this article, I will show the effect of wattage on the sound output of car stereo. In addition, I will answer some most common questions regarding the selection of stereo so that you know which numbers are important when buying your radio. 

How Many Watts Should a Car Stereo Have?

The unit used to measure the power output of a car stereo is the wattage, and it is the most important factor while choosing a stereo for your car. 

The loudness of the sound system depends on the per-channel wattage output of the car stereo or amplifier. 

The car stereo ranges between 8 – 30 watts. On average, most double DIN stereos with 7-inch displays have 15 Watts, and the strong ones 22W.

But why do we always check the RMS and not the peak wattage?

To properly understand this concept, let’s get acquainted with some basic terminology. 

Wattage

It is a unit to measure electrical power. It is the rate at which energy is produced or used at a specific moment. The wattage in car stereos is the power it can provide to amps, speakers, etc. 

1 watt = 1 volts X 1 ampere

RMS Wattage

RMS wattage or root mean square wattage is the continuous amount of power that a device can handle. 

Peak Wattage

Peak wattage is the power that a device can handle for a shorter time, not continuously without risk of being damaged. 

How To Convert RMS to Peak Watts?

In short, RMS wattage = 0.7071 X Peak Wattage 

RMS wattage is always smaller than peak wattage. Most of the factory car stereo models are labeled as “50 watts x4” or 200 watts.

This 50 x 4 wattage rating represents the peak power rating, and it is different from RMS ratings. The RMS power available per channel, in this case, is between 10 – 15 watts which is not sufficient to operate a high-quality sound system at higher volumes. 

The peak power rating of an amplifier or head unit represents the power output for shorter bursts, like for a single loud note, but the RMS wattage rating measures the constant power output.

Higher RMS of car stereo means that the stereo can deliver higher wattage for an extended time. Aftermarket car stereos can produce more than 20 Watts RMS per channel, ensuring no distortion at higher volumes. 

Moreover, a higher RMS rating car stereo can handle more powerful amplifiers and other audio equipment without burning itself. 

Do More Watts Mean Better Sound?

In most car sound systems, if you want a good audio experience, you have to upgrade your factory audio.

By upgrading, I mean using a high-end car stereo, amp, speakers, and they need more wattage for louder sound.

More wattage does mean better sound. While wattage is an essential factor at higher volumes, the efficiency and sensitivity of speakers also play a huge role. Doubling the wattage does not mean that you get twice as much as sound output. It only leads to an increase of 3 dB.

For example, if you have 10W speakers and replace them with 20W speakers, you will notice an increase in volume, but it does not double.

To understand the relation between wattage and sound, let’s look at some of the basic terminologies of sound. 

Decibel

Decibel, abbreviated as dB, is a unit to measure sound intensity by comparing it to a level on a logarithmic scale.

Well, don’t get overwhelmed with the complex definition. In simple terms, it means that you can’t simply add two numbers on a logarithmic scale as you do with natural numbers. On a log scale, a double does not mean “twice as much.”

For example, 100dB does not mean double 50dB but many times more than 50dB because it is a logarithm value. 

Sound Pressure Level (SPL)

The loudness is measured in SPL, and the pressure in the sound wave determines its loudness.

On a rough scale, a 10db increase in sound level leads to doubling the loudness, and if you double the wattage, it increases in 3dB SPL only.  

Now the question comes: 

How Much Wattage Is Needed to Double the Sound?

Let’s imagine two amps. One makes 10W and the other 20W. We know that the doubling of wattage only leads to an increase in 3dB, but to double the sound output, we need to increase the SPL level to at least 10 dB.

  • 2 times of power = 3 dB SPL
  • 4 times of power = 6 dB SPL
  • 10 times of power = 10 dB SPL

This means a ten times increase in wattage leads to doubling of loudness. Or in other words, to increase the speaker’s sensitivity up to 10dB, we have to apply ten times more wattage. 

So, if you use a 10W amp and want to double the loudness, you have to replace it with 100W.

Is a 200 Watt Car Stereo Good?

When it comes to a great sound experience, the car stereo should be powerful enough to provide enough wattage output needed by amplifiers, speakers, and other audio components. 

In general, a 200-watt car stereo is good if you would like to listen to your stereo at higher volumes. But remember, these are peak watts, not the RMS. Unfortunately, many car stereo manufacturers use this marketing trick. 

In many cases, a car stereo is getting power from an audio amplifier chip rated at 50 watts for each of four channels. For example, in Pioneer, this is a Mosfet built-in amp.

In RMS wattage, it turns out to be 13 – 18 watt per channel. This amount of power will not be able to deliver continuous maximum output at higher volumes. 

Is 50 Watts per Channel Enough for a Car Radio?

Wattage sets up an upper limit on how much loader your sound system can go without distorting your favorite song. The amount of wattage required for a car radio depends on your taste in music. 

If you listen to light jazz, classical music, then 50 watts per channel is sufficient. But if you like to listen to uncompressed loud music and have over 90dB speakers, then 50 watts per channel out of the stereo will not impress you. 

As I mentioned earlier, many car stereos are labeled with a 50W per channel. For 50 watts per channel, the actual RMS output is between 10 -14 watts, which is not very powerful for good sound quality.

In that case, you need to upgrade your car audio with an external amplifier with at least 60-80W RMS if you want to have a real improvement in the sound quality. 

Should Speaker Wattage Be Higher Than Radio?

For good audio output, the ratings of speakers, radio, and amp must match but matching speaker impedance, and receiver wattage is complex and technical work.

It is OK to connect higher wattage speakers with the radio, but if you are using a radio with very low power compared to speakers, your audio experience will not be great.

You will end up increasing the volume, but the sound from the speakers will remain the same. It may also happen that the radio or amp may burn itself because you are demanding more power.

I always recommend using an amplifier with the RMS output per channel around 1.5x of speakers’ RMS. 

On the other hand, don’t ever use low impedance speakers with high wattage radio or amplifiers because it can damage the speaker coil. What is happening, in this case, is that speakers are not able to dissipate excess heat generated by extra wattage, which in turn burns the coil spring.

You can check speakers’ impedance rating, sensitivity, and wattage rating that can be used with your selected radio or amp on its user manual. 

To decide whether a car radio (or amplifier) and a set of speakers can work together or not, you have to consider three parameters:

  • Power handling (measured in watts)
  • Power output (measured in ohms)
  • Sensitivity  

Let’s discuss some key terms that are used in selecting speakers for car radio or amp:

Impedance

For a powerful synergy and great sound, the impedance of radio and speakers should match.

Impedance is the electrical resistance offered by a component, and it is measured in ohms. It is represented by the symbol omega “Ω”—as in 4Ω.

The most common impedance ratings in car audio are one, two, or four ohms. For lower ohm ratings, the car radio has to work harder to drive the speakers.

On the other hand, if impedance levels do not match as specified in manuals, it can permanently damage your car radio or speaker.

Power Handling

Power handling is expressed in wattage. It represents how much the speaker can handle and how much the car radio or amp gives out.

The speaker requires high wattage at high volumes, but if your amp or car radio is not producing enough power, you will get distorted output. 

Sensitivity

The sensitivity of speakers is expressed in decibels. It is the speaker’s loudness when it drives one wattage of power at a distance of one meter. Thus, the sensitivity of the speaker directly affects the loudness.

The lower sensitivity of speakers says 85 dB is much quieter than 88 dB, and to increase 3dB, you have to double the wattage of the receiver. 

Conclusion 

While selecting a car stereo or amplifier, always check for RMS wattage output per channel. Unfortunately, many car stereo manufacturers misguide the customer by highlighting something like 1000W, but actually, they show peak wattage.

More wattage means more sound, but sensitivity (decibels) of the speakers and their efficiency also plays an essential role in determining the quality of sound at higher volumes.

To increase the loudness of speakers up to 3dB, you have to double the wattage and to double the loudness, you have to increase the wattage by ten times.

Martin

Welcome to ImproveCarAudio! I am Martin, and I love to write about everything related to car sound systems. I strive to provide the most accurate and helpful information about car audio through extensive research, as well as my experience with car audio installations.

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