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Mini Split Sizing Calculator

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

To use the calculator, first enter your room name, then select room height, and then enter the width, length, number of windows, and number of occupants.

Then, select your climate zone using our climate zone chart below the calculator. Lastly, select your home's insulation state and the room location. Now you're ready to hit "Calculate BTU"!

In the case of multi-room setups, tap on "Add Room." The added room will be added below the climate region chart. You can delete the room using the "Delete Room" button.

Should you have a more intricate arrangement and need sizing guidance, please get in touch with us at or 256-633-6553.

Cooling BTU's Required:
0 Btu
Heating BTU's Required:
0 Btu
Recommended Unit: 0 BTU
The Trade Table Mini Split Calculator

Added Rooms:

Mini Split Sizing Calculator Chart

BTU Capability                 Square Feet

6,000 BTUs                                                                                  Up to 260 sq ft

9,000 BTUs                                                                                  240 - 390 sq ft

12,000 BTUs                                                                                360 - 500 sq ft

15,000 BTUs                                                                                480 - 620 sq ft

18,000 BTUs                                                                                600 - 750 sq ft

24,000 BTUs                                                                             720 - 1,000 sq ft

30,000 BTUs                                                                             960 - 1,240 sq ft

36,000 BTUs                                                                          1,200 - 1,500 sq ft

42,000 BTUs                                                                          1,440 - 1,740 sq ft

48,000 BTUs                                                                          1,680 - 2,000 sq ft

54,000 BTUs                                                                          1,920 - 2,240 sq ft

60,000 BTUs                                                                          2,160 - 2,600 sq ft

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How Do I Calculate What Size Mini Split I Need?

To determine the right size for your mini split system, calculate the room's square footage by multiplying its length by width. Generally, you'll need about 20 BTUs for each square foot. However, adjust this figure based on specific room characteristics, like the quality of insulation, amount of natural light, and how the room is used. For instance, kitchens or crowded spaces may need a higher BTU count. Also, consider increasing BTUs for rooms with ceilings taller than 8 feet or decreasing for heavily shaded rooms. It's advisable to seek advice from HVAC experts for an accurate assessment, ensuring you select a mini split that efficiently and effectively heats or cools your space without leading to energy wastage or inadequacy.

 Is it OK to Slightly Oversize Mini Split?

Opting for a mini-split system that's larger than your calculated needs is generally fine. A slightly oversized unit can offer quicker temperature adjustments and operate more efficiently at lower settings, extending its lifespan. Yet, it's important to stay within the bounds of oversizing, as a unit that's much larger than necessary can lead to frequent on-off cycles, inadequate air dehumidification, higher energy usage, and increased upfront costs. Therefore, while a modestly larger mini-split can have benefits, excessively large units should be avoided.

What is The Rule of Thumb for Mini-Split Sizing?

A standard guideline for determining the size of a mini-split system is to estimate around 20 BTUs per square foot of the area you intend to condition. For example, a 500-square-foot room would generally require a mini-split with a capacity of 10,000 BTUs. This basic rule should be tailored to various factors, such as the quality of room insulation, the height of the ceilings, the level of sunlight exposure, and how many people typically use the space. Rooms with specific uses, like kitchens or those frequently occupied by many people, may need a higher BTU capacity.

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