How to Calculate Appliance Electricity Consumption and Cost
Every electrical appliance has a wattage power rating located on its UL label or user manual. To calculate operating cost, convert power draw to kilowatt-hours (kWh), which is the billing unit used by electric utility companies.
1. Kilowatt-Hours (kWh) Consumption Formula
Daily Energy (kWh)=
Power (Watts) × Usage Hours per Day1,000 (Watts per kW)
2. Electricity Operating Cost Equation
Daily Cost ($)=Daily kWh × Utility Electricity Rate ($/kWh);Monthly Cost=Daily Cost × 30.4 days
Step-by-Step Calculation Breakdown
Step 1: Calculate Daily Kilowatt-Hours (1,500W Space Heater @ 6 Hours/Day)
Daily Watt-Hours = 1,500 Watts × 6 Hours = 9,000 Watt-hours
Daily kWh = 9,000 ÷ 1,000 = 9.00 kWh / day
Daily kWh = 9,000 ÷ 1,000 = 9.00 kWh / day
Step 2: Calculate Daily & Monthly Operating Cost (@ $0.16 / kWh)
Daily Cost = 9.00 kWh × $0.16/kWh = $1.44 per day
Monthly Cost = $1.44 × 30.4 days = $43.78 per month
Step 3: Calculate Annual Operating Expenditure & Carbon Footprint
Yearly Cost=9.00 kWh × 365 × $0.16=$525.60 / year (3,285 kWh / 2,792 lbs CO2)
Common Household Appliances Power & Operating Cost Benchmark
| Appliance | Avg Wattage | Daily Usage | Monthly Cost (@ $0.16/kWh) |
|---|---|---|---|
| Central AC (3 Ton 16 SEER) | 3,500 W | 8 hrs/day | $136.20 / mo |
| Electric Water Heater (50 Gal) | 4,500 W | 3 hrs/day | $65.70 / mo |
| Electric Space Heater | 1,500 W | 6 hrs/day | $43.80 / mo |
| Clothes Dryer | 3,000 W | 1 hr/day | $14.60 / mo |
| Refrigerator / Freezer (Energy Star) | 150 W | 24 hrs/day | $17.50 / mo |
| 55" 4K Smart TV | 110 W | 5 hrs/day | $2.68 / mo |