Mini Split BTU Per Sq Ft (What Size For 200-2000 Square Foot?)

How many square feet does a mini split cool? What about heat? In other words, what’s the mini split BTU per square foot?

The quick answers are right here, followed by a complete explanation below.

Cooling: A mini split cools 200 to 2,000 square feet based on its size.

The rule contractors use to size a mini split is 20 to 25 BTU per square foot for cooling/AC.

For example, if your space is 1,000 square feet, a 24,000 BTU system would be just about right for air conditioning.

Heating: Mini split systems can also potentially heat 200 to 2,000 square feet, but there is a catch.

The contractor’s rule for mini split heating is 30 to 60 BTUs per square foot. So, a system large enough to cool your home might not do the heating job in extreme winter cold.

It all depends on your climate, home size and other factors addressed here. But first, here are two handy Pick HVAC charts that answer the question – how many square feet does a mini split cool and heat?

Mini Split Cooling Size Chart

This table is based on pro contractor recommendations. The column on the left is room size from a small room to a whole house. The right column gives you the BTUs needed for spaces this size in most climates.

Mini Split Cooling Size Chart (Square Footage to BTU)

Room SizeMini Split Size
200 sq ft5,000 BTU
300 sq ft7,000 BTU
400 sq ft9,000 BTU
500 sq ft12,000 BTU
600 sq ft14,500 BTU
700 sq ft16,500 BTU
750 sq ft18,000 BTU
800 sq ft19,000 BTU
900 sq ft21,500 BTU
1,000 sq ft24,000 BTU
1,200 sq ft28,800 BTU
1,300 sq ft32,000 BTU
1,400 sq ft34,000 BTU
1,500 sq ft36,000 BTU
1,600 sq ft38,000 BTU
1,700 sq ft42,000 BTU
1,800 sq ft43,500 BTU
2,000 sq ft48,000 BTU

Mini split for 800 sq ft?

For AC only, you’ll need about 20,000 BTU. But if you plan to heat the space too, something 24,000 BTU for a warm climate and up to 48,000 BTU for a cool or cold climate will be needed, according to the chart below which shows mini split size for heating.

What size mini split for 24×24 garage?

That’s 576 square feet, and the chart says about 14,500 BTU for AC. However, if the garage isn’t well-insulated, and most aren’t, consider a 24,000 to 36,000 BTU system for AC. And if you plan to heat it too, then go as high as 48,000 – the colder your climate, the more BTUs needed.

Mini Split Heating Size Chart

Since mini split heat pumps are used for heat from chilly days in Florida to all winter long in northern climates, the range is a lot broader. And definitely see the note below the table.

What size mini split for 500 sq ft?

12,000 to 30,000 BTU. If you’re cooling the space only, you will need 12,000 BTU for an average climate. If you want heat too, the chart right below indicates that up to 30,000 BTU will be necessary based on how cold winters are.

Mini Split Heating Size Chart (Square Footage to BTU)

Room SizeMini Split Heating Size
200 sq ft6,000-12,000 BTU
300 sq ft9,000-18,000 BTU
400 sq ft12,000-24,000 BTU
500 sq ft15,000-30,000 BTU
600 sq ft18,000-36,000 BTU
700 sq ft21,000-42,000 BTU
800 sq ft24,000-48,000 BTU
900 sq ft27,000-54,000 BTU
1,000 sq ft30,000-60,000 BTU
1,200 sq ft36,000-72,000 BTU
1,300 sq ft39,000-78,000 BTU
1,400 sq ft42,000-84,000 BTU
1,500 sq ft45,000-90,000 BTU
1,600 sq ft48,000-96,000 BTU
1,700 sq ft51,000-100,000 BTU
1,800 sq ft54,000-110,000 BTU
2,000 sq ft60,000-120,000 BTU

Mini split for 1000 sq ft?

24,000 BTU for AC and up to 60,000 BTU for heating based on your climate. Obviously, the colder your winters are, the larger the system will need to be. In Florida or Arizona, a 24,000 BTU system might handle 1,000 square feet for heating and AC.

Mini split for 400 sq ft?

A 12,000 BTU unit is ideal for heating and cooling 400 square feet in a warmer climate. In a colder climate, consider an 18,000 or 24,000 BTU system to make sure it will heat the room or zone.

How many sq ft to BTU for mini split systems?

We get that question once in a while, but the answer would be like .04 (divide 500 square feet by 12,000 BTUs, which is the proper amount for that size). Asking it the other way, BTU per square foot, makes more sense. 

Check Out our Calculator for mini split sizing. It allows you to input your room or whole house size, select your climate zone on a map and get a precise calculation about the mini split heat pump size for both heating and air conditioning your space.

Should I Have the Same Cooling and Heating BTU for Mini Split?

First, we should say that most mini split systems DO have the same, or very close, number of BTUs for AC and heating. 

But you probably won’t use the same number of BTUs for heating and AC – unless you live in a temperate climate without extreme heat or cold.

Let’s discuss how many BTU per square foot for mini split AC and heating separately. And then we’ll make mini split system size recommendations based on your climate. 

Cooling: In cool climates, summer temperature might climb to 90 or occasionally a little hotter. Most people set their thermostat to 76 to 80 in AC mode. So, the temperature differential from outside air to what they desire inside isn’t that great. Even in hot climates when it is 100 to 110 outside, you are only looking at a change in temperature of 20-35 degrees.

Yes, it gets up to 115 or 120 in some places – very few places like the desert west – but air is easier to cool when it is dry. And in air that dry, a lot of desert dwellers would start shivering if you set the AC to 75F. It’s much more comfortable at about 80F or a little higher.  

Heating: Heating is a different story. The recommended mini split square footage ratio is 30 to 60 BTUs per square foot. Why the difference? Because if you want it 70F inside and it is 50F outside, then sure, you don’t need a ton of BTUs.

But if it is below freezing – maybe down to freezing – and you want it 70F inside, the temperature rise from outside air to comfy indoors can be 50 to 70 degrees. There’s another reason – the colder it gets outside, the harder it is for any heat pump to collect air out there, so the system needs more total heating power (total BTUs) to get the job done.

If heating and cooling btu are the same on specs, should I size it based on heating or cooling btu?

This is a pretty straightforward choice:

Cold Climates: Choose a system rated for the heating BTUs you need. You could select one based on cooling BTU, but you might end up needing to use space heaters on very cold winter days, and space heaters use a lot of electricity and will definitely raise your electric costs. 

Warm Climates: Choose a mini split heat pump for the cooling BTUs you need

Temperate Climate: It might work out that you need about the same amount of heating and cooling BTUs, but where there is a difference, and there usually is, always pick the larger system. 

The secret of inverter technology! All mini split heat pumps are built with inverter compressors that modulate up and down to deliver the precise amount of heat or AC needed. So, for example, even if you have a 48,000 BTU mini split and only need 30,000 BTU for cooling, the system won’t “over-cool” the space. It will only supply what’s needed to do the job. 

Can You Slightly Oversize A Mini Split?

Sure, it might be OK to slightly oversize a heat pump in some circumstances such as if you’re installing one in an RV. And as we said above, because of the way the compressor works, it won’t overheat or overcool your space if it’s a little bigger than what you absolutely need.  

Here are other times this might be beneficial:

Climates with extreme heat or cold – a few thousand extra BTUs might come in handy during hot streaks or cold snaps.

Attic or garage installation: A garage usually isn’t well insulated. And a converted attic, sitting at the top of the house, can be really hot. So again, a little too big is OK. A sunroom falls into this general idea too – they get pretty hot. And if anyone is considering a mini split in a shed or pole building, then yes, oversize it.

A basement: The basement in most homes is frigid, so yes, extra heat will turn it from cold to cozy. And the basement can be humid since it is below grade. A slightly too-big heat pump will remove more moisture and make the air more comfortable. Look for a mini split with a “Dry” mode – in this mode it works as a dehumidifier to lower humidity without changing temperature. That’s a nice option to have.

How Big is Too Big? The International Code Council advice on HVAC system design is that the maximum size of an inverter mini split heat pump is 1.3 times what is necessary to properly heat and cool the area. For example, if a load calculation determines that the zone requires 30,000 BTUs, then maximum system size would be 30K x 1.3 = 39,000 BTUs

What about a grow room? It really depends on where the grow room is located – is it part of the house and  well-insulated, or located in the garage for example. And it depends on what you are growing. Tomatoes, for one, love heat, so going a little too big on the heat side won’t hurt as long as you consider the moisture needs of the plants.

Caution: Where we would avoid oversizing the mini split is in a small room like a 10×10 bedroom or a bathroom. You can quickly make it uncomfortably warm or cool in a small space because the system heats or cools too fast for the thermostat to respond. Also, the system would turn on and off more often than a properly sized mini split would, and that causes a lot more wear and tear on the heat pump. This is called short cycling, and a system that is too large is one of its main causes, though not the only one. 

Can One Mini-Split Indoor Unit Cool 2-3 Rooms?

Yes, possibly, if the floorplan is open. In that case, the rooms might be considered a zone instead of separate rooms.

Open floor plan: Maybe. If a living room joins a dining area off the kitchen, for example, or a large bedroom suite has a sitting area, then yes. It is possible for a large indoor unit – backed by an outdoor unit with plenty of BTUs – to cool 2 rooms. Three rooms might be a stretch.

Non-open floor plan: No. If there are doors between rooms, then one indoor unit won’t effectively cool the space. If you size the indoor unit for the total square feet of two rooms, and a door sits between the rooms, you will quite likely end up with one chilly room and one warm room. Putting a fan between them to move cooled air into the other room will help – just a tip if you end up in this predicament.

Written by

Rene has worked 10 years in the HVAC field and now is the Senior Comfort Specialist for PICKHVAC. He holds an HVAC associate degree and EPA & R-410A Certifications.
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