Guide
What size HVAC do I need?
A quick, honest ballpark for sizing an AC, heat pump, or furnace by home size and climate — enough to catch an oversized quote, which is the most common way you get overcharged.
The quick rule
Cooling load runs roughly 18–28 BTU per square foot depending on climate. Multiply your conditioned square footage by that, then divide by 12,000 to get tons (1 ton = 12,000 BTU/h). Hotter, sunnier, or poorly-insulated homes land at the high end.
Typical system size by home size
| Home size | Cold / mild | Temperate | Hot / humid |
|---|---|---|---|
| 1,000 sq ft | 1.5 ton | 2 ton | 2 ton |
| 1,500 sq ft | 2 ton | 2.5 ton | 3 ton |
| 2,000 sq ft | 2.5 ton | 3 ton | 3.5 ton |
| 2,500 sq ft | 3 ton | 3.5 ton | 4 ton |
| 3,000 sq ft | 4 ton | 4 ton | 5 ton |
Ballpark for a whole-home central system. Tighter, well-insulated homes need less; lots of glass, high ceilings, or a hot climate push it up.
Why bigger is not better
An oversized system short-cycles — it blasts cold then shuts off before it pulls humidity out, so the house feels clammy, the equipment wears out faster, and you paid more up front. Right-sizing is cheaper to buy, cheaper to run, and more comfortable. A contractor's Manual J load calculation (windows, orientation, ductwork, local design temps) is the real answer — but if a quote is a full ton above the ballpark above, ask why before you sign.