BTU for Room Cooling Calculator
BTU/hr needed = ft² × climate factor (20-30 BTU/ft² for typical US climates).
Result
BTU/hr needed
6,250
0.52 tons of cooling.
- Area250 ft²
- Climate factor25 BTU/ft²
- Base BTU/hr6250
- Extra occupants0
- Total BTU/hr6,250
- Tons0.52
Step-by-step
- Base = 250 × 25 = 6250 BTU/hr.
- Add 600 per extra occupant: 0.
- Total = 6,250 BTU/hr (0.52 tons).
How to use this calculator
- Enter room area.
- Pick climate / sun exposure.
- Add extra occupants beyond 2.
About this calculator
Room AC sizing follows the rule of thumb: 20-30 BTU per ft², adjusted for sun exposure, insulation, and occupants. Window units are typically 5-25k BTU/hr; central AC is sized in tons (1 ton = 12,000 BTU/hr). Oversizing causes short-cycling and poor humidity control; under-sizing means the unit runs constantly.
Frequently asked
Hotter / sunnier rooms need more cooling per ft². A south-facing room with big windows: 30+ BTU/ft². A shaded interior: 20 BTU/ft².
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