Car Amplifier Calculator

Use this tool to calculate the amplifier output power for a car audio system. The system consists of an amplifier, speakers and subwoofers.

How to use the calculator

  • Enter
    • Amplifier RMS output power per channel
    • Amplifier impedance in ohm (Ω)
    • Impedance in ohm (Ω) for each speaker connected to the amp
  • The tool will provide RMS output power

Example Calculation

Let’s use the following car amplifier from DS18 as an example. It has an RMS power rating of 200 W per channel at impedance of 4 ohm.

DS18 SXE-3000.4D/RD Car Amplifier Stereo Full-Range Class D 4-Channel 200x4 RMS @4 OHM 3000 Watts - Powerful and Compact Amp for Speakers in Car Audio System

If we want to match them with these JBL Speakers, with 60 W nominal power and 2.3 Ω impedance, there’s a risk that these speakers will be damaged as according to the calculator the amplifier will deliver 350W of power to the speaker.

On the other hand, let’s consider the following speakers with 250 W RMS and 4 Ω impedance. In this case, the amplifier will be able to deliver 200 W RMS with the impedance match. This is a compatible solution.

DS18 PRO-X6.4BM Loudspeaker - 6.5", Midrange, Red Aluminum Bullet, 500W Max, 250W RMS, 4 Ohms - Premium Quality Audio Door Speakers for Car or Truck Stereo Sound System (1 Speaker)

Note that the power estimate provided by the calculator on this page is an ideal approximation.

As an example let’s consider this amplifier. According to the specification it is able to provide the following:

  • 320 W x 4 CH at 2-ohms
  • 200 W x 4 CH at 4-ohms

According to the calculator it should only be able to provide 160 W at 4 ohm.

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