AC Size Calculator
Estimate the central air conditioner size for a whole home. Enter the conditioned square footage, your climate and how well the home is insulated.
How to use the AC Size Calculator
- Enter the home’s conditioned floor area.
- Choose your climate and insulation level.
- Enter your ceiling height.
How it works
Cooling load ≈ area × BTU per sq ft, using about 20 BTU/sq ft for cool climates up to 35 for hot ones, adjusted for insulation and scaled for ceilings above 8 ft. The result is converted to tons (1 ton = 12,000 BTU/h) and rounded up to the next half-ton, the size steps in which residential systems are sold.
Professionals use an ACCA Manual J load calculation, which accounts for windows, orientation, duct leakage and more. Use this estimate as a starting point.
Typical AC size by home size (moderate climate)
| Home size (sq ft) | Load (BTU/h) | AC size |
|---|---|---|
| 1,000 | 25,000 | 2.5 tons |
| 1,200 | 30,000 | 2.5 tons |
| 1,500 | 37,500 | 3.5 tons |
| 1,800 | 45,000 | 4 tons |
| 2,000 | 50,000 | 4.5 tons |
| 2,400 | 60,000 | 5 tons |
| 3,000 | 75,000 | 6.5 tons |
Frequently asked questions
What size AC do I need for 2,000 sq ft?
Typically about 3.5–4.5 tons, depending on climate and insulation.
Is a bigger AC better?
No. An oversized system short-cycles, wastes energy and removes less humidity.
What is a ton of air conditioning?
A ton is 12,000 BTU per hour of cooling — the heat needed to melt a ton of ice in 24 hours.