Aircon (BTU) Calculator
Work out the cooling load in BTU and kW and the recommended air-conditioner size for a room — from its area, ceiling height, sun exposure, and occupants. Free, instant, no sign-up.
Room
Conditions
Your aircon sizing
Cooling load2,70 kW
Cooling load9 212 BTU/hr
Recommended unit12 000 BTU
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Create a free account →How the aircon sizing works
watts = area × 135 × (ceiling ÷ 2.4) × sun_factor + extra_people × 100 BTU/hr = watts × 3.412 unit = round up to the nearest standard size (9k, 12k, 18k, 24k…)
FAQ
- What size air conditioner do I need for a room?
- As a rule of thumb, allow about 135 watts of cooling per square metre for a moderate room at a 2.4 m ceiling, then adjust up for sun exposure, higher ceilings, and extra people. This calculator gives the BTU/kW load and rounds up to the nearest standard unit.
- How do I convert kW to BTU for an aircon?
- Multiply kilowatts by 3,412 to get BTU per hour. So a 2.6 kW room load is about 9,000 BTU — a common small split-unit size.
- What size aircon for a 20 m² room?
- A moderate 20 m² room needs roughly 2.7 kW (about 9,000–12,000 BTU). West-facing, sunny, or high-ceiling rooms move toward the 12,000 BTU end.
- Is this a proper load calculation?
- No — it is a quick sizing estimate. For a precise specification (Manual J or equivalent) an HVAC professional accounts for insulation, glazing, and orientation. Create a free BuilderBuddi account to quote the install.
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