### Simple 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).

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 calculators below.

### Calculator for Speakers in Parallel

Below is my new calculator 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 for each speaker is a calculated percentage. The shows how the power output of the amplifier is shared between the speakers. Power sharing is a consideration when using speakers with different impedance. See How Multiple Speakers Share Power for further details.

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

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.

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 in parallel, please read the FAQs before submitting your question. You also find an answer in the comments below.

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 »

Hi Andy, I think the only thing you are doing wrong is thinking you will get more power when adding extra transducers. If you have a 50 watt amp, then it will only produce 50 watts. Adding extra transducers (or speakers) will mean that 50 watts is shared by all the transducers. As you have seen, if you connect all three in parallel the impedance is too low for the amp. If the connect them in series, the total impedance is higher (not two high for most amps, but it will reduce the maximum power output form the amp). You… 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 »

Hi Andrew, I agree your idea will work. The impedance is taken care of and the power is good too. My only comment is that if the amp is 250 watt peak into 4 ohms, it is probably a lot less into 8 ohm, so you may want to check out how much lower it will be. Also check if the 250 peak watts is total or per channel. Either way, the 4 ohm will take 50% of the amp’s output and the two 8 ohm speakers will take 25% each, will be close to the distribution you are after.… 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

Hi Jeemon,

As you can tell from the calculator, running 2 lots of 6 ohms speakers in parallel will give a total load impedance of 3 ohms, which is double what the amp is designed for. Therefore wiring them in parallel is not wise.

However you can wire them in series. The total impedance will be 12 ohms – your amp will like this better. While the power will be slightly less, I doubt this will be a problem.

hope this helps

Geoff

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 »

Hi Victor, First up, car audio is not topic, but the principles should be the same. Wiring the 2 ohm and 4 ohm is parallel will give the amp a total load impedance of 1.3 ohms as you can see from the calculator above. While the amp will cope with this, the 2 ohm speaker will take twice the power as the 4 ohm speaker. So it will sound a bit louder (3dB). Is it possible to wire the 2 ohms as a 4 ohm speaker? this is would make the power even across both subs. However it may decrease… 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.

Hi Jay, Other than a tube amp, all amps will work into a higher load impedance, but they don’t like a lower load impedance. As you say, 1.3 ohms is way too low. Series parallel will work fine, but the one on its own will be louder than the two in parallel. All three in series will give a total load impedance of 12 ohms, as you say. This will not hurt the amp. It just means the amp won’t work as hard as if it had a 4 ohm load, so its maximum power output will not be as… Read more »

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

THX

Hi Ashraf, I don’t normally give advise on particular gear. It is like asking “what car should I buy?”. In general though, you should get the speaker that sounds best to you. Check the impedance is within the range of the amp – this normally means it needs to be above 4 ohms. For power, it is best to have the amp slightly more powerful than the speakers can cope with. But you should never run the speakers load enough that they distort. For normal listening levels in a home, I would think both the speakers you mention will sound… Read more »

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?

Hi Jeremy, Good point, and you are correct that the speaker with lower impedance will draw more power, if they are wired in parallel. However if they are wired in series, then the higher impedance speaker will draw more power. In a series circuit, the current through both speakers is the same. As the formula for power is the current squared times the resistance, the speaker with the highest resistance will draw more power. For example, let say there is 5 amps going through both speakers. 25 x 2 ohms will draw 50 watts. 25 x 4 ohms will draw… Read more »

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 André,

You are correct. As along as you don’t need to switch any one pair on/off, wiring them in series is the best for the amp. It does lower the power to the speakers but it does keep the amp happy. Certainly, wiring them in parallel would over load the amp.

If you want individual control over each pair, then a speaker selector switch would be required.

Hope this helps,

Geoff

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 »

Ha! I’m disappointed you don’t like my falsetto voice! However my wife’s voice is far more pleasant than mine. I think you have confused the power sharing with the impedance calculations. Six 8 ohm speakers in parallel will share the power with each getting 1/6 of the available power. However six 8 ohm speakers in parallel will have a total impedance of only 1.33 ohms – way below the 8 ohms your amp needs. That is why speaker switches with a series resistor are popular as they provide a minimum resistance in the load. However a 10 ohm 15 watt… 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

Hi Stelios,

Two 8 ohm speakers in parallel is 4 ohms. As your amplifier is designed for a load impedance of 4 ohms or more, you can simply wire each pair in parallel.

Geoff