Ductless Mini-Split or A Window Unit: What's Best for You?

Key Points

• Window unit air conditioners are a cooling solution for a single room. Window units are renter-friendly, boasting a design that’s easy to install and move between rooms.
• Ductless mini splits are a permanent climate control solution often used in a single room, though some have the capacity to support multiple zones.
• Both window units and mini splits are great options for supplemental temperature control in tandem with a central system, or as a standalone system.
• Heat pumps provide both heating and cooling performance, where window unit ACs only offer cooling relief in hot conditions.

At the end of the day, convenience and comfort truly reign supreme. If you’re not sold on that idea, just look at the number of homeowners snatching up window units and mini splits. The sales volume alone showcases these factors as top priorities. Being able to adjust your climate control without leaving the couch is an unmatched advantage in tailoring your indoor ambiance. Both window units and mini splits are solutions designed to support a single room, meaning you can crank the dial down for a movie marathon without freezing out the rest of your family. Since both of these options are easier to install than a full central system and cater to your temperature preferences, the hardest part of the process is deciding which HVAC unit is right for you. With IWAE giving you the down-low on both of these options, you can choose a system that suits your needs with ease.

What is a Mini Split?

Ductless mini split systems are a zoned climate control solution that typically consists of two parts: an exterior condenser and a single interior air handler connected by a line set. More often than not, mini split systems integrate an outdoor heat pump for the condenser. If you’re unsure how a heat pump works, the long and short is that they remove heat from inside to cool the space during summer and supply heat to keep you warm during winter. Some mini splits support multiple air handlers with a single condenser, extending your customized climate control to multiple rooms. Since mini splits tend to be highly efficient, more homeowners have been turning to these systems as a whole-home comfort solution, rather than just as a supplemental option for a single room.

For more information on what mini split system is right for your needs, check out our Ductless Mini Split Heat Pump Buying Guide.

Pros & Cons of Mini Splits

• Pro: Your installation options are not limited to locations with a window since air handler options for mini splits are often mounted to the wall or nestled between ceiling joists.
• Pro: Since most mini splits are heat pump systems, you have heating and cooling capabilities from a single outdoor unit.
• Con: The line set will have to travel through the wall to connect the internal and external hardware, so you or a licensed professional will have to drill a hole in your home. This factor makes mini splits a more permanent and less renter-friendly, solution for climate control than window units.

What is a Window Unit?

Window units are a common cooling and heating unit in homes, apartments, and all kinds of residences. Window units are usually a large box-shaped unit that is installed in a window. Older window units eliminate the ability to use the window where they’re installed, though newer options tend to be less intrusive and allow you to open the window without removing the unit. Window units get a bad rap for being inefficient, a reputation that has become less and less accurate over time. Many window units have progressed to the point of efficiency that their integration can actually lower your overall energy costs. Efficiency for almost every other heat pump and AC system is measured in SEER, but window units tend to list their efficiency by their EER rating. Remember: just like SEER, a higher EER rating is more efficient.

Pros & Cons of Window Units

• Pro: Window units are affordable, easy to install, and readily available at most places that sell HVAC hardware. In most instances, you can purchase a window unit and have it set up the same day.
• Pro: Window units offer quicker relief in uncomfortable environments, though they are generally less efficient than mini splits.
• Pro: Window units are easy to install and take down without major changes to the space, making them a rent-friendly option.
• Con: There are window units that heat, but air conditioning only window units are the standard. Heat pump window units do exist, working similarly to mini split heat pumps without the need to drill through the wall.

Important Features to Consider

There are many factors to consider when purchasing new HVAC hardware, whether you’re buying a whole-home solution or a way to keep a single room comfortable. If you're looking for a single-room system, you probably want something that can provide fast results. To make your decision count, choose a system with features that will tailor your comfort to you. Here are a few things to keep in mind when comparing a window unit and a mini split for your home:

• A standard feature with most mini splits that adds a new level of convenience is the ability to connect to the unit and control it with a smartphone app. This option lets you adjust the temperature without searching for the remote or leaving the couch. This app integration provides a means to track a mini split unit's energy usage, set a schedule for your unit, and access a variety of other functions. Newer window units can often support a similar app integration, though many units must be manually operated.
• You'll want a system that has an Eco mode or energy-saving feature if you want to save money and reduce your footprint. Since mini splits are already more energy efficient, systems with these options boost efficiency levels even more by lowering output and decreasing energy use. Window units without this type of inclusion can lead to increased energy bills after a few months of use.
• Some systems include a quiet mode or sleep mode that ensures operation won't affect your sleep. These settings shut off any noises the unit might make and turn off any display lights. Quiet or sleep mode features will vary by system, but they often bolster energy savings by slowly raising the set-point in summer and lowering it in winter during the night while you’re asleep to conserve energy while maintaining comfort. These settings then restore your chosen settings at your wake-up time.

No two mini splits or window units are exactly alike, so checking for features you want in product brochures to choose a system is the best way to find a good fit. While both types of systems can include any of the features listed above, mini splits and window units have many differences that may be the deciding factor in which works for your situation:

• Installation: You can install most window units by yourself, but many mini splits require you to hire an HVAC contractor for setup. This isn't true in every case, though, as MrCool offers a variety of DIY ductless mini split heat pumps that can be self-installed. The line set used with the DIY series is pre-charged and equipped with Quick Connect fittings, eliminating the need for any special tools to handle installation steps like vacuuming. Most window units can simply be plugged into a nearby outlet, whereas mini splits often need to be hardwired to a disconnect box.
• Removal: A mini split is designed to stay where it’s installed. An HVAC professional may be able to help you move it, but that can quickly become a complex and costly process. With window units, you install and uninstall the hardware as many times as you want for additional flexibility. Many people are fans of the “set it and forget it” mindset with HVAC, though some enjoy the freedom of moving their AC around the house with them.
• Size: Window units tend to be around the same size since they are all designed to fit in a standard window. The air handler in a mini split system is typically larger than a window unit, the most common handlers being wall-mounted units that are around 3 feet long. Some mini split systems have air handler options that are less intrusive, like ceiling cassettes and concealed ducts. Keep in mind that, as the heating and cooling capacity of the system increases, the size of the air handler is likely to increase as well.

What Size Should I Get?

Deciding on the specific size of your unit once you know which type of system you’d like should be the easy part. The only way to truly guarantee you’re choosing the right size system for your space is for an HVAC tech to perform a Manual J load calculation. Some of the details that influence how big a unit you need are:

• The square footage of the room where you want the unit installed
• The climate in your area, particularly if you deal with harsh seasonal temperatures
• The insulation quality of your home (check out our How to Winterize Your Home article for tips and tricks to better seal your home)
• The height of your ceilings
• How many people reside in your home

Both window units and ductless mini splits are usually sized in terms of BTUs, rather than tons. The most common sizes for mini splits are 9k BTUs, 12k BTUs, 18k BTUs, 24k BTUs, and 36k BTUs, though there are some larger options used in multi-zone systems that are listed in the 40k-55k BTU range. The smallest mini split systems we offer currently are listed at 9k BTU. Window units have a bit more variance in sizing, though the most common units roughly align with mini split options. Below is a guide on basic sizes for both systems. While this list is not a definitive guide, it's a helpful tool to use as a starting point when picking a new system:

• 6k BTU: 100-300 square feet
• 8k BTU: 350 square feet
• 9k BTU: 375 square feet
• 10k BTU: 450 square feet
• 12k BTU: 500 square feet
• 18k BTU: 750 square feet
• 24k BTU: 1000 square feet
• 36k BTU: 1500 square feet
• 48k BTU: 2000-2400 square feet

Should I Get a Window Unit or a Ductless Mini Split?

Let’s do a quick comparison of the 20k BTU AC Window Unit from Friedrich Kuhl and the 18k BTU Olympus Ductless Heat Pump Mini Split from MrCool:

*these values reflect the price at the time this article was written, 4/3/2026
**price is determined by which air handler is chosen when purchasing the bundle

When you look at these two units side by side, it’s easy to see why ductless mini splits have the edge on window units bang for buck. For a similar price and matching coverage area, the MrCool mini split heat pump gives you a better warranty and comprehensive climate control capabilities, not just cooling. The MrCool system uses a modern, energy-efficient refrigerant, helping the system earn an EER2 rating more than two points higher than Friedrich Kuhl’s window unit AC.

IWAE's Favorite Mini Splits

In this day and age, we tend to suggest a mini split for most scenarios. If you’re looking to set up a system yourself, the MrCool DIY series we mentioned earlier in the article can’t be beat. With options that range from one to six zones, you can tailor a single room or your entire home with unique temperatures that leave everyone satisfied. For an entry-level ductless heat pump, Trane’s RunTru ductless mini splits and Daikin’s Entra series have a budget-friendly price point and high SEER2 ratings.

Tailor Your Indoor Temperatures with IWAE

Now that you’ve had a peek behind the HVAC curtain, it shouldn’t be a tough task to see the different use cases for both mini splits and window units. Window units are more of a one-trick pony, whereas mini split systems are crafted to level up your temperature regulation from every angle. If you’re still on the fence about which type of system is best for your use case, reach out to the customer service experts at IWAE. We’ll walk you through the potential solutions for your unique needs so you can be confident in your climate control choice.