Electricity cost calculator
Take the wattage from the label, say how long it runs, and add your tariff. Standby draw is counted separately, because it runs for the other twenty-odd hours a day and is where the surprises are.
- Cost per year
- $1,135.68
- Cost per day
- $3.111
- Cost per use
- $3.120
- Energy per year (kWh)
- 873.6
- Share from standby
- 0.0 %
- Standby cost per year
- $0.00
The formula
kWh = watts × hours ÷ 1000, and cost = kWh × tariff. Standby energy uses the remaining hours of the week, so the yearly figure is (active kWh + standby kWh) × 52.
Worked example
A 1,200 W appliance used two hours a day, seven days a week, at 1.30 per kWh: 94.64 a month and 1,135.68 a year, from 873.6 kWh.
How to use it
- 1The wattage is on the rating plate or in the manual. Where a range is given, use the higher figure for a heating element and the lower for a motor.
- 2Find the per-kWh price on your bill, including any standing charge spread over your usage if you want the true marginal cost.
- 3Measure standby with a plug-in energy monitor if you can. Guessing understates it more often than not.
Questions people ask
Is standby power really worth worrying about?
Collectively, yes. A single device at 15 W costs over 170 kWh a year — more than a kettle boiled twice daily. Across a household of set-top boxes, chargers and speakers it adds up to a noticeable share of the bill.
Why is my bill higher than this suggests?
Because this covers one appliance. Heating, hot water and refrigeration usually dominate a bill, and tariffs often have a standing charge and tiered or time-of-day rates on top.
Last reviewed: 2026-10-20