Room Cooling Heat Load Calculator
Estimate how much cooling a room needs. Enter the floor area, then adjust for occupants, sun exposure and a kitchen to see the recommended BTU per hour and tonnage.
How to estimate a room cooling load
- Enter the room floor area in square feet.
- Set how many people regularly use the room.
- Flag a sunny room or a kitchen to add their heat load.
- Read the total BTU per hour and the recommended tons.
Examples
300 sq ft bedroom
300 sq ft, 2 occupants, normal sun, not a kitchen
6,000 BTU per hour, about 0.5 tons
300 sq ft sunny kitchen, 4 people
300 sq ft, 4 occupants, sunny, kitchen
11,800 BTU per hour
Frequently asked questions
How many BTU does a room need per square foot?
This estimate uses the common rule of thumb of 20 BTU per hour per square foot. It is a guideline, not a Manual J load calculation, so treat the result as a starting point.
Why do extra occupants add cooling load?
Each person gives off heat. The rule assumes a baseline of two people, then adds about 600 BTU per hour for every additional occupant.
How much does sun exposure add?
A room with a lot of direct sun gains extra heat. This estimate adds roughly 10 percent of the base load for a sunny room.
Why does a kitchen need more cooling?
Ovens, ranges and other appliances throw off significant heat, so kitchens get about 4,000 extra BTU per hour added to the load.
How many BTU are in a ton of cooling?
One ton of cooling equals 12,000 BTU per hour, so the tool divides the total load by 12,000 to report the recommended tonnage.
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