Garden Appliance running cost calculator
A space heater bought for $40 can burn through more than that in electricity in a month. Wattage is printed on almost every appliance, usually on a plate near the plug or on the back, and turning it into an annual figure takes one multiplication that manufacturers rarely do for you.
How this is calculated
kWh per day = watts × hours ÷ 1,000. Cost = kWh × your rate per kWh, multiplied up by days of use per year.
Source: US average residential electricity price from the EIA Electric Power Monthly
Worth knowing: Wattage on the plate is the maximum draw, not the average. Anything that cycles on a thermostat — a fridge, a space heater, an air conditioner — spends much of its running time off, so real consumption is often half the plate figure or less. For those, a $20 plug-in energy monitor gives you a true number rather than a worst case.
Common questions
Where do I find the wattage?
Usually on a rating plate on the back or underside, near where the cord enters. It may be given in watts directly, or as volts and amps — multiply those together to get watts. Failing that, the manual or the manufacturer spec page will list it.
Why is my real bill lower than this?
Because most appliances do not run at full power continuously. Anything thermostatically controlled cycles on and off, so a 1,500 W heater set to maintain a comfortable room might only draw full power a third of the time. This calculation gives you the figure for continuous running, which is the honest worst case.
What is a kilowatt-hour?
One thousand watts drawn for one hour. A 1,000 W appliance run for an hour uses exactly 1 kWh; a 100 W one run for ten hours uses the same. It is the unit your utility bills you in.
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