Window AC
5,000–24,000 BTU
Sits in a double-hung window and cools one room. The cheapest way to add cooling.
- Installed cost
- $300–$1,100
- Install
- DIY, about 30 minutes
- Efficiency
- Good
- Noise indoors
- Moderate
Best for: Single rooms and rentals
AC size chart: BTU and tons by square feet
Type your square footage and the chart marks your row. Room sizes follow the ENERGY STAR chart; whole-house sizes follow typical central AC tonnage.
Short answer
Rooms: about 20 BTU per sq ft (a 12×15 bedroom ≈ 6,000 BTU). Whole homes: about 1 ton per 500–600 sq ft, so a 2,000 sq ft house usually needs 3.5–4.5 tons.
LOOKUP
Single rooms (ENERGY STAR)
| Room area | Metric | BTU/h | Tons | Best fit |
|---|---|---|---|---|
| 100–150 ft² | 9–14 m² | 5,000 | 0.42 | Window / portable |
| 150–250 ft² | 14–23 m² | 6,000 | 0.50 | Window / portable |
| 250–300 ft² | 23–28 m² | 7,000 | 0.58 | Window / portable |
| 300–350 ft² | 28–33 m² | 8,000 | 0.67 | Window / portable |
| 350–400 ft² | 33–37 m² | 9,000 | 0.75 | Window or mini-split |
| 400–450 ft² | 37–42 m² | 10,000 | 0.83 | Window or mini-split |
| 450–550 ft² | 42–51 m² | 12,000 | 1.00 | Window or mini-split |
| 550–700 ft² | 51–65 m² | 14,000 | 1.17 | Window or mini-split |
| 700–1,000 ft² | 65–93 m² | 18,000 | 1.50 | Mini-split or small central |
| 1,000–1,200 ft² | 93–111 m² | 21,000 | 1.75 | Mini-split or small central |
| 1,200–1,400 ft² | 111–130 m² | 23,000 | 1.92 | Mini-split or small central |
| 1,400–1,500 ft² | 130–139 m² | 24,000 | 2.00 | Mini-split or small central |
| 1,500–2,000 ft² | 139–186 m² | 30,000 | 2.50 | Central AC or multi-zone |
| 2,000–2,500 ft² | 186–232 m² | 34,000 | 2.83 | Central AC or multi-zone |
Whole house (central AC)
| Home size | Metric | AC tons |
|---|---|---|
| 1,000 ft² | 93 m² | 1.5 – 2 |
| 1,200 ft² | 111 m² | 2 – 2.5 |
| 1,500 ft² | 139 m² | 2.5 – 3 |
| 1,600 ft² | 149 m² | 3 – 3.5 |
| 1,800 ft² | 167 m² | 3 – 4 |
| 2,000 ft² | 186 m² | 3.5 – 4.5 |
| 2,200 ft² | 204 m² | 4 – 5 |
| 2,500 ft² | 232 m² | 4.5 – 5 |
| 3,000 ft² | 279 m² | 5+ |
Adjust for ceiling height
The charts assume 8 ft ceilings. For higher ceilings multiply the BTU by your height ÷ 8: a 10 ft ceiling needs about 25% more.
| Ceiling | Multiply BTU by |
|---|---|
| 8 ft | × 1.00 |
| 9 ft | × 1.13 |
| 10 ft | × 1.25 |
| 12 ft | × 1.50 |
Common rooms, sized
- Bedroom 10×12 ft (120 ft²): 5,000 BTU.
- Primary bedroom 14×16 ft (224 ft²): 6,000 BTU; 7,000–8,000 if it gets afternoon sun.
- Living room 16×22 ft (352 ft²): 9,000 BTU.
- Open kitchen + living 20×25 ft (500 ft²): 12,000 + 4,000 for the kitchen = 16,000 BTU.
- Studio apartment 600 ft²: 14,000 BTU.
BTU CONVERTER
1 ton = 12,000 BTU/h = 3.517 kW · 1 kW = 3,412 BTU/h
Which type of air conditioner fits your room?
Once you know the BTU, the type decides the cost: a window unit for one room is a few hundred dollars, a ductless mini-split a few thousand, and central air for the whole house five figures.
Portable AC
5,000–14,000 BTU
Rolls on the floor and vents hot air through a hose to a window. Easy to move, but the least efficient type.
- Installed cost
- $250–$950
- Install
- No tools, about 10 minutes
- Efficiency
- Lowest
- Noise indoors
- Loudest
Best for: Windows that do not fit a window unit, HOA rules
Ductless mini-split
6,000–36,000 BTU
A quiet wall unit connected to an outdoor inverter compressor. Cools and heats, room by room.
- Installed cost
- $2,500–$6,000
- Install
- Licensed installer
- Efficiency
- Highest
- Noise indoors
- Quietest
Best for: Additions, garages, homes without ducts
Central AC
18,000–60,000 BTU
An outdoor unit and indoor coil that cool the whole house through ductwork, controlled by one thermostat.
- Installed cost
- $5,300–$10,500
- Install
- Licensed installer
- Efficiency
- High (SEER2-rated)
- Noise indoors
- Quiet inside
Best for: Whole homes that already have ducts
Installed cost: HomeGuide 2026 (mini-split shown as a single-zone system). Efficiency and noise are relative comparisons between types.
Questions homeowners ask
What size AC do I need for a 1,500 sq ft house?
Usually 2.5–3 tons (30,000–36,000 BTU) for a central AC, depending on climate and insulation.
What size AC for a 2,000 sq ft house?
Typically 3.5–4.5 tons. Hot climates and poorly insulated homes sit at the top; mild climates at the bottom.
How many square feet does a 12,000 BTU AC cool?
About 450–550 square feet.
Is it bad to oversize an air conditioner?
Yes. It short-cycles, removes less humidity, wears out faster and costs more up front. Match the chart, then adjust for sun and occupancy.
Best HVAC Repair GuideAC size chart: BTU and tons by square feet
Updated
ScaleNot to scale — ranges are national averages
Sources
Estimates for planning only. Prices vary by region, home, and contractor. Gas, refrigerant, and high-voltage work must be done by a licensed technician.