Energy

Electricity Appliance Cost Calculator

Wattage on a label means very little until it meets your tariff and your habits. Enter both and see what a specific appliance adds to your electricity bill.

What this calculator does

Converts an appliance wattage, the number of units, hours of daily use and days per month into kilowatt-hours consumed and a monthly and yearly cost at your electricity tariff.

How to interpret the result

The monthly cost is what that appliance adds to your bill at your usage pattern. Compare it across your appliances: the two or three largest usually explain most of your consumption, so they are the ones worth changing first.

Assumptions

• The appliance draws its rated wattage whenever it is on.
• Your price per kWh stays constant (no tiered or time-of-use pricing).
• Days used per month reflects your typical usage, not a peak month.

Limitations

• Cycling devices such as fridges and heaters are overestimated if you enter 24 hours — use roughly a third of the day.
• Standing charges, taxes and always-on devices are not captured per appliance.
• Standby draw is small per device but adds up across a household and is not modelled here.

How it works

Wattage multiplied by the number of appliances and hours per day, divided by 1,000, gives daily kilowatt-hours. That is multiplied by days used per month for monthly consumption, then by your price per kWh for the cost. The yearly figure is twelve monthly bills.

Worked example

A 1,200 W appliance used four hours a day is 4.8 kWh daily and 144 kWh a month. At 0.28 per kWh that is about 40.32 a month, or roughly 484 a year.

How to use it

1. Find wattage on the rating plate or in the manual; use the running figure, not peak.
2. For appliances that cycle, such as fridges, estimate effective hours at roughly a third of the day.
3. Take your price per kWh from a recent bill including standing charges where possible.
4. Use Reset between appliances to avoid mixing values.

Factors to consider

• Heating and cooling devices dominate bills because they combine high wattage with long runtimes.
• Standby draw is small per device but continuous across a household.
• Tiered or time-of-use tariffs mean your marginal rate may be higher than your average rate.

Useful for

• Finding which appliance contributes most to your bill before replacing it.
• Estimating the running cost of a new appliance before buying.
• Comparing an old device against an efficient replacement over a year.

Frequently asked questions