AC Tonnage per Square Foot — How Many Tons Do You Need?
This AC tonnage per square foot calculator estimates the air-conditioner size your home needs from its square footage and climate zone — using the tons-per-square-foot rule of thumb (about one ton per 400–600 sq ft). Enter your area below for a recommended tonnage, or use the square-footage-to-tonnage chart to look it up at a glance.
Want a precise size, not a rule of thumb? Run the full BTU Calculator or a Manual J load calculation — they factor in insulation, windows, and sun.
Enter square footage & climate
Recommended AC size
≈ 2.50 tons exact
Cooling load
30,000 BTU/hr
Coverage
≈ 600 sq ft / ton
See the breakdown
A square-footage rule of thumb for planning. Confirm with a Manual J load calculation before buying — insulation, windows, and sun can shift the size by a half-ton or more.
Square footage to AC tonnage chart
Approximate central-AC tonnage by home size and climate, using 28 BTU/ft² (hot), 20 (mixed), and 15 (cold). Round up when between sizes.
| Home size | Hot climate | Mixed climate | Cold climate |
|---|---|---|---|
| 1,000 sq ft | 2.5 tons | 1.5 tons | 1.5 tons |
| 1,500 sq ft | 3.5 tons | 2.5 tons | 2.0 tons |
| 2,000 sq ft | 4.5 tons | 3.5 tons | 2.5 tons |
| 2,500 sq ft | 6.0 tons | 4.0 tons | 3.0 tons |
| 3,000 sq ft | 7.0 tons | 5.0 tons | 4.0 tons |
Rules of thumb for planning only. Above ~5 tons, homes usually use two systems or zoning. Always confirm with a Manual J load calculation.
The rule, explained in plain English
Tons per square foot is just a shortcut for cooling load. Pick a BTU-per-square-foot rate for your climate, multiply by area, and divide by 12,000 BTU per ton.
Why "one ton per 600 sq ft" isn't universal
600 sq ft per ton fits a mixed climate. In Phoenix it's closer to 400; in Minnesota, 700+. Using a single number across climates is the most common sizing mistake.
Why square footage isn't the whole story
Two identical-size homes can differ by a full ton based on insulation, window area, orientation, and air leakage — which is exactly what a Manual J load calculation captures.
Round up, but not too far
Go to the next half-ton, not the next whole ton. Oversizing makes the AC short-cycle, leaving humidity behind and wearing out the compressor.
Tons, BTU, and square feet
One ton = 12,000 BTU/hr. So "20 BTU per sq ft" is the same as "600 sq ft per ton" — two ways of saying the same rule of thumb.
Frequently asked questions
Common questions about sizing AC by square footage.
How many tons of AC do I need per square foot?
A common rule of thumb is one ton of cooling per 400–600 square feet — about 600 sq ft per ton in a mild climate and closer to 400 in a hot one. That comes from roughly 20 BTU per square foot (12,000 BTU = one ton); this calculator adjusts that baseline for your climate zone.
How many square feet does one ton of AC cover?
Roughly 400 to 600 square feet per ton, depending on climate. In hot southern climates plan on about 400–450 sq ft per ton; in mixed climates around 600; and in cool northern climates up to 700–800, because the cooling load per square foot is lower.
What size AC do I need for a 2,000 square foot house?
In a mixed climate, 2,000 sq ft works out to about 3 to 3.5 tons (40,000 BTU). A hot climate pushes it toward 4.5 tons and a cold climate down toward 2.5. Enter your exact square footage and climate above for a tailored number.
Does climate change the tons per square foot?
Significantly. The same house needs more cooling capacity per square foot in Phoenix than in Minneapolis, so BTU per square foot ranges from about 28 in hot zones to 15 in cold ones. That's why a single national rule of thumb over- or under-sizes equipment depending on where you live.
Is square footage enough to size an air conditioner?
Square footage gives a solid starting estimate, but it ignores insulation, windows, sun, and ceiling height. For an accurate size, run a Manual J load calculation or the full BTU Calculator, which is also required for permits.
How do I convert square footage to AC tonnage?
Multiply square footage by the BTU-per-square-foot rate for your climate (15–28), then divide by 12,000 to get tons. For example, 1,800 sq ft × 20 BTU = 36,000 BTU ÷ 12,000 = 3 tons. The calculator does this and rounds to the nearest half-ton.
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