Speakers in Parallel Calculator

The calculator below is useful in determining the total impedance of speakers in parallel. It also calculates how the power is shared between the speakers. If all the speakers have the same impedance, the calculation is relatively simple. 

Simple Impedance Calculation for Speakers in Parallel

If all the speakers in parallel have the same impedance, then the calculation is easy. Simply divide the impedance by the number of speakers in parallel.

Example 1: Four 8 ohm speakers in parallel: 8 divided by 4 = 2 ohms.

Example 2: Two 4 ohms speakers in parallel: 4 divided by 2 = 2 ohms.

Not so Simple Calculations for Speakers in Parallel

For calculations involving speakers in parallel with different impedance, the following formula is required (it can be used with speakers of similar impedances too).

\large{Imp_{Total}}=\frac{1}{\frac{1}{Imp_1}+\frac{1}{Imp_2}+\frac{1}{Imp_3}+ ...}

If you have a calculator with 1/x button then this calculation is not too difficult. If you don’t have that function on your calculator, or if you don’t like formulas, check out the calculator below.

Using the Calculator

The calculator can be used for 2, 3 or 4 speakers wired in parallel. 

Simply type the impedance of each speaker into the white boxes (or use the drop-down values). Use N/A for unused speakers in this calculator. The total impedance will be calculated for the entered speakers.

Also calculated for each speaker is its percentage share of the amplifier’s output power. This is useful as power sharing is a consideration when using speakers with different impedance.

“Power Differential” is the final calculation. This calculates in dB (decibels) the power level difference between the highest and lowest power as it is shared across the speakers. This shows the power level difference when using speakers with different impedance.

Amplifier Power Calculator

The bottom section of the calculator helps in matching the speaker combination with your amplifier. This is not necessary if you only want to know the total impedance and/or the power ratios.

However if you are connecting these speakers to your amplifier, it may be helpful to input the amplifier power and the associated speaker impedance. In the specifications for your amplifier, it should say something like:

Amplifier power: 80 watts continuous average power @ 4 ohms (2 channels driven, THD 0.08%, 20Hz-20kHz)

This tells you the maximum continuous power the amplifier will deliver into a 6 ohm load is 80 watts. In the calculator below, for this example, you type in 80 for the power and 6 for the impedance. Be aware, some specifications state RMS power rather than continuous power. These are effectively the same.

The calculator will display the effective power of the amplifier for the calculated total impedance of the series speakers. Also displayed (under each speaker’s power %) is the actual maximum power the amplifier will supply each connected speaker. A comment on the suitability of the calculated total impedance for your amplifier is also provided.

Download Calculator
as Excel File
Prices in US$

Note: the calculated output power for the amplifier is based on a theoretical “ideal” amplifier. In practise, your amplifier may produce slightly more power.

Further Reading

This calculator will help you understand the total speaker load on your HiFi amplifier. For a better understanding of this and what to do about it, read the articles How do I Connect Multiple Speakers to my HiFi Amplifier and How to wire four HiFi speakers or How to connect 2 speakers to one amplifier or watch the video in the article Understanding Speaker Impedance.Also see How Multiple Speakers Share Power for further details about the percentage power calculations. For more details about the effective amplifier power at higher impedance loads, see How Impedance Changes Amplifier Power.

Please Note: all these calculations are for connecting manufactured speakers (boxes). They are not used when building your own speaker boxes and connecting multiple speakers in a cabinet using a crossover circuit. A crossover splits the signal into different frequencies for each of the speakers and makes the total impedance calculation complex (as impedance is frequency dependent). That is why speaker designers get the big money, and as installers we benefit from their expertise.

If you need further advice on connecting speakers (boxes) in parallel, please read the FAQs before submitting your question. You may also find an answer in the comments below.

Please Note: During the Covid-19 crisis I'm very busy with a number of streaming projects, and have very limited time to attend to this website.. I'm currently over a week behind in answering questions and may not get to them in a hurry. Sorry for any inconvenience.

Disclosure: If you buy through this Amazon USA link Geoff receives a small commission from each sale.
European and Australian readers can use the links on the side panel - Thanks for the support

Sean Gill (Atlanta, USA)

Hi Geoff:
I’m confused and need help.

I have a car with front (dash – two Memphis Audio 4″ speakers with 20Wrms and 40W peak), front (door – 6.5″ but they are busted) and rear speakers (two Alpine SPR 5.25″ speakers rated at 90W rms and 270W peak). The door speakers are mid range speakers.

I am not running any amps just power for the front and rear from the Head Unit. I am planning to install the Pioneer DEH 80PRS.

How do I wire the speakers especially as the front dash and rear are 4 ohms each.


Sonny V (Philippines)

Hi Geoff, Nice blog. Good Job! I would like to ask your help about my project,

I have 1 unit Bosch PLM 4P220 Amplifier which has 4 channels (each 220 watts/Can bridge 1-2 chanel @ 385 watts) and I have 9 speakers (8 ohm/75 watts).Can you suggest what is the best wiring for all the speakers? And is it future proof? How many speakers can I add in the future?


Ross (Spain)

Hi Geoff, I have a studiomaster 708 powerhouse mixer/amp: Max output per channel 350w @ 4ohms, 210w @ 8ohms. At the moment its hooked up to 2 400w PA speakers, but a change in regulation means we need to down size and use smaller cabinet speakers. My idea was to use several smaller speakers and spread the sound around the area more oppose to all coming from one corner as it currently is. So I’m trying to work out what would be the best way to do this, I have 6x 200w 8ohm small speakers I’ve looked about at several… Read more »

Guy (Leeds, England)

I have a Crown xls 2000 amp, 2 18in 1200w subwoffers at 8ohm and 1 pair of 800w 4ohm floor standing bass to midrange speakers.
What would be the best set up for the amp and these speakers?
The amp can handle a 2ohm load but im afraid that my speakers in series might be harmful to my amp!
I want as much power as i can get out of it. i have active speakers for the highs and mid so its just for the bass really!
thank you for reading =)

prince mathew (Kollam, India)

I have 250w ahuja amp and 100w ahuja speaker as normal working. but i want to add my 2 radio speakers each with 4 ohm as feedback speakers, how can i connect it safely,,,,plz reply me….

Peyton (Indiana, US)

Hi Geoff. Sorry if my wording seems strange I’ll try to explain what I’m trying to accomplish best I can. For starters, I have a 35 watt 6Ω ampplifer that has 4 positive/negative imputs. Out of terminal 1, I want to connect 4 speakers. Two are one one side of the barn and two on the outside of the barn. Right now. They are connected in parallel (I believe wired them in parallel correctly) but seem to not be as loud as what they should be. That’s question 1, how do I get those to sound as they should? Next,… Read more »


Hi, I have an older power amp with A and B connectors on the back. There is also a sliding switch that lets me select 8 ohms or more OR less than 8 ohms. I currently have it set at less than 8 ohms, as my speakers are 6 ohms. I am getting another set of 6 ohm speakers which I wanted to connect to the B connectors. All 4 speakers are of the same brand, but the the two pairs of speakers themselves are not the same. The amplifier manual doesn’t specify minimum ohms and I assume I would… Read more »

Pepe (Carpinteria, U.S.)

I would like to know how many speakers rated 8 ohm can i hook on my Amp that has A-B terminals and it shows that if i use A+B the speakers have to rated 8-16 ohms,i have now 4 speakers on A and 4 speakers on B,they all are 8 ohms and the Amplifier performs good at low volume(haven’t tried hi volume),but after reading about Amplifiers i’m wondering if my set up it’s ok or if i have to modify something,please help!

anne moon (Danville)

hi geoff i have a carver tfm35 amp (250 watts into 8 ohms stereo) 1 pair hales revolution three each speaker 4 ohms 1 pair hales revolution two each speaker 4 ohms ( pretty sure, i bought them ,long ago) i previously had all 4 hooked up in what I was sure was 2 speakers in parallel per channel now i moved to a new house, hooked up 2 speakers to each of the outputs on the back of the amp and the amp almost instantly blew i repaired the amp, have only been running 1 pair of speakers but… Read more »

Graham (Perth, Western Australia)

Im wiring up a car stereo with multiple speakers and would like to find out some resistor values for an unusual set up. I’m running a 4x50watt stereo and several amps wired to subs. I’ll start with my front channels description and questions. Ive got 3 sets of speakers all rated over 120watts so overdriving isnt an issue. Ive calculated for 3x4ohm speakers on one channel being a 1.3ohm load requiring a 2.7ohm resistor to get total impedence back up to a 4ohm load. One of the three speakers is a 2″ tweeter with a capacitor wired to it in… Read more »

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