Air Conditioner Size Calculator

Step 1: Calculate Base BTU Requirements

Start with the basic formula: Room Area x 20 BTU per square foot.

• Small bedroom (12' x 10'): 120 sq ft x 20 = 2,400 BTU
• Living room (16' x 20'): 320 sq ft x 20 = 6,400 BTU
• Large room (20' x 25'): 500 sq ft x 20 = 10,000 BTU

Step 2: Apply Room Type Adjustments

Different rooms have different cooling needs:

• Bedroom: Standard (1.0x multiplier)
• Living room: More activity (1.1x multiplier)
• Kitchen: Heat from appliances (1.3x multiplier)
• Bathroom: Moisture and heat (1.2x multiplier)
• Garage: Heat from vehicles (1.5x multiplier)

Step 3: Factor in Additional Heat Sources

Add BTUs for occupants and environmental factors:

• Each person adds 600 BTU
• Heavy sunlight exposure: multiply by 1.2
• Poor insulation: multiply by 1.3
• Hot climate zones: multiply by 1.3

Step 4: Convert to AC Size

Air conditioner sizes are measured in tons (1 ton = 12,000 BTU):

• 6,000 BTU = 0.5 tons (small rooms)
• 12,000 BTU = 1 ton (medium rooms)
• 18,000 BTU = 1.5 tons (large rooms)
• 24,000 BTU = 2 tons (very large rooms)

Bedrooms

Bedrooms typically need standard cooling (20 BTU per sq ft). Consider if it's a master bedroom with more occupants or if you prefer cooler sleeping temperatures. Add 600 BTU per regular occupant.

Living Rooms and Family Rooms

These spaces see more activity and often have electronics that generate heat. Increase BTU requirements by 10% and account for the typical number of people using the space.

Kitchens

Kitchens generate significant heat from appliances, cooking, and often have poor ventilation. Increase BTU requirements by 30% minimum. Consider adding extra capacity if you cook frequently.

Home Offices

Computer equipment and monitors generate heat. Account for all electronics that will be running during work hours. Good insulation is especially important for consistent comfort.