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.
Frequently asked questions
Is 8,000 BTU enough for a bedroom?
Usually yes for rooms under 250 sq ft with average insulation. Larger masters or sunny rooms often need 12,000 BTU. Run the room calculator with your exact dimensions.
Do I count closet square footage?
Include closet floor area if cooled air reaches them through open doors or louvered doors. Closed-off closets add little load — skip them for a closer estimate.
One mini-split for two small bedrooms?
Only if doors stay open and airflow reaches both rooms. Closed bedrooms need their own head or a multi-zone system — one head in a hallway rarely cools closed rooms evenly.
HVAC Calculators provides estimates for planning only — not professional HVAC engineering or installation advice. Verify sizing with a licensed contractor before purchasing equipment. Read disclaimer