Speaker Power Rating: What Do RMS and Peak Power Mean?

The speaker power rating refers to the amount of electrical power a speaker can handle before it will distort or break. It is an essential consideration for anyone looking to buy new speakers.

It will usually be listed alongside all the other speaker specifications – most of which you don’t understand, right? I know. It isn’t straightforward.

However, many people often misunderstand the power specification – but it can be important when putting together a sound system.

While you will unlikely have issues if you are careful, you don’t want to be that person who disintegrates the speaker cones of your new set of speakers.

So what do you need to know about speaker power ratings?

Speaker or Amplifier Power?

Firstly, don’t confuse amplifier power ratings and speaker power specifications.

It is obvious when you think about it, but the speaker doesn’t generate power – the amplifier does.

Therefore, the power specification that you will see for speakers – measured in watts – refers to how much power the speaker can safely receive from an amplifier before it starts to distort.

If a speaker is driven too hard, it distorts and gets very hot. If so, you may permanently damage the speaker, making it unusable.

So you really don’t want to be doing that!

Amplifiers are not all made equal, so you must check the wattage per channel the amplifier can output.

By the way, if you’re interested, the power of an amplifier in watts is calculated by multiplying the volts and amps that it generates. The voltage essentially pushes the electrical current (amps) through the speaker wire to drive the speaker.

If the amount of power it can output is well within the speaker’s capabilities, then you can be confident that you won’t ever damage the speaker by driving it too hard.

Minimum Power Ratings

When looking at the speaker specifications, you may see a minimum value for the power.

This is the minimum power level required to drive the speaker to make any useful noise, so your amplifier will need to deliver this amount of power at the very least.

This shouldn’t ever be a problem, so you don’t need to worry about this figure unless you’re trying to do something extreme – like driving speakers rated for 500 watts with a 10-watt amplifier.

Maximum Power Ratings

More important is the maximum figure, which is the power level the speaker can take before it starts to distort or clip.

Ideally, you don’t want to be going over this number.

However, remember that many of the figures you see in the specifications are often quite conservative; in reality, you could exceed them for short periods without a problem.

So, if the speaker specification says maximum power of 130 watts (as in the example pictured here), you want to avoid hooking them up to an amplifier rated at 1000 watts output.

This is because it won’t take much to get that amplifier to send more than 130 watts, potentially damaging the speaker.

Having said that, as long as you are careful with the volume control, you can drive any set of speakers with any amplifier – regardless of its power.

It’s just safer to match them a bit better to avoid breaking something.

What Does RMS Mean For Speakers?

RMS is short for “Root Mean Square.” It tells you how much power a speaker can handle non-stop in real-world conditions. Think of this as ‘average power,’ or it is sometimes referred to as continuous power.

It’s essential to think about RMS when picking speakers because it helps you know how much power a speaker can manage without distorting or breaking.

RMS power helps you know how well a speaker works during everyday use.

If you ensure the RMS power levels delivered by the amplifier match the speakers, you will give your speakers a manageable amount of power and will avoid damaging them.

RMS Power vs Peak Values

Peak power is different. It’s the most power a speaker can take for a very short time. It is sometimes called maximum power or peak music power.

If you are looking at the specifications for a speaker, it should clarify if the power rating is RMS (average) or peak (maximum). Although it often won’t.

In the example above, if the 130-watt maximum power is average (RMS), the speaker would comfortably handle a peak power signal from the amplifier of around 300 watts.

However, if the 130-watt value is a peak value, the average power it can handle would be more like 70 watts.

So RMS and peak values are entirely different things, and it is important to compare like with like if you are matching the power of an amplifier to a set of speakers.

Always try to compare two RMS values or two peak values. Don’t be fooled into matching the RMS output for the amplifier – to the peak output for the speaker.

If it doesn’t say if it is a continuous power or peak value, I would assume it is a peak value.

Some manufacturers, especially budget brands, like to give the highest figure as it generally sounds better!

The more well-known speaker manufacturers will usually be clear about the numbers – although not always.

Learn more: Choosing home theater speakers

Power Specifications and Impedance

This is another potential area of confusion.

Any power rating you see should be given to a particular load – or impedance.

Therefore, if an amplifier rating provides 100 watts of RMS power into 8-ohm speakers, it will be different if you attach 6-ohm speakers.

Always compare like with like.

If the amplifier power specs are rated at 8 ohms, then the speaker power specs should be measured at 8 ohms if you compare them.

Learn more: Speaker impedance matching: ohms & speakers explained

Suggested Amplifier Power Range

A specification for speakers that is becoming more common is a suggested amplifier power range.

Many speaker manufacturers give a suggested range for amplifier power that can comfortably be used with their speakers.

The suggested range is often around 50 to 200 watts per channel, so you’ll have to buy a pretty powerful amplifier before worrying about this.

I think this is a better way of describing a speaker’s capabilities as it clarifies which amps will comfortably drive these speakers – and it keeps it simple to understand.

It also makes the point that you have much more flexibility in matching the electrical power of an amplifier with speakers than you may have thought.

You really don’t need to precisely match a 100-watt amplifier with a 100-watt speaker.

The reality is that any reasonably close match will be fine – and only if you go to extremes, then you may start to have problems.

Consider Speaker Sensitivity

Another way of getting more volume in your room without increasing the amplifier power is to increase speaker sensitivity. More efficient speakers will provide more volume with the same power input.

So if you are always close to the limit for your current speakers, you can save yourself from buying a completely new setup by upgrading your speakers to more sensitive models.

This should allow you to keep the volume control pulled back a little while still getting a good loudness in the room.

Learn more: What is speaker sensitivity and efficiency?

The Bottom Line

The main point is that you want your amplifier and speaker power ratings to be reasonably close to get the best performance from both.

You want to drive the output of the amplifier reasonably hard to get a comfortable listening volume in your room – but also have enough headroom to comfortably handle the odd musical peak.

Or, for the times when you really want to crank up the volume!

Similarly, you want the speakers to be driven relatively hard to get the best sound out of them – but to have enough headroom available to cope with the really loud bits.

Modern speakers will comfortably handle the power from most amps and receivers designed for home use.

So, while checking a speaker’s power rating is helpful, don’t worry about getting an exact numerical match, as you have plenty of room for error.

Some suggest having an amplifier that is more powerful than the speaker ratings is better than less.

This is because you can easily limit the volume you send to the speakers. Remember that you are in charge of the volume control!

Plus, you will hear if you are starting to reach the limits of your speakers before you do any serious damage.

However, with an underpowered amplifier, you will need to turn up the volume control very high to get an acceptable sound level.

And if you do this for long periods, your amplifier may start to send clipped waveforms to the speaker – which probably will do some damage.

Main Takeaways: Speaker Power Rating

So what have you learned about the speaker power rating?

Well, don’t worry about it too much!

Most speakers will be fine for most amplifiers designed for a home environment.

They will work fine together unless you connect an amplifier to entirely incompatible speakers.

You’ll have to try pretty hard to damage your speakers with most standard amplifiers and speakers available today.

Remember, you have two things on the side of your head perfectly designed to detect problems between your amplifier and speakers.

Yes, your ears should tell you if you’ve got the volume too loud for your speakers. If you hear any distortion, then it’s time to turn it down a bit!

As long as you are sensible and don’t connect completely mismatched equipment, you are unlikely to have too many problems.

However, if you know you love to crank up the volume for long periods, you should be more careful matching the right speakers for your amplifier.

If all this sounds too complicated, don’t forget you can buy an all-in-one or a soundbar system instead.

These will come with an amplifier and speakers designed to work well together; you don’t have to worry about it.

Frequently Asked Questions

Here are some quick and easy answers to some of the most common questions about speaker power.