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What size mini split do I need?
Measure the room. The size comes straight from ENERGY STAR's published sizing chart, not a guess, and you see the real units built in that size.
Units in this size
Every number comes from the maker's own spec sheet or the AHRI directory. If a maker doesn't publish a number, it says so instead of guessing.
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Where the numbers come from
The size comes from ENERGY STAR's room air conditioner sizing chart. Find the row for the room's square footage, then adjust:
- Heavily shaded room: reduce capacity by 10 percent.
- Very sunny room: increase capacity by 10 percent.
- More than two people regularly in the room: add 600 BTU for each extra person.
- A kitchen: add 4,000 BTU.
The chart's capacities are calculated for an 8-foot ceiling. The tool then picks the smallest mini split size that covers the result, because ENERGY STAR warns that bigger is not better: an oversized unit costs more, wastes energy, and cools the room before it removes the humidity.
Source: ENERGY STAR, Room Air Conditioners: find the correct cooling capacity. Retrieved October 30, 2026.
Questions
How many BTU per square foot does a mini split need?
There's no single number. The chart steps up by room size: 6,000 BTU for 150 up to 250 sq ft, 12,000 BTU for 450 up to 550 sq ft, and 18,000 BTU for 700 up to 1,000 sq ft. Then sun, people and kitchens adjust it.
Is a bigger mini split better?
No. Per ENERGY STAR, an oversized unit costs more to buy, wastes energy, and cools the room before it has removed the humidity.
Do high ceilings change the size?
The chart is built on 8-foot ceilings. With higher ceilings, treat the answer as a minimum and have an HVAC pro run a load calculation (ACCA Manual J) before you buy.
Will it plug into a regular outlet?
Not the ones listed here. Even the 115V units list a 20A or 25A breaker in their specs, so they don't just plug into a wall outlet, and the larger sizes need 230V. Each unit's card shows its voltage, taken from the maker's spec sheet.
| Area to be cooled | Capacity needed |
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