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Sizing Guide for a Mini Split Air Conditioner

Sizing Guide for a Mini Split Air Conditioner

Jon Hubal
5 minute read

So you want to go ductless, realizing a mini-split will solve all your climate control needs – but now you have to figure out how to size your mini-split sizing.

Have no fear. Sizing the correct unit is simple. Our mini split sizing calculator and mini spit sizing chart will help guide you to the correct mini split size for your home.

Mini-Split Sizing Calculator

Leverage our mini-split sizing calculator to size your ductless system, whether you need a mini-split for a single room or multiple rooms.

In the case of multi-room setups, just tap on "Save Room." If you need to delete a room, simply hit the delete button next to the room name. Should you have a more intricate arrangement and need sizing guidance, don't hesitate to contact us at

Cooling BTU's Required:
0 Btu
Heating BTU's Required:
0 Btu
Recommended Unit: 0 BTU

Saved Rooms:

The Basics of Mini Split Sizing

Ductless minis are known for their efficiency, but only if you size the suitable unit for the space required. Sizing the right mini is the most critical part of installing one.

Avoiding Oversized or Undersized Units

Bigger isn't always better. If your mini system is oversized, you'll waste money on an unnecessarily large unit and risk high utility bills. Overpowered units suffer from short cycling, quickly turning on and off, using more energy, and wearing faster over time. 

If your system is undersized and can't effectively condition the space, that's a big issue. They'll work much longer and harder than they should, and like oversized units, they become incredibly inefficient and wear much quicker. 

Let's start by understanding how units are measured in HVAC.

How to Size a Mini Split System

The size of a system refers to how much heating or cooling it can provide every hour. Conventionally used for heat, BTU (British Thermal Units) is the standard measurement of temperature in the industry. In technical terms, it measures the energy required to change one pound of water by one degree Fahrenheit. In layman's terms, it measures how much energy your air conditioner uses to add or remove heat from your home.

You must determine how many BTUs you need per hour – or BTU/hr. 

Mini Split Sizing

Calculating Mini Split Size: Measuring Your Space for Accurate Sizing

How you get, there is by figuring out the size of the space you need to control. This means measuring the area of all the rooms you want conditioning. Achieve this by multiplying the length of the individual room by the width.

This will give you the square foot area – or sqft, the standard measure used for ductless system sizing.

If you have uniquely sized rooms or desire to be as efficient as possible, calculating the square foot area with the room height (sqft x room height) can provide a more accurate estimate for your actual energy needs. 

Buck Cool Mini-Split EZ Connect 24K BTU Complete Installation Kit

Buck Cool Mini-Split EZ Connect 24K BTU Complete Installation Kit


Buck Cool Mini-Split EZ Connect 24K BTU Complete Installation Kit The Buck Cool Mini-Split EZ Connect Complete Kits are designed to offer a simple solution for your heating and cooling needs. The pre-charged EZ Connect line sets allow for a… read more

Sizing Your Ductless Mini-Split

The total area you want to condition (sqft) determines the required heat output (BTU/hr), determining the unit size you need. 

The total area is the square feet of all the rooms added together. You need the total because this is how much energy the outdoor condenser unit will need to sufficiently service all your areas.

Using Sizing Calculators for Mini Split Systems

Once you have your total square footage, using a sizing calculator is the easiest way to do this. Licensed technicians have already done much of the math for you – why not take advantage!

There are simple charts that take just your square feet and tell you what BTU/hr you need, providing a quick and relatively accurate assessment (seen below). More in-depth calculators that consider region and other factors for an even closer estimate. 

Mini Split Sizing Chart

mini split sizing chart

Sizing Mini Split System

Though it may sound daunting, sizing a ductless HVAC system is much easier than you think. With fairly simple calculations, there is not much math involved, and there are plenty of useful charts and calculators designed by certified pros to help you along the way. 

Follow this guide, and you'll have the perfect system for the perfect home! We've also made it easy to find the mini split you need now that you've figured out the size you need by adding categories like 2-ton mini split, 36K BTU mini split, mini split for 1500 sq ft, and more.

MRCOOL E Star DIY 4th Gen 24k BTU Ductless Mini-Split Heat Pump Complete System - 208-230V/60Hz

MRCOOL E Star DIY 4th Gen 24k BTU Ductless Mini-Split Heat Pump Complete System - 208-230V/60Hz


DIY 4th Generation E Star 24k BTU Ductless Mini-Split Heat Pump Complete System 208-230V/60Hz The MrCool 4th Generation DIY 24K BTU, 20.5 SEER Ductless Heat Pump is an all-in-one system that seamlessly combines efficiency, durability, and simplicity. This system can… read more

Interested in Learning More About Mini-Splits?

To further expand your knowledge about mini-splits, be sure to check out our other related blog posts. We have articles that cover topics such as the benefits of mini-splits, how to properly maintain them, and their energy efficiency compared to traditional HVAC systems. Read more about the Best Mini Splits 2023: The Ultimate GuideMini-Splits Increase Your Home's Value. and an Installation Guide on Where to Install Your Mini Split.

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