How to Calculate Speaker Impedance

Once you know whether speakers are wired in series or parallel, the total impedance is a short calculation. Here are the formulas — and a calculator to do it for you.

Impedance calculator

Choose how many speakers you have, their impedance, and how they're wired. The result is the load your amplifier will see.

Series formula

In series, add the impedances together:

Parallel formula

In parallel, add the reciprocals and invert. For identical speakers there is a shortcut: divide one speaker's impedance by the number of speakers.

Series-parallel

Series-parallel means you calculate in two steps. Work out each series string first, then treat those strings as parallel loads.

Worked example: four 8Ω speakers

• Step 1 — two series pairs: 8Ω + 8Ω = 16Ω each.
• Step 2 — two 16Ω strings in parallel: 16 ÷ 2 = 8Ω.

The result is a safe 8Ω load from four speakers — which is exactly why series-parallel is the standard way to run four or more.

Put it to use

• Understand the wiring itself in series vs. parallel speaker wiring.
• Apply it in how to connect multiple speakers to an amplifier.
• Make sure the result suits your amp in matching speakers to amplifiers.