How to Size an Air Conditioner by Room Area
Cooling capacity (W) = room area (m2) x load factor. For wood-frame homes use about 220 W/m2: a 20 m2 room (about 12 tatami) needs 20 x 220 = 4400 W. Heating uses about 130 W/m2.
Open the interactive Everyday Lifestyle tool →Cooling formula: W = area m2 x 220
Key facts
| Cooling formula | W = area m2 x 220 |
|---|---|
| Cooling load (wood) | 220 W/m2 |
| Heating load | 130 W/m2 |
| 20 m2 cooling | 4400 W |
| 20 m2 heating | 2600 W |
Frequently asked questions
What size AC for a 20 m2 room?
About 4400 W of cooling capacity for a wood-frame room: 20 x 220 W/m2.
How much for heating?
About 2600 W for the same 20 m2 room: 20 x 130 W/m2.
Does insulation change this?
Yes. Better-insulated or RC buildings need less; these factors assume average wood-frame homes.
Related pages
Air Conditioner Size by Room is part of Everyday Lifestyle on GOAT Lab — a free reference you can use without signing up, and it works offline. Open the tool above for any custom value.
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