Room size → BTU, tonnage & unit type
Enter your room size and conditions to get the cooling BTU, tonnage, and unit type you need — plus a furnace estimate for heating. Works in both imperial and metric.
Cooling needed
2,900 BTU
Recommended unit
5,000 BTU
Tonnage
0.4 ton
Furnace (heating)
6,000 BTU
Best unit type
Window unit or single-zone mini-split
Alternative: Portable AC
Real, widely available units in the Up to 12,000 BTU class. Independent picks — we're not affiliated with any manufacturer or retailer and earn nothing from these links. Always match the unit's BTU to the size above.
Best overall
8,000–12,000 BTU
Window · inverter · U-shape · ~36 dBA · window still opens
The U-shape puts the compressor outside the glass, so it runs about as quiet as a whisper and you can still open the window. Inverter compressor sips power.
Find on AmazonQuietest
8,000–14,000 BTU
Window · dual inverter · Dual-inverter · Wi-Fi · very quiet
LG’s dual-inverter compressor ramps up and down instead of cycling on/off — quieter, steadier temps, and lower running cost than a fixed-speed unit.
Find on AmazonBudget pick
5,000 BTU
Window · fixed-speed · Cheapest way to cool a small room
A no-frills window unit that reliably cools a small bedroom, office, or dorm up to ~150 sq ft for the lowest upfront cost.
Find on AmazonBest value
8,000–12,000 BTU (SACC)
Portable · inverter · No permanent mount · inverter
When a window mount isn’t an option, this inverter portable is one of the few that actually cools like its rating instead of falling short.
Find on AmazonEstimate only, from a simplified ≈20 BTU/sq-ft model with documented adjustments. Confirm with a Manual J load calculation before buying or installing equipment.