Air Conditioner Size Calculator
BTU capacity for a room.
Enter your values
Results update instantly as you type — no submit needed.
Results
- Required capacity
- 6,000 BTU/h
- In tons
- 0.5
- Typical unit to buy
- 1 ton
- Estimated running watts
- 600
- Room area
- 300 sq ft
Quick answer
Start from 20 BTU per square foot, then adjust for sunlight, ceiling height, kitchens and extra occupants.
BTU = area × 20 + adjustments
How to use the Air Conditioner Size Calculator
- 1Measure the room's floor area in square feet.
- 2Enter ceiling height and occupancy.
- 3Adjust for sun exposure and kitchen heat.
Frequently asked questions
Is bigger better?
No — an oversized unit short cycles and leaves the room humid.
What about insulation?
Poorly insulated rooms need 10–20% more capacity.