Free Electricity Cost Calculator
Calculate how much it costs to run any electrical device. Enter watts, usage hours, and your electricity rate to see daily, monthly, and yearly energy costs. Compare multiple appliances side by side.
Daily
$0.10
0.80 kWh
Monthly
$3.12
24.0 kWh
Yearly
$37.96
292 kWh
Compare Appliances
Formula
Cost = (Watts × Hours per Day ÷ 1,000) × Rate per kWhUnderstanding Electricity Costs
Electricity is one of the largest recurring household expenses, yet most people have little visibility into what drives their bill. Understanding how individual appliances and devices contribute to your total electricity cost can help you make informed decisions about energy usage and potentially save hundreds of dollars per year.
The basic concept is straightforward: every electrical device uses a certain amount of power (measured in watts) for a certain amount of time. This energy consumption is measured in kilowatt-hours (kWh), and your utility company charges you a specific rate per kWh. Our calculator makes it easy to determine the exact cost of running any device.
How Electricity Usage Is Measured
Power is measured in watts (W) or kilowatts (kW), where 1 kW = 1,000 W. This represents the rate at which a device consumes energy at any given moment. Energy consumption — what you're actually billed for — is measured in kilowatt-hours (kWh), which represents using 1,000 watts for one hour.
To calculate energy usage: multiply the device's wattage by the number of hours it runs, then divide by 1,000 to convert to kWh. For example, a 60W light bulb running 5 hours per day uses 0.3 kWh daily, or about 9 kWh per month. At $0.13/kWh, that's roughly $1.17 per month — or $14 per year for a single bulb.
Common Appliance Energy Usage
Here's a breakdown of typical wattage for common household items to help you estimate your costs:
- LED light bulb: 8-12 watts (compared to 60W for incandescent)
- Laptop: 30-70 watts
- Desktop computer: 100-500 watts (gaming PCs can draw 500W+)
- Refrigerator: 100-400 watts (runs about 8 hours/day on average)
- Window AC unit: 500-1,500 watts
- Central air conditioning: 3,000-5,000 watts
- Electric space heater: 1,500 watts
- Clothes dryer: 2,000-5,000 watts
- Electric oven: 2,000-5,000 watts
- Hair dryer: 1,000-1,800 watts
Phantom Power and Standby Costs
Many devices continue drawing power even when "off" — this is called phantom power, vampire power, or standby consumption. Devices with clocks, remote controls, or instant-on features are common culprits. While individual standby draws are small (1-10 watts each), they add up across dozens of devices in a modern home.
The average US household spends $100-200 per year on phantom power alone. Using power strips that can be switched off, or smart plugs that cut power completely, can eliminate this waste. Our appliance comparison tool helps you identify which devices are worth monitoring.
Time-of-Use Pricing
Many utility companies now offer time-of-use (TOU) pricing, where electricity rates vary throughout the day. Peak hours (typically late afternoon to early evening) cost more, while off-peak hours (overnight) cost less. If you're on a TOU plan, running high-energy appliances like dishwashers, washing machines, and EV chargers during off-peak hours can significantly reduce your bill.
Tips for Reducing Electricity Costs
- Switch to LEDs — they use 75% less energy and last 25 times longer than incandescent bulbs
- Use smart thermostats — automatically adjusting temperature when you're away saves 10-15% on heating/cooling
- Seal air leaks — weatherstripping and caulking reduce HVAC workload
- Maintain appliances — clean refrigerator coils, dryer vents, and HVAC filters for peak efficiency
- Consider solar — rooftop solar can eliminate or drastically reduce electricity bills over time
Frequently Asked Questions
How do I find the wattage of my appliances?
Check the label on the back or bottom of the device — it usually lists wattage (W) or amperage (A) and voltage (V). If only amps and volts are listed, multiply them to get watts (W = A × V). You can also check the product manual, manufacturer's website, or use a plug-in electricity meter like a Kill-A-Watt for the most accurate measurement.
What is a kilowatt-hour (kWh)?
A kilowatt-hour is a unit of energy equal to using 1,000 watts for one hour. It's how electric companies measure and bill your usage. For example, a 100-watt light bulb running for 10 hours uses 1 kWh (100W × 10h ÷ 1,000 = 1 kWh). Your electricity rate is the price you pay per kWh, which varies by location and provider.
What is the average electricity rate in the US?
The average US residential electricity rate is approximately $0.13 per kWh, but this varies significantly by state. Hawaii has the highest rates (around $0.33/kWh), while states like Louisiana and Washington have some of the lowest (around $0.08-0.10/kWh). Check your electricity bill for your exact rate, as it may also vary by time of day with time-of-use plans.
Which household appliances use the most electricity?
The biggest energy consumers are typically HVAC systems (heating and cooling), water heaters, clothes dryers, and electric ovens/ranges. Among always-on devices, refrigerators and freezers are significant because they run 24/7. Space heaters, gaming PCs, and pool pumps can also be major energy users depending on how often they're used.
How can I reduce my electricity costs?
Switch to LED bulbs (use 75% less energy than incandescent), unplug devices when not in use (standby power adds up), use a programmable thermostat, run major appliances during off-peak hours if you have time-of-use pricing, and consider Energy Star rated appliances when replacing old ones. Even small changes like air-drying clothes can save $50-100 per year.