ROOM AC SIZE 🇺🇸 US
What size AC
does your room need?
Type your room size — get the capacity band stores use. No sign-up, nothing leaves this page.
Room size
Fine-tune (sun, kitchen, people)
People2
Your room needs4,500–5,500 BTU/hr20 BTU per sq ft rule (ENERGY STAR) ±10% ·
reference only — why?
Ceiling height, insulation and climate shift the real need — use this as a shortlist range, not an installation spec.What to buy for this room 🇺🇸 US market basis
Room ACs sell in fixed label sizes — the bold number below is what to look for on the box.
MOST COMMON PICK
Window unit the American standard for one room
Buy the 6,000 BTU size — the smallest label that covers your 4,500–5,500 BTU/hr need (sold as "up to ~250 sq ft")
Midea · GE · LG≈ $21/mo rated
Portable if a window unit can't go in
Buy 8,000 BTU — one label size up, because portables cool below their sticker number
wheels + window vent kit · priciest to run≈ $33/mo rated
Mini-split permanent · quietest
The smallest sold size, 9,000 BTU, already covers this room — all-inverter tech: most efficient per BTU, quietest, and real bills land below the rated pill because it modulates; needs professional install
for owners, not renters≈ $24/mo rated
Sizes & room coverage as sold on Amazon US · checked 2026-07-19
Run-cost pills = that label's rated draw, 8 h/day at 17¢/kWh (US average); real use lands below — tune yours in Running cost →
Run-cost pills = that label's rated draw, 8 h/day at 17¢/kWh (US average); real use lands below — tune yours in Running cost →
Make sense of the numbers
What's a BTU, actually?
BTU (British Thermal Unit) is how American AC power is labeled. An AC's BTU/hr number says how much heat it can pull out of a room every hour — so a bigger or sunnier room needs more BTU. As a feel: a small bedroom sits around 5,000 BTU, a living room around 8,000–12,000. Too few BTU and the room never cools; way too many and it cools so fast the air stays damp and clammy.