Most bedrooms need a 5,000 to 8,000 BTU air conditioner, sized to the room’s square footage using ENERGY STAR’s official chart.
Choosing the right air conditioner for a bedroom comes down to one measurement: the room’s square footage. Pick a unit that’s too small and it will run nonstop without cooling the space; too large and it will cycle on and off, leaving the room damp and chilly. The official sizing baseline comes from ENERGY STAR’s room air conditioner chart, which matches room area to BTU capacity.
BTU Sizing Chart For Bedrooms
Find your bedroom’s square footage to see the correct BTU range.
| Room Size (sq ft) | Recommended Capacity (BTU/hr) |
|---|---|
| 100–150 sq ft | 5,000 BTU |
| 150–250 sq ft | 6,000 BTU |
| 250–300 sq ft | 7,000 BTU |
| 300–350 sq ft | 8,000 BTU |
| 350–400 sq ft | 9,000 BTU |
| 400–450 sq ft | 10,000 BTU |
| 450–550 sq ft | 12,000 BTU |
| 550–700 sq ft | 14,000 BTU |
Most standard bedrooms fall in the 100–350 sq ft range, which puts the correct size between 5,000 and 8,000 BTU. A 5,000 BTU unit handles a small bedroom up to 150 sq ft, while a 6,000–8,000 BTU unit covers most average-sized bedrooms.
How To Measure Your Bedroom For An AC
Measure the length and width of your bedroom in feet, then multiply the two numbers to get the square footage. For a room that’s 12 feet by 14 feet, the area is 168 sq ft, which points to a 6,000 BTU unit.
Bedrooms with higher ceilings hold more air, so those rooms may benefit from a unit at the higher end of the range or the next size up.
For a comfortable fit, measure only the space the AC needs to cool — a connected walk-in closet that stays closed doesn’t add to the cooling load. If the door between rooms is usually open, include that space in your calculation.
Adjusting BTU For Sun, Shade, And Occupants
Add 600 BTU/hr for each person beyond two who regularly occupies the room. A very sunny bedroom needs 10% more capacity, while a heavily shaded room can drop 10%.
For a 200 sq ft bedroom with three people and afternoon sun, that means starting with a 6,000 BTU unit, adding 600 BTU for the extra person, and 10% for sunlight — landing at roughly 7,260 BTU, so a 7,000 or 8,000 BTU unit is the right call.
If the unit also serves a kitchen,
Common Sizing Mistakes To Avoid
One widespread shortcut — multiplying square footage by 20 BTU — is not the method ENERGY STAR uses. Their official chart relies on bracketed room-size ranges rather than a flat per-square-foot rule, so a 180 sq ft room and a 240 sq ft room don’t necessarily need proportionally different units.
Ignoring ceiling height is the other frequent error. A bedroom with vaulted ceilings may need more capacity than the floor-area chart suggests, since the unit has to cool a larger volume of air.
When you’re ready to buy, our roundup of the best air conditioners for bedrooms covers tested models that match these BTU sizes.
Remember that this sizing guidance applies to room air conditioners and window units, not central whole-home systems. For installation, follow the electrical and safety requirements in the manufacturer’s manual for your specific unit — BTU sizing is only one part of a safe setup.
FAQs
Is a 5,000 BTU air conditioner enough for a bedroom?
A 5,000 BTU unit is adequate for a bedroom up to 150 square feet with an 8-foot ceiling, per ENERGY STAR’s sizing chart. Rooms larger than that will need 6,000 BTU or more to cool effectively without running constantly.
What happens if my air conditioner is oversized?
An oversized AC cools the room quickly but shuts off before it removes humidity, leaving the space feeling cold and clammy. The frequent cycling also wears the unit faster and wastes energy compared to a correctly sized model.
Does ceiling height affect AC sizing?
Yes.