🔗 Speaker Impedance Calculator
Add speakers or voice coils, choose series, parallel, or series-parallel wiring, and see the total ohms your amp will see — with a clear warning when the load falls below what most amplifiers can safely drive.
🔗 Total load
✅ Safe for most amps
This load is safe for most car amplifiers. Always confirm the amp's minimum rated impedance.
Wire it to a load your amp can handle
Every extra speaker or voice coil changes the impedance your amplifier sees, and impedance is what decides how much current the amp draws and how much power it makes. Wire it too low and the amp overheats and shuts down or fails; too high and you leave power on the table. This tool combines any set of drivers by series, parallel, or series-parallel wiring — dual-voice-coil subs included — so you land on a safe, sensible load.
Pair it with the Amplifier Power Calculator to size the amp for that load, and the Subwoofer Box Calculator to build the enclosure your subs need.
❓ Frequently Asked Questions
How do I calculate total speaker impedance?
In series, impedances add up: Z = Z₁ + Z₂ + … (two 4Ω speakers in series make 8Ω). In parallel, use the reciprocal rule: Z = 1 / (1/Z₁ + 1/Z₂ + …), so two 4Ω speakers in parallel make 2Ω and four make 1Ω. Series-parallel wires the drivers into equal series groups and then connects those groups in parallel — four 4Ω drivers become two 8Ω series pairs in parallel, for a 4Ω total.
What is a dual-voice-coil (DVC) subwoofer?
A DVC sub has two separate voice coils on one cone, each with its own impedance, so a single DVC 4Ω sub gives you two 4Ω loads to wire. Enable the dual-voice-coil option and each impedance you enter is treated as two coils. Wiring a DVC 4Ω sub's coils in parallel gives 2Ω; in series gives 8Ω — a handy way to present the load your amp wants.
Why does impedance matter for my amplifier?
Amps are only stable down to a rated minimum impedance. Wire your speakers too low and the amp draws more current than it's designed for, overheats, and either goes into protection or fails. This calculator flags loads under 2Ω as caution and under 1Ω as danger, but the real limit is your specific amp's rating — check it before wiring.
Series or parallel — which should I use?
Wiring choice sets the final impedance the amp sees, which in turn sets how much power it makes. Parallel lowers impedance and raises power but risks going below the amp's safe limit; series raises impedance and lowers power. Pick the combination whose total matches your amp's optimal rated impedance, then confirm the amp is stable at that load.