Aircon Size Calculator
What capacity does your room actually need? Adjust the sliders and get an answer in BTU and kW - with the sun, glazing and ceiling height accounted for.
Recommended capacity
How this calculation works
Sizing an air conditioner is really a heat-load problem: how much heat enters the room, and how fast must it be removed to hold a comfortable temperature on a hot day?
The starting point of roughly 600 BTU per square metre assumes a reasonably insulated room, average window area, a 2.4 m ceiling and normal occupancy. Every one of those assumptions can be wrong in your building, which is why the calculator layers adjustments on top.
Ceiling height
You cool a volume of air, not a floor. At 3 m the same floor plan holds 25% more air than at 2.4 m. Double-volume lounges and converted warehouse spaces are routinely under-specified because somebody sized from floor area alone.
Orientation and sun
This matters more in Gqeberha than people expect. A west-facing room takes the full afternoon sun exactly when the outside air is already at its hottest, so the unit is fighting peak solar gain and peak ambient temperature simultaneously. The same room facing south is a materially easier problem.
Glazing
Glass is a poor insulator and an excellent solar collector. A full-height slider onto a west-facing patio can add a third again to the cooling load of a room. Shading, films and thermally broken frames all help, but the glass still has to be accounted for.
Internal heat gain
Everything electrical in the room eventually becomes heat in the room. Ovens, servers, display lighting, gym equipment and people all contribute. A busy shop floor with spotlights and a dozen customers is a very different load to an identically sized empty storeroom.
What this tool cannot do: it cannot see your insulation, your roof colour, whether your ceiling void is vented, or how long your pipe run will be. Treat the result as a sanity check on quotes you receive - if a contractor proposes something far below it, ask them to show their calculation.
Common room sizes in Gqeberha homes
| Room | Typical area | Usual capacity |
|---|---|---|
| Second bedroom | 9–12 m² | 9 000 BTU |
| Main bedroom | 14–20 m² | 12 000 BTU |
| Lounge | 22–30 m² | 18 000 BTU |
| Open-plan living | 35–45 m² | 24 000 BTU |
| Small office / consulting room | 12–18 m² | 12 000 BTU |
| Shop floor | 50 m²+ | Ducted, cassettes or VRF |
Try the running cost calculator next to see what that capacity will cost you each month, or read more about how we install and size systems.
What people ask about capacity
How many BTU do I need per square metre?
Around 600 BTU per square metre is a sensible starting point for a well-insulated room with average sun exposure and a standard 2.4 m ceiling. That figure then has to be adjusted, sometimes heavily. A west-facing lounge with a full-height glass slider can need 40-50% more than the same room facing south with small windows.
The calculator above applies those adjustments for you, but a formal heat-load calculation on site is still the only way to be certain.
Is it better to buy a bigger unit to be safe?
No, and this is the most expensive misconception in the industry. An oversized air conditioner cools the air quickly, satisfies the thermostat, and switches off before it has removed any moisture. You get a cold, clammy room, a compressor that short-cycles itself to an early grave, and a higher electricity bill than a correctly sized unit would have produced.
Correct sizing means the unit runs longer at lower output, which is both more comfortable and cheaper.
Does ceiling height really matter?
Yes, because you are cooling a volume of air, not a floor. A room with a 3 m ceiling holds 25% more air than the same floor area at 2.4 m, and needs capacity to match. Double-volume spaces and converted warehouses catch people out constantly for exactly this reason.
What about kitchens and rooms with equipment in them?
Every appliance that uses electricity ultimately turns it into heat in the room. A commercial kitchen, a server cupboard, a gym or an office with a dozen workstations all carry significant internal heat gain on top of the building load. Set the room use accordingly in the calculator, and tell us about the equipment when we survey.