How this Florida calculator works
A ton of cooling is 12,000 BTU per hour. The calculator gives two answers in one box, and they can disagree because it depends on the house.
- Quick rule of thumb (square feet only): about 22 BTU per square foot, roughly 545 sq ft per ton. National shortcuts like “1 ton per 400 square feet” push a lot of Florida houses too big. The rule of thumb is the same for every house of that size, so treat it as a ceiling check, not a design number.
- Refined for your house: adds up heat through windows (by glass type, direction, and shade), walls, the ceiling under a hot attic, outside air leaking in, people, appliances, and duct gain, using your city’s design-day temperature and humidity. Newer homes with low-E glass, good attic insulation, and sealed ducts often come in a ton or more below the rule of thumb. Older, leaky, west-facing homes can come in above it.
Equipment sizes are shown as a 90–115% window around the load, because residential equipment is sold in half-ton steps (1.5, 2, 2.5, 3, 3.5, 4, 5).
Why Florida humidity changes the answer
Florida air is not just hot. It is wet. A large share of what an AC does in July and August is pull moisture, not just drop the thermostat. That only happens when the system runs long enough for the coil to get cold and stay there.
An oversized unit cools the air fast, hits setpoint, and shuts off. Indoor air can feel chilly and still sticky. You also get more short-cycling, which is hard on compressors. If this calculator puts you between two sizes, the smaller one is often the better Florida choice after a real Manual J — not a bigger “just in case” unit.
Example results: rule of thumb vs house-specific
Outputs of this calculator for Orlando, one story, 8 ft ceilings. “Typical” means double-pane clear glass, block walls with furring, R-30 attic, dark shingle roof, average air leakage, typical attic ducts, four people. These are examples, not a promise about your house.
| House | Rule of thumb | Refined load | Sizes that fit |
|---|---|---|---|
| 1,200 sq ft, typical | About 2 tons | 1.79 tons | 2 ton |
| 1,800 sq ft, typical | About 3.5 tons | 2.40 tons | 2.5 ton |
| 2,000 sq ft, typical | About 3.5 tons | 2.61 tons | 2.5 ton |
| 2,400 sq ft newer build (tight, low-E, R-38, sealed ducts) | About 4.5 tons | 1.94 tons | 2 ton |
| 2,000 sq ft older (leaky, single-pane west glass, no shade, R-19, old ducts) | About 3.5 tons | 4.83 tons | 5 ton (get a real Manual J first) |
Same square footage, a two-ton swing. That is why the refined inputs matter more than the size of the house.
What a real Manual J adds
- Every wall, window, and door measured room by room, not whole-house averages
- Exact glass SHGC and overhang geometry for each window
- Measured duct leakage and duct runs (hot Florida attics punish leaky ducts)
- Blower-door infiltration instead of an age-based guess
- Room-by-room loads so airflow can be balanced
Tonnage alone is not the whole job. Airflow, duct static, and whether the house needs help with humidity (runtime, coil temperature, sometimes a whole-home dehumidifier) all matter.
Common questions
How many square feet per ton in Florida?
The rule of thumb here is about 545 sq ft per ton. House-specific results commonly run 600–1,200 sq ft per ton for newer, well-insulated homes and closer to 400–500 for older, leaky, sunny ones. It depends on the house. 400 sq ft per ton is a common internet number and it oversizes a lot of Florida houses.
What size AC for 2,000 square feet in Florida?
The quick rule of thumb says about 3.5 tons. Refined for a typical Orlando house it is closer to 2.6 tons of load (2.5 ton equipment). A newer tight house can drop to about 2 tons, and an older leaky west-facing one can push toward 5. Confirm with Manual J before you shop. Longer answer: what size AC for 2,000 sq ft in Florida.
Is a bigger AC better in Florida heat?
Usually no. Bigger is not more comfortable here. Runtime is what dries the air. See 3 ton versus 3.5 ton in Florida humidity.
Can I use this to buy a system online?
Please don’t. Wrong tonnage is expensive to undo, and Florida code and manufacturer warranties expect a proper load calculation.
Next, not a sales pitch
If you are replacing a unit, take this range to a contractor and ask to see the Manual J, not just a square-footage guess. If you are a tech, treat 22 BTU/sq ft as a Florida-aware ceiling check, use the refined inputs for a closer number, then let the real load calc win.
Also: SEER2 savings calculator using your region’s planning hours and rate (cooling kWh only).