Electricity Cost Calculator

The Formula

Calculate the energy cost of any electrical appliance. First find kilowatt-hours (kWh), then multiply by your electricity rate.

Variable Definitions

How to Use This Calculator

1. 1

   Select an appliance from the Quick Select list to auto-fill wattage, or enter a custom value.

2. 2

   Enter the average hours of use per day.

3. 3

   Choose a period (Day, Week, Month, or Year) or use the default 30-day calculation.

4. 4

   Enter your electricity rate in $/kWh (US average is ~$0.14).

5. 5

   Set the number of identical appliances (e.g., 10 LED bulbs).

Electricity cost calculation: appliance wattage is converted to kilowatt-hours, then multiplied by the electricity rate.

Understanding the Concept

Electricity is billed per kilowatt-hour (kWh), which represents 1,000 watts used for one hour. This calculator converts appliance wattage to kilowatt-hours, multiplies by your local electricity rate, and projects costs over daily, monthly, and yearly periods. Understanding appliance energy costs helps you identify energy-saving opportunities and manage your electric bill. Practical example: a gaming PC drawing 500W used for 6 hours per day. Daily consumption: (500 × 6) / 1000 = 3 kWh. At $0.14/kWh, daily cost = $0.42, monthly cost (30 days) = $12.60, yearly cost = $153.30. Compare with an LED TV (120W) used 6 hours: 0.72 kWh/day, $0.10/day, $3.02/month, $36.74/year. The gaming PC costs over 4 times more to run. Edge cases: for appliances with variable power draw, such as refrigerators and air conditioners that cycle on and off, the nameplate wattage overestimates actual consumption — a refrigerator rated at 700W typically runs only about 30% of the time, averaging 210W. Use a plug-in power meter (like a Kill-A-Watt) for accurate measurements. For electric vehicle charging at Level 2 (7,000W for 4 hours), consumption is 28 kWh/day, costing $3.92/day, $117.60/month, $1,430.80/year. Time-of-use billing can significantly affect costs — charging overnight at off-peak rates (potentially $0.08/kWh) versus peak rates ($0.30/kWh) can cut EV charging costs by 70%. For standby power (vampire power), devices like cable boxes, game consoles, and phone chargers draw 1-10W continuously — 10 such devices at 5W each, 24/7, costs about $0.50/month at average rates, or $6/year in wasted energy.

Frequently Asked Questions

Sources & References