6 Smallest Mini Split Air Conditioner On The Market

If you want to cool a small room but don’t want to install ductwork, then you have to decide the type of room air conditioner that would suit your needs. Would it be a portable air conditioner, window air conditioner, or small mini-split system?

All of these air conditioning units have their pros and cons. However, if you want to invest in a cooling system for years to come, choose the smallest mini air conditioner. These units are energy-efficient and allow you to heat and cool individual rooms.

Most of the smallest mini split ac I’ve reviewed have cooling capacities between 9000 BTUs -12000 BTUs. If that’s is too much for your room, you can go for Mitsubishi 6,000 Single Zone Ductless Mini Split.

Remember, these are single-zone units that are ideal for small rooms between 100 to 450 square feet. For multizone mini-splits, you’ll have to choose a higher BTU rating.

If you’re in a hurry, here is our top pick

Pioneer Air Conditioner WYS009A-19 Wall Mount...
  • Save money all year-round with a highly efficient ductless mini split inverter+ heat pump system
  • Ultra-silent and beautifully built: perfect for home or light commercial use
  • Use for both cooling and heating at 9000 BTU/hour with 19 SEER and 10 HSPF efficiency
  • Comes with every needed component in the box including an easy-install 16ft copper piping kit
  • Free tech support and a 5 year coverage on the parts and compressor

Mini Split Sizing

Installing a ductless mini-split doesn’t have to be complicated. The most challenging, yet the most crucial, aspect is sizing. Selecting the correct size for your unit is essential. A unit that is not sized correctly will not run efficiently, cost you more in energy bills, and eventually malfunction.

One very efficient HVAC system is the mini-split system, which uses inverter technology to generate the exact amount of cooling or heating your home needs to maintain a steady temperature. 

You must get the correct size unit, even if your system has inverter technology. This article discusses how to size your mini-split and what affects sizing. 


BTU, or British Thermal Unit, is what we use to measure thermal energy. More specifically, a BTU is how much heat is needed to increase the temperature of a pound of water by 1 degree Fahrenheit.

BTU ratings tell you how big or small of a room an HVAC system can heat. The bigger the room you need to heat or cool, the higher the BTU rating you need. Mini-split systems have a wide range of BTU ratings. You don’t want the BTU ratings on your system to be too large or too small. 

Why is Proper Ductless Mini-Split Sizing Crucial?

how to size the smallest mini split

If your ductless mini-split system is too large or too small for the room you need to cool or heat, it could affect the temperature of your home, your system could break, and it could raise your energy costs. 

Sizing a mini-split is also known as load calculation. This refers to determining how many BTUs your unit must have to keep the entire area constant, comfortable temperature.

While there are calculators on the internet you can use to determine which size unit to get, they are not always accurate. That’s because other factors affect which size you will need. 

What Happens with an Undersized Mini-Split?

If your mini-split is not big enough, it will not work efficiently, leading to an uncomfortably warm or uncomfortably cool home. 

An undersized mini-split unit will run continuously, raising the cost of your energy bill without adequate heating or cooling your home. The energy an undersized unit uses will be wasted because it must work harder, and it will create cold spots or hot spots in different sections.

A unit that works continuously will wear out quicker than a properly sized one and eventually break down. 

Can you Slightly Oversize a Mini Split?

An oversized mini-split is just as bad as an undersized one. If you use an undersized mini-split, you won’t save any money on energy.

Also, oversized mini-splits will short cycle. This refers to your unit turning off and on frequently. This short cycling leads to unnecessary wear, which may lead to your unit breaking down or malfunctioning.

A short-cycling oversized mini-split is also not effective at decreasing humidity, which makes it less effective at heating your home and makes the air feel damp even when the unit is cooling your home. 

How to Size your Mini-Split

To correctly size your mini split, consider how big the room or rooms your unit will be heating or cooling. If you don’t know how to size a mini split, get help from a professional.

Step one is to calculate each room’s square foot. Calculate the length and the width of the room, then multiply them together. Step two is to use a chart to determine the exact BTU rating based on square footage. You can also multiply your square footage by 25.

Ductless BTU Sizing Chart

Area Size BTU
150 to 300 sq. ft. 6,000
300 to 500 sq. ft. 9,000
400 to 650 sq. ft. 12,000
500 to 800 sq. ft. 15,000
600 to 1000 sq. ft. 18,000
800 to 1,300 sq. ft. 24,000
1,000 to 1,650 sq. ft. 30,000
1,200 to 2,000 sq. ft. 36,000
1,400 to 2,300 sq. ft. 42,000
1,600 to 2,650 sq. ft. 48,000
1,850 to 3,100 sq. ft. 56,000

Factors that Affect the Ductless Sizing

While square footage is the most determinate factor in choosing which size mini-split to install, other factors affect sizing as well. 

a woman controlling a small wall mounted air conditioner


How old your house affects which size ductless mini-split to choose. That’s because older homes don’t have as good of insulation as newer homes. Poor insulation means your unit has to work harder to heat or cool your home. 

Therefore, if you have an older house, increase your BTU calculation by 30% to combat the poor insulation.


If your home is in an extremely hot or cold climate, you should increase your BTU calculation by 30%. If you live in a climate with cold winters and hot summers, you don’t have to worry about increasing BTUs. This only refers to extreme climates.


It is obvious that high ceilings make rooms bigger, therefore you need more BTUs to heat or cool your home. If the space you want to heat or cool has high ceilings, increase your BTU rating by 20%.

Windows and doors

Windows and doors have cracks and gaps that let hot or cold air in. The more windows or doors your home has, the higher BTU rating you will need for your HVAC unit. 


Direct sunlight can heat a room quickly. This also applies to your home in general. Is your home surrounded by tall trees, or is it in the middle of a field? If your home is exposed to direct sunlight, you will need a higher BTU rating.

Also, if the room you are looking to cool gets a lot of direct sunlight through windows, your unit will have to work harder to combat this extra heat. Therefore, you will need a higher BTU rating. 

Number of people

Because people generate body heat, the number of people in your home affects how big you need your mini-split. Before you decide which size you need, keep in mind how many people live in your home. 

Floor type

The last thing that can affect which size mini-split you need is what the floor is made of. For example, a carpeted floor has more insulation than hardwood. 

The most important factor, and step number one, to determine what size mini-split you need is square footage. To calculate this, measure the length and width of the room you are looking to heat or cool and multiply them together. Multiply this number by 25 to determine how high of a BTU rating you need.

Each mini split unit can provide a max amount of BTUs, meaning it has a set heating and cooling power. If you want to heat or cool multiple rooms, you will need individual air handlers in each room, each with the right BTU rating for that room. You can take the total BTUs of each room to determine the total outdoor capacity you need.

Environmental factors also affect the BTU rating you need in your ductless mini-split unit. Things that negatively affect BTU ratings include poor insulation, high ceilings, lots of direct sunlight, many windows and doors, and a large number of people living in your home. Things that positively affect BTU ratings include tall, shady trees, a moderate climate, and good insulation.

Smallest Mini Split AC Reviews 2021

 1. Pioneer WYS009AMFI17RL Mini Split Air Conditioner

Pioneer Air Conditioner WYS009A-19 Wall Mount...
  • Save money all year-round with a highly efficient ductless mini split inverter+ heat pump system
  • Ultra-silent and beautifully built: perfect for home or light commercial use
  • Use for both cooling and heating at 9000 BTU/hour with 19 SEER and 10 HSPF efficiency
  • Comes with every needed component in the box including an easy-install 16ft copper piping kit
  • Free tech support and a 5 year coverage on the parts and compressor

If you need efficient climate control in your home, then the Pioneer WYS009AMFI19RL mini-split system is just right for you. With 9000 BTUs cooling power and 17 SEER efficiency, it’s ideal for spaces up to 400 square feet.

This air conditioner operates quietly regardless of the fan speed you use. On top of that, it features a “sleep function” for extra quiet as you sleep. 

It comes with a wireless remote control fitted with a large LCD backlit screen for easy operation even in the dark. Use the remote to change between the different available operation modes and adjust the temperature to your liking wherever you are in the room. 

The available operation modes are cooling, heat, dry(dehumidify), and auto, where the unit chooses a mode depending on the set specifics and the overall climate of your room.

This Pioneer WYS009AMFI19RL system’s packaging also includes a complete installation kit including a pair of insulated copper tubing, interconnecting signal wiring, wall sleeve liner & cap, putty, wrapping tape, and a drain line extension. S

o you don’t need to spend the extra bucks to get your unit to full function. Installation is easy, but you have to use a professional to avoid the risk of damaging the unit and voiding your warranty.


  • Operates quietly
  • 17/19 SEER energy efficiency
  • Remote-controlled for smooth operation.
  • 2-year limited warranty for parts and a 5-year limited warranty for the compressor.
  • It has washable air filters for easy maintenance.


  • No DIY Installations.

2. Senville SENL-09CD Mini Split Air Conditioner Heat Pump

Senville LETO Series Mini Split Air Conditioner...
  • 4-in-1 Mini Split Air Conditioner with Heat Pump. Built-In Air Conditioning, Heating (Up to 5F/-15C), Dehumidifier, Fan and Turbo Function.
  • Great for Bedrooms, Additions, Living Rooms, Garages, and Commercial Applications. Can Be Installed in Virtually Any Home, Condo or Space.
  • Whisper Quiet Operation (25dB). Energy Efficient Consumption and Engineered for the Harshest Climates.
  • 5 Year Manufacturer . Senville Trusted Quality and Design. Free Technical & Installation Support Included.
  • Includes 16 Ft. Installation Kit with Communication Cable and Copper Lines (Pre-Flared) and Remote Control. R410A Pre-Charged (25 Ft. ) *Requires Professional Installation.

The Senville SENL-09CD is an excellent appliance addition to your home to serve your cooling and heating purposes. Packing a 9000 BTU cooling capacity and a temperature range between 62°-86°, this Senville unit is sure to keep your rooms comfortable throughout the seasons.

The unit is fitted with a variable inverter compressor to limit the amount of energy it uses. This feature, combined with the 19 SEER efficiency and 8.20 HSPF of the unit, will save you a lot on energy bills at the end of the day. 

Moreover, you can set the unit to “Eco mode” to run it at a standard 75°F to conserve even more energy. It also has washable and replaceable filters for easy maintenance and a turbo function to help you achieve the desired set temperatures fast.

The Senville 09CD also provides you with angled airflow for better even heating and cooling of your space. You just manually set the horizontal angle of the airflow on the indoor unit then use the remote to adjust the vertical flow as you please.


  • It has four operational modes – cooling, heating, dry, and auto mode.
  • Sleep function
  • The indoor unit has a multi-speed fan
  • Operates quietly
  • Comes with a 5-year limited warranty
  • The purchase includes an installation kit.


Installation requires a ¼” by ⅜” line set kit, which is not included during purchase.

3. Della 12000 BTU Mini Split Air Conditioner

The Della 048-MS-12K1V-17S-1+0 mini split unit can cool or heat spaces between 450-750 square feet. It’s ideal for homes, offices, and light commercial places like cafes and retail stores. The unit is multi-functional, offering you cooling, heating, dehumidification, and ventilation operations all in one. 

It also has a smart remote control with a built-in proximity sensor to adjust the temperature and airflow depending on the distance between you and the indoor unit to give you absolute personal comfort at all times. The remote will sense the temperature at the remote then adjust the flow and temperature accordingly.

The Della 048-MS-12K1V-17S-1+0It also has inverter technology making it one of the most energy-efficient HVAC systems on the market. While conventional systems run at full capacity to regulate room temperature, the inverter technology in this Della unit uses just enough power to reach the preferred settings. It then lingers there until more energy is needed – the perfect way to give you consistent comfort and save energy.

Also, the unit has some automatic functions like auto defrost and self-cleaning, which makes maintenance a piece of cake.


  • Operates quietly
  • Has a pre-charged condenser
  • The unit is remote controlled
  • Performs four functions in one
  • Fitted with inverter technology for energy efficiency.
  • AHRI and ETL certified.


  • Parts from Della are hard to come by.
  • Poor customer service 

4. Klimaire 9,000 BTU KSIV Ductless Mini-Split 

Klimaire KSIV009-H119-S(W) mini-split air conditioner has a built-in KSIV inverter that optimizes the energy uses to cool your home. Coupled with the 9,000 BTU and 19 SEER, this ductless mini split ac will ensure your electricity bills stay low at the end of the month.

The auto-clean function keeps the evaporator clean and dry to keep away mildew and maintain fresh, healthy, and quality indoor air always. 

The outdoor unit has a built-in base pan heater that keeps the system fully functional even in temperatures as low as 5°F. It has a pre-charged compressor and has an automatic defrost function that prevents damage to the compressor at extremely low temperatures.

The Klimaire also includes a home-away freeze protection feature that maintains a 46°F temperature to keep your space warm enough whenever you are away for a long time. 


  • Purchase includes a 15ft installation kit
  • Follow me remote function
  • Has a programmable timer 
  • Auto-restart function to quickly restart and maintain your settings in case of a power outage.
  • Unlimited free tech support and a 5-year manufacturer warranty


  • It is costly to install

5. DAIKIN Wall-Mounted Ductless Mini-Split A/C Heat Pump 

 The Daikin mini-split system with a heat pump is an excellent option for new or remodeled homes or rooms between 350-400 square feet. When set to eco mode, the unit’s compressor run at a slow speed, which in turn forces the motor to use less energy to heat or cool your room.

You can use the remote control to adjust temperature and switch between modes with ease especially when your unit is too far to operate manually

Daikin uses blue fin aluminium technology to protect the outdoor unit against corrosion and harsh climate, so you’re assured that the unit will last for a long time. The indoor unit also has a titanium deodorizing air filter that removes odors and keeps your home smelling fresh and clean always.


  • Fitted with variable inverter technology for energy efficiency
  • Has a built-in programmable thermostat
  • Comes with a 10-year warranty for parts
  • Operates quietly
  • Remote controlled


  • Getting hold of technical support is a problem sometimes.

6. Classic America Ductless Wall Mount Mini Split

Classic America Ductless Wall Mount Mini Split...
  • Classic America Mini Split Inverter Ductless Air Conditioner/Heat Pump. Uses 108-120 VAC electrical power, 16 SEER High Efficiency Rating, ETL Approved. Toshiba/GMCC Compressor and charged with R410A refrigerant.
  • Indoor unit has a modern and sleek appearance. The outdoor unit provides a powerful, dependable and efficient performance. Easy Installation kit and a wireless remote controller included.
  • Installation kit includes: 16 Feet Insulated Copper-Aluminum Refrigeration Tubing, Wiring Cables, Cable Tie - Pipe Wrap, Wall Sleeve Pipe.
  • Easy to use. Automatic air swing, Sleep function, Timer function, Auto-Restart, 3 Speed Fan, Anti-Freeze Pipe Sensor , Elegant Design, Washable Filters.
  • Perfect equipment for additions, conversions and ultimate independent zone control.

The Classic America KFR-35GW/MA3B Mini-split AC is another multi-functional unit that heats, cools, dehumidifies, and circulates air using the fan mode. All these operating modes can be accessed using the remote.

Its outdoor unit has a Toshiba compressor that is pre-charged with R410A. So you won’t need extra services for adding the refrigerant. 

The indoor unit has an automatic air swing function that ensures even air circulation in your room. Together with the multi-speed fan in the unit, you get total control of your indoor climate and assured comfort in all corners of the room.

You can also set this ductless mini-split system to sleep mode. In sleep mode, the unit mirrors the room temperature, and your body temperature then adjusts the functions accordingly. 

There is also a temperature monitoring device (thermistor) fitted into the evaporator coil, which works well to maintain whatever temperature you choose for your space.


  • Has an active carbon filter for odor control
  • Auto restarts in case of power surges
  • 16ft installation kit included during purchase
  • Remote controlled
  • 1-year warranty
  • ETL approved
  • Operates quietly


  • Getting a hold of tech support is hard sometimes

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