Air-Con Running Cost Formula Explained, With Examples
Every air-con running cost result comes from one formula. Once you understand what goes into it, you can sanity-check any figure you are given, whether by an employer, a bank, a teacher or another website.
The formula
kWh = watts ÷ 1,000 × hours; cost = kWh × tariff.
What each input means
- Air-con power (watts): the value you enter in the calculator.
- Hours used per day: the value you enter in the calculator.
- Tariff (cents per kWh): the value you enter in the calculator.
Example
For example, with these inputs:
- Air-con power (watts): 1,200
- Hours used per day: 8
- Tariff (cents per kWh): 30
the calculator returns:
- Monthly kWh: 288 kWh
- Monthly cost: S$86.40
How the result changes
The table keeps the other inputs at their example values and changes air-con power (watts).
| Air-con power (watts) | Monthly kWh | Monthly cost |
|---|---|---|
| 1,200 | 288 kWh | S$86.40 |
| 600 | 144 kWh | S$43.20 |
| 900 | 216 kWh | S$64.80 |
| 1,500 | 360 kWh | S$108.00 |
| 1,800 | 432 kWh | S$129.60 |
Why it matters
Interest rates, instalments and returns compound over years, so a small difference in rate or tenure turns into thousands of dollars. Working the numbers out yourself makes it easier to compare bank offers, avoid expensive debt and plan savings goals.
Inflation erodes buying power, so a savings goal set in today's dollars needs to be adjusted upwards for the years it will take to reach it. Singapore's core inflation has varied widely over the past decade, so it is worth testing a range of rates.
An emergency fund of three to six months of essential expenses protects you from having to borrow at high rates when something unexpected happens. Once that buffer is in place, extra savings can go towards longer-term goals and investments.
Interest in Singapore is quoted in several ways. Mortgages and savings accounts use effective annual rates, while car loans and many personal loans are advertised at flat rates that look much lower than their true cost. Banks must disclose the effective interest rate, and comparing on that basis gives a fair picture.
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Use the Air-Con Running Cost Calculator to plug in your own numbers.
Run your own numbers: Air-Con Running Cost Calculator