How is electricity cost calculated for an appliance?
Formula: Cost = (Wattage × Hours/Day × Days) / 1000 × Price per kWh. The division by 1000 converts watts to kilowatts. Example: 1,500W heater, 8 hrs/day, 30 days/month, $0.16/kWh = (1500 × 8 × 30) / 1000 × 0.16 = 360 kWh × $0.16 = $57.60/month. Common appliance wattages: refrigerator (150-400W continuous), washing machine (500W), dryer (3000-5000W), AC window unit (500-1500W), space heater (1500W), laptop (50-100W), LED TV (50-100W), desktop computer (200-500W). Note that many appliances don't run continuously — a refrigerator cycles on/off and averages about 150W over 24 hours despite a 400W compressor. For appliances with varying wattage, use the average or check the Energy Guide label.