Bedroom BTU by common sizes
Bedrooms usually need less load than kitchens or sunrooms because they have fewer heat sources and often less window area.
A 10×10 bedroom (100 sq ft) calculates to about 2,500 BTU at 25 BTU/sq ft — but practical retail minimums are 6,000–9,000 BTU. A 9,000 BTU mini-split or window unit is the common choice.
A 12×12 bedroom (144 sq ft) calculates to roughly 3,600 BTU — again, buy 9,000 BTU minimum for comfort and dehumidification.
Master bedrooms of 300–400 sq ft often need 9,000–12,000 BTU depending on sun exposure and insulation.
Factors that push bedroom load up
Mark the room as sunny in the calculator if one wall gets afternoon sun. Shaded north-facing bedrooms can use a lower factor.
- Large south- or west-facing windows with direct sun
- Top-floor rooms under a hot roof with poor attic insulation
- Home offices with PCs, monitors, and printers running all day
- Ensuite bathrooms with steam from showers (open door = extra humidity load)
- Cathedral or vaulted ceilings — more volume to cool
Right-size for sleep, not oversize
Oversized AC cools fast but short-cycles — the room feels cold and clammy because the unit never runs long enough to dehumidify. Match calculated load, then round up one retail step.
Inverter mini-splits modulate down at partial load, which helps in small bedrooms where minimum BTU still exceeds calculated load.
Bedroom sizing quick reference
Run exact dimensions in the room AC calculator. Compare ductless vs window units in our mini-split vs window AC guide before buying.
- 10×10 (100 sq ft): calc ~2,500 BTU → buy 9,000 BTU head
- 12×12 (144 sq ft): calc ~3,600 BTU → buy 9,000 BTU head
- 14×16 (224 sq ft): calc ~5,600 BTU → 9,000 BTU usually sufficient
- 16×20 master (320 sq ft): calc ~8,000 BTU → 9,000–12,000 BTU depending on sun
- 400 sq ft master suite: often 12,000 BTU with average insulation