Ask five people and you'll get "500 square feet per ton" five times — and it's wrong often enough to cost real money. Sizing depends on your climate zone, insulation, windows, ceiling height and sun exposure. Our free sizing calculator weighs all of it in about 30 seconds.
Why bigger is not better
An oversized AC cools the air fast and shuts off before it dehumidifies — you get a cold, clammy house, constant start-stop cycling (the hardest thing on a compressor), and higher bills. Right-sized beats oversized every single time. If a contractor's answer to everything is "go bigger," get a second number.
The rough map (before the real math)
| Home size | Typical range* |
|---|---|
| 1,000–1,400 sq ft | 2 – 2.5 tons |
| 1,500–1,900 sq ft | 2.5 – 3.5 tons |
| 2,000–2,600 sq ft | 3.5 – 4.5 tons |
| 2,700–3,300 sq ft | 4.5 – 5 tons |
*Hot-humid climates trend higher, mild climates lower — which is exactly why the calculator asks.
When to insist on a full Manual J
New construction, additions, or a home that never felt right with the old system: ask for a room-by-room load calculation. Our free simplified Manual J is in the calculator hub if you want to sanity-check a contractor's number yourself.
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