Car Amplifier Speaker Wattage Calculator

This tool calculates the total power consumption of a set of speakers. It also gives the car amplifier requirements to drive these speakers.

Enter the wattage of the speakers with each value separated by a comma.

Example Calculation

If you have three 75 W speakers, the total wattage is 225 W. These speakers require an amplifier capable of producing between 202 and 270 Watt. It’s best to pick an amplifier at the higher end of this range – closer to 270 W.

RMS Power Rating

RMS Power Rating, also referred to as the root mean square power rating, is a measure of the continuous power handling capability of the speaker. It is expressed in watts – a unit of power.

Peak Power Rating

Peak Power Rating is the maximum power that a speaker can tolerate. A speaker is only able to handle this wattage level for a short time duration although the time period is almost never specified in the data sheet. Running a speaker at this level for an extended duration will cause the coil to overheat and result in damage so it’s recommended to never operate at this power.

What’s the difference between Speaker RMS and Peak Power Rating?

The RMS power rating indicates the Average Power that a device can handle continuously without overheating or causing damage. It is a more accurate representation of the power handling capacity compared to Peak power ratings, which only reflect the maximum power output for short bursts.

The RMS power rating helps consumers determine the appropriate power requirements for their audio systems, such as speakers or amplifiers. For example, a speaker with a higher RMS wattage can handle more power from an amplifier without damage. So, understanding the RMS power handling rating is crucial for achieving optimal performance without compromising the longevity of the equipment.

Many manufacturers will emphasize the peak power rating because it’s a larger number and looks more impressive than the average power. The peak can for instance be 300 Watt with RMS equal to only 150 Watt.

💡 When looking at the manufacturer’s data sheet specifications, use the RMS power and not peak power number.

Can I drive my speakers with a lower wattage amplifier?

Yes you can. The downside is that you won’t be able to maximize the performance of the speaker.

⚡ If you are using a lower wattage amplifier, make sure that the amp is not operating at levels where distortion or clipping can occur. This will increase the risk of damaging the speaker due to a higher average power as a result of the harmonic content in the amplifier output.


This calculator provides the total power consumption for a set of speakers. It also provides the amplifier requirements to drive all the speakers.

In addition to the above, it’s important to check the impedance (or resistance) specifications of both the speakers and the amplifiers.

An amplifier manufacturer will tell you the range of impedance values it’s capable of driving, the number of speakers and the wattage at each of these values.

Alternatively use the Car Amplifier Power calculator to find the RMS output power of an amplifier as a function of its output impedance and that of the speaker.


[1] How much amplifier power do I need for my speakers?

Related Calculators

  • Amplifier Speaker Matching – Gives the recommended output power from an amplifier to hit a target Sound Pressure Level within a car.