Calculators / Heating and cooling
What size mini split do I need for my garage?
Measure the floor and the ceiling, then tell us how well it's insulated. You'll get the single-zone size to buy, already bumped up for a garage.
Updated · How we check our numbers
Buy this size
24,000 BTU mini-split
That's 2 tons. It covers 576 sq ft with a 9 ft ceiling, sized up for your garage.
- Floor
- 576 sq ft
- Load
- 15,400 BTU
- Ceiling
- 9 ft
- Unit
- 24,000 BTU
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Estimate for planning only, not professional advice. Check the manufacturer’s instructions, your local code and a licensed professional before you buy, build or install. Use at your own risk. Terms.
floor = 24 x 24 ft = 576 sq ft
chart = 14,000 BTU at an 8 ft ceiling
sun = no change
ceiling = +10% for 1 ft over 8 ft
load = 15,400 BTU
smallest unit that covers it = 18,000 BTU
size up 1 step for insulation
Too big a unit cools fast, shuts off and never pulls the humidity out. Go one step up only for the reasons above.
How we work it out
We start with the ENERGY STAR room sizing chart, which goes by square feet and assumes an 8 ft ceiling. Then we adjust it for your garage.
load = chart BTU × sun (0.9 shaded, 1.1 sunny) × (1 + 0.1 per ft of ceiling over 8 ft)
unit = the smallest size that covers the load, then up one size for poor insulation and one for a hot, humid climate
Sizes run 9,000, 12,000, 18,000, 24,000, 30,000 and 36,000 BTU. That's 0.75 to 3 tons. Past 36,000 you're into two heads or a multi-zone system.
A garage loses more heat than a bedroom. The big door is the weak spot, and most of them have little or no insulation. That's why Pioneer and MRCOOL both say to size up for a garage. If your door is bare, insulating it does more than buying a bigger unit.
This is a rule of thumb. For a shop you heat all winter in a cold state, an HVAC contractor's Manual J load calc is the real answer.
Where the numbers come from
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Heating and cooling
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