Calculate energy costs from wattage and usage time
Check the device label or manual for wattage. For appliances with variable usage, use the average. You can also find wattage on EnergyGuide labels.
Enter how many hours per day the device runs. For always-on devices like refrigerators, estimate the actual compressor run time (typically 8-12 hours).
Find your electricity rate on your utility bill (measured in $/kWh). The US average is about $0.12/kWh but varies by state.
At $0.12/kWh, a 1500W heater running 8 hours/day costs about $1.44/day, $43.20/month, or $525.60/year.