Air Conditioner BTU Calculator
Size an air conditioner correctly: room dimensions, insulation, sun exposure and climate give the BTU and tonnage needed.
Frequently asked questions
- Is bigger always better?
- No. An oversized unit cools the air without removing humidity and short-cycles, which wastes energy and leaves rooms clammy.
- Where does the 20 BTU per square foot come from?
- It is the industry rule of thumb, then adjusted for ceiling height, insulation, sun exposure and climate.
- Does this cover multiple rooms?
- No — run it once per room. Whole-home sizing needs a Manual J load calculation from an HVAC contractor.
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