How to calculate electricity cost
Every appliance's running cost comes down to three numbers: how much power it draws, how long it runs, and what you pay for electricity.
- Convert watts to kilowatts. Divide the wattage by 1,000. A 100 W TV draws 0.1 kW.
- Multiply by hours of use to get kilowatt-hours (kWh). Four hours of TV is 0.4 kWh.
- Multiply by your rate. At 17.5¢ per kWh, 0.4 kWh costs about $0.070.
Cost = Watts × Hours ÷ 1,000 × Price per kWh
What common appliances cost to run
Typical costs at 17.5¢/kWh, the U.S. average residential rate (EIA, 2025). Your numbers will depend on your device and your utility's rate.
| Appliance | Usage | Per month | Per year |
|---|---|---|---|
| LED light bulb | 10 W · 5 h/day | $0.27 | $3.19 |
| TV (55-inch LED) | 100 W · 4 h/day | $2.13 | $25.55 |
| Gaming PC (while gaming) | 450 W · 3 h/day | $7.19 | $86.23 |
| Space heater | 1,500 W · 5 h/day | $39.92 | $479.06 |
| Air conditioner (mini-split) | 1,100 W · 8 h/day | $46.84 | $562.10 |
Tips for a more accurate estimate
- Use the rate from your own bill, including delivery charges, rather than a national average.
- For devices that cycle — fridges, heaters, air conditioners — use average draw, not peak wattage.
- A plug-in power meter shows real consumption, including standby power.
Frequently asked questions
How do I calculate the electricity cost of an appliance?
Multiply the appliance's wattage by the hours it runs, divide by 1,000 to get kilowatt-hours (kWh), then multiply by your electricity rate. A 1,500 W heater running one hour uses 1.5 kWh; at 17.5¢ per kWh that costs about $0.26.
What is a kilowatt-hour (kWh)?
A kilowatt-hour is the unit your utility bills you in. It is the energy used by a 1,000-watt device running for one hour, or a 100-watt device running for ten hours.
Where do I find my electricity rate?
Your electric bill lists the price per kWh, sometimes split into supply and delivery charges. Add those together for the most accurate result. If you don't have a bill handy, the calculator starts with the U.S. average residential rate.
How do I find an appliance's wattage?
Check the nameplate or label on the back or bottom of the device, the power adapter, or the manual. If only amps are listed, multiply amps by volts (120 V for most U.S. outlets). For the most accurate figure, measure it with a plug-in electricity usage meter.
Why is my estimate different from my bill?
Many appliances don't run at full power all the time. Refrigerators, air conditioners and heaters cycle on and off, and electronics draw less when idle. Bills also include fixed monthly fees that don't depend on usage.
More calculators
- Air Conditioner Running Cost
Daily and monthly cooling costs, including how often the compressor runs.
- Gaming PC Electricity Cost
Gaming, idle and sleep power, plus monitors and peripherals.
- Space Heater Running Cost
Heater wattage, hours and thermostat cycling.
- Refrigerator Electricity Cost
From the EnergyGuide label's kWh per year or a measured reading.
- Smart Plug Energy Cost
Turn kWh or watt readings from an energy-monitoring smart plug into real costs.
- Natural Gas Cost
Your gas bill from therms, CCF or meter readings, with price per therm and fixed charges.
- Water Bill & Hot Water
Water and sewer bills in gallons or CCF, tiered rates, plus what hot showers cost to heat.
- Home Heating Cost
Electric heat vs. gas furnace vs. heat pump, with your prices and equipment efficiency.
- Home Lighting Cost
Every bulb in the house, plus LED vs. CFL vs. incandescent and the savings from switching.
- Laundry Cost
Washer and dryer as one load: electricity, water, sewer and gas.
- Total Home Utility Cost
All your bills in one place — by category, month by month, with a yearly projection.