Air Conditioner BTU Calculator
Estimate room air conditioner capacity from room area, occupancy, and sun exposure.
Room details
Room area: 180 ft²
Each room is estimated separately. Combined capacity is the sum of the room estimates, not a central-AC Manual J load calculation.
YOUR ESTIMATE
Estimated cooling capacity
9,000BTU/h
Refrigeration tons0.75 ton
Cooling capacity2.64 kW
Total area180 ft²
Calculation breakdown
Use this as an initial room-AC estimate, not a substitute for a professional cooling-load calculation.
How to Use the Calculator
- Select Single Room or Whole Home.
- Choose US or Metric units and enter each room’s dimensions.
- Select room type, typical occupancy, and sun exposure.
- For Whole Home, add each conditioned room to see a combined room-AC capacity estimate.
How It Works
The calculator starts with a room-area sizing range based on ENERGY STAR’s published room-air-conditioner guidance, then adjusts the estimate for sun exposure, additional occupants, and kitchen use. It also converts the result to refrigeration tons and kilowatts. In Whole Home mode, the room estimates are added together.
Assumptions and Limitations
- Base capacity uses ENERGY STAR’s published room-air-conditioner sizing table. It is a screening estimate, not a room-by-room engineering load calculation.
- Heavy shade reduces the base capacity by 10%; very sunny exposure increases it by 10%; each regular occupant above two adds 600 BTU/h; kitchens add 4,000 BTU/h.
- The published room-AC chart assumes a typical room with an 8-foot ceiling. Higher ceilings trigger a caution but no numerical ceiling-height adjustment.
- Whole Home sums the estimated capacity for separate room AC units. It must not be used to size one central HVAC system; central systems generally require a detailed load calculation such as ACCA Manual J.
- Actual capacity needs vary with climate, windows, insulation, air leakage, ventilation, equipment, and room layout. Check manufacturer guidance and consult a qualified HVAC professional when needed.
