Zerdly

Speaker Impedance (Series/Parallel) Calculator

Combine the impedance of up to four speakers wired in series or in parallel. Series wiring adds the impedances together, while parallel wiring lowers the total — the result tells you the load your amplifier will actually see.

100% FreeRuns in your browserBasic
How to use this calculator

Enter Values

Enter your values and press Calculate to see results.

How to use this calculator

  1. Enter the nominal impedance (in ohms) of at least two speakers.
  2. Leave the third and fourth boxes blank if you are only combining two speakers.
  3. Read the series total and the parallel total, then check both against your amplifier's minimum load rating.

How it works

For speakers in series the total impedance is simply the sum of the individual impedances (Z = Z1 + Z2 + …). For speakers in parallel the total is the reciprocal of the sum of the reciprocals (1 / Z = 1/Z1 + 1/Z2 + …). Two identical 8 Ω speakers therefore give 16 Ω in series but only 4 Ω in parallel.

Worked example

Worked example. Two 8 Ω speakers: series total = 8 + 8 = 16 Ω; parallel total = 1 ÷ (1/8 + 1/8) = 4 Ω. Four 8 Ω speakers give 32 Ω in series or 2 Ω in parallel.

Common mistakes

  • Wiring too many speakers in parallel and dropping below the amplifier's minimum load, which can overheat or damage the amp.
  • Confusing nominal impedance with DC resistance — use the speaker's rated (nominal) impedance.
  • Forgetting that a mix of series and parallel (series-parallel) needs to be calculated in stages, not in one step.

Frequently asked questions

Why does parallel wiring lower the impedance?

Adding a parallel path gives current an extra route, so the combined load draws more current for the same voltage — which the amplifier sees as a lower impedance. Two equal speakers in parallel halve the impedance.

What is a safe load for my amplifier?

Never take the total load below the amplifier's stated minimum (commonly 4 Ω for home amps, 2 Ω for many car amps). Running below it forces the amp to deliver more current than it is designed for.

Related tools

Explore more in Audio, Acoustics & AV.

Tip: Enter any known values to calculate the remaining results.

All calculations run in your browser. Your inputs are never saved or transmitted.