ComfortSizer
ENERGY STAR sizing chart

BTU Chart

How many square feet does each air conditioner size cool? Tap a BTU rating to see the room size it is made for.

Pick an air conditioner size (BTU)
Cools a room of 300–350 sq ft 28 to 33 m² · about 16 × 20 ft · 0.67 tons
5,000100–150 ft²
6,000150–250 ft²
7,000250–300 ft²
8,000300–350 ft²
9,000350–400 ft²
10,000400–450 ft²
12,000450–550 ft²
14,000550–700 ft²
18,000700–1,000 ft²
21,0001,000–1,200 ft²
23,0001,200–1,400 ft²
24,0001,400–1,500 ft²
30,0001,500–2,000 ft²
34,0002,000–2,500 ft²

Areas assume an 8 ft ceiling and normal sun. Need a custom number? Use the BTU calculator.

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BTU to square feet

The ENERGY STAR room air conditioner chart, with metric areas and the BTU per square foot each size works out to.

CapacityRoom areaMetricBTU / sq ft
5,000 BTU100 to 150 sq ft9 to 14 m²33.3–50.0
6,000 BTU150 to 250 sq ft14 to 23 m²24.0–40.0
7,000 BTU250 to 300 sq ft23 to 28 m²23.3–28.0
8,000 BTU300 to 350 sq ft28 to 33 m²22.9–26.7
9,000 BTU350 to 400 sq ft33 to 37 m²22.5–25.7
10,000 BTU400 to 450 sq ft37 to 42 m²22.2–25.0
12,000 BTU450 to 550 sq ft42 to 51 m²21.8–26.7
14,000 BTU550 to 700 sq ft51 to 65 m²20.0–25.5
18,000 BTU700 to 1,000 sq ft65 to 93 m²18.0–25.7
21,000 BTU1,000 to 1,200 sq ft93 to 111 m²17.5–21.0
23,000 BTU1,200 to 1,400 sq ft111 to 130 m²16.4–19.2
24,000 BTU1,400 to 1,500 sq ft130 to 139 m²16.0–17.1
30,000 BTU1,500 to 2,000 sq ft139 to 186 m²15.0–20.0
34,000 BTU2,000 to 2,500 sq ft186 to 232 m²13.6–17.0

Adjust for your room: −10% if heavily shaded, +10% if very sunny, +600 BTU per person above two, +4,000 BTU in a kitchen.

Reading the BTU chart

The chart matches floor area to cooling capacity for a typical room. Notice that BTU per square foot falls as rooms get bigger: a 150 sq ft bedroom needs about 33 BTU per square foot, a 2,000 sq ft open space about 15. Walls, windows and people add heat in proportion to the room's perimeter and use, not only its floor area.

If your room sits between two sizes, or if it is sunny, busy or a kitchen, the next size up is usually the right call. If it is shaded and lightly used, the smaller size may be enough. The BTU calculator applies those adjustments for you.

Tons and BTU

Larger systems are rated in tons: 1 ton = 12,000 BTU per hour, 2 tons = 24,000, 3 tons = 36,000. Whole-house central systems should be sized with a Manual J load calculation rather than a room chart.

FAQ

Room size questions

How many square feet does an 8,000 BTU air conditioner cool?
300 to 350 square feet, according to the ENERGY STAR chart, for a room with an 8 ft ceiling and normal sun.
How many square feet does a 5,000 BTU air conditioner cool?
100 to 150 square feet, about the size of a small bedroom or home office.
What size room will a 10,000 BTU air conditioner cool?
400 to 450 square feet with an 8 ft ceiling and normal sun. In a very sunny room, take about 10% off that area.
How big a room does a 12,000 BTU air conditioner cool?
450 to 550 square feet. 12,000 BTU is also one ton of cooling.
How many square feet will 14,000 BTU cool?
550 to 700 square feet. For a portable unit, check that 14,000 is the SACC rating and not the older ASHRAE figure.
How many BTU per square foot for air conditioning?
It depends on the room size: from about 33 BTU per sq ft for a 150 sq ft room down to about 14 for a 2,500 sq ft space. The common 20 BTU per square foot rule is only right for mid-size rooms.