Aircon Running Cost Calculator
What does your air conditioner actually cost to run? Put in your own tariff and hours, and see the figure per hour, per day and per month.
Estimated monthly cost
Where the numbers come from
An air conditioner does not consume electricity equal to its cooling output - it moves heat rather than creating cold, which is why it can deliver several kilowatts of cooling for one kilowatt of power. That ratio is the coefficient of performance, and it is the single biggest variable in what you pay.
The calculator converts your unit's BTU rating into kilowatts of cooling, divides by the COP for the unit type you selected to get the electrical draw, then applies a realistic duty cycle. That last step matters: an air conditioner does not run flat out for eight hours. Once the room reaches temperature it either cycles off (fixed speed) or throttles back (inverter), and ignoring that produces wildly overstated figures.
Why inverters cost less to run
A fixed-speed compressor has two states: full output, or stopped. It overshoots the setpoint, shuts down, lets the room drift, then starts again - and motor start-up is the most power-hungry moment in the cycle. Repeat that all day and the waste adds up.
An inverter varies compressor speed continuously. After the initial pull-down it settles at perhaps a third of its maximum output and simply holds the room there. It is quieter, the temperature is steadier, and in typical use it draws substantially less power for the same comfort.
The things that cost you money without you noticing
- A dirty condenser coil. Salt and dust block the fins, head pressure rises, and the compressor works harder for less cooling. This is the quiet one - nothing breaks, it just costs more every hour it runs.
- Blocked filters. Less air across the evaporator means longer run times for the same effect.
- An oversized unit. Short cycling is inefficient and wears the compressor out early.
- Setting 16°C. It does not cool faster. It just runs longer. Each degree lower adds roughly 6–10% to the bill.
- Open doors and windows. Obvious, routinely ignored.
A realistic expectation: these figures are estimates built on sensible assumptions, not a metered measurement. Your actual cost depends on how hot it is outside, how well your building holds temperature, and how disciplined everyone is about doors. Use the number to compare scenarios - inverter versus fixed speed, six hours versus ten - rather than as a billing prediction.
Not sure what capacity you need in the first place? Use the aircon size calculator. If your unit is running more than it should, the troubleshooter may explain why.
What it really costs
How much does it cost to run an aircon in South Africa?
For a typical 12 000 BTU inverter unit running about eight hours a day on a domestic tariff, most households land somewhere in the region of a few hundred rand a month. The spread is enormous though, because tariffs differ, run hours differ, and a neglected unit can draw far more than a clean one for the same cooling.
Put your own tariff and hours into the calculator above rather than trusting a generic figure.
Is an inverter aircon really cheaper to run?
Yes, meaningfully, for anything used regularly. A fixed-speed unit only has two states: flat out, or off. It overshoots, switches off, drifts back, and starts again - and the start-up surge is the most expensive moment in its cycle.
An inverter varies compressor speed to match the actual heat load, so after the initial pull-down it settles at low output and simply holds the temperature. That typically cuts consumption by roughly a third in real use, while also being quieter and more stable.
Does setting a lower temperature cool the room faster?
No. This is probably the most common and most expensive myth about air conditioning. The unit has one cooling output; setting 16 degrees instead of 22 does not make it work harder or faster, it simply means the unit keeps running long past the point where you were comfortable.
Set the temperature you actually want. Each degree lower adds roughly 6-10% to running cost.
What actually makes the biggest difference to running cost?
In order: correct sizing, clean filters and a clean outdoor coil, a sensible setpoint, and closing doors and windows. None of those involve buying anything. A fouled condenser can push consumption up substantially while delivering less cooling, which is why servicing pays for itself rather than being an expense.