AC size calculator: what size AC do I need?
Estimate what size central air conditioner your home needs in tons and BTU, and what that size typically costs to install.
–
Rule-of-thumb estimate based on about 20 BTU per square foot, adjusted for climate, sun, insulation and occupants (about 600 BTU per person beyond two). A Manual J load calculation by a contractor gives the real answer.
AC size by square footage
| Home size (sq ft) | AC size | Installed cost |
|---|---|---|
| 600 – 1,100 | 1.5 tons | $4,700 – $6,500 |
| 900 – 1,400 | 2 tons | $5,000 – $6,800 |
| 1,200 – 1,600 | 2.5 tons | $5,400 – $7,200 |
| 1,500 – 2,100 | 3 tons | $5,800 – $7,800 |
| 1,800 – 2,300 | 3.5 tons | $6,200 – $8,300 |
| 2,100 – 2,700 | 4 tons | $6,500 – $8,800 |
| 2,500 – 3,500 | 5 tons | $7,000 – $9,500+ |
Why proper sizing matters
An oversized air conditioner short-cycles: it cools the air fast but shuts off before removing humidity, wasting energy and wearing out the compressor. An undersized one runs nonstop on hot days. Ask contractors for a Manual J load calculation rather than simply matching your old unit.
Ready to budget? See AC replacement cost or use the HVAC cost calculator.