Electricity Cost Calculator - What a Device Really Costs
Electricity cost calculator
Applied to the remaining hours of the day.
| Period | Energy | Cost |
|---|---|---|
| Per day | — | — |
| Per month | — | — |
| Per year | — | — |
What this tool does
An electricity bill arrives as a single number, which tells you nothing about where the money went. This page takes it apart one device at a time: watts times hours gives energy, energy times your tariff gives money, and seeing it as a yearly figure changes which habits feel worth changing.
How to use it
- 1 Find the watts on the label, the plug or the manual.
- 2 Estimate honestly how many hours a day it actually runs.
- 3 Enter your tariff from the bill, not a national average.
Typical power for common devices
Use these to sanity check a number, not as a substitute for the label. The ranges are wide because size, age and efficiency class matter more than the category does.
| Device | Typical | Note |
|---|---|---|
| Fridge-freezer | 100–200 W | Runs all year but cycles on and off |
| Electric heater | 1500–2500 W | The most expensive thing in most homes |
| Electric kettle | 1500–3000 W | High power, but only minutes at a time |
| Television | 60–200 W | Screen size matters more than the brand |
| Laptop | 30–90 W | Cheap to run; the charger idles at about 1 W |
Standby is small per hour and large per year
A set-top box drawing 8 W around the clock uses about 70 kWh a year, which is more than a laptop used every working day. That is why the standby field is separate: it applies to the hours the device is not in use, which for most things is the majority of the day.
Watts on the label are the maximum
Anything with a thermostat or a motor spends much of its time below the rated figure. A fridge marked 150 W is not drawing 150 W all day; it runs in bursts. For those devices, use the yearly consumption printed on the energy label if you have it, and treat the watt figure as an upper bound.
Your tariff is not one number either
Bills usually carry a standing daily charge on top of the per-unit price, and many tariffs change by time of day or by consumption band. The standing charge does not depend on this device, so leave it out here; but if you are on a time-of-use tariff, enter the rate for the hours the thing actually runs.