What Size Mini Split Should You Put In Your Garage (Based On Size)

Mini-split units are commonly installed in garages to regulate temperature. These units can provide both heating and cooling capabilities to make your garage more comfortable. 

Installing a mini-split unit gives you full control over your temperature settings in this space. With a mini-split unit, you can zone sections of your property independently from your whole-home HVAC system.

Garages typically require between 6,000 and 12,000 Btu. Before you buy a mini-split unit, you need to measure your space. Having a correctly-sized mini-split ensures that you can heat or cool your garage adequately. 

Garage TypeGarage Width(Ft)Garage Length(Ft)Square Footage(SF)What Size Mini-Split You Need
One-Car Garage12 22 2649,000 Btu
Two-Car Garage242457615,000 Btu
Three-Car Garage322270418,000 Btu
Four-Car Garage402288024,000 Btu

If you’re not sure where to begin when shopping for a mini-split unit for your garage, you’re in the right place. This article will help you understand mini-split systems. 

This includes how mini-split systems work, picking the right size, and how to get one for your garage.

What is a Mini-Split AC System?

A mini-split system is HVAC equipment used to control the temperature in a small space. They can provide both heat and air conditioning (cooling). Units with the heating option must have a heat pump.

These systems also go by another name: ductless air conditioners. That’s because they require little to no ductwork. Instead, they are installed directly in the space that needs temperature control.

A mini-split system is usually made up of two main components. The exterior component is attached to the outside of a building (roof or on the ground), similar to an AC compressor. 

The components of Mini Split AC
The components of Mini Split AC
Image Credits to: www.blog.totalhomesupply.com

The interior component, attached to the inside wall or ceiling, is called the air handler, and it helps circulate the conditioned air. The two components are connected through a few conduit lines that run through a small hole in the wall or ceiling.

Mini-split units have many advantages over centralized systems. Because there are no ducts, the system experiences less heat loss as air travels into the room. This makes mini-split systems more energy efficient.

Mini-split systems provide a simplified solution for heating and cooling your home when compared to traditional HVAC setups. They provide easy access for repairs and additions. They also allow you to regulate the temperature separately from the rest of your thermostat-controlled areas.

How Mini-Split AC Systems Work

Ductless mini-splits work the same as traditional heating and cooling systems, but on a smaller scale and without the ducts. In a sense, they are standalone systems. 

If you’ve ever used a space heater or a window-unit air conditioner, these are the same basic components present in a mini-split system. 

The smaller condenser and air handler components found in mini-split units can manage a small space, like a garage, easily. 

How Mini-Split AC Systems Work
Image Credits: www.myexpresspros.com

Here are the basic steps of how a mini-split system works for cooling:

  1. Hot air is pulled into the interior unit
  2. The air travels to the exterior unit and is cooled in condenser coils
  3. Cool air is pumped into the room with the air handler

When in heating mode, the flow of refrigerant changes inside the same components to switch modes.

You can usually control your mini-split system with a remote control. This allows you to turn the unit on and off, and change the temperature settings.

There are two types of mini-split systems: single-zone and multi-zone. If you’re simply adding heating to a garage, you’ll use a single-zone system.

A multi-zone mini-split system allows you to connect two or more indoor units together with a single outdoor unit. This allows a user to control the temperature independently in multiple rooms or larger spaces.

Can You Put a Mini-Split in the Garage?

Yes, you can install a mini-split unit in your garage. This is a good solution to keeping temperatures comfortable in this in-between space. 

In the winter, mini-splits can keep your garage above freezing while your home stays warmer with your main heating system. In the summer, you can cool the garage only as needed while your home stays comfortably cool all summer with your main air conditioner.

Mini-split Aircon in the Garage
Mini-split Aircon in the Garage

It’s common to find that your home was not built with heating or air conditioning inside the garage. Mini-split units provide a simple solution to retrofit heating and cooling to this space.

Trying to make your existing HVAC system extend to your garage can be challenging and expensive. It usually requires adding ductwork and/or up-sizing your existing centralized equipment (furnace and AC unit). 

You can save money by opting for a new mini-split on your existing garage rather than trying to add to your existing centralized system. 

What Temperature Should You Keep Your Garage in Winter?

Set your temperature in your garage between 40 and 65 degrees Fahrenheit in the winter. This keeps the air well-above freezing. 

If you live where snow and ice are common, keeping your garage above freezing will encourage it to melt off. That way, your vehicle stays dry and clean.

Keeping your garage set above this range also keeps the temperature above the dew point to avoid condensation and moisture problems.

Of course, it’s also fine to set your garage temperature higher than 65 degrees in the winter for comfort if you spend much time in the space.

What Size Mini-Split Do You Need For Your Garage?

You’ll need about 25 Btu per square foot to heat your garage if it has average nine–foot ceilings. Measure square footage by taking the length multiplied by the length of your garage. 

For example, if your garage is 12 feet wide by 22 feet long, your square footage equals 264 square feet. Take 264 multiplied by 25 Btu, which equals 6,600 Btu minimum.

Mini-splits range in size from 6,000 up to 56,000 Btu. Let’s take a look at what size mini-split you’ll need based on different garage sizes.

One Car Garage

A small single-car garage may be able to get away with installing a 6,000 Btu mini-split unit. To be on the safe side—a 9,000 Btu is more adequate to meet the heating needs for this size space. 

Let’s do the math on an average one-car garage that is 12 feet wide by 22 feet long. This is the same example we showed above (264 SF X 25 Btu), requiring at least 6,600 Btu for your mini-split.

Senville LETO Series Mini Split Air Conditioner- 9000 BTU

It’s better to go with a system that exceeds the Btu requirements rather than under-sizing.

Two Car Garage

A two-car garage requires a 12,000 Btu mini-split for those that are on the smaller side. A 15,000 Btu mini-split is a safe bet for most two-car garages.

The size of an average two-car garage is about 24 feet square. So, taking 24 multiplied by 24 equals 576 square feet. Taking 576 SF X 25 Btu equals a minimum requirement of 14,400 Btu.

Mitsubishi 21.6 Seer Single Zone Ductless Mini Split – 15,000 Btu

Keep in mind that if you have vaulted ceilings in your garage, you may want to opt for an even larger mini-split to account for the additional air volume.

Three Car Garage

Either an 18,000 or 24,000 Btu mini-split is required for a three-car garage. This is a much larger space that requires a substantially-sized mini-split unit.

Doing the math, a three-car garage is about 32 feet wide by 22 feet long, or 704 square feet. Take 704 SF multiplied by 25 Btu, which gives a required rating of 17,600 Btu minimum.

ApooDr Mini Split Heat Pump – 24 000 BTU

The design of three-car garages varies more than single or double garages. Take this into consideration when calculating your volume. Don’t forget to add additional heating power if your ceilings are vaulted over nine feet.

Four Car Garage

A four-car garage requires at least a 24,000 Btu mini-split unit. Dimensions for custom four-car garages vary greatly. Therefore, it’s best to calculate your square footage to determine minimum Btu requirements.

Let’s take an example of a 40–foot wide by 22–foot deep four-car garage. With 880 square feet, at 25 Btu per square foot, you’ll need at least a 22,000 Btu mini-split unit for a garage this size if it has an average ceiling height.

Hessaire  Ductless Mini Split A/C Heat Pump – 24000 BTU/H

Since mini-split units around this size come in 18,000 or 24,000 Btu, you’ll want to go up to the higher-sized mini-split.

Use the chart below for a quick look at average-size garages and what size mini-split you need. These are based on a nine–foot ceiling height.

Size Comparison for Mini-Split in Garage

Garage TypeGarage Width(Ft)Garage Length(Ft)Square Footage(SF)What Size Mini-Split You Need
One-Car Garage12 22 2649,000 Btu
Two-Car Garage242457615,000 Btu
Three-Car Garage322270418,000 Btu
Four-Car Garage402288024,000 Btu

If your square footage doesn’t fit into these categories, you may need a different-sized unit. Mini-splits are available in the following common sizes:

  • 6,000 Btu
  • 9,000 Btu
  • 12,000 Btu
  • 15,000 Btu
  • 18,000 Btu
  • 24,000 Btu
  • 30,000 Btu
  • 36,000 Btu
  • 42,000 Btu
  • 48,000 Btu
  • 56,000 Btu

How Much Does it Cost To Install a Mini-Split in a Garage?

It can cost between $1,000 to $4,000 for professional installation of a mini-split system for average-size garages. 

A 12,000 Btu, which is adequate for a 20 x 20foot garage, has an average installed cost of around $3,000. 

Larger garages and more complicated setups will increase the cost of your mini-split unit and installation. 

If you want to save money on installation and are feeling handy, you can install your mini-split unit yourself. Depending on the manufacturer, you can find 12,000 Btu mini-split units for under $1,000 at local big box stores. 

It requires minimal tools and hardware. There are plenty of videos available online to walk you through a DIY mini-split installation.

Is a Mini-Split the Best Choice For a Garage?

Yes, a mini-split is the best way to heat or cool your garage. It provides separate controls, affordable installation, and runs quietly and efficiently

Keep your garage comfortable and temperature-controlled by installing a mini-split system sized to match your garage size.


Sweating or freezing out in your garage when the temperatures outside reach their extremes is no fun. It makes your garage almost unusable. 

If you’ve decided it’s time to install a heating and cooling system out there, you’ll be happy you went with a mini-split system. Turn your garage into a more comfortable place to hang out when you can control the temperature. 

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