Appliance Electricity Cost Calculator: Watts to kWh to Dollars

A watt rating tells you how quickly a device uses energy when operating at that power. Your bill generally reflects kilowatt-hours (kWh). The calculator below assumes a constant average wattage; variable-duty appliances need measured or time-weighted wattage for an accurate estimate.

How to interpret the result

Example: A device averaging 120 W for six hours a day uses 0.72 kWh/day. At $0.18/kWh over 30 days, that is about $3.89 of variable energy charges. A refrigerator cycles on and off; using its peak label wattage continuously will overestimate typical consumption.

Use better inputs when possible

Use energy labels, a plug-in meter for compatible small devices, or manufacturer documentation. Never use plug meters on loads beyond their ratings. For hardwired HVAC, electrical panels, or circuits, use qualified personnel.

Compare your results with your utility bill and consider monitoring options if you want to locate major household loads.

Examples of what the numbers mean

A 100 W device running eight hours daily for 30 days consumes 24 kWh. At an illustrative $0.18/kWh energy rate, the modeled energy charge is $4.32 for those 30 days, before fees or time-varying pricing. A 1,500 W space heater used for the same eight daily hours would consume 360 kWh; at that illustrative rate, its modeled energy charge would be $64.80. Neither example proves a household's actual use or final utility charge.

Use a measurement method suited to the appliance

• Plug-in appliance: use a properly rated plug meter when safely applicable and measure over a representative cycle.
• Hardwired system: rely on appropriate circuit or manufacturer data and qualified electrical help where necessary.
• Variable-load equipment: measure energy over time instead of multiplying maximum nameplate watts by every operating hour.

For heating, cooling and refrigerators, cycling and seasonal changes can make a one-hour spot reading misleading. Use multiple days when possible, and do not confuse the calculator's energy-cost estimate with a prediction of total monthly utility charges.