What Size AC Unit Do I Need? Tonnage by Square Footage (2026)

Most Florida homes between 1,000 and 2,000 square feet need a 2.5- to 4-ton unit — roughly one ton per 400–600 square feet. But square footage alone isn’t enough; insulation, windows, ceilings, and Florida’s heat all shift the number. Only a Manual J load calculation gives your exact 2026 AC size.

Home Square Footage (approx.)	Typical AC Size (Tons)	Cooling Output (BTU/hr)
Under 1,000 sq ft	1.5 – 2 tons	18,000 – 24,000
1,000 – 1,500 sq ft	2 – 2.5 tons	24,000 – 30,000
1,500 – 2,000 sq ft	2.5 – 3.5 tons	30,000 – 42,000
2,000 – 2,500 sq ft	3.5 – 4 tons	42,000 – 48,000
2,500 – 3,000 sq ft	4 – 5 tons	48,000 – 60,000

How AC Tonnage Is Measured

“Tonnage” is the old term for an air conditioner’s cooling capacity. One ton equals the cooling power needed to melt one ton of ice in 24 hours, which is 12,000 British Thermal Units (BTUs) per hour. So a 3-ton unit delivers about 36,000 BTU/hr. You’ll see tonnage on the unit’s model number — for example, an “036” on a 3-ton system usually signals 36,000 BTU/hr.

AC size is expressed in half-ton increments: 1.5, 2, 2.5, 3, 3.5, 4, and 5 tons. Most single-family Florida homes fall in the 2.5 to 4-ton range. Anything above 5 tons generally indicates either a very large home or that ductwork and design need closer review — oversized equipment is rarely the fix.

Why “Bigger Is Better” Is Wrong for AC

An AC that’s too large cools the air fast but short-cycles — it turns on and off constantly without running long enough to remove humidity. In muggy Florida that leaves a home feeling cold but clammy, spikes your electric bill, and wears the compressor out early. An AC that’s too small runs nearly nonstop, struggles to reach the thermostat on the hottest days, and also wastes energy. Matching the size to your home’s actual cooling load is what keeps humidity out and efficiency high.

This is why the square-footage chart above is only a starting point. A proper Manual J load calculation accounts for your home’s insulation, window count and orientation, ceiling height, shading, number of occupants, and local climate. A good contractor won’t guess the tonnage — they’ll run the load calculation and size the system to it, not to a sales target.

Florida-Specific Sizing Factors

Florida homes run a few special considerations. High humidity and long cooling seasons can favor slightly different sizing decisions, and older, poorly insulated homes often need more capacity per square foot than the chart suggests. Conversely, a newer home with radiant-barrier roofing, tight windows, and good insulation may need less than the rough rule of thumb.

If your current unit is always short-cycling or running nonstop, that’s a strong clue the original sizing was off — and it’s worth having a Manual J done before you replace it, rather than just matching the old tonnage. In 2026, with the industry moving to R-454B systems, getting the sizing right matters even more because the new equipment is optimized around matched coil-and-condenser performance.

FAQ: What Size AC Unit Do I Need?

Q: What AC size do I need for 1,200 square feet?
A: A 1,200 sq ft Florida home typically needs a 2- to 2.5-ton unit (24,000–30,000 BTU/hr). Exact size depends on insulation, windows, and whether you have a heat strip or heat pump.

Q: What AC size for a 2,000 square foot house?
A: Roughly a 3- to 3.5-ton system (36,000–42,000 BTU/hr). A professional load calculation will narrow it down — 2,000 sq ft homes vary widely with layout and sun exposure.

Q: Is a 3-ton AC enough for a 1,800 square foot house?
A: Often yes, though some 1,800 sq ft homes land closer to 3.5 tons. If it short-cycles in normal weather, it may be oversized; if it runs constantly on hot afternoons, it may be undersized, and a load calc is worth it.

Q: How do I know what tonnage my current AC is?
A: Find the model number on the outdoor condenser’s data plate. A number ending in “036” usually means 36,000 BTU/hr, or 3 tons; “024” is 2 tons. Divide by 12,000 to get tons.

Q: How many square feet does a 1-ton AC cover?
A: Roughly 400–600 square feet in typical climates, but Florida heat and humidity can push the required tonnage higher per square foot, especially in older homes.

Q: What happens if I undersize or oversize my AC?
A: An undersized unit runs nonstop and can’t keep up on hot days; an oversized one short-cycles and fails to dehumidify. Both waste energy and shorten equipment life. Correct sizing is the single biggest efficiency factor.

Q: Should I just replace my AC with the same tonnage as the old one?
A: Only if the old unit was properly sized. If you’ve seen constant short-cycling or a swampy-feeling home, the old size may have been wrong — get a Manual J load calculation before choosing the replacement.

Call to Action

Not sure what size AC your Florida home really needs? Getting it right the first time saves you money on every electric bill — and Chilly Air can help you find the exact fit. Call 813-445-6228 or email orders@chillyairllc.com to talk through your home’s cooling load, or browse our AC systems to see energy-efficient options in the size your home needs.

*Last updated: September 16, 2026. Sources: EPA AIM Act HFC phasedown schedule (epa.gov/hfcs, updated 2026-09-14); US DOE heat & cool calculators and Manual J load calculation standards; industry standard BTU-to-tons conversion (1 ton = 12,000 BTU/hr).