Use this free AC size calculator to find the right HVAC system size for your home. Enter your square footage, ceiling height, climate zone, and insulation quality to get an instant BTU and ton recommendation — no math required.
Sizing an AC system is critical: too small and it runs constantly without cooling your home; too large and it short-cycles, wasting energy and failing to dehumidify. Our AC sizing calculator uses the industry-standard Manual J method to give you an accurate recommendation.
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Find the right HVAC system size for your home
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| Home Size (sq ft) | AC Size (tons) | BTU |
|---|---|---|
| 1,000 – 1,200 | 2 tons | 24,000 |
| 1,200 – 1,500 | 2.5 tons | 30,000 |
| 1,500 – 1,800 | 3 tons | 36,000 |
| 1,800 – 2,200 | 3.5 tons | 42,000 |
| 2,200 – 2,600 | 4 tons | 48,000 |
| 2,600 – 3,200 | 5 tons | 60,000 |
Get free, no-obligation quotes from licensed HVAC contractors in your area. Our calculator tells you what size you need — these services help you find someone to install it.
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AC size (cooling load) is calculated using Manual J methodology: base load = square footage × 20 BTU/sq ft, then adjusted for ceiling height, climate zone, insulation quality, number of occupants, and sun exposure. Our AC size calculator applies these adjustments automatically. The result is the minimum cooling capacity needed to maintain comfort on a design day.
An undersized AC runs constantly without reaching set temperature — higher bills, faster wear. An oversized AC short-cycles (turns on/off frequently) — poor dehumidification (muggy feeling), uneven temperatures, premature failure. Both waste energy and money. Getting the right size from our AC calculator prevents both problems.
No. Bigger is not better for air conditioners. An oversized system cools your home too quickly without running long enough to remove humidity, leaving your home feeling damp and muggy. It also costs more to install and operate. Always size based on actual load calculation, not a guess. Use our AC sizing calculator to find the correct size.
General rule: 20 BTU per square foot for cooling in average conditions. But this ignores climate, insulation, and occupancy — the factors our AC size calculator accounts for. Hot climates (Zone 1–2) may need 22–25 BTU/sq ft. Cool climates (Zone 5–6) may need only 16–18 BTU/sq ft. Always use a proper load calculation, not just the rule of thumb.
This calculator provides estimates for informational purposes only. For accurate sizing, consult a licensed HVAC contractor who performs a Manual J load calculation.