What Size AC Do I Need for My Home?
Bigger isn't better. An oversized AC short-cycles and leaves your home humid. Here's how correct sizing actually works.
By the Airo Service HVAC Team · Reviewed by a licensed FL technician · Updated July 1, 2026
AC size is measured in tons, and in South Florida a rough starting point is one ton per 400–600 square feet — but humidity, insulation, windows and sun exposure change that a lot. The only reliable way is a Manual J load calculation, not a rule of thumb. Call (305) 846-0155 for honest sizing.
Why bigger isn't better
Many homeowners assume a larger AC cools better. The opposite is true. An oversized system cools the air quickly but shuts off before it removes humidity — so your home feels cold and clammy, the unit short-cycles, and parts wear out early. An undersized system runs constantly and never quite keeps up.
How pros size it — Manual J
A proper AC installation starts with a Manual J load calculation. It accounts for your home's square footage, insulation, ceiling height, window count and orientation, and air-sealing — then sizes the system to your actual cooling load, not a guess.
South Florida factors that change the math
- Humidity — our biggest comfort challenge; correct sizing controls it.
- Sun exposure — west- and south-facing glass adds significant load.
- Insulation & attic heat — a hot attic raises the load; good insulation lowers it.
- Ductwork — leaky ducts waste capacity, so sealing matters as much as tonnage.
The takeaway: don't just replace "the same size" — have it calculated. It's the difference between even, dry comfort and a decade of humidity complaints.
FAQ
How many square feet does a 3-ton AC cool?
Roughly 1,500–1,800 sq ft in South Florida, but it depends on insulation, windows and sun — a load calculation confirms it.
Is it bad to oversize my AC?
Yes — it short-cycles and leaves your home humid. Correct sizing beats bigger every time.
Do you charge for a sizing assessment?
We provide free, no-pressure in-home estimates that include proper sizing.
Talk to a Local Airo Service Tech
Questions or ready to book? Fast response — often same-day. No pressure.
- ✔ Free, No-Obligation Estimate
- ✔ Upfront Written Pricing — No Surprises
- ✔ 10-Yr Parts / 1-Yr Labor Warranty
- ✔ Serving Miami-Dade, Broward & Palm Beach
Prefer to talk? Call (305) 846-0155.
