Find the right power value
Look for watts, kilowatts, voltage and amperage, or a yearly energy figure on the product label, manual, or manufacturer documentation. Do not confuse voltage with power: voltage is electrical pressure, while watts describe power use.
The U.S. Department of Energy’s Energy Saver guidance recommends using the appliance rating and the hours of use to estimate energy consumption, while recognizing that real-world use varies.
Build a realistic schedule
Record how many hours the appliance is active on a typical day and how many days it runs in a month. For a refrigerator, heat pump, or other cycling appliance, the nameplate maximum may overstate the average because the compressor or heating element switches on and off.
- Use a representative schedule rather than the longest possible day.
- Separate active hours from standby or idle time when the values are known.
- Recheck seasonal appliances in both high-use and low-use months.
- Use a plug-in energy monitor only when it is rated for the appliance and used safely.
Understand the estimate
The calculation is simple: power in kW × hours per day × active days × local price per kWh. It answers “what might this schedule cost?” rather than promising an exact bill or a guaranteed saving.
ENERGY STAR or a manufacturer’s annual energy figure may use a standardized test cycle. Treat it as a comparison tool, then adjust for your household’s settings, frequency, climate, and tariff.
Try the appliance calculator
Enter the appliance’s wattage, your realistic usage schedule, and the all-in price from your bill in the Appliance Running Cost Calculator. For a broader household view, use the Electricity Cost Calculator and compare scenarios rather than relying on one default.