What size window AC for a bedroom?
A 10×12 bedroom (144 sq ft) needs about 3,600 BTU calculated — retail minimums are 5,000–6,000 BTU. A 9,000–10,000 BTU window unit is the practical sweet spot for comfort and dehumidifying.
Window AC Calculator
Window air conditioners are sold in fixed BTU steps — 5,000 through 15,000+ BTU. We calculate your room load so you pick a unit that cools and dehumidifies without short-cycling.
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Bedroom and office sizing
A 10×12 bedroom calculates to ~3,600 BTU but store minimums are 5,000–6,000 BTU. A 9,000–10,000 BTU window unit is the practical sweet spot for most sleeping rooms.
Compare ductless options in our mini-split vs window AC guide — same BTU math, different install and noise.
Fitting the window opening
Rated BTU must match calculated load — do not buy the largest unit that fits the sash. Oversized window units cool fast but leave humidity high.
Related guides
Frequently asked questions
Can a window AC be too big?
Yes. Oversized window units cool fast but leave humidity high. Match rated BTU to calculated load — do not buy the biggest unit that fits the opening.
Window AC vs mini-split BTU — same math?
Room load calculation is the same. Mini-splits are quieter and more efficient but cost more. Use the same BTU result when comparing types.
Related calculators
HVAC Calculators · https://hvaccalculators.net/window-ac-calculator/