How to Use the Electricity Calculator
Understanding what your appliances cost to run helps you make informed decisions about energy usage. This calculator gives you precise cost estimates.
Step-by-Step Instructions
- 1 Enter the power rating of your appliance in watts.
- 2 Enter how many hours per day you use it.
- 3 Enter the number of days in your billing period.
- 4 Enter your electricity rate in dollars per kWh (found on your utility bill).
- 5 Review the daily and total energy consumption and cost.
Understanding the Inputs
Power (watts)
The power rating of your electrical device in watts. Found on the appliance label or in the user manual. Common examples: LED bulb 10W, laptop 65W, space heater 1500W, central AC 3500W.
How to find it: Look for a label on the appliance or its power adapter that lists wattage (W) or amperage (A). If only amps are listed, multiply by voltage (120V in US) to get watts.
Why it matters: Wattage directly determines energy consumption. A 1500W space heater uses 15 times more energy than a 100W light bulb running for the same duration.
Type: number · Default: 0
Hours per Day
The number of hours per day the appliance runs. For always-on devices like refrigerators, use 24 hours. For occasional devices like a microwave, use the actual daily runtime.
How to find it: Estimate your typical daily usage. For devices with thermostats (refrigerators, AC), the compressor cycles on and off. A good estimate is 8-12 hours per day for cycling appliances.
Why it matters: Usage hours multiply the power consumption. A device running 24 hours costs twice as much as the same device running 12 hours per day.
Type: number · Default: 0
Number of Days
The number of days to calculate over. Typically a monthly bill cycle of 30 days, but can be any period you want to analyze.
How to find it: Your electricity bill shows the billing period length. Monthly bills typically cover 28-33 days.
Why it matters: Days determine the total period for the cost calculation. Longer periods accumulate more energy consumption linearly.
Type: number · Default: 0
Rate ($/kWh)
Your electricity rate in dollars per kilowatt-hour ($/kWh). This is the amount your utility charges for each kilowatt-hour of energy consumed.
How to find it: Find the rate on your electricity bill. It is usually listed as Energy Charge or Rate per kWh. US average is about $0.12-0.15/kWh, but varies by state from $0.08 to $0.40.
Why it matters: The rate determines the cost per unit of energy. A rate of $0.30/kWh means an appliance costs more than double what it would at $0.12/kWh.
Type: number · Default: 0
Tips & Best Practices
- ✓ The average US electricity rate is about $0.12-0.15 per kWh, but this varies significantly by state.
- ✓ Heating and cooling typically account for about 50% of home energy use.
- ✓ Many utility companies offer time-of-use rates where electricity is cheaper at night.
Try the Electricity Calculator
by CalculatorPro Tools · Updated 2026-07-29