BTU Calculator for Air Conditioning
This BTU calculator helps you choose the right size of air conditioner for a room. Buying a unit that is too small means it runs non-stop without ever reaching a comfortable temperature, while an oversized unit cools too fast, cycles on and off constantly and wastes energy without properly removing humidity. Just enter the floor area of the room in square meters, how many people usually occupy it, whether it receives strong direct sun and whether it is a kitchen, and the calculator returns the cooling capacity you need — expressed in BTU/h, in frigorías per hour and in approximate kilowatts. It is a fast, practical way to compare split, window and portable air conditioners before you buy, so you can match the equipment to the real needs of the space.
BTU/h needed
Frigorías/h
Approx. kW
Rule-of-thumb estimate. Insulation, ceiling height and the local climate also matter, so the actual figure may vary. When in doubt, pick a slightly more powerful unit.
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How it works
The calculation starts from a common rule of thumb: about 20 BTU per hour for each square foot of floor area. Since the input is in square meters, the area is converted using 1 m² = 10.764 ft², so a room of A square meters needs roughly A × 10.764 × 20 BTU/h as a base figure. That base is then adjusted for the real conditions of the room: if it receives strong direct sunlight the requirement increases by 10%; each person beyond the first two adds 600 BTU/h because bodies release heat; and a kitchen adds a fixed 4000 BTU/h to account for the heat produced while cooking. Finally the result is shown in two more units for convenience: frigorías per hour, where 1 frigoría/h ≈ 0.252 × BTU/h, and kilowatts, where 1 kW ≈ 3412 BTU/h.
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Preguntas frecuentes
- How many BTU do I need per square meter?
- As a rough guide, count on roughly 215 BTU/h per square meter (that is 20 BTU per square foot converted). A 20 m² living room therefore needs around 4300 BTU/h before adjustments for sun, people and heat sources. This calculator applies those adjustments automatically.
- What is the difference between BTU and frigorías?
- Both measure cooling capacity, they are just different units. One BTU/h equals about 0.252 frigorías/h, so a 12000 BTU/h unit is roughly 3000 frigorías/h. Manufacturers in some countries label equipment in frigorías, so it helps to know both figures.
- How do BTU relate to kilowatts?
- Kilowatts (kW) express the same cooling power in the metric system: 1 kW ≈ 3412 BTU/h. So a 12000 BTU/h air conditioner is about 3.5 kW of cooling. This calculator shows the kW value alongside the BTU figure.
- Why add BTU for sun exposure, extra people and a kitchen?
- They all add heat that the air conditioner must remove. A room in full sun gains extra heat through windows and walls, so we add 10%. Each person releases body heat, so every occupant beyond two adds 600 BTU/h. A kitchen adds a fixed 4000 BTU/h for the heat of cooking.
- Is a bigger air conditioner always better?
- No. An oversized unit cools the air quickly but shuts off before removing enough humidity, then cycles on and off frequently. That wastes energy, wears the compressor and leaves the room feeling damp. Sizing the unit to the room, as this calculator does, gives more comfortable and efficient cooling.