BTU Calculator
Calculate how many BTUs of cooling your room needs. Factors in room size, ceiling height, insulation, sun exposure, occupants, and kitchen heat to recommend the right air conditioner or mini split size.
Frequently Asked Questions
How many BTUs do I need per square foot?
Plan on roughly 20-25 BTU per square foot for cooling a room with standard 8-foot ceilings. A 300 sq ft bedroom needs about 6,000-7,000 BTU, while a 500 sq ft living area needs 10,000-12,000 BTU. Poor insulation, tall ceilings, and strong sun push you toward the high end.
What happens if my air conditioner is too big?
An oversized AC cools the air quickly but shuts off before it dehumidifies, leaving the room cold and clammy. It also cycles on and off constantly, which wastes energy and wears out the compressor. Match the BTU rating to the room instead of buying the biggest unit available.
What size mini split do I need?
Use the same BTU math as any AC: room square footage times 20-25 BTU, adjusted for insulation and sun. Common mini split sizes are 9,000, 12,000, 18,000, and 24,000 BTU. Pick the size at or just above your calculated load — mini splits modulate down efficiently but cannot exceed their rating.
How many BTUs is a ton of air conditioning?
One ton of cooling equals 12,000 BTU per hour. So a 2-ton central AC delivers 24,000 BTU/hr, enough for roughly 1,000-1,200 sq ft in an average home. Central systems for whole houses typically run 2 to 5 tons.
Related Calculators
Ready to See These Colors in Your Room?
Upload a photo of your room and see it transformed with AI. Try different colors, styles, and layouts - get instant results.
Try AI Room Designer - FreePlanning a bigger redesign? Get free AI design advice →