How we calculate running costs

Every cost on this site comes out of the same three-line sum. We publish it here so you can check our working, or redo it with your own numbers.

The sum

Kilowatt-hours × your usage rate = cost.

More precisely, for any appliance:

1. Take its average draw in watts and divide by 1,000 to get kilowatts.
2. Multiply by the hours it actually runs.
3. Multiply by your usage rate in dollars per kilowatt-hour.

A 2,400W kettle boiling for three minutes draws 2.4 kW × 0.05 h = 0.12 kWh. At the New South Wales reference rate of 33.14c, that is about 4c a boil. Do that four times a day and it is roughly $58 a year.

Where the prices come from

We use 2026-27 reference prices: the regulated default offer in the places that have one, and the dominant retailer’s standard residential plan everywhere else.

• New South Wales, south-east Queensland and South Australia: the Australian Energy Regulator’s Default Market Offer.
• Victoria: the Victorian Default Offer, averaged across its five zones.
• Western Australia, Tasmania, the ACT and the Northern Territory: the standard residential plan of the dominant retailer, because no competitive default is set.

These are deliberately conservative choices. The default offer is a cap, so a household on a sharp market offer pays less than our figures, and one on an old legacy plan can pay more.

What our numbers deliberately exclude

• The daily supply charge. It runs from 62c to $1.92 a day depending on where you live, and you pay it whether you switch anything on or not. Including it in an appliance’s cost would be double-counting, so we keep it separate - and we have a whole article about what it does to your bill.
• Time-of-use and demand tariffs. If your rate changes by the hour, running something at 2pm and at 6pm cost different amounts. Our figures use flat rates.
• Solar. A kilowatt-hour you generated yourself costs you nothing to use, so anything you run in the middle of a sunny day is cheaper than we say.
• Controlled load. Hot water and pool pumps are often on a separate, cheaper circuit. Where that is usual, the article says so.

What we cannot know

We do not know your plan, your tariff type, your appliance’s age, how well your house holds heat, or what the weather did last week. Our appliance wattages are mid-range figures for common Australian models, not your model. The label on your unit and the rates on your bill always beat our table.

What we can do is show the arithmetic, keep the prices current, and be specific about the assumptions. If a number here is wrong, tell us and we will fix it.