Cooling capacity calculator
With the load per square metre visible, so you can adjust it.
Your inputs
Your inputs are processed on your device and are not sent to a server.
Example loaded. You can change any value.
There is no figure yet: nothing is calculated until you ask for it.
- Enter your measurements.
- Check the units and the assumptions.
- Press Calculate, or load the example.
Rather see a worked case? Press “Load example” and change any value afterwards.
Next step
The room-by-room breakdown explains where every watt of that capacity comes from.
Where each number comes from Conversion constants are exact; densities and coverage rates come from cited sources; everything else is an assumption you can change. Methodology · Sources and updates
How to use it
- Choose whether you start from floor area or from a known heat load.
- If you use area, check the specific load per m2 or per m3.
- The result gives frigories, BTU/h and kW at once.
- It includes the nearest commercial size.
How it is calculated
This is the transparent version of sizing: instead of breaking the load into components, it starts from a specific load you can see and change.
Dwellings typically run 80 to 120 W/m²: the low end for well-insulated, shaded rooms or mild climates, the high end for top floors, south and west orientations or harsh summers.
A frigorie is simply a kilocalorie per hour, exactly 1.163 W. It is widely used in Spain and Latin America, while the English-speaking world talks in BTU/h and tons.
Worked example
A 215 sq ft room with a specific load of 100 W/m²:
- Power: 20 m² x 100 = 2,000 W
- Frigories: 2,000 / 1.163 = 1,720 frigories/h
- BTU/h: 2,000 x 3.412 = 6,824 BTU/h
- Commercial size: 9,000 BTU/h
Good to know
- This is a guideline estimate. A professional heat-load calculation considers the real build-up of every wall and roof, thermal bridges, infiltration, humidity and hour-by-hour climate data.
- Load per square metre is not universal. A top-floor room under an uninsulated roof and a sheltered middle floor have nothing in common, however similar their size.
- Ceiling height matters. Above about 9 ft, calculate by volume rather than by area.
- Capacity is not consumption. The BTU/h, frigories or kW on a label measure the heat the unit removes from the room, not the electricity it uses. For that you need the efficiency rating or the rated input power.
Frequently asked questions
How much cooling capacity do I need per square foot?
At a typical 100 W/m² load, about 32 BTU/h per square foot. The usual domestic range is 25 to 38 BTU/h per square foot.
What exactly is a frigorie?
One kilocalorie per hour of cooling power, equal to 1.163 W. It measures cooling output, not electricity consumption.
How many frigories is 3,000 W?
2,580 frigories/h, since 3,000 divided by 1.163 gives that figure. In BTU/h it is 10,236.
Which load per square metre should I use?
80 W/m² for well-insulated, shaded rooms; 100 W/m² as a middle value; 120 W/m² for top floors, west-facing rooms or very hot summers.
This calculator or the sizing one?
This one if you want to see and adjust the specific load directly. The sizing one if you would rather it was built up from insulation, windows, people and appliances.