Car Amplifier Speaker Matching Calculator

This tool calculates the Amplifier (or Amp) Output Power (Watt) required to provide a specified Sound Pressure Level (SPL) within a car.


  • Speaker sensitivity (1W/m) in dB
  • Amplifier Headroom (in dB)
  • Distance from the speaker (in feet or meters)
  • Target Sound Pressure Level (dB) at this distance



Example Calculation

As an example let’s design an audio system where

  • The listening position is 3 feet (or 0.9 meters) away from the speaker
  • The desired Sound Pressure Level is 105 dB SPL

The speaker chosen for the job (shown below) has a sensitivity rating of 92 dB. Apply a minimum recommended amplifier headroom of 3 dB.

Kenwood KFC-1666S 300 Watts 6.5" 2-Way Car Coaxial Speakers with Sound Field Enhancer - Pair

According to the calculator, an amplifier that can supply at least 33 watts to the loudspeaker is required.

This uses the Sound Pressure Level vs Distance relationship

What is speaker sensitivity?

Sensitivity measures how well power input to the speaker is converted to sound energy.

As an example, the sensitivity of a speaker is rated as 92 dB (1W/1m). This means that speaker produces a level of 92 dB when driven with an amplifier that provides 1 Watt of power. The measurement is made 1 meter in front of the speaker.

The higher the number in dB, the more sensitive the speaker and the more efficient it is in converting the power output of an amplifier to audio.

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