Speaker Impedance Calculator (with Examples)

This calculator determines the total effective resistance (ohm) of any number of speakers in series and parallel configurations.

The total impedance depends on how the speakers are configured. There are two main configurations – series or parallel.

Use the calculator to find a configuration that matches your amplifier.

Series Impedance Calculator

Enter the impedance values in ohm (Ω) separated by commas.

Series Resistance Formula

The picture below shows a set of three speakers connected in series. The total impedance is simply the sum of individual impedances.

Rtotal = R1 + R2 + R3 +…. + Rn

Series Speaker Configuration

Example Calculation

Consider four speakers in series: 1 Ω, 2 Ω, 4 Ω and 8 Ω. The total effective resistance is 15 Ω.

If you have two resistors – one large and the other small in series, the effective resistance is closer to the larger value. Take for instance 1 Ω and 16 Ω in series. The effective resistance is 17 which is close to 16 Ω.

Parallel Impedance Calculator

Enter the resistor values separated by commas.

Parallel Resistance Formula

The picture below shows three speakers connected in parallel. Note that the voltage across each speaker will be the same.

Rtotal = (1/R1 + 1/R2 + 1/R3 +…. + 1/Rn)-1

Parallel Speaker Configuration

Example Calculation

Consider four speakers in parallel: 1 Ω, 2 Ω, 4 Ω and 8 Ω. The total effective resistance is Ω.

Why calculate Speaker Impedance?

It’s important to match the speaker impedance with the amplifier.

Impedance matching between speakers and amplifiers is crucial for efficient power transfer and preventing damage to both the speakers and the amplifier.

This is easy to do when it’s one speaker (described in this post). When using multiple speakers, care needs to be taken that they are configured to result in an impedance that is matched to the amp.

The impedance of a number of speakers that are wired together is different from that of an individual unit.

If the speaker impedance is too low for the amplifier, it can overload the amplifier, potentially causing overheating and distortion. Conversely, if the speaker impedance is too high for the amplifier, it may not deliver enough power to the speakers, leading to inadequate sound quality.

Therefore before wiring anything up, it’s important to use the tool on this page to calculate the impedance of the speaker combination.

Which speaker configuration is better – Series or Parallel?

When speakers are connected in series, the total impedance of the system increases. This can be useful in situations where you want to raise the total impedance to match the amplifier’s minimum load impedance rating.

However in the series configuration, the amplifier power delivered to each speaker decreases as the number of speakers is increased.

Use the calculator on this page to see that a 1000 W Amplifier rated at 4 Ω will deliver only 500 W per speaker when two 4 Ω speakers are connected in series.

As a result speakers are always louder when wired in parallel

When connecting in parallel, it’s important to ensure that the effective impedance is not lower than the recommended impedance. For instance two 4 Ω speakers will have an effective impedance of 2 Ω. If the amp cannot support 2 ohm (check the spec sheet), this will overload it and cause it to shut down.

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