Electricity Cost Calculator for Home Appliances

How to use this calculator

You need four numbers. Here is where to find each one.

1. Watts. Look for a label or nameplate on the back or bottom of the appliance, or check the manual. Space heaters and hair dryers often say 1,500 W. If the label lists amps and volts instead, multiply them (for example, 10 amps × 120 volts = 1,200 watts) to estimate the maximum.
2. Hours per day. Count the hours it actually runs. A heater set to a thermostat may run only part of each hour it is switched on.
3. Days per year. For seasonal items, count the season. A winter-only heater might run about 120 days; a dehumidifier might run all summer. The tool caps this at 366.
4. Rate per kWh. On your utility bill, add up the electricity charges and divide by the kWh you used. Enter dollars, so 17 cents is 0.17.

The result shows yearly energy use in kWh, the yearly cost and an average monthly cost. Try changing the hours to see how much a timer or thermostat could save.

How this calculator works

The calculator turns watts into kilowatt-hours, then multiplies by your rate.

Yearly kWh   = Watts × Hours per day × Days per year ÷ 1,000
Yearly cost  = Yearly kWh × Rate per kWh
Monthly cost = Yearly cost ÷ 12

Dividing by 1,000 converts watt-hours to kilowatt-hours, the unit on your bill. The monthly figure is a yearly average. If you only use the appliance in winter, those months will cost more and the rest will cost nothing.

Worked examples

Example 1 (hypothetical, using the tool’s default inputs). A 1,500-watt space heater runs 4 hours a day for 120 days a year, at 17 cents per kWh.

• Yearly kWh: 1,500 × 4 × 120 ÷ 1,000 = 720 kWh
• Yearly cost: 720 × $0.17 = $122.40
• Average monthly cost: $122.40 ÷ 12 = $10.20

Spread over the 120 days it is actually used, that is about $1.02 a day.

Example 2 (hypothetical, a dehumidifier in a damp basement). A 500-watt dehumidifier runs 12 hours a day for 180 days, at the same 17 cents per kWh.

• Yearly kWh: 500 × 12 × 180 ÷ 1,000 = 1,080 kWh
• Yearly cost: 1,080 × $0.17 = $183.60
• Average monthly cost: $183.60 ÷ 12 = $15.30

The dehumidifier draws one third of the heater’s power but costs more each year because it runs much longer. Hours matter as much as watts.

What your result means

The result is an estimate of the most the appliance will cost if it runs at its rated power for the time you entered. Appliances with motors, compressors or thermostats cycle on and off, so their real use is often lower. Use the result to compare options: a timer, a lower setting, a newer model, or a different way to solve the problem, such as sealing drafts instead of running a heater. Our winterize your home guide covers low-cost fixes that cut heating needs.

If you are shopping for a new appliance, compare the estimated yearly energy use on product labels and look for ENERGY STAR certified products.

Rules that change the answer

• Your state and utility. The U.S. Energy Information Administration reported an average residential price of 18.31 cents per kWh in July 2026. Among states, it ranged from 12.72 cents in Louisiana to 48.00 cents in Hawaii that month (EIA). The same 720 kWh heater from Example 1 would cost about $91.58 a year at Louisiana’s rate and $345.60 at Hawaii’s.
• Season and time of day. EIA says prices are usually highest in summer, and some utilities offer time-of-day pricing that charges more in peak hours (EIA). If you are on such a plan, running an appliance off-peak can cost less than this tool shows.
• Tiered rates. Some utilities charge more per kWh once you pass a monthly limit. Your rate for the extra use may be higher than your average.
• Federal credits have ended. The IRS says the Energy Efficient Home Improvement Credit is not allowed for property placed in service after December 31, 2025 (IRS). Local utility rebates may still exist.

Common mistakes

• Entering cents instead of dollars. Type 0.17, not 17. Entering 17 makes the cost 100 times too high.
• Counting hours switched on as hours running. A thermostat-controlled heater or a fridge does not draw full power all the time.
• Using only the energy charge. Your bill may add delivery or transmission charges per kWh. Divide total electricity charges by kWh for a fuller rate.
• Forgetting the season. A monthly average hides a big winter or summer spike.
• Using the maximum watts for everything. Electronics often draw far less than the power supply rating.

Comparing everyday appliances

All figures are hypothetical, at 17 cents per kWh. Check your own appliance’s label.

Limits and when to get help

This tool assumes the appliance draws its rated watts for every hour you enter. It does not model thermostats, standby power, gas use, tiered or time-of-day pricing, or taxes and fixed fees on your bill. The defaults are hypothetical examples. For a precise number, a plug-in usage meter measures real use on standard 120-volt plugs, and your utility may offer a free home energy audit or hourly usage data online.

Call a licensed electrician if a breaker trips when an appliance runs, if outlets or cords feel warm, or before adding a large new load like a heat pump or electric car charger. For the bigger picture of yearly home costs, see our seasonal home maintenance checklist and the home maintenance calculator.