Electricity Cost Calculator
Enter an appliance's wattage, daily usage hours, number of days, and your electricity rate to find the monthly cost, annual cost, and daily energy consumption in kilowatt-hours. Great for comparing appliances and estimating utility bills.
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Formula
Monthly Cost = (Watts ÷ 1000) × Hours/Day × Days × Rate/kWh
Watts divided by 1,000 converts to kilowatts. Multiplying by hours per day gives daily kilowatt-hours (kWh). Multiplying by days gives monthly kWh. Multiplying by the rate per kWh gives the monthly cost in dollars. Annual cost uses 365 days for a full-year projection.
How to use the Electricity Cost Calculator
- 1
Enter your appliance wattage (w)
- 2
Enter your hours used per day
- 3
Enter your days per month
- 4
Enter your electricity rate ($/kwh)
- 5
Read your results instantly
Results update in real time as you type.
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Finding Appliance Wattage
The wattage is printed on a label on the appliance or listed in the owner's manual. Common values: LED bulb 10W, incandescent bulb 60W, laptop 50W, desktop PC 200W, refrigerator 150W (average), window AC 1,500W, electric dryer 5,000W. If only amps and volts are listed, multiply them: Watts = Amps × Volts (120V in the US). A smart plug with energy monitoring can measure actual consumption.
Finding Your Electricity Rate
Your rate per kWh is on your electricity bill, usually expressed in cents (e.g., 13¢/kWh = $0.13). The US national average is about $0.16/kWh as of 2024, but rates range from under $0.10 in some states to over $0.30 in Hawaii. Time-of-use plans have peak and off-peak rates — if you are on such a plan, use the blended average rate or run the calculator separately for peak and off-peak hours.
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Reducing Your Electricity Bill
The biggest savings come from heating and cooling (40-50% of a typical bill), water heating (14-18%), and large appliances. Switching to LED bulbs reduces lighting cost by 75%. Running the dishwasher and laundry off-peak on a time-of-use plan can cut those costs significantly. Unplugging devices on standby (vampire power) can save $100-200 per year in some households.
Tips & Insights
Compare Two Appliances
Run the calculator for an old appliance and a new energy-efficient model. The annual cost difference often justifies the upgrade price within a few years.
Calculate Standby Power
Many devices draw 1-5 watts on standby 24/7. Enter 2 watts, 24 hours/day, 30 days to see how much that one device costs per month — then multiply by the number of idle electronics in your home.
Budget for AC Season
Enter your AC wattage and estimated daily hours to forecast your summer electricity bill increase before it arrives.
Worked Examples
1000W Space Heater (8 hrs/day)
$31.20/month, $374.60/year, 8 kWh/day.
LED Bulb (10W, 5 hrs/day)
$0.20/month, $2.37/year, 0.05 kWh/day.
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Frequently Asked Questions
Where do I find my electricity rate?
Check your electric bill — it shows kWh used and total cost. Divide total cost by kWh for your effective rate. Or look for a rate schedule on your utility's website.
What is a kilowatt-hour?
One kWh is the energy used by a 1,000-watt appliance running for one hour. A 100W bulb running 10 hours = 1 kWh.
How do I reduce my electricity bill most effectively?
Focus on heating/cooling and water heating, which account for 55-65% of a typical home's electricity use. Programmable thermostats and efficient HVAC deliver the biggest savings.
Can I calculate solar panel savings with this?
Use this tool to find your monthly kWh consumption, then compare that to your solar system's projected monthly kWh output to estimate net metering savings.
Is this calculator accurate for variable-use appliances?
It assumes consistent daily usage. For appliances used sporadically (like a dryer), estimate average weekly cycles, convert to daily hours, and enter that average.
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