How much does it cost to run a microwave? (Australia)

Using the Australian average of 48.69c/kWh — the Australian Energy Regulator, the 2026–27 Default Market Offer, from 1 July 2026.

The 1,200 W here is what the microwave DRAWS, not the 900 W of cooking power on the front of it. The detail below explains why those are different numbers.

What drives the cost

The number on the front of a microwave is not the number on the meter. A microwave sold as 900 W delivers 900 W of cooking power into the food, but draws more like 1,200 to 1,400 W from the wall to do it, because the magnetron and its transformer are not perfectly efficient. That is why the wattage here is the higher figure — the label people quote is the output, and the bill is charged on the input.

Even so, a microwave is one of the cheapest ways to heat food, because it puts the energy into the food rather than into the air, the dish and the oven walls. Reheating a plate for three minutes costs a fraction of a penny. Compare it against the electric oven page: for anything small, the oven's twenty-minute preheat costs more than the entire microwave cycle.

How this is worked out

Electricity is billed per kilowatt hour. An appliance's kilowatt hours are its power in kilowatts multiplied by the hours it runs — so a 2,000 W appliance running for 30 minutes uses 1 kWh. Multiply that by your unit rate and you have the cost. The standing charge is not included here because you pay it whether or not you switch anything on.

What this assumes

The appliance draws its rated power for the whole time it is on. Anything thermostatically controlled — ovens, heaters, fridges — cycles on and off, so the real figure is lower.
Your unit rate stays flat all day. On a time-of-use tariff the same appliance costs materially different amounts depending on when you run it.
A year is 52 weeks of identical use, which overstates seasonal appliances and understates ones you use in bursts.
The rate filled in for you is an average that spreads fixed charges across a year's usage, so it sits above what one extra unit really costs. Entering the unit rate from your own bill gives a closer answer.

Questions

Why does my microwave say 900 W but use 1,400 W?

Because those measure different things. The 900 W is cooking power — the energy actually delivered into the food. The higher figure is what the appliance draws from the socket, and the difference is lost as heat in the magnetron and transformer. The rating plate on the back gives the input figure, which is the one your meter sees.

Is a microwave cheaper than an oven?

For small quantities, dramatically. An oven has to heat a large insulated box and everything in it before the food gets warm, and most of that heat is thrown away when the door opens. A microwave heats the food and almost nothing else. For a full roast the oven wins, because a microwave cannot do the job at all — but for reheating, it is not close.

Does this include the standing charge?

No, and deliberately. The standing charge is a fixed daily fee for being connected at all, so it does not change when you run an appliance more or less. Including it would make every appliance look more expensive than it is.

Where do I find the wattage?

On the rating plate — usually a sticker on the back, base or inside the door — or in the manual. It is written as W or kW. If it only quotes amps, multiply amps by 230 to get watts.

Why is my bill higher than the total this gives?

Because this prices one appliance. Heating, hot water and the constant background draw of everything left plugged in usually make up more of a bill than the appliances people think to check.

Sources

Ofgem — price cap unit rates — checked 2026-08-21
Energy Saving Trust — quick tips to save energy — checked 2026-08-21

Rates from AER for the 2026–27 Default Market Offer, from 1 July 2026. Last reviewed 3 September 2026.

How much does it cost to run a microwave?

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