5 Smallest Mini Split Air Conditioners (Under 450 Sq Ft, 9,000 BTU)

Small mini split air conditioners are incredibly popular. With the new below 10,000 BTU mini splits, we now have the capability to cool small, medium-sized, and big rooms.

Here’s the deal about the smallest mini split air conditioners:

Nowadays, everybody wants a mini split. That’s quite understandable. Mini split AC units are very reliable, extremely energy efficient (18+ SEER rating), very quiet (compressor is in the outdoor unit) and have a very low running cost likely saving you up to $100/season in electricity cost. All HVAC experts recommend it primarily due to high SEER ratings.

Up until quite recently, most mini splits were big. We’re talking 2-ton (24,000 BTU), 3-ton, and up to 6-ton unit (72,000 BTU). The new small inverter mini split compressors and air handlers, however, have enabled us to make very small mini split air conditioners.

In fact, these below 1-ton mini splits are small enough to be used as a room air conditioner. Most of the smallest split system air conditioners have the only 3/4-ton capacity (that’s 9000 BTU ASHRAE capacity). The single smallest Mitsubishi mini split has an unbelievable only 1/2-ton or 6,000 BTU/h capacity. Having a half-ton mini split is a wonderful example of AC engineering.

To help you out pick the best small mini split air conditioner for small rooms (as well as standard and bigger rooms), LearnMetrics has complied a list of the best small below 10,000 BTU ductless mini split AC units on the market.

You can check the list, complete with the spec-by-spec comparison table (we compare capacity, room coverage, SEER, HSPF rating, as well as brand reputation) and individual reviews of every selected small mini split air conditioner here:

Skip To List Of 5 Smallest Mini Splits

Before we look at these room mini split air conditioners, however, let’s go quickly through the specs. This will help you understand what size mini split AC unit you need, how SEER and HSPF rating lower running costs, and which brand makes the best small mini split air conditioners:

What Size Mini Split AC Do I Need For A Room? (BTU And Room Coverage)

In the past, you could only use mini splits to cool 2 or more rooms. With these new small ductless mini split AC units, you can just install a unit to cool (and heat) 1 room. Of course, that doesn’t mean that even a small mini split can’t provide adequate cooling for 2 or even 3 small rooms.

The basic rule of thumb the Department of Energy (DOE) gives for mini split AC sizing is this:

20 BTU per 1 sq ft of living space.

This is a general rule that doesn’t account for ceiling height, location, or insulation, but it works surprisingly well when you have to size a small mini split AC.

Here’s how it works:

Let’s say you have a 20×20 room and would like to use a ductless mini split AC to cool it. How many BTU mini split you need for adequate cooling?

20×20 room has a total square footage of 400 sq ft. To get the BTU cooling output you need from the mini split, you have to multiply the square footage by 20 like this:

20×20 Room Mini Split Size = 400 Sq Ft × 20 BTU/Sq Ft = 8,000 BTU

That means you would need an 8,000 BTU mini split for a 20×20 room, or thereabout.

As you will see in the comparison of the best small mini-split AC units below, most of these units are capable of producing 9,000 BTU of cooling output. That means they can, according to this DOE’s rule of thumb, adequately cool areas with up to 450 sq ft.

The incredibly small #1 Mitsubishi mini split has a record-low 6,000 BTU cooling capacity. That means that it has sufficient cooling output to adequately cool spaces up to 300 sq ft.

Of course, if you’re looking to cool a 500+ sq ft area, you would need a bigger 10,000+ BTU mini split (after 9,000 BTU, the next capacity class is 12,000 BTU; those are the 1-ton mini splits).

Note: It’s vital you don’t oversize the air conditioner. Getting an AC unit that’s too big for the space will inevitably lead to AC short cycling, wearing down quickly, and skyrocketing the electricity bill. That’s why the small mini split AC units are so useful; it’s almost impossible to oversize an AC if you pick one of the smallest mini splits.

Small Mini Split SEER Rating (Cooling Energy Efficiency)

If you’ve heard one thing about mini split AC units is this:

“Mini splits are incredibly energy efficient. The electricity costs for cooling will be slashed on your first bill. You won’t believe it.”

This is obviously true even for small mini split AC units. The reason for such a high energy efficiency is easy to see. Mini splits basically work as heat pumps; they gather the available cool air from outdoors (they can utilize even incredibly hot 120°F+ air and gather coolness) and bring it indoors.

That means they don’t have to ‘create’ cool air. Mini split use the refrigerant-cycle based system to transfer cool air indoors in the summer and warm air in the winter.

We express the energy efficient of small mini split ACs with the SEER rating. SEER stands for Seasonal Energy Efficiency Ratio, and it’s defined as a specified weighted ratio of EER ratings at different AC loads (namely, EER_25%, EER_50%, EER_75%, EER_100%).

Here’s what you need to know about mini split energy efficiency:

A higher SEER rating means higher energy efficiency. This equates to lower running costs and lower electricity bill for cooling.

It is federally mandated that all air conditioners achieve at least 14 SEER rating. Mini split AC units, even the smaller ones, surpass that requirement by a large margin. Most mini splits have at least 16 SEER. Energy efficient mini splits can achieve a SEER rating of 18, or maybe even 20. If you check the comparison table below, you can see that the #1 Mitsubishi small 6,000 BTU unit hits it out of the park with an unbelievable 33.1 SEER rating.

Here’s how much you can save with a higher SEER small mini split AC:

Let’s say that a standard 14 SEER unit costs $100 to run per month. 18 SEER unit is 28% more energy efficient. That means that an 18 SEER unit will have a running cost of $72 versus the $100 running cost of a 14 SEER unit.

Here’s the bottom line:

It pays to pick a highly energy efficient AC. Even in the case of small split system air conditioners that use, due to their smaller BTU capacity, a minimal amount of electricity, higher SEER rating can save you more than $100 per season. In 20 years, that’s $2,000+ savings just due to a high 16+ SEER rating.

Small Mini Split HSPF Rating (Heating Energy Efficiency)

With mini splits, we are primarily looking for a mini split air conditioner.

Almost all small mini split air conditioners, however, are capable of heating as well. Mind you, these are the smallest heat pumps we know; their primary purpose is to transfer heat. That’s why small mini splits can be used as heating and cooling units for small rooms.

In the winter, you just flip a switch, the refrigerant cycle is reversed (refrigerant just flows in the reverse direction), and instead of cooling, you get heating. Because this heating function is useful to most homeowners and it’s dead easy to implement even in the smallest mini split, you will also find another energy efficiency rating on the specs sheets:

HSPF rating.

This rating denotes how energy efficient a small mini split is at heating (in the winter). HSPF stands for Heating Seasonal Performance Factor and is in the same metric category as the SEER rating. The difference is that the SEER is for cooling efficiency and HSPF is for heating efficiency.

The same rules apply here as well:

The higher the HSPF rating, the more efficient heating you will enjoy from your small mini split. That’s why it obviously makes sense to invest in a high HSPF small mini split unit.

What Is The Best Brand For Small Mini Splits?

The brand is important. According to the HVAC statistical survey, the overwhelming 38% of homeowners said that systems reliability is the most important factor when choosing an air conditioner.

The best way to guarantee a small mini split will be reliable is to pick a well-known brand with a superb track record.

As far as the smallest mini split AC units are concerned, you have two big brands that make these small units: Mitsubishi and MrCool. Bigger and affordable brands include Cooper & Hunter and Senville, as you can see from the comparison table below.

Smaller lesser-known brands like DELLA might have questionable reliability because they lack the decades-long track-record brand like Mitsubishi has. Nonetheless, they usually offer small mini split air conditioners at a lower price and can have some extra features (because they want to offer something extra to the consumer, knowing they have to bridge their lack of brand awareness).

With all this in mind, let’s look at the smallest mini split air conditioners on the market:

5 Smallest Split System Air Conditioners

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1. Smallest Mini Split AC On The Market: Mitsubishi ‎MZ-FS06NA 6k

Mitsubishi ‎MZ-FS06NA is an incredible engineering achievement by itself (in more than 1 way). First of all, this is the world’s smallest mini split air conditioner (6,000 BTU or 1/2 ton). Secondly, with a 33.1 SEER rating, this is also the most energy efficient small mini split AC unit; it leaves most other mini splits, even the bigger ones, in the dust.

Most other companies used their engineering expertise to produce the small 9,000 BTU mini splits. This seems like an impossible task only a few years ago. Mitsubishi, on the other hand, went the extra mile even in this: they have created the world’s smallest mini split with only 6,000 BTU cooling output. We’re talking a 1/2 ton mini split.

With 6,000 BTU, you can adequately cool down rooms up to 300 sq ft. This is the perfect mini split for small rooms.

What’s even more impressive is the SEER rating. Mitsubishi ‎MZ-FS06NA has a 33.1 SEER rating. For comparison, the federal minimum standard is 14 SEER rating and most of the small mini splits have a 16-18 SEER rating. Mitsubishi ‎MZ-FS06NA is about 50% more energy efficient than most mini splits. That means that you will see a 50% reduction in running cost if compared to other mini splits.

On top of that, it also has a record-setting 13.5 HSPF rating for heating. Hyper Heat functionality will allow the Mitsubishi ‎MZ-FS06NA to work at considerable performance even at -13°F. Low temperatures are usually the bane for mini splits and heating output; not for Mitsubishi ‎MZ-FS06NA.

Mitsubishi overall is one of the best and most reliable brands for small mini splits.

The drawback of the Mitsubishi ‎MZ-FS06NA is apparent as well. It’s the price. Yes, it’s a conveniently small mini split, has the minimum possible running costs, but it also costs almost $3,000. In comparison, other small 9,000 BTU mini splits cost less than $1,000.

All in all, the Mitsubishi ‎MZ-FS06NA is the world’s best small mini split air conditioner. It has record-breaking low BTU output, highest SEER and HSPF rating, and is made by Mitsubishi. If you can handle the higher upfront cost, this is the engineering wonder you want:

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2. Smallest Mr Cool Mini Split AC: MrCool Advantage 9k

MrCool Advantage 9k is one of the most popular small mini split air conditioners. This is a 9,000 BTU mini split that can handle areas up to 450 sq ft.

The key advantage of MrCool Advantage 9k  is the low ambient cooling. With 9,000 BTU cooling output, the MrCool Advantage 9k has the capability to decrease the room temperature down to 5°F. That’s something most other small mini splits simply can’t do.

With a 19 SEER rating, this unit also has a very high cooling energy efficiency. 10 HSPF rating will also ensure that the heating costs associated with running the small 9,000 mini split will be very low.

In short, MrCool Advantage 9k is the most popular small mini split for a good reason. It can adequately cool small rooms, it’s easy to install, very energy efficient and available for less than $1,000:

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3. Very Small Ductless Mini Split Unit: Cooper & Hunter 9k

Cooper & Hunter 9k is another top-rated small mini split AC unit. This is one of the quietest small units; with an indoor air handler producing less than 48 dB noise levels.

This unit also has a 3/4 ton capacity (9,000 BTU). That means that can provide adequate cooling in the summer and heating in the winter for spaces up to 450 sq ft. With low noise levels, this is a perfect small ductless mini split for the bedroom.

Energy efficiency-wise, the Cooper & Hunter 9k has a 19 SEER rating and 10 HSPF rating. This is the above-average energy efficient most of the best small mini splits have.

With the Cooper & Hunter 9k, you get a 16 ft copper line. You can install this mini split through the bedroom wall. On the outdoor size, you have the outdoor unit with the compressor (compressor is the primary source of noise). Indoors you install an air handler that’s remarkably silent. It also runs on 110V voltage.

Cooper & Hunter has quite a good reputation. With below $1,000 price tag, the Cooper & Hunter 9k is a solid choice for a small 9,000 BTU mini split:

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4. Smallest Senville Split System AC: Senville LETO 9k

Senville LETO 9k is one of the cheapest small mini split air conditioners. With about a $750 price tag, it is priced similarly to top portable air conditioners and window air conditioners. Of course, this small mini split has all the advantages all mini splits have.

That means it’s a quiet and energy efficient unit. Despite the low price, the Senville LETO 9k still has a high 19 SEER rating for cooling season and a 10 HSPF rating for the heating season.

This is a 9,000 BTU mini split with up to 450 sq ft coverage. That will be enough to provide sufficient cooling (and heating) to small, medium-sized, and even bigger up to 22×22 rooms.

It is also worth mentioning that every small mini split provides a dehumidification function. It basically works as a dehumidifier.

All in all, if you’re looking for a cheap mini split for small, medium-sized or even bigger rooms, the Senville LETO 9k is a good and reliable choice:

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5. Small Cheap Mini Split Air Conditioner Unit: DELLA 9k

DELLA is a relatively new brand. They have engineered their own version of the smallest mini split AC; the DELLA 9k unit. What is surprising here is that DELLA 9k has an above-average 20 SEER rating and is about 6-7% more energy efficient than the 18 SEER rated mini splits.

That’s the cooling part. Where DELLA falls short is the heating part. With an 8 HSPF rating, it is 20% less energy efficient than the 10 HSPF units we have seen so far.

The maximum cooling capacity DELLA can achieve is 9,000 BTU. Thus it is counted among small ductless mini split AC units.

Nonetheless, with the newer brand, you have to think long and hard about reliability. DELLA units seem to be performing well but we don’t have data about how reliable they are in a 20-year lifespan.

All in all, DELLA 9k is another good example of a very small mini split AC unit with up to 450 sq ft and available for less than $1000:

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This has been an insight into these new engineering wonders; below 1-ton mini splits. If you have any questions regarding these units, you can pose a question in the comments below and we’ll try to help you out.