500 Watts to kWh - Cost per Hour, Day & Month
At the US average rate of 0.16 per kWh, 500 watts costs about 0.080 per hour when running continuously. Adjust hours and rate for your bill.
Appliance Details
Enter wattage and usage to calculate cost.
Choosing a preset auto-fills wattage.
Energy Cost
500W · 8h/day · $0.16/kWh
Monthly cost
$19.20
120.0 kWh/month
Methodology and limitations
Last reviewed:
Methodology
Converts wattage and runtime to kWh, then multiplies by the entered rate per kWh to estimate daily, monthly, and annual electricity cost.
Limitations
Actual bills include fixed charges, taxes, tiered rates, and time-of-use pricing. Use your utility bill rate for the most accurate estimate.
Official sources
How Electricity Cost is Calculated
At the US average rate of 0.16 per kWh, 500 watts costs about 0.080 per hour when running continuously. Adjust hours and rate for your bill.
Method used
The calculator converts appliance wattage and daily runtime into kilowatt-hours (kWh), then multiplies by your electricity rate to estimate daily, monthly, and annual cost.
kWh = Watts ÷ 1,000 * Hours per day; Cost = kWh * Rate per kWh
Practical example
A 150-watt refrigerator running 8 hours per day at $0.16/kWh uses about 1.2 kWh daily, costing roughly $0.19 per day or $5.76 per month.
- Appliance: Refrigerator (150 watts)
- Usage: 8 hours per day, 30 days per month
- Rate: $0.16 per kWh
The result shows kWh per day, month, and year, plus cost per hour, day, month, and year.
Assumptions
- Wattage is the average or rated power draw entered by the user.
- Usage hours apply uniformly across the selected days per month.
- The rate is a flat $/kWh and does not model tiered or time-of-use pricing.
What this includes
- Wattage, hours per day, days per month, rate per kWh, 23 appliance presets, and US regional rate references.
What this excludes
- Demand charges, fixed monthly fees, taxes, surcharges, seasonal rate changes, standby vampire load modeling, and solar net metering credits.
Frequently Asked Questions
How do I calculate electricity cost?
Multiply the appliance wattage by the hours used per day to get watt-hours. Divide by 1,000 to convert to kilowatt-hours (kWh). Multiply by your electricity rate (found on your utility bill) to get the daily cost. Multiply by days in a month for monthly cost.
Where do I find my electricity rate?
Your rate (in $/kWh) is on your monthly electricity bill, usually listed as the "energy charge" or "rate per kWh." The US average in 2024 is approximately $0.16/kWh, but rates vary widely - California averages $0.26, while Texas and Florida average around $0.13.
How do I find the wattage of an appliance?
Check the label on the back or bottom of the appliance, or look in the owner's manual. It may list watts directly, or amps and volts (Watts = Amps * Volts). In North America, standard voltage is 120V for most outlets and 240V for large appliances like dryers and ovens.
Which appliances use the most electricity?
Electric water heaters, central air conditioning, electric furnaces, and clothes dryers are typically the largest electricity consumers in a home, each potentially using thousands of kWh per year. Refrigerators, lighting, and entertainment electronics are significant but smaller contributors.
How can I reduce my electricity bill?
Switch to LED bulbs (use 75-80% less energy than incandescent), use a programmable thermostat, run dishwashers and laundry full, unplug vampire loads (devices that draw power when off), and consider a smart power strip. ENERGY STAR appliances use 10-50% less energy than standard models.