Electricity Cost Calculator
Calculate how much it costs to run any electrical appliance based on wattage, usage hours, and your electricity rate. See also Fuel Cost Calculator and Solar Panel Calculator.
How the Electricity Cost Calculator Works
This calculator estimates the electricity cost of running any appliance or device. Enter the wattage (found on the device label or manual), how many hours per day you use it, and your electricity rate from your utility bill. The calculator converts watts to kilowatt-hours (kWh) and multiplies by your rate to determine cost.
Electricity Cost Formula
Daily kWh = (Wattage x Hours per Day) / 1000
Monthly kWh = Daily kWh x Number of Days
Cost = kWh x Electricity Rate ($/kWh)
What is a Kilowatt-Hour (kWh)?
A kilowatt-hour is a unit of energy equal to using 1,000 watts for one hour. For example, a 100W light bulb running for 10 hours uses 1 kWh. Your electricity bill charges you per kWh consumed. The average US residential rate is approximately $0.12-$0.16 per kWh, though this varies significantly by state and provider.
How to Calculate Your Electricity Cost
- Find the wattage of your appliance (check the label, manual, or use a watt meter).
- Estimate how many hours per day the appliance runs.
- Find your electricity rate on your utility bill (usually listed as $/kWh).
- Multiply wattage by hours, divide by 1000 to get daily kWh.
- Multiply daily kWh by your rate for daily cost.
- Multiply by 30 for monthly or 365 for yearly estimates.
Common Appliance Wattages and Monthly Costs
| Appliance | Wattage | Typical Hours/Day | Monthly kWh | Monthly Cost |
|---|---|---|---|---|
| Central AC | 3,500W | 8 | 840 | $100.80 |
| Space Heater | 1,500W | 8 | 360 | $43.20 |
| Refrigerator | 150W | 24 | 108 | $12.96 |
| Clothes Dryer | 3,000W | 1 | 90 | $10.80 |
| Washing Machine | 500W | 1 | 15 | $1.80 |
| Television (LED) | 100W | 5 | 15 | $1.80 |
| Desktop Computer | 200W | 8 | 48 | $5.76 |
| Laptop | 50W | 8 | 12 | $1.44 |
| LED Light Bulb | 10W | 8 | 2.4 | $0.29 |
| Microwave | 1,200W | 0.5 | 18 | $2.16 |
| Dishwasher | 1,800W | 1 | 54 | $6.48 |
| Electric Oven | 2,500W | 1 | 75 | $9.00 |
* Based on $0.12/kWh electricity rate. Actual costs vary by location and utility provider.
Energy Saving Tips
- Switch to LED bulbs — they use 75% less energy than incandescent bulbs.
- Unplug devices when not in use to eliminate phantom/standby power draw.
- Use a programmable thermostat to reduce heating/cooling when away.
- Run dishwashers and washing machines with full loads only.
- Air dry clothes when possible instead of using the dryer.
- Use power strips to easily cut power to multiple devices at once.
- Set your refrigerator to 37-40 degrees F and freezer to 0-5 degrees F.
Frequently Asked Questions
How do I find the wattage of my appliance?
Check the label on the back or bottom of the device, look in the owner's manual, or search for the model number online. You can also use a plug-in watt meter for an exact reading.
What is the average electricity rate in the US?
The average US residential electricity rate is approximately $0.12-$0.16 per kWh, but it varies widely by state. Hawaii has the highest rates (over $0.30/kWh) while states like Louisiana and Washington have lower rates (under $0.10/kWh).
What is the difference between watts and kilowatt-hours?
Watts (W) measure power — the rate of energy use at any instant. Kilowatt-hours (kWh) measure energy — the total amount consumed over time. A 1000W device running for 1 hour uses 1 kWh of energy.
Why is my electricity bill higher than calculated?
Your bill includes all appliances, standby power, and may have tiered rates, demand charges, or fixed fees. Also, some appliances cycle on and off (like refrigerators), so actual usage may differ from rated wattage.
What uses the most electricity in a home?
Heating and cooling typically account for 40-50% of home electricity use. Water heating is second (about 14%), followed by appliances, lighting, and electronics.
How much does it cost to run a space heater all day?
A typical 1500W space heater running 24 hours at $0.12/kWh costs about $4.32 per day or $129.60 per month. Running it only 8 hours per day reduces this to $1.44/day or $43.20/month.