Room AC Tonnage Calculator
Calculate the perfect air conditioner size for your room based on dimensions, climate, and usage patterns
Room Details
How AC Tonnage is Calculated
AC tonnage refers to the cooling capacity of an air conditioner. One ton equals 12,000 BTU per hour of cooling. The calculation considers multiple factors to determine the right size for your room.
Calculation Formula
Step 1: Base BTU = Area (sq ft) × 20 BTU per sq ft
Step 2: Adjust for climate (×0.9 to ×1.3)
Step 3: Add sun exposure (0 to 10 BTU per sq ft)
Step 4: Add occupants (600 BTU per person)
Step 5: Add appliance load (0 to 4,000 BTU)
Final: Tonnage = Total BTU ÷ 12,000
Important Factors
- Room Size: Larger rooms require more cooling capacity
- Climate: Hotter regions need 20-30% more cooling power
- Sun Exposure: South and west-facing rooms heat up more
- Occupancy: Each person adds approximately 600 BTU of heat
- Appliances: Electronics and appliances generate heat
- Insulation: Poor insulation increases cooling requirements
- Ceiling Height: Higher ceilings require more capacity
AC Selection Tips & Best Practices
Sizing Considerations
- • Never oversize - wastes energy and money
- • Undersizing means inadequate cooling
- • Round up to nearest 0.5 ton increment
- • Consider future heat load changes
- • Check ceiling height impact
Energy Efficiency
- • Look for high SEER ratings (14+)
- • Inverter ACs save 30-50% energy
- • Use programmable thermostats
- • Maintain proper insulation
- • Regular filter cleaning essential
Installation Tips
- • Hire certified HVAC professional
- • Ensure proper ductwork sizing
- • Install in shaded outdoor location
- • Seal all air leaks first
- • Consider room layout and airflow
Frequently Asked Questions
What does 1 ton AC mean?
One ton of air conditioning capacity equals 12,000 BTU per hour of cooling. The term originates from the amount of cooling provided by melting one ton of ice in 24 hours. A 1-ton AC can cool approximately 100-120 square feet in moderate climate conditions.
What happens if I buy an oversized AC?
An oversized AC cools the room too quickly without properly removing humidity, leading to a cold but clammy environment. It also cycles on and off frequently, wasting energy, increasing wear on components, and raising electricity bills. Always size your AC correctly for optimal comfort and efficiency.
How much area can a 1.5 ton AC cool?
A 1.5 ton AC (18,000 BTU) typically cools 150-180 square feet in moderate climates with standard ceiling height (8-10 feet). However, this varies based on climate zone, sun exposure, insulation quality, occupancy, and heat-generating appliances. Use our calculator for a personalized recommendation.
Should I consider ceiling height when choosing AC tonnage?
Yes, absolutely. Standard calculations assume 8-10 feet ceilings. If your ceiling is higher (12+ feet), you need additional cooling capacity because there's more air volume to cool. Add approximately 10-15% more capacity for very high ceilings or consider our calculator which factors in room volume.
What's the difference between BTU and tonnage?
BTU (British Thermal Unit) measures the amount of heat energy needed to raise one pound of water by 1°F. Tonnage is simply BTU divided by 12,000. For example, 18,000 BTU = 1.5 tons, 24,000 BTU = 2 tons. Both measure cooling capacity but tonnage is more commonly used in residential AC sizing.
How can I reduce my AC size requirement?
Improve insulation, seal air leaks, install reflective window film or curtains, use ceiling fans, shade outdoor AC units, and minimize heat-generating appliances. Better insulation can reduce cooling needs by 20-30%, allowing you to use a smaller, more efficient AC unit and save on energy costs.
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