Air Conditioner Size Calculator
Calculate the right air conditioner size for your space.
Base BTU = Area × 20 BTU/sq ft\nAdjust for ceiling > 8 ft: ×1.25\nAdjust for sun: ×0.9 (shaded) or ×1.1 (sunny)\nAdd 600 BTU per person beyond 2\nAdd 4,000 BTU if kitchen\nTonnage = Total BTU ÷ 12,000
Example:\n20 ft × 15 ft = 300 sq ft\n8 ft ceiling, moderate sun, 2 people\n\nBase = 300 × 20 = 6,000 BTU\nNo adjustments needed\nTonnage = 6,000 ÷ 12,000 = 0.5 ton\nRecommended: 0.5 - 1 ton unit
How many BTU do I need per square foot?
Rule of thumb: 20 BTU per sq ft. Adjust for ceiling height, sun exposure, occupants, and appliances.
What is tonnage?
1 ton of cooling = 12,000 BTU/hr. A 2-ton AC removes 24,000 BTU/hr of heat.
Can I oversize my AC?
Oversized units cycle on/off frequently, reducing efficiency and humidity control. Proper sizing is important.
Should I add extra for kitchen?
Yes, add 4,000 BTU for kitchens due to heat from appliances.
What other factors affect sizing?
Insulation quality, window count, climate zone, ductwork, and local building codes. Professional load calculation recommended.
🔗 Related Calculators
📐 Formula
Base BTU = Area × 20 BTU/sq ft\nAdjust for ceiling > 8 ft: ×1.25\nAdjust for sun: ×0.9 (shaded) or ×1.1 (sunny)\nAdd 600 BTU per person beyond 2\nAdd 4,000 BTU if kitchen\nTonnage = Total BTU ÷ 12,000
📝 Example Calculation
Example:\n20 ft × 15 ft = 300 sq ft\n8 ft ceiling, moderate sun, 2 people\n\nBase = 300 × 20 = 6,000 BTU\nNo adjustments needed\nTonnage = 6,000 ÷ 12,000 = 0.5 ton\nRecommended: 0.5 - 1 ton unit
❓ Frequently Asked Questions
How many BTU do I need per square foot?▼
Rule of thumb: 20 BTU per sq ft. Adjust for ceiling height, sun exposure, occupants, and appliances.
What is tonnage?▼
1 ton of cooling = 12,000 BTU/hr. A 2-ton AC removes 24,000 BTU/hr of heat.
Can I oversize my AC?▼
Oversized units cycle on/off frequently, reducing efficiency and humidity control. Proper sizing is important.
Should I add extra for kitchen?▼
Yes, add 4,000 BTU for kitchens due to heat from appliances.
What other factors affect sizing?▼
Insulation quality, window count, climate zone, ductwork, and local building codes. Professional load calculation recommended.