Welcome! I’ve worked hard to create what I think is the best speaker Ohms calculator on the internet for *you*.

My speaker Ohms calculator will let you:

**Find the total speaker Ohms for almost any series, parallel, or series-parallel speaker wiring.**- Find the total power your amp or stereo will output (or warn you when it can’t produce that amount of power).
- See the power supplied to each speaker for your wiring configuration.
- Find out if your speaker setup could cause amp or stereo damage
*before*you try it out.

**Note:** Javascript must be enabled in your browser to see or use the tool.

Contents

## SPEAKER OHMS CALCULATOR

**HOW TO USE THE SPEAKER OHMS CALCULATOR**

**Choose your speaker configuration/wiring:**

- Series connected speakers
- Parallel connected speakers
- Series-parallel speakers: up to 4 “strings” of 1-4 series speakers, all series strings in parallel. (*Using 1 speaker in each string will effectively be the same as the Parallel speaker option)
- Parallel-series: up to 4 speakers in parallel which are then in series with 1 or more speakers.

**Input your speaker Ohms and power values:**

**Speaker impedance (Ohms):**Fill in the speaker Ohms value for as many or as few speakers as you’d like.**OPTIONAL****Amp/stereo power & min. Ohms rating:**Input the amplifier or stereo’s power (RMS or continuous) power rating and the min. specified speaker Ohms. This will allow the calculator to determine power to each speaker in any configuration.

You can use whole numbers (2, 5, etc.) or decimal values (6.3Ω, etc.) for Ohms as needed. If using the power option, **use the RMS or continuous power rating in whole Watts for your amplifier or stereo.** “Peak” or “maximum” ratings are misleading and will give the wrong results.

The speaker Ohms calculator will output:

**Total speaker Ohms:**This is the*total*speaker load the amp or radio will see based on the speaker Ohms you’ve entered.**[Optional] Total power draw from the amp or stereo:**This shows the total amount of power the calculated speaker Ohms load will draw from the amp or stereo.- NOTE! If the total speaker load would draw excess current (exceed the power rating you specified), this means an unsafe condition would happen and you’ll see “–” to indicate an error/invalid power amount.
**[Series-parallel option] String (“Str**The series Ohms value for each string of speakers, 1 to 4 speakers each.*x*“) ohms:**Power to each speaker (“S**Power, in Watts, each speaker will receive.*x*“):

## How to calculate series, parallel, or series-parallel speaker Ohms (DIAGRAM and examples)

Figuring out the total Ohms speaker load for nearly any wiring configuration isn’t as hard as it may seem. As you can see from my diagram above, there are 3 main ways to do this:

- Find the total
**series**speaker Ohms. - Find the total
**parallel**speaker Ohms. - Using a combination of #1 & #2 for more complicated speaker systems.

### 1. How to find the total series speaker Ohms value

These are the simplest to deal with. **To find the total speaker resistance (impedance) for series speakers, simply add them all together.**

For example, let’s say we have 3 speakers we’d like to use: two 8 ohm and one 16 ohm.

We’d just add these together like so: 8Ω + 8 234 + 16Ω = **32Ω**

When speakers are connected in series, they share the same electrical current. The amplifier, radio, or stereo’s power will be divided among them. Note that **if the total speaker load is higher than the maximum power output Ohms rating for your amp or stereo, the total power you can get will be lower.**

(I’ll go into more detail about this in another section below)

### 2. How to calculate the total Ohms load for parallel speakers.

When it come to finding the total speaker impedance for parallel wiring, there are two ways to do this:

- If the speaker Ohm ratings are all the same, you can just divide by the number of speakers used.
- For parallel speakers of the same or different values, you can use the universal parallel speaker formula below. You can call this the “inverse sum of the reciprocals”, which just means we add up all the inverse (1/x) values then take one final inverse function to get the result. (I’ll explain how to do this.)

**Example #1:** Let’s say we have three 4 ohms speakers wired in parallel. We can use simple division to find the total speaker load:

*Rparallel* = 4Ω/3 = **1.33Ω**

**Example #2:** In this example, we have four speakers of different values: two 8 ohm and two 16 ohm speakers, all wired in parallel. What is the total speaker load?

*Rparallel* = 1/(1/8 + 1/8 + 1/16 + 1/16)

= 1/(.125 + .125 + .0625 + .0625)

= 1/(0.375) = **2.67Ω**

### 3. Series-parallel and other wiring types

For anything other than just series or parallel speaker wiring, we can just break it down into a few of same calculations and then add them all together.

**Example #3: **We have four “strings” of four 8 ohm speakers each. All four series strings are wired in parallel. We can solve this pretty easily!

**(a.)** Finding the series speaker Ohms: each string of four speakers is 8Ω + 8Ω + 8Ω + 8Ω or 8Ω x 4. This is 32Ω total for each series string.

**(b.)** Find the total parallel speaker Ohms: we have four strings, so this is 1/(1/32 + 1/32 + 1/32 1/32) or just 32Ω/4 since they’re all the same value.

So the total is 32Ω [each series string] / 4 strings = **8Ω total in series-parallel**

### How to find parallel speaker ohms (inverse sum of reciprocals) on a calculator

Many calculators (especially scientific ones, although that’s not a requirement) have an inverse function.

**An inverse key (inverse function, or reciprocal function) is simply dividing one by some number. **Having a button handy makes it much faster and less likely you’ll make a mistake, too.

**Note:**The inverse button is sometimes also be written as a negative power of 1 (“^-1”) as it’s mathematically identical.

Let’s take example #2 from earlier to show how you can easily find any parallel speaker load using a calculator. I’ll show where I’m using the buttons you’d use on a real calculator.

**(Example #2: **We have four speakers of different values: two 8 ohm and two 16 ohm speakers, all wired in parallel.)

**(a.)** You would enter on your calculator:

8 1/*x * **+ **8 1/*x * **+ **16 1/*x * **+ **16 1/*x *

which will give 0.125 + 0.125 + 0.0625 + 0.0625 = **0.375**

**(b.)** Then we’ll take the reciprocal (inverse) of this to get our result:

0.375 1/*x * = **2.67 Ω** (rounded from 2.66666… as we don’t need that much precision).

You might find it helpful to use a scientific “pretty print” calculator as they display the math you’re entering just like you’d write it on paper. This helps you be sure of what you’re entering as you go.

## Amplifier power vs the speaker Ohms load

The total speaker load you end up with can have a very big impact on the power you can use. That’s because **home or car stereos, amplifiers, and radios can only produce up to a certain output voltage to deliver power to speakers. If the speaker load (Ohm value) is higher, they can’t deliver as much electrical current, resulting in a lower total power provided.**

### How to calculate amp and speaker power for different speaker loads

**Example #1:** How to estimate total amplifier power at different speaker Ohm loads

For example, let’s use an example of a guitar amplifier that can provide 50 watts RMS continuous per channel into a min. of 8 ohms. As power is related to voltage and resistance, we can rearrange the formula for power to help us:

**(a.)** Power (P) = (Voltage (V))^2 / Resistance (R)

We can rearrange this to find voltage: **Voltage (V) = square root(Power x R)**

**(b.)** Doing a little bit of math, that means the output voltage at full power into an 8 ohm speaker would be:

V = square root(50 x 8) = √(400) = **20V**(Max. output)

What happens if we connect two 8Ω woofers in series? How much power can we expect?

This would be (20V)^2 / 16Ω = 400/16 = **25 Watts**

This makes sense! After all, the electrical current *decreases* as the resistance increases*. *Therefore, the amp can’t deliver as much power at 16Ω as it can at its 8Ω specification. **There’s nothing wrong with using a higher impedance speaker load, but you’ll have to live with the compromise and less overall power.**

**Example #2:** Estimating power to each speaker vs the total power delivered

Using example #1 above, we have 25W delivered in total to our 16Ω speaker load. For speakers in series, you can find the power each speaker will get even if they have different Ohm ratings.

In this case, we can use: Pspeaker = Ptotal (total power) x Speaker1/(Speaker1 + Speaker2)

This gives us: P1 (power to speaker one) = 25W*8/(16) = 25W*0.5 = **12.5W**

So each speaker will receive 12.5W in this case which is 1/4 of what a single 8 ohm speaker would receive for this amplifier.

## What speaker Ohm load should I use for the best power?

**When using multiple speakers the best Ohms load for power is the lowest acceptable total speaker load the stereo or amplifier is rated to handle at maximum power output.**

This is because many amplifiers (and some radios and stereos etc.) have their maximum power output possible at the minimum Ohms rating specification. This is sometimes called the Ohm rating they are “stable to.”

For example, a 2Ω stable car subwoofer amplifier may be rated like this:

- 250W x 1 @ 4 ohms
- 500 W x 1 @ 2 ohms

The specifications tell us:

- This amplifier is designed to handle as low as 2 ohms minimum
- It will produce maximum power output (maximum current) safely at a total speaker load of 2 ohms

This means to get all the power we paid for, we’ll ideally have a total speaker load that adds up to 2Ω. **The problem is that when using multiple speakers it can be difficult to get match the min. speaker Ohm rating.**

You’ll have to match *at least* the min. acceptable Ohms rating specified. Too low of a rating (say 1Ω in this case) and the amplifier can shut off, overheat, or suffer permanent damage.

Using dual voice coil speakers may help as they offer multiple speaker ohms configurations. However, it’s very common (especially if you’ve already bought speakers) to not be able to get the “perfect” total speaker Ohms load.

You’ll have to live with some compromises which may mean less total power available.

My math isn’t mathing. Looking for some help on wiring 6, 4ohm dvc subs. I’d like to get close to a 2ohm final load. Can you assist in this? A simple wiring diagram would be a huge help. Thanks.

Hello Greg. It will be a bit tricky to get close to 2 Ohms since we have 6 subwoofers instead of a number that’s a multiple of 2 (ex: 2, 4, 8..). However, here’s the way thats the best compromise and will meet your needs assuming you need a min. of 2 Ohms total:

This will give a total of 1Ω + 1Ω + 1Ω = 3 Ohms. It will also distribute the power evenly between each subwoofer which is what we want for equal power & volume. Here’s a link to the diagram I’ve created for you.

Best regards.

Thanks perfect. Thanks so much!!

Hi Marty, and thanks for such an in depth tutorial on speaker ohms.

I just purchased a Marantz PM-52 amplifier for my home set up, but I’m not sure how to use your method to calculate the speaker impedance.

https://www.hifiengine.com/manual_library/marantz/pm-52.shtml

This amp has 4 channels output, and it specifically says 8 to 16 ohms if using only 2 channels, and 16 ohms if using the 4 channels.

I’m going to use an individual speaker for each output/channel; two of the speakers are 8 ohms , while the other two are 4 ohms.

How to make this calculation?

Thank you in advance,

Jose

Hi Jose. Ok, so with amplifiers or receivers with these types of Ohm ratings, they’re essentially like a 2-channel stereo output. With all 4 speakers connected, that means the amp sees two speakers connected in parallel per channel (hence why you can use 4x 16Ω and get a safe 8Ω load on each side).

If you want to use one 8 Ohm and one 4 Ohm per side, that would be 1/(1/8 + 1/4) =

about 2.67Ω.In this case there’s not an easy way to solve this problem without big compromises.The best all-around advice I have is this:

• For the 8 Ohm speakers, connect them to one pair of output channels normally.

• For the 4 Ohm speakers, use an affordable speaker impedance adapter built into a speaker volume control like this one set to the 1:2 option. Connect it to the second pair of outputs.

This allow you to drive all 4 speakers with full power safely, and will deliver equal power to all 4 speakers. You can also add more speakers to the volume control/imp. adapter later if you like (it has more speaker pair settings available).

Best regards!

Hi Marty,

Great, thank you! So what should each speaker Ohm rating be, in order to connect/use all o/p channels? Having all four speakers with 16Ω?

You mention 8Ω to be a safe load for each side, is there a right or correct load value for this amplifier? Or higher the better? Just so I understand which speakers I should to get for it.

Thank you once again,

Best regards!

Hello again, Jose.

> “

Having all four speakers with 16Ω?”Yes, unless you use the device I recommended. It will let you multiple speaker pairs or even lower impedance speakers than can normally be used.

> “

You mention 8Ω to be a safe load for each side, is there a right or correct load value for this amplifier? Or higher the better?”Based on the amp’s specs, as long as it’s

at least8 Ohms, it’s fine. If you use two speakers per channel (example: in this case, four 16Ω speakers wired to all four speaker output connections) that’s fine, because thetotalpower output will be whatever the amp’s rated power output is at 8 Ohms.However, if you increase the speaker impedance, the amp will deliver less

totalpower. For example (just as an example), if we connected four 32Ω speakers, the total Ohms load per side would be 16 Ohms of course.That’s perfectly safe for the amp since we’ve met the minimum of 8 Ohms. However, the total output power would 1/2 that of using 4x 16Ω speakers. That’s because a 16 Ohm load allows 1/2 the electrical current to flow versus 8 Ohms. This means 1/2 power of its power rated for 8 Ohms can be delivered to the speakers.

If you want to use more speakers, mix speaker impedances, or use 4 Ohm speakers, etc., a speaker impedance adapter allows the amp to “see” a safe total Ohms load and also deliver the most power it can. Otherwise, you’ll need to get the correct impedance speakers – but 16Ω speakers aren’t very common.

Hopefully that makes sense and helps a bit! :)