Free Electricity Cost Calculator
Calculate how much any appliance costs to run per day, month, and year. Enter watts, hours, and your electric rate to estimate costs.
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US average: ~$0.12/kWh
Daily kWh
8.00 kWh
Daily Cost
$0.96
Monthly
$28.80
Yearly
$350
Formula
Cost = (Watts × Hours / 1000) × Rate per kWhHow to Calculate Electricity Cost for Any Appliance
Every electrical device has a wattage rating that tells you how much power it draws. To calculate the cost of running it, you multiply the wattage by the number of hours you use it, convert to kilowatt-hours (kWh), and multiply by your electricity rate. This calculator does all of that instantly.
The formula is straightforward: Cost = (Watts × Hours) ÷ 1000 × Rate. The division by 1,000 converts watt-hours to kilowatt-hours, which is the unit your electric company uses for billing.
Common Appliance Wattages
- LED light bulb: 8-12 watts — costs pennies per day to run
- Laptop: 30-70 watts — very efficient compared to desktops
- Desktop computer: 100-300 watts — gaming PCs can draw 500+ watts
- Refrigerator: 100-200 watts — runs 24/7 but cycles on and off
- Window AC unit: 500-1,500 watts — one of the biggest summer costs
- Space heater: 1,500 watts — expensive to run continuously
- Electric dryer: 2,000-5,000 watts — high draw but short runtime
- EV charger (Level 2): 7,200-9,600 watts — adds $30-$60/month for typical driving
Tips to Lower Your Electricity Bill
The easiest way to cut costs is targeting your highest-wattage, longest-running appliances. Here are practical strategies:
- Switch to LED bulbs — they use 75% less energy than incandescent bulbs
- Use a smart power strip — eliminates phantom power draw from idle electronics
- Run major appliances off-peak — some utilities charge less during nights and weekends
- Set your AC to 78°F — each degree lower adds 3-5% to cooling costs
- Air-dry clothes when possible — dryers are one of the most expensive appliances to run
Understanding Your Electric Bill
Your bill is measured in kilowatt-hours (kWh). One kWh equals running a 1,000-watt appliance for one hour, or a 100-watt bulb for ten hours. The average US household uses about 900 kWh per month, costing roughly $100-$140 depending on local rates.
Use this calculator to identify which appliances cost the most. You might be surprised — that old space heater or window AC unit could be costing more per month than your entire kitchen.
Frequently Asked Questions
How much does it cost to run a space heater all day?
A typical 1,500-watt space heater running 24 hours at $0.12/kWh costs about $4.32 per day, or roughly $130 per month. Running it only 8 hours drops that to about $1.44/day or $43/month.
What uses the most electricity in a home?
Heating and cooling systems are the biggest electricity consumers, accounting for about 40-50% of most electric bills. Water heaters, dryers, and electric ovens are also major contributors. Appliances like refrigerators run 24/7 but are relatively efficient at 100-400 watts.
How do I find my electricity rate?
Check your electric bill — the rate is listed as a cost per kWh (kilowatt-hour). In the US, the average is about $0.12-$0.16/kWh, but it varies widely by state. California and Hawaii tend to be highest ($0.25+), while states like Louisiana and Idaho are lower ($0.08-$0.10).
Does leaving things plugged in use electricity?
Yes — this is called phantom load or vampire power. Devices like TVs, game consoles, chargers, and cable boxes draw 1-10 watts even when off. Collectively, phantom loads can add $100-$200 to your annual electric bill.
How many watts does a typical household use?
The average US household uses about 30 kWh per day, or roughly 900 kWh per month. That works out to an average continuous draw of about 1,250 watts. Your usage depends on climate, home size, and appliance efficiency.