Appliance Wattage & Running Cost Calculator
Find how many watts an appliance uses and its daily or monthly running cost based on your local electricity rate.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Cost = (Watts / 1000) x Hours x Days x Electricity Rate
Convert watts to kilowatts by dividing by 1000, then multiply by usage hours to get kWh (kilowatt-hours). Multiply kWh by your electricity rate ($/kWh) to get the cost. Scale by days per week and weeks per period for weekly, monthly, and annual costs.
Worked Examples
Example 1: Space Heater Running Cost
Problem:A 1500-watt space heater runs 4 hours per day, 5 days a week during winter. Electricity costs $0.15/kWh. What is the monthly cost?
Solution:Convert to kilowatts: 1500W / 1000 = 1.5 kW\nDaily energy: 1.5 kW x 4 hrs = 6 kWh\nWeekly energy: 6 kWh x 5 days = 30 kWh\nMonthly energy: 30 kWh x 4.345 = 130.35 kWh\nMonthly cost: 130.35 kWh x $0.15 = $19.55
Result:Monthly Cost: $19.55 | Yearly Cost: $234.00 | Daily: $0.90
Example 2: Gaming PC Energy Consumption
Problem:A gaming PC draws 500 watts and is used 6 hours daily, 7 days a week. Rate is $0.12/kWh. What is the annual electricity cost?
Solution:Convert to kilowatts: 500W / 1000 = 0.5 kW\nDaily energy: 0.5 kW x 6 hrs = 3 kWh\nWeekly energy: 3 kWh x 7 days = 21 kWh\nYearly energy: 21 kWh x 52 = 1,092 kWh\nYearly cost: 1,092 kWh x $0.12 = $131.04
Result:Annual Cost: $131.04 | Monthly: $10.92 | Daily: $0.36
Frequently Asked Questions
What is wattage and how does it relate to electricity cost?
Wattage measures the rate at which an electrical device consumes energy. It represents the amount of power the appliance draws while operating. To calculate electricity cost, you convert watts to kilowatts by dividing by 1000, then multiply by the number of hours used to get kilowatt-hours (kWh). Your electricity bill charges you per kWh consumed. For example, a 1500-watt space heater running for 2 hours uses 3 kWh, which at $0.13 per kWh costs about $0.39 per use. Understanding wattage helps you identify which appliances consume the most energy in your home.
How do I find the wattage of my appliance?
You can find appliance wattage in several ways. Check the label or nameplate on the appliance itself, which is usually located on the bottom, back, or inside the door. This label shows the rated wattage or voltage and amperage from which you can calculate watts (Volts x Amps = Watts). You can also check the product manual or manufacturer website for specifications. For a more accurate reading, use a plug-in electricity monitor like a Kill-A-Watt meter, which measures actual power consumption. Note that the rated wattage is often the maximum draw and actual consumption may be lower during normal operation.
How can I reduce my appliance electricity costs?
Several strategies can significantly reduce appliance energy costs. Replace old appliances with Energy Star certified models, which use 10% to 50% less energy than standard models. Use appliances during off-peak hours if your utility offers time-of-use pricing. Unplug devices when not in use to eliminate phantom power draw, which can account for 5% to 10% of your electric bill. Use smart power strips to automatically cut power to idle devices. Adjust thermostat settings, run full loads in washers and dishwashers, and air-dry clothes when possible. Regular maintenance like cleaning refrigerator coils and dryer vents also improves efficiency substantially.
What is phantom or standby power and how much does it cost?
Phantom power, also called standby power or vampire load, is the electricity consumed by devices when they are turned off but still plugged in. Many modern electronics continuously draw small amounts of power for features like remote control receivers, digital displays, and network connectivity. Common phantom power culprits include televisions (1 to 5 watts), game consoles (1 to 25 watts), computer monitors (1 to 3 watts), and chargers left plugged in (0.1 to 0.5 watts). The U.S. Department of Energy estimates that phantom loads can add 5% to 10% to your electric bill, costing the average household $100 to $200 per year in wasted energy.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy