Calculate how much an appliance costs to run per day, month, and year based on wattage, usage hours, and your electricity rate.
The formula is: Cost = (Watts / 1000) x Hours x Rate. Watts divided by 1000 gives kilowatts. Multiply by hours to get kilowatt-hours (kWh), then multiply by your electricity rate to get the cost.
Example: A 1,000W space heater running 8 hours/day at $0.12/kWh: (1000/1000) x 8 x $0.12 = $0.96/day = $28.80/month = $350.40/year.
Electricity is measured and billed in kilowatt-hours (kWh). One kilowatt-hour is the energy consumed when a 1,000-watt appliance runs for one hour. The average US household uses about 10,500 kWh per year, or roughly 886 kWh per month. At the national average rate of about $0.16 per kWh, that translates to a monthly electricity bill of approximately $142. However, rates vary enormously by location -- from under $0.10/kWh in some states to over $0.30/kWh in Hawaii and parts of New England.
Your electricity bill typically includes several components beyond just the energy charge. There are delivery charges (for maintaining the power grid), demand charges (in some commercial settings), taxes, and various surcharges. The rate this calculator uses should be your all-in rate, which you can find by dividing your total bill by the total kWh consumed in that billing period. This gives you the effective rate per kWh including all fees.
Knowing exactly how much each appliance costs to run empowers you to make smarter energy decisions. That old secondary refrigerator in the garage might be costing you $20 per month. A space heater running all day could add $30-60 to your monthly bill. By identifying the biggest energy consumers in your home, you can target your energy-saving efforts where they will have the most impact.
| Appliance | Watts | Hrs/Day | Monthly Cost* |
|---|---|---|---|
| LED light bulb | 10 | 8 | $0.29 |
| Laptop | 50 | 8 | $1.44 |
| Television (55") | 100 | 5 | $1.80 |
| Refrigerator | 150 | 24 | $12.96 |
| Space heater | 1500 | 8 | $43.20 |
| Central AC | 3500 | 8 | $100.80 |
| Electric car charger | 7200 | 4 | $103.68 |
*At $0.12/kWh, 30 days/month
Switch to LED lighting. If you still have incandescent or CFL bulbs, switching to LED saves 75-80% on lighting energy. A 10W LED produces the same light as a 60W incandescent. For a home with 30 light bulbs running 5 hours daily, switching from incandescent to LED saves about $200 per year.
Use smart power strips. Many electronics draw "phantom" or "vampire" power even when turned off. A TV, game console, and set-top box on standby can draw 25-50 watts continuously. Smart power strips cut power completely when devices are in standby, saving $100-200 per year for an average household.
Optimize heating and cooling. HVAC accounts for nearly half of a typical home's energy use. Setting your thermostat 2 degrees lower in winter and 2 degrees higher in summer can reduce energy bills by 5-10%. Programmable or smart thermostats automate this by adjusting temperatures when you are asleep or away from home.
Upgrade old appliances. A refrigerator from the 1990s might use 1,000 kWh per year, while a modern Energy Star model uses only 400 kWh. The annual savings of $72 (at $0.12/kWh) means the new fridge can pay for itself within a few years while providing better performance and reliability.
Multiply the wattage by hours of use, divide by 1000 to get kWh, then multiply by your rate. Formula: (Watts x Hours) / 1000 x Rate = Cost.
The national average is approximately $0.16 per kWh, but rates range from $0.10 in states like Idaho and Louisiana to over $0.30 in Hawaii and Connecticut.
Heating and cooling account for about 46% of energy use. Water heating is next at 14%, then appliances (13%), lighting (9%), and electronics (4%).
A typical 1,500W space heater costs about $0.18/hour at $0.12/kWh. Running it 8 hours daily costs $1.44/day or $43.20/month.
A kWh is a unit of energy equal to using 1,000 watts for one hour. It is the standard unit for electricity billing. Running ten 100W bulbs for one hour uses 1 kWh.