The cost to run anything electrical comes down to one line: watts, times hours, times your rate. Get the wattage off the rating plate, decide how many hours a day it runs, and multiply by what you pay per kWh. Here is the method — and where the money actually goes.
The formula
Cost = watts ÷ 1,000 × hours × rate ($/kWh). The watts ÷ 1,000 turns watts into kilowatts; multiply by hours for the energy in kWh, then by your rate for the cost.
Example: a 2,000 W heater running 4 hours a day uses 2,000 ÷ 1,000 × 4 = 8 kWh. At $0.15/kWh that is $1.20 a day, about $36 a month.
| Appliance | Typical power | 1 hr/day @ $0.15 |
|---|---|---|
| LED TV | 100 W | ~$0.45 / month |
| Fridge (cycling) | ~150 W average | ~$16 / month (runs all day) |
| Space heater | 2,000 W | ~$9 / month |
| Water heater | 3,000 W | ~$14 / month |
Appliance Running Cost Calculator
Pick appliances or enter watts, set hours and your rate, and total the cost per day, month and year.
Finding an appliance’s wattage
Check the rating plate or manual — it shows watts, or amps and volts (watts = amps × volts). One catch: thermostat-controlled appliances like fridges, irons and heaters cycle on and off, so their average draw is well below the plate figure. The plate is the peak, not the running average.
Where the money goes
Anything that makes heat and runs for long periods dominates the bill: water heaters, space heaters, tumble dryers, ovens and pool pumps. Electronics are individually small but run all day — and standby losses across a whole house commonly add up to 5–10% of the bill on their own.
Why the real bill differs
Cycling appliances average less than their rated watts, usage hours swing with the season, and many tariffs are tiered or time-of-use rather than one flat rate. Treat the result as a solid comparison tool — which appliance is worth replacing or rescheduling — rather than a bill prediction. To pin down a suspect appliance exactly, put a plug-in energy meter on it for a week.