How many BTU for a 12x12 room?
A 12′ × 12′ room is 144 sq ft, so ENERGY STAR recommends about 5,000 BTU, which means a 5,000 BTU air conditioner.
Method: ENERGY STAR room air conditioner sizing chart with its official adjustments for sun, people and kitchens.
Cooling capacity needed
5,000 BTU
Buy a 5,000 BTU unit · 0.4 tons · 144 sq ft
| ENERGY STAR base for 144 sq ft | 5,000 |
| Total | 5,000 BTU |
- • Bigger isn't better: an oversized AC cools too fast to remove humidity, leaving the room cold and clammy.
ENERGY STAR AC size chart
| Area to cool | Capacity needed | Tons |
|---|---|---|
| 100–150 sq ft | 5,000 BTU/h | 0.4 |
| 150–250 sq ft | 6,000 BTU/h | 0.5 |
| 250–300 sq ft | 7,000 BTU/h | 0.6 |
| 300–350 sq ft | 8,000 BTU/h | 0.7 |
| 350–400 sq ft | 9,000 BTU/h | 0.8 |
| 400–450 sq ft | 10,000 BTU/h | 0.8 |
| 450–550 sq ft | 12,000 BTU/h | 1 |
| 550–700 sq ft | 14,000 BTU/h | 1.2 |
| 700–1,000 sq ft | 18,000 BTU/h | 1.5 |
| 1,000–1,200 sq ft | 21,000 BTU/h | 1.8 |
| 1,200–1,400 sq ft | 23,000 BTU/h | 1.9 |
| 1,400–1,500 sq ft | 24,000 BTU/h | 2 |
| 1,500–2,000 sq ft | 30,000 BTU/h | 2.5 |
| 2,000–2,500 sq ft | 34,000 BTU/h | 2.8 |
How the calculation works
The base capacity comes from the ENERGY STAR room air conditioner sizing chart, which assumes 8 ft ceilings. ENERGY STAR then recommends four adjustments: reduce capacity by 10% for a heavily shaded room, increase it by 10% for a very sunny room, add 600 BTU for each person beyond two who regularly uses the room, and add 4,000 BTU if the unit is for a kitchen. For taller ceilings, the calculator scales the result by ceiling height, a common industry adjustment.
For whole-house central air or heat pumps, an HVAC contractor should run a Manual J load calculation, which also accounts for insulation, windows and your local climate.
More AC size guides
- 100 sq ft
- 150 sq ft
- 200 sq ft
- 250 sq ft
- 300 sq ft
- 350 sq ft
- 400 sq ft
- 450 sq ft
- 500 sq ft
- 600 sq ft
- 700 sq ft
- 800 sq ft
- 1,000 sq ft
- 1,200 sq ft
- 1,500 sq ft
- 2,000 sq ft
- 2,500 sq ft
- 10x10 room
- 10x12 room
- 12x14 room
- 14x16 room
- 15x15 room
- 16x20 room
- 20x20 room
- Bedroom
- Living room
- Kitchen
Frequently asked questions
How many BTU do I need per square foot?
ENERGY STAR's chart works out to roughly 20 BTU per square foot for typical rooms, adjusted for sun, people and kitchens.
What size AC for a 12x12 room?
A 12′ × 12′ room is 144 sq ft, which needs 5,000 BTU according to ENERGY STAR. A sunny room needs about 5,500 BTU, so a 6,000 BTU unit.
What size AC for 1,000 sq ft?
ENERGY STAR recommends 18,000 BTU, or 1.5 tons, for 700–1,000 sq ft.
Is a bigger air conditioner better?
No. An oversized unit cools the room before it removes humidity, so the room feels cold and clammy and the unit wears out faster.
How many square feet does 1 ton of AC cool?
One ton is 12,000 BTU, which ENERGY STAR matches to 450–550 sq ft.