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Calculate how much it costs to run an appliance based on wattage, usage, and your electricity rate.
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Daily Cost
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Convert watts to kilowatts by dividing by 1,000, multiply by hours used per day and your electricity rate to get daily cost, then multiply by 30 or 365 for monthly or annual cost.
Daily Cost = (Watts ÷ 1,000) × Hours Used × Rate per kWh
Wattage measures the rate of power an appliance draws while running, while a kilowatt-hour (kWh), the unit utilities bill by, represents 1,000 watts used for one hour. Converting an appliance's wattage into a kWh-based cost requires accounting for both how much power it draws and how long it runs, since a high-wattage appliance used briefly can cost less than a lower-wattage one left running for hours.
Appliances that generate heat, electric water heaters, clothes dryers, space heaters, and ovens, typically draw significantly more power than appliances that don't, like LED lighting or electronics, making heat-generating appliances the largest contributors to a home's electricity bill relative to their usage time. Air conditioning and refrigeration also represent major, often continuous, electricity draws.
Some utilities charge different electricity rates depending on the time of day (time-of-use pricing), with higher rates during peak demand hours. This calculator uses a single flat rate for simplicity; if your utility uses time-of-use pricing, shifting appliance use to off-peak hours can meaningfully reduce actual costs beyond what a flat-rate estimate shows.
Many electronics and appliances continue drawing a small amount of power even when turned "off" but still plugged in, sometimes called phantom or standby load. While individually small, this can add up across many devices in a household over a full year, making unplugging rarely-used electronics a legitimate, if modest, way to reduce electricity costs.
Convert the appliance's wattage to kilowatts (divide by 1,000), multiply by hours of use and your electricity rate per kilowatt-hour to get the cost for that period.
Wattage is typically printed on a label on the appliance itself, in the owner's manual, or on the manufacturer's product specification page. Some appliances list amps and volts instead, which can be multiplied together to estimate watts.
A kilowatt-hour (kWh) is the standard unit utilities use to bill electricity, representing 1,000 watts of power used for one hour. Your electricity rate, shown on your utility bill, is typically expressed as cents or dollars per kWh.
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