❄️Air Conditioner BTU Calculator
Find the right air conditioner size in BTU for any room.
Your room
You'll need about
6,000 BTU
Choose a 6,000 BTU unit · 300 sq ft
unit size
6,000
sq ft
300
tons
0.5
🛒 Shopping list
- Air conditioner, 6,000 BTU1 unit
Too big isn't better — an oversized AC cools fast but leaves the room damp. Pick the closest size at or just above your number.
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How it works
Start at 20 BTU per sq ft, then adjust for ceiling height (vs 8 ft), sun (±10%), people (+600 BTU for each person past 2) and kitchens (+4,000 BTU). We then round up to the next common unit size.
Worked example
A 15 × 20 ft bedroom, 8 ft ceiling, normal sun, 2 people:
- 300 sq ft × 20 = 6,000 BTU
- Pick a 6,000 BTU unit
Questions people ask
British Thermal Unit — a measure of how much heat an AC can remove per hour.
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Last updated September 28, 2026. These results are friendly estimates to help you plan — always double-check before buying or making big decisions.