What Size Portable Air Conditioner Do I Need? BTU Sizing Guide
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For most rooms, you need about 10,000 BTU (ASHRAE) of portable air conditioning per 300 square feet, 12,000 BTU for 400 square feet, 13,000 BTU for 500 square feet, and 14,000 BTU for spaces up to 600 square feet. Here is the full sizing method Whynter uses across its lineup.
Quick Sizing Table
| Room Size | BTU (ASHRAE) | Whynter Models |
|---|---|---|
| Up to 300 sq ft | 10,000 | ARC-102CS |
| Up to 350 sq ft | 11,000 | ARC-110WD |
| Up to 400 sq ft | 12,000 | ARC-122DS, ARC-12SD |
| Up to 450-500 sq ft | 12,000-13,500 | ARC-0850XP, ARC-1280WX, ARC-1050XP |
| Up to 500 sq ft | 14,000 | ARC-14S, ARC-147WF |
| Up to 600 sq ft | 14,000 (inverter) | ARC-1230WN, ARC-1230WNH |
Adjust for Your Room's Conditions
Square footage is the starting point. Size up one step when the room has high ceilings (over 8 feet), large sun-facing windows, a kitchen with heat-producing appliances, or more than two regular occupants. Size up for open floor plans where cool air spreads into connected spaces.
Why Bigger Is Not Always Better
An oversized unit cools the air faster than it removes moisture, leaving the room cold but clammy, and it cycles on and off more, wasting energy. Match the rating to the room, then let features like inverter compressors and dehumidifier modes handle the rest.
Dual Hose Helps at Every Size
Dual hose models cool faster at the same BTU rating because they avoid negative room pressure. Read our full dual hose vs single hose comparison.
Frequently Asked Questions
What does BTU mean?
British Thermal Units per hour, a measure of how much heat the unit removes. Higher BTU means more cooling capacity.
Why do I see two BTU numbers on the same unit?
ASHRAE is the traditional lab rating. SACC is a newer standard adjusted for real-world conditions. Read our ASHRAE vs SACC explainer.
Can one portable AC cool my whole apartment?
One unit cools one zone. For open plans up to 600 square feet, the ARC-1230WN has the largest coverage in the Whynter line.
Compare every model in the portable air conditioner collection.