Enter Room Details

Standard height is 8-9 ft (2.4-2.7 m)
Recommended AC Capacity
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Enter room details to calculate
Room Area
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BTU/h
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Tons
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kW
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Why Proper AC Sizing Matters

Choosing the right air conditioner size is crucial for comfort, efficiency, and cost savings. An undersized unit won't cool effectively and will run constantly. An oversized unit will short-cycle, wasting energy and failing to dehumidify properly.

Base BTU = Room Area (sq ft) × 20 BTU/sq ft Adjusted BTU = Base BTU × Climate × Insulation × Sun × Occupancy Tons = Total BTU ÷ 12,000 kW = Tons × 3.517

Base Factor: 20 BTU/sq ft for standard 8-ft ceilings

Climate: 0.9 (cool) to 1.2 (hot/humid)

Insulation: 0.9 (excellent) to 1.1 (poor)

Occupancy: +600 BTU per person beyond 2

AC Capacity Reference Chart

Quick reference for common room sizes (standard 8-ft ceilings, average conditions):

Room Size (sq ft) Room Size (m²) Recommended BTU Tons Typical Use
100-150 9-14 5,000 BTU 0.4 tons Small bedroom, office
150-250 14-23 6,000 BTU 0.5 tons Medium bedroom, living room
250-300 23-28 7,000 BTU 0.6 tons Large bedroom, small living room
300-400 28-37 9,000 BTU 0.75 tons Master bedroom, open plan
400-550 37-51 12,000 BTU 1.0 ton Large living room, studio
550-700 51-65 14,000 BTU 1.2 tons Open floor plan, small apartment
700-1,000 65-93 18,000 BTU 1.5 tons Large apartment, small house
1,000-1,200 93-111 21,000 BTU 1.75 tons Medium house section
1,200-1,400 111-130 24,000 BTU 2.0 tons Large living area

Energy Efficiency Tips

Maximize AC Efficiency
  • Right Size Matters: Properly sized AC uses 20-30% less energy than oversized units
  • Seal Leaks: Weatherstrip doors/windows to prevent cool air loss
  • Use Ceiling Fans: Circulate air to feel 4°F cooler, allowing higher thermostat setting
  • Close Blinds: Block direct sunlight to reduce cooling load by 10-30%
  • Maintain Filters: Clean filters monthly for optimal airflow and efficiency
  • Set Smart Thermostat: 78°F (26°C) when home, higher when away saves 10% per degree
  • Consider Inverter AC: Variable-speed compressors use 30-50% less energy than fixed-speed
  • Professional Installation: Proper refrigerant charge and duct sealing boost efficiency 15-20%

Why Use This Calculator?

Guessing AC size leads to discomfort and wasted money. Our calculator uses industry-standard Manual J principles to estimate your cooling needs based on room characteristics, climate, and usage patterns. Use these results to compare AC models and get accurate quotes from HVAC professionals.

Learn More About AC Sizing

Master AC selection, understand SEER ratings, and optimize your cooling system with our comprehensive AC Sizing Guide — includes Manual J basics, efficiency tips, and installer questions! 📚

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