A mini-split allows for zoned cooling, helpful for cooling spaces like garages. Learn the cost to install a mini-split unit in a garage with this guide.
What Size Mini-Split Do I Need? How to Calculate
Get quotes from heating and air conditioning pros near you
No obligation · 100% free
Get quotes from heating and air conditioning pros near you
No obligation · 100% free
Need Help With a Project? Connect With a Pro
The mini split size you need depends on your room's square footage, calculated by multiplying length times width to determine the right BTU output.
Expect to pay $2,000 to $14,000 for professional mini split installation, with costs varying based on the number of zones and your home's setup.
Calculate your BTU requirements by multiplying your square footage by 25, ensuring your mini split system provides adequate cooling without wasting energy.
Hiring a local HVAC company keeps installation simple and accurate, matching the right unit to your space and handling electrical work safely.
Get quotes from up to 5 pros!
Enter a zip below and get matched to top-rated pros near you.
Picking the right mini-split size is essential for efficiency, comfort, and cost savings. A unit that’s too small won’t cool effectively, while an oversized unit can waste energy and cycle on and off too frequently. To get that perfect level of comfort, you’ll need to do a little math—but don’t worry, no geometry degree is necessary for this project. It all starts with your room's square footage and ends with finding the perfect number of British Thermal Units (BTUs) to keep things cool. Let’s take a deeper dive.
Mini-Split Sizes Based on Square Footage
When it comes to cooling a room, size matters—in this case, it’s all about the square footage. Pick a mini-split unit with too few BTUs, and your system will be working overtime just to keep up. Go too big, and you'll waste energy (and money) faster than you can say “climate control.” The chart below shows the sweet spot for your space—so that comfort isn’t a guessing game.
| Square Footage | Recommended BTUs |
|---|---|
| 100-150 | 5,000-6,000 |
| 150-250 | 6,000-9,000 |
| 250-350 | 9,000-12,000 |
| 350-450 | 12,000-15,000 |
| 450-600 | 15,000-18,000 |
Calculating Mini-Split Sizes
Using your square footage measurements, apply the following formula to determine how many BTUs your mini-split needs:
BTUs = Square Footage x 25
How to Measure Square Footage
Before selecting the perfect mini-split, you’ll need to determine your space’s square footage. Luckily, it’s easier than it sounds: just grab a tape measure, measure the length and width of the room, multiply the two, and there you have it—your square footage.
Length × Width = Square Footage
For oddly shaped rooms, break the space into squares or rectangles, calculate the square footage of each individual shape, and then add them all up.
Who to Hire to Install a Mini-Split
Tomasz Zajda/ Adobe Stock
Once you do the heavy lifting of determining what size mini-split you need, stop there—now’s the time to hire your local HVAC professional to install the unit for you. Although experienced DIYers can likely handle smaller installations, it’s best to leave this job to an expert who can have your new mini-split up and running in no time. This way, you won’t break a sweat and can instead enjoy the cool reward once the unit’s installed.
Frequently Asked Questions
Heating and air conditioning services reviews from real Angi homeowners in Columbus, OH
4.5★ avg. • 115 total reviews
- Carol M.
I have used Columbus Worthington Air for years and recommend them whenever I have a chance. The staff is quick, courteous, and well-trained.
ARS Columbus Worthington Air - Dawn G.
This service was great. My air conditioner went out during the heat spell that we had. My husband has health issues and they came out that night and at 9:30pm the air conditioner was fixed and running. We are sooo very thankful, this is the company I will be using from now on and would...
Mr. Mechanical Ohio - Peggy B.
I recently moved to another state and chose United Trust Van Lines after comparing several companies. Their team was punctual, professional, and extremely careful with my belongings. I was especially impressed with how they handled my home office setup and fragile items. Everything arrived on...
United Trust Van Lines, LLC - Jeanann S.
Very professional, knowledgeable and helpful! Completed the install on time and as expected.
Ward's Services - Adam E.
Cole has been handling plumbing and general contracting for our four properties over the past three years, and he’s always done a great job. Most recently, he installed a sink and countertop in our retail store where none existed before, and it turned out exactly how we needed. He’s...
ANB Renovations LLC - Tom T.
We have bought and sold numerous times over the past 50 years. Sherman Hall and Top Line are top notch. Thorough and detailed, he explains every possibility, probability, and eventuality. High class and pleasant. The best.
Top Line Home Inspections, LLC - Aaron G.
Very easy to talk to, helped me enormously and will be back for more projects I have. Quick and knowledgeable, very professional and a high quality personality!
Elwood's Mobile Welding - Stacy S.
Couldn't ask for a better company. Josh and Dee were Very professional, efficient, courteous and takes major pride in their work. They will travel to come to your home and will still give you a fair price. They are honest and trust worthy. Their focus is on their work and their work is...
Supreme brick & chimney - Carl D.
I had a tight deadline for a commercial painting project, and Custom Paint Jobs LLC delivered on time and within budget. Their efficiency and quality are top-notch.
Custom Paint Jobs, LLC - Kellyn D.
Koby and Kyle are amazing!! They were super fast and friendly, highly recommen!
All My Sons Moving & Storage
The homeowners guide to heating and air conditioning services
From average costs to expert advice, get all the answers you need to get your job done.
When your window AC isn’t cutting it, but central AC is too expensive, installing a new ductless mini-split AC may be the cooling solution you’re looking for. Find out what a mini-split costs and how to hire the right pros to get the job done.
Looking for a new mini-split air conditioning system? Use this guide to mini-split sizes to see how many BTUs you’ll need to heat or cool your home.
A ductless mini-split heat pump can cool and heat your home without all of the costly and complicated ductwork. Learn more about how a mini-split works.
Mini split systems are an energy-efficient option to regulate your house’s temperature. Learn more about how mini splits work to cool or heat your home.
Keep your AC running smoothly with this mini-split maintenance checklist.