Mini-split heat pump systems have become increasingly popular in homes because they are ductless and functional. Getting a mini-split system installed can help your home stay comfortable when the surroundings are too hot or cold. However, with so many sizes available, I know how difficult it is to choose which size (in BTUs) you should get for the space you need to heat and cool in your home.
In my experience, most mini-split heat pump manufacturers include or recommend a “coverage area” in square feet for their heat pumps. Usually, you just need to measure your room or space (in square feet) and make sure it is under (and near) the mini-split’s coverage area. However, if your space has vaulted ceilings, lots of windows, or poor insulation, basing it on square footage alone won’t be accurate. To get the best fit, you can hire an HVAC company to perform a Manual J calculation.
In this blog, we’ll talk about what size of a mini-split is best for your home. The sizes listed below should be used as a starting point for finding the right size and capacity for your application.
Wondering if a mini-split is right for your home? This video explains the pros and cons of ductless mini-split AC systems compared to traditional central AC systems:
How to Choose the Right Mini Split Size
Here’s the deal: bigger isn’t always better. Before buying a mini-split system, you should consider the improvements you made to your home, including any insulation and window placements. Usually, homeowners with good ventilation systems and insulation in their homes won’t need mini-split systems with higher power requirements.
To make sure you get the right mini-split size, hire HVAC professionals to do a Manual J-load calculation to see what size ductless mini-split your house will need.
How to Size a Mini Split Heat Pump?
A ductless heating and cooling system is sometimes known as a mini-split heat pump. They perform the same functions as most air-conditioning units, but they don’t require ductwork and are often used to heat or cool a single room.
To determine the suitable mini-split air conditioner size, try the following procedures:
- Determine the lot area of the room in square feet. Note that you must multiply the length and the width of the room to get the area.
- Multiply the room area by 25 to get the recommended British Thermal Unit (BTU) capacity of a mini-split.
- Note: Many mini-splits include a specification for its coverage area in square feet. In this case, you will just need the area you calculated in step 1.
Note that there are other factors to consider before buying a mini-split, such as:
- The number of people who will be in the room at any given time
- The level of insulation in your home/building
- The height of your ceiling – large vaulted ceilings will require a larger size mini-split
- The number of windows in your home
- The orientation of the room you want to heat/cool (south-facing windows tend to let in more heat than north-facing ones due to the sun’s position in the Northern hemisphere)
- How much sun exposure your home ha
If any of these conditions apply to your home, you should consult with an HVAC expert.
How Many Mini-Splits Do I Need?
Each room in your house requires one small split zone. Large areas, such as an open living space, may require two indoor units to guarantee adequate heating and cooling capabilities.
If you have more than four rooms to cool or heat, a multi-zone system might be necessary. In this case, you will have several indoor units (evaporators or air handlers) and one outdoor unit (condenser).
On average, a one-ton mini-split is 37 x 36 x 19 inches and weighs around 100 pounds. Note that 1 ton equals 12,000 BTU per hour of cooling capacity.
Mini-split Sizing By Square Footage
Use the dropdown sections below to learn about mini-split sizing for different areas:
According to MiniSplit Warehouse, “A Mini-split with 8,000 BTUs per hour of power, can cool a space up to 300 square feet—perfect for small living areas and bedrooms. The HVAC system will be able to heat or cool these areas without much trouble.” If you need to cool a 300-square-foot room, take a look at how much running a 8000 BTU AC costs.
A mini-split with at least 13,000 BTU per hour capacity can cool or heat rooms up to 500 square feet in size. Mini-splits with 13,000 BTU are ideal for living rooms or home offices that are not too large but require more powerful heating and cooling units due to their size and layout.
Mini-splits with at least 24,000 BTUs per hour are perfect for rooms between 500 and 900 sq ft — including bedrooms, living rooms, dining rooms, and kitchens. Ductless mini-splits rated at 24,000 BTU per hour are powerful enough to cool anything from a studio apartment to a large 2-car garage.
Mini-splits with at least 36,000 BTU per hour capacity will be able to cool a large room or open floor plan.
If you have a large open space (like an office or living room), consider a mini-split with at least 48,000 BTU per hour of heating and cooling capacity. These units will be able to cool larger areas more efficiently and effectively than smaller units.
Why Choosing the Right Mini-Split Size is Critical
Choosing the right size ductless mini-split is important for many reasons:
- Comfort: A correctly sized mini-split will cool and heat your room or space evenly and reduce hot and cold spots
- Efficiency: A mini-split that is too small will run often and never properly cool or heat your space. On the other hand, a mini-split that’s oversized will turn on and off frequently and cause uneven heating/cooling in your room. This makes it less efficient, leads to more wear and tear, and makes your electric bill skyrocket.
- Cost: Buying the correct size you need reduces your cost compared to a pricier, oversized unit. Plus, since the correct size is more efficient, you’ll reduce your electricity bills in the long run, too.
- Lifespan: Correctly sized mini-splits run more efficiently than improperly sized ones. They experience less wear and tear, which reduces breakdowns.
How Many BTUs Do I Need For a Mini-Split?
For reference, here is a mini-split sizing guide based on specific room areas. The sizes below are recommended for houses with good insulation.
| Room area (square foot) | BTU required (per hour) |
| 100-250 | 6,000 BTUs |
| 250-300 | 7,000 BTUs |
| 300-350 | 8,000 BTUs |
| 350-400 | 10,000 BTUs |
| 400-500 | 12,000 BTUs |
| 500-550 | 13,000 BTUs |
| 550-650 | 14,000 BTUs |
| 650-750 | 18,000 BTUs |
| 750-1,000 | 24,000 BTUs |
| 1,000-1,500 | 36,000 BTUs |
Mini-split Sizing By Room Type
Use the dropdown sections below to learn about mini-split sizing for different functional spaces:
A mini-split with 6,000 BTU per hour energy capacity can cool a 15 x 15 square foot 1-car garage, and a 12,000 BTU unit can cool most 2-car garages. On the other hand, I recommend mini-splits with at least 24,000 BTU per hour for larger 3-car garages.
A mini-split with 6,000 to 7,000 BTUs of cooling and heating capacity will be enough for most bedrooms.
Consider having a mini-split 12,000-14,000 BTU per hour capacity for small living spaces and 18,000 BTU per hour for larger living rooms.
If you’re looking for a mini-split for your retail store, you need to think about two main things: capacity and square footage. I recommend at least 24,000 BTU per hour for stores around 1,000 square feet in area.
Mini-splits with 34,000 BTU per hour energy capacity are recommended for spa salons, big restaurants, and large stores larger than 1,000 square feet. If you have multiple offices, mini-splits rated at 34,000 BTU per hour should be enough to heat up or cool down your entire office space.
Factors Affecting Mini-Split Sizing
Several factors influence the appropriate mini-split size for your home. Consider these key elements when determining the best unit for your needs.
Local Climate
Your local climate plays a significant role in mini-split sizing. Homes in regions with extreme temperatures will require more powerful units to maintain a comfortable indoor environment.
House Layout
The layout of your home, including the number and size of rooms, affects mini-split sizing. Open floor plans may require larger or multiple units to ensure adequate coverage.
Insulation and Age
Homes with newer/more efficient insulation retain your home’s temperature better, meaning you’ll need a smaller mini-split to heat and cool it compared to an older home with no or little insulation.
Ceiling Height
Rooms with vaulted ceilings and 2-story great rooms will need larger mini-split heat pumps to heat and cool these spaces.
Number and Type of Windows
Windows can significantly impact mini-split sizing. Large windows, especially those facing south or west, allow more heat gain, requiring a more powerful unit to counteract the effect.
Additional Factors
Other factors that can influence mini-split sizing include:
- Number of occupants
- Appliances and electronics that generate heat
- Shading from trees or nearby buildings
- Personal temperature preferences
Final Thoughts on Determining Mini-split Size Needs
So there you have it! For most homes, you can base the mini-split size you need on the square footage, but if your home is poorly insulated, has many windows, is in direct sunlight for several hours, or has vaulted ceilings, you may need a larger size. For these scenarios, it is best to have an HVAC technician perform a Manual J calculation to determine the best space for your space.
I hope that my quick breakdown of the recommended sizes for mini-split systems has helped you make a more informed decision on your purchase. The ideas mentioned above should give you a quick overview of the size and BTU of different mini-splits, but you must know that buildings are not all made the same. Whether your walls are wood, concrete, drywall, plywood, or double-pane glass, the building’s walls will make a difference in the BTU output you need to efficiently cool or heat your space.
If you still aren’t sure what size mini-split your home needs, don’t sweat. Enter your zip code below to connect with local HVAC pros:
FAQs About Mini Split Sizes
Can a mini-split cool 1,000 square feet?
It is recommended to have mini-splits with 36,000 BTU energy capacity to cool a 1,000-square-foot house. However, mini splits with at least 18,000 BTU per hour are enough for a well-ventilated area.
Is it possible to cool an entire house with a mini-split?
A mini-split can cool the entire home when the appropriate size system, with multiple indoor units, is installed.
How many square feet does a one-ton mini-split cool?
A standard HVAC unit can cool 500 to 1,000 square feet of residential space per ton of cooling capacity.
Is it OK to get a bigger mini-split?
If you have a mini-split that is too big, your home will feel cold and damp.
A bigger mini-split will cool the house down quickly but not remove any moisture from the air or latent heat from inside the home. In other words, it doesn’t get rid of humidity or prevent mold from growing in your house.
How many square feet does a two-ton mini-split cool?
Mini-splits with a power of 24,000 BTU per hour can warm or cool areas ranging from 1,000 to 1,500 square feet.
If your home is 1,000 sq ft and you want to heat it in the winter, then a 2-ton mini-split would be able to do so for you. Or if your house is 1,500 sq ft and you want to cool it in the summer, then a 2-ton mini-split can provide adequate cool air.
Can I install a mini-split heat pump myself?
Yes, you can install a mini-split yourself and many manufacturers offer DIY kits. However, if you’re not handy or don’t have time for a long project, hiring an HVAC contractor is the best route.
Where does the mini-split go?
Most mini-splits are designed to be hung high up on a wall, out of the way. They connect (via refrigerant lines) to an outdoor unit (condenser) that sits on a pad just outside your home.
