“I have a 1,500 sq ft house. How many mini splits do I need?”
This is a standard question about the number of mini splits required. A 1,500 sq ft house would need about 30,000 BTU (2.5 ton) of cooling output; that means you would need 1, 2, or 3 mini splits (we talk about single-zone, 2-zone, and 3-zone mini splits).
Now, we get a lot of questions regarding how many mini splits you should install. Here are just a few of them (we are going to address and answer all of them further on):
- “How many rooms can a mini split cool?”
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“How many air handlers do I need?”
- “Do you need a mini split in every room?”
- “How many square feet does a mini split cool?”
- “How many BTU per square foot for a mini split?”
According to Statista 2016 report, single-zone mini splits and multi-zone (2-zone, 3-zone, 4-zone, 5-zone, 6-zone, 7-zone, 8-zone) mini splits represent 77% share of all air conditioners worldwide. In short, a mini split is the most popular type of AC unit used today, so it’s no surprise that so many people are trying to figure out how many mini splits they need.
To help everybody out how many mini splits you need, we have included a Mini Split Number Calculator and Mini Split Number Chart below. You can consult both of them to get a grip on how many mini split units you need.
However, let’s first learn how these multi-split calculations work and answer questions along the way.
Here’s how determining if you need 1, 2, 3, 4, 5, or more mini splits work:
- Based on the size of your home, calculate the BTU requirements (primary factor). Usually, we use a 20 BTU per sq ft rule of thumb. Example: For a 1,500 sq ft home, you would need 1,500×20 = 30,000 BTU output. You can use one 30,000 BTU mini splits, two 15,000 BTU mini splits, or three 10,000 BTU mini splits.
- Be aware of the airflow and access to different rooms (secondary factor). Matching the cooling output (BTUs) is not enough. If you have a larger space, the airflow from a single 30,000 BTU mini split, for example, won’t be able to flow into all the rooms adequately. You will be left with hot pockets and inhomogeneous temperature dispersion. Having closed doors also prevents the cool air from coming into a closed room.
Based on these two factors, we can quite easily determine how many mini splits you need. We are going to show you how to calculate the BTUs, which mini split indoor handler sizes you can choose from, and how many mini splits you need for how many rooms. Let’s what with the BTUs:
How Many BTUs Do You Need From Your Mini Splits?
When we talk about multi-zone mini splits, this is what we have in mind:
- 1 outdoor unit. This is where the compressor and all the power comes from.
- Several indoor units or air handlers. 1 outdoor unit can power 1, 2, 3, 4, 5, 6, 7, or even 8 indoor air handlers. We call this 1-zone, 2-zone, 3-zone, 4-zone, 5-zone, 6-zone, 7-zone, and 8-zone mini splits, respectively. Indoor air handlers can produce anywhere from 9,000 BTU to 3,6000 BTU (3-ton) cooling output.
The first thing you need to do is determine how many BTUs you need. The easiest way to find this out is either to use this AC BTU calculator (gives a more precise estimate) or to use a simple HVAC rule of thumb, stating:
“You need 20 BTU per sq ft of living area (8 ft ceiling height).”
This simply means that you need to multiply the square footage of your home you want to cool by 20 BTU.
Example 1: How many BTU do you need for a 1,000 sq ft house? How many mini splits for a 1,000 sq ft house?
BTU Requirement (1,000 Sq Ft) = 1,000 Sq Ft × 20 BTU = 20,000 BTU
You know you need about 20,000 BTUs. You have to choose between combination of air handlers. Namely, most HVAC producers sell 9,000 BTU, 12,000 BTU, 15,000 BTU, 18,000 BTU, 24,000 BTU, 30,000 BTU and 36,000 BTU units.
In this case, you can go for:
- 1-zone mini split with 24,000 BTU air handler. This is a bit more than 20,000 BTU requires but it’s better to have a bit more than a bit less.
- 2-zone mini split with 9,000 BTU and 12,000 BTU air handlers. The combined cooling output is 21,000 BTU; very close to the 20,000 BTU required.
Let’s do another example to illustrate this:
Example 2: How many BTU do you need for a 3,000 sq ft house? How many mini splits for a 3,000 sq ft house?
BTU Requirement (3,000 Sq Ft) = 3,000 Sq Ft × 20 BTU = 60,000 BTU
In this case, we need 60,000 BTU of cooling output. How many mini splits is that? Here are the combinations you can use:
- 2-zone mini split with two 36,000 BTU air handlers. Total output: 72,000 BTU.
- 3-zone mini split with two 24,000 BTU units and one 18,000 BTU unit. Total output: 66,000 BTU.
- 4-zone mini split with two 12,000 BTU units and two 18,000 BTU units. Total output: 60,000 BTU.
- 5-zone mini split with five 12,000 BTU units. Total output: 60,000 BTU.
- 6-zone mini split with three 9,000 BTU units and three 12,000 BTU air handlers. Total output: 63,000 BTU.
- 7-zone mini split with seven 9,000 BTU air handlers. Total output: 63,000 BTU.
As you can see, there are many available combinations. In general, it’s better to use more indoor air handlers than less. This is because of the airflow and homogeneous cooling. Let’s account for that as well:
How Many Rooms Can A Mini Split Cool? (Airflow Factor)
Correctly calculating the BTUs is not enough. You also have to be aware of how the cool air from indoor air handlers will propagate through your home. A classic question here is if you need a mini split for every room.
You don’t.
A single air handler can adequately cool 2, 3, 4, or even 5 rooms. What you need to remember, however, is that all those rooms are considered an open space – no closed doors between them.
Example: Let’s say you have an 18,000 BTU mini split in the living room. 18,000 BTU can cool down rooms with combined square footage of about 900 sq ft. That means that 1 mini split can cool your living room, adjacent kitchen, adjacent bathroom, and even an adjacent bathroom.
How many rooms can a mini split cool basically depends on your layout. With an open layout and no closed doors, the more powerful air handlers (18,000 BTU and above) can cool 3 or 4 rooms.
Nonetheless, a better practice is to use smaller (below 18,000 BTU) air handlers and install more of them.
In our example above for a 3,000 sq ft house, the most optimum number of mini splits would be 5 or 6. These include a combination of smaller 9,000 BTU and 12,000 BTU units that can cool 1 or 2 rooms (two rooms have to be adjacent to each other, without closed windows).
Using smaller units will enable multiple points of airflow. With multiple units cooling your house, it’s easier to get a homogeneous temperature through the house. If you would use bigger units, you might run into some hot pockets in rooms the farthest away from the air handler.
To help you make a rough estimate of how many zones mini split you need, we have created this Mini Split Number Calculator. It uses a 20 BTU per sq ft rule of thumb and will tell you how many 12,000 BTU air handlers you need to adequately cool your home:
Mini Split Number Calculator
Just insert the square footage, and you will get the result (we’ll explain how to read this result below the calculator):
As you can see, the calculator tells you exactly (to the 1st decimal point) how many mini splits you need. For a 1,500 sq ft house, you would need 2.5 12,000 BTU mini splits. In these cases, it’s always better to round up the number. Namely, for a 1,500 sq ft you would need 3 12,000 BTY mini splits. You could also use 2 12,000 BTU units and 1 9,000 BTU unit.
You can play around with the numbers to see how the number of mini splits needed changes. You can also consult this chart to see how many mini splits you would usually need to cool certain square footage:
Mini Split Number Chart
| Home Size (Square Footage): | Number Of Mini Splits Needed: |
| 500 Sq Ft | 1 Mini Split |
| 750 Sq Ft | 1-2 Mini Splits |
| 1,000 Sq Ft | 1-2 Mini Splits |
| 1,250 Sq Ft | 1-3 Mini Splits |
| 1,500 Sq Ft | 2-3 Mini Splits |
| 1,750 Sq Ft | 3-4 Mini Splits |
| 2,000 Sq Ft | 3-5 Mini Splits |
| 2,500 Sq Ft | 4-5 Mini Splits |
| 3,000 Sq Ft | 5-6 Mini Splits |
| 3,500 Sq Ft | 5-7 Mini Splits |
| 4,000 Sq Ft | 6-8 Mini Splits |
This chart gives you a general idea of how many below 15,000 BTU mini splits you would need to adequately cool your home.
Hopefully, you now have a bit clearer understanding of how to pick the right number of mini splits.
Of course, every house is unique and you would need a custom-tailored estimate of how many mini splits you indeed need. If you have a bit of difficulty finding adequate information in this article, you can give a bit of information in the comment section below and we’ll try to help you out.
For specific suggestions on which multi-zone mini splits you can check:
Hello, my questions is, if my current units are too small for the open spaces and larger areas or the house, will i run the risk of damaging the handlers by running them 24/7?
Hello Jeannette, air handlers are made to run continuously. Under constant strain, the mini split lifetime can be reduced by some years, but that’s quite expected. Hope this helps.
Are mini splits ideal for off grid use?
Hi Richard, well, they have the highest SEER ratings (most energy efficient). That means you can use solar panels to run a mini split unit (using minimum electricity input). Example: A 2 ton 20 SEER unit will run on average of 1,200 watts power input. That’s much less electricity usage than for a same-size window AC unit, for example. Ideal might be a strong word here but mini splits are quite useful for off grid use, yes.
Hi I have a 600 sqft 20’*30′ home with half the home being the dining room and living roomand it a open layout so 10’*30′ and 7’*10′ kitchen that is open to that same area I have only two rooms closed off by doors which would be a 15’*10′ bedroom and the bathroom that is 10’*5′ what should I go with? I was thinking just putting one 18000 mini split located in the open area centered in the house and just try and leave the doors open to the two rooms as much as I could what are your thoughts? You can just email me a answer back also! Thanks
Hi Bennet, 18,000 BTU would be a sufficient cooling output for a 600 sq ft house. Now, if the air can be evenly distributed, you would only need 1 air handler (open area placement, as you have correctly suggested, is perfect). You will have to have those doors open, however. Alternatively, you can go with a 2-zone mini split, putting 1st one in the open area and the second one in the bigger 15×10 bedroom. It’s quite a dilemma but in both options you will have to open the doors between the rooms. Hope this helps.
I have an 8 room home, 3 bedrooms upstairs where the doors are almost always closed. Down stairs is an open floor plan, kitchen, living room and dining room. Downstairs there is an in law set up with small galley kitchen, dinning area and living area are combined and a bedroom that when occupied the door is closed. Any suggestions on what kind of equipment I would need and if possible a ball park figure on cost.
Hi Beth, you would usually require 1 air handler for every closed room. That’s 3 small air handlers (9000 BTU) for 3 upstairs. For downstairs – if it is 1 open area with up to about 1200 sq ft – you would need 1 big air handler (24000 BTU, 30000 BTU or 36000 BTU). A better but more expensive choice would be 2 medium-sized 12000 BTU, 18000 BTU, or combination (totaling 30000 BTU) air handlers, just to ensure that the temperature is as even and stable as possible. So, we are talking 4-zone or 5-zone mini splits.
Cost-wise, you are looking at about $10,000 price tag for the unit itself and the installation. A lot of factors such as SEER rating, BTU rating, your location, and so on, will affect the price but this is the ball park figure. Hope this helps.
I have a 720 sq ft home, it’s split in half from a big wall.
The layout is the living room connected to the kitchen open space then door way, a bedroom, bathroom and another bedroom. So it’s like 360 sq feet separated by a wall and then the other 360 sq ft is 2 bedrooms & a bathroom. Sorry if this is confusing.
Would I be able to get either two 7,000BTU split systems or should I get two 9,000BTU split systems?
Hi Candace, alright, this layout calls for 2 or even 3 mini splits. Let’s figure out the total BTUs needed; for 720 sq ft, you would need a bit more than 14400 BTU (20 BTU per sq ft), so two 9000 BTU air handlers would be ideal.
You put the 1st one in the living room and the 2nd one is one of the bedrooms. Here it is key to understand that the bedroom doors should be open in order to facilitate an even air distribution. That might be a bit awkward since these are bedrooms. If you have the option to put 6000 BTU air handlers in both bedrooms, that will remove the need for the bedroom doors to be opened since each bedroom has it’s own air handler. Hope this helps a bit.
What difference would a 9ft ceiling make? How would you change the calculations to accommodate?
Hi Joel, 9 ft ceiling does make a difference. Namely, all the calculations predispose that you have the standard 8 ft ceiling height. If you have a 9 ft ceiling height, there is 12.5% more air in the room that needs to be cooled/heated. That’s why you have to add 12.5% to the 8 ft ceiling calculation (just multiply the result by a 1.125 factor). Hope this helps.
i have a 3 room apt with a 350sf bedroom with a bathroom included with 10’ ceilings, another 400sf bedroom with a bathroom included with 10’ ceilings and an open living room and kitchen 480sf with half with 10’ ceilings and the other average 13’ vaulted ceiling. insulated concrete floor, walls & ceiling sealed and insulated very well. Was looking at a 36,000 btu with (3) 12,000 handlers. Midwest area. Does this seem close?
Hi Jason, alright, the total square footage is 1230 sq ft, and we have a 10 ft ceiling height. For the Midwest area, 36,000 BTU should be sufficient. The distribution of the indoor air handlers should be taken with care. The suggested 3 x 12,000 BTU is perfect for this apartment. That 480 sq ft living room + kitchen might need a 15,000 BTU unit just to be safe. Hope this helps.
Hello there. for my first question, how much more efficient is it to use a 5-zone multisplit vs. 5 individual minisplits?
Hi Joe Joe, the SEER rating determines the efficiency. The one which has a higher SEER rating – either 5-zone or 5 single-zones – will be more efficient. Now, 5 single-zones will be more expensive; but if one outdoor unit breaks, you still have other 4 in the middle of the summer. If, however, the 5-zone outdoor unit fails, you will be without AC for some time. Hope this helps a bit.
I’m about to purchase a small 760 sqft house. Living/dining are one room with a doorway from dining to kitchen. On the living room side there is a small hallway with the bathroon at the end of the hall and the 2 bedrooms on the left of the hall. I live alone so leaving bedrooms open isnt an issue. Im looking at a Mr. Cool DIY so I can do all the install myself. Im leaning towards the unit with the 30k btu 9k,9k, and 12k air handler unit. Seems overkill for the bedrooms, but I dont want to buy 2 mini splits as I am limited on space for 220v breakers in my box. Any thoughts on a 30k units for this size house?
Hi Stephen, thanks for all the details. The 30k unit seems a bit big for a 760 sq ft house. 24k MrCool or even 18k unit would be sufficient here. You don’t really have to worry about the air distribution; it’s a fairly small house and you can leave the bedroom doors open. Maybe a two-zone mini split with two 12k air handler units would be a good compromise here. Hope this helps.
Building a 1500 sq ft bardo with open living/kitchen area of about 500 square ft with and three bedrooms two that average 144 square ft and master with bath at 200 square ft all the bedroom doors will be closed how should I approach this layout?
Hi Rebecca, alright, let’s first think about the capacity. If you use the 20 BTU per sq ft rule of thumb, you would require about 30,000 BTU capacity. Now, you have 4 separate room, which would presume a 4-zone mini split. However, an indoor air handler for a 144 sq ft bedroom would be overkill. The best layout would be one 12,000 BTU air handler in the open living/kitchen area, one 9,000 BTU in the master bedroom, and one 9,000 BTU air handler in one of the smaller bedrooms (the one with higher sun exposure, more windows). So, ideally, you would be looking for a 3-zone mini split. That one smaller 144 sq ft bedroom without an air handler would be conditioned by having the door open a few hours per day. Hope this helps.
Building a 300 feet casita in AZ with a small bathroom (only closed when in use). Do I need a two zone or is one sufficient?
Hi Claudia, for a 300 square feet casita and open space concept (bathroom doors open), 1-zone will be more than enough.
Can a 9K inside unit be placed over a refrigerator in the Kitchen ? Are there any down sides to doing that. Unfortunately there are few other options in the Kitchen / Dinning area
Hi Kevin, in theory, you can put the indoor air handler anywhere. The one rule of thumb is just to put it close to the center of the space you want to condition; in order for the air distribution to be as even as possible.
Now, the consideration for placing it over the fridge in the kitchen is that the back of the fridge produces heat, and that heated air rises towards the air handler. The negative effect that would have on the air handler (in theory, it could warm the indoor coils a bit) is insignificant. The outdoor temperature determines the efficiency of the mini split, the indoor unit is not all that important. So, it’s good that you made sure everything is OK with this over the fridge setup, you can go right ahead.
I live in the high desert above 5,000 feet don’t need much air conditioning but do need it every now and again in the mid sumner months. Would generally keep doors closed. Will have a 800 square foot living/kitchen, 450 square foot bedroom, 200 square foot bathroom, 136 square foot grow room, 525 square foot shop. Hopefully an attic that might be converted to a living space that will be over the shop. Can I put the compressor in the attic? If so is it a pain to move it if I convert the attic into a living space. Because of the snow wouldn’t it be better? Also what layout would you recommend?
Hi Rosie, a compressor produces quite a lot of heat and humidity. If you put it in the attic, you will have a hot and humid attic, and you should probably open the attic windows to allow for airflow. Putting the compressor in the attic is not exactly ideal, but it can be done. For precaution, check the local regulations on that, it might go against those. Just in case.
Now, the total square footage here is 2,011 sq ft. Applying the 20 BTU per sq ft rule would result in 40,220 BTU of cooling output requirement (that’s about 3.5 tons). Given that you are located 5,000 feet above sea level and that you don’t need all that much cooling, it would be safe to say that you would only need about 10 BTU per sq ft. That means you are looking at 1.5 ton or 2 ton unit (with combined up to 24,000 BTU cooling output).
Since this is quite a spacious home, you should go for dual-zone mini split (3-zone would be even better for cool air distribution, but you would have excessive cooling output with that). You can go with 12,000 BTU unit in the 800 sq ft living room/kitchen, and 12,000 BTU unit in the bigger 450 sq ft bedroom. That might leave the shop a bit warmer.
Alternatively, you can go with 3-zone mini split, with 1st 9,000 BTU air handler in the living room/kitchen, 2nd 9,000 BTU air handler in the bigger bedroom, and the 3rd 9,000 BTU air handler in the shop.
Given this is a desert and very high altitude, calling a HVAC tech for hands-on evaluation would be a good idea. Hope this helps a bit.
Hi: We are in the planning process for a barndominium. It will be a total of 1800 sqft with 630 sqft for an RV garage and the remaining 1170 living space. About 600 sqft are open space for living room and kitchen. The remaining are a master bedroom 130 sq ft with attached master bath 120 sqft and attached walk in closet 50 sq ft. Then one more closed off office 100 sq ft and second bathroom 70 sq ft. What would you recommend?
Hi Claudia, the optimum solution here would be a 3-zone mini split. The 1st air handler (9,000 BTU) goes into the garage, the 2nd (12,000 BTU) in the living room, and the 3rd (9,000 BTU) goes into the master bedroom. You should keep open doors into other smaller rooms in order to get the cool air in there as well. Hope this helps.