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 pandemic I'm busy with a number of streaming projects, and have very limited time to attend to this website. I'm currently taking up to a week to answer questions. 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

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Hi Geoff. Thanks for your page, it is very helpful. But alas.. I am still a little confused. I already have 2 (50wrms 4ohms)transducers wired to my game chair in stereo(1 on each channel). I am thinking of adding either 2, or 4 more 20wrms 8ohms smaller transducers. (These smaller ones also come in 20wrms 16ohms). I am trying to figure out if I can power all of them with one amp?? Option 1) Add 2 smaller transducers: Left: 50wrms 4ohms + 20wrms 8ohms(or 16ohms) Right 50wrms 4ohms + 20wrms 8ohms(or 16ohms) Option 2) Add 4 smaller transducers: Left: 50wrms… Read more »

Thank you very much for your reply Geoff! Since I am trying to get the correct wattage to each transducer (50, 20, and 20 wrms) I was thinking a 250 watt 4ohm amp should work using your Parallel / Series design. (250w x .707 = 176wrms, which is 2x88wrms) Just so I know that I understand what suggested, here is a diagram that I drew up for the design. Can you please take a look and see if I got it right? I really do appriciate you taking the time to help me. Thanks, Andy http://imgur.com/a/aoV16 This design makes sense… Read more »

Thank you, and Merry Christmas!

hi sir
i have a onkyo 175W/ch @ 6ohms and i want to connect 2 speakers each on surround LR and Atmos LR.and i have wharfedale speakers @6Ohms each .please advice and if we connect 2 speakers on each channel is the 175W/Ch divided to 2 speakers ? please advice on what impedance i should use and in parallel or series connection it should be.

thank you

Hello Geoff, My question is car audio related. What would be the best way to wire 2 subs with different impedances and how much power would I potentially be getting to each sub? I have a 2 channel amp that has a rated output of 1500w @1ohm stable. Both subs are 400w RMS and dual voice coil. 1 sub is 4 ohm and the other is 2. Bought the 2nd sub at a swap meet already wired up in a box and didn’t realize what the resistance was until I got to messing with the wiring. So now I’m stuck… Read more »

[…] Whether resistance goes up or down with multiple speakers depends entirely upon how you wire them. If you wire them in series, then the resistance the amp sees will increase. If you wire 3 speakers in series, for example, the total resistance will be R1+R2+R3. If you wire them in parallel, however, the resistance will decrease. The formula for resistance in parallel wiring is more complicated. In general, if you are talking about 2 identical speakers, then the resistance of the pair will be double if you wire them in series and will be half if you wire them… Read more »

I have an amplifier that handles 4 ohm speakers per channel. I want to hook up three 4 ohm speakers per channel. Is it better for the impedance to be higher for the amp to be happy. Three 4 ohm speakers in parallel is 1.3 ohms which is too low and three in series is 12 ohms. A series/parallel combination would be 6 ohms, which is slightly higher than the amplifier requires.

what is the best for sony DSX-A30 50wx4
1-pioneer TS-A6969E 300W 40W NOM
2- SONY XS-N6950 600W RATED POWER 85W 100RMS

This calculator is confusing me. If I have 2 speakers in series and one is 2 ohms and the other is 4 ohms and the amp is 200 watts. Why would the speaker with higher ohms get more power? That is what the calculator is telling me. Shouldn’t the speaker with lower ohms get more power?

Thank you for responding Geoff!

Hi Geoff, I have bought a Yamaha micro hi-fi system, the mcr-n560, with two speakers included. I have also bougth a second pair of speakers, the Yamaha ns-pb182, which is exactly the same speakers, obviously with the same specs, as the ones included. So my question is, after reading most of the related articles and understanding some of it, am I doing the right thing to series wire the speakers to the amp? SPECS Center unit: Total Harmonic Distortion(CD to Sp Out, 20 Hz-20 kHz) 0.05% Output Power/Channel (6 ohms, 1 kHz, 10% THD) 32 W + 32 W Speaker… Read more »

Hi Geoff, after lots and lots of online searching, I found your guides to be the best at explaining the “ins and outs” of whole house speakers. Still, I have some questions regarding calculating impedance for 6, 8 Ohm dual input stereo speakers for background music, as well as when to use the selector switch protection circuit switch. My stereo receiver is capable of 100w per channel. It has an A/B switch rated 4-8 Ohm A or B, 8 Ohm A and B. My plan is to use B—with or without A turned on—to feed a 6 speaker selector switch… Read more »

Hi Geoff

Thank you for your insight and patience to share your knowledge with all of us!

My question is: I have a 2 way amp (Cambridge 851W, 200 watts per channel into 8 ohms
350 watts per channel into 4 ohms) and i would like to test it by connecting 4 speakers (2 left, 2 right, 8 ohms/spk). What would be the optimal method of doing so?

Thank you