Electricity Cost Calculator

What this calculator estimates

This tool estimates how much any electrical appliance costs to run, based on its power draw (in watts), how many hours per day you use it, and your utility's rate in dollars per kilowatt-hour. Common uses include monthly budgeting for electricity, comparing the running cost of two appliances before you buy, and hunting down the energy hogs that are quietly inflating your bill. You can add as many appliances as you like and the totals update instantly, so you can model a whole household at once.

If you also drive and want to compare energy costs across different fuel types, see our fuel cost calculator. For converting watt-hours to joules or other energy units, try the unit converter.

How electricity cost is calculated

Electricity is billed in kilowatt-hours (kWh). One kilowatt-hour is the amount of energy used by a 1,000-watt device running continuously for one hour. Your toaster using 1,000 W for an hour consumes 1 kWh; your phone charger drawing 10 W for the same hour consumes just 0.01 kWh. The kilowatt-hour is the universal unit on every electricity bill worldwide.

The math has just two steps:

1. Energy used (kWh) = (Power in watts ÷ 1,000) × Hours used
2. Cost = kWh used × Price per kWh (your rate)

Your rate appears on your monthly electricity bill, usually labeled "energy charge" or "$/kWh." The US average is roughly $0.13–$0.17 per kWh, but it ranges from about $0.08 in Louisiana to over $0.40 in Hawaii. Some utilities also have tiered rates that charge more once you exceed a baseline — if yours does, use your blended average rate for the most accurate estimate.

Typical appliance wattages

The wattage printed on an appliance is its nameplate (maximum) draw — the actual average draw is often lower because the device cycles on and off or operates at partial load. A refrigerator's compressor might draw 400 W but only runs about 35% of the time, giving an effective average of around 150 W. Use nameplate watts when the appliance runs continuously (an electric oven baking); use measured or average watts for devices that cycle.

For the most accurate results, check the label on the back or bottom of the appliance, or use a plug-in power meter (sometimes called a Kill A Watt meter) to measure actual draw.

How to cut your electricity bill

Once you know which appliances are costing the most, you can target the highest-impact changes first. A few proven strategies:

• •Eliminate standby and phantom load. Devices in standby — TVs, game consoles, cable boxes, phone chargers left plugged in — collectively draw 5–10% of a household's electricity without doing any useful work. Smart power strips and unplugging chargers when not in use are zero-cost fixes.
• •Replace incandescent and CFL bulbs with LED. Modern LED bulbs use roughly 75% less energy than incandescent equivalents and last 15–25 times longer. A home with 30 bulbs switching from 60 W incandescent to 10 W LED saves about 1,500 W of continuous demand — roughly $175 a year at average US rates.
• •Run major appliances during off-peak hours. Many utilities charge higher rates during peak demand periods (typically late afternoon and evening on weekdays). Shifting dishwasher, washing machine, and dryer use to nights or weekends can meaningfully lower your blended rate.
• •Improve thermal insulation and sealing. Heating and cooling account for 40–50% of the average home's energy use. Air-sealing gaps around windows, doors, and utility penetrations, plus adding attic insulation up to code, typically pays back in two to five years and reduces HVAC runtime for the life of the home.
• •Use a programmable or smart thermostat. Setting the thermostat back 7–10°F for eight hours a day (while you sleep or are away) saves about 10% on annual heating and cooling costs with no comfort sacrifice.

For other cost comparisons, see our fuel cost calculator to weigh electricity costs against gasoline, diesel, or other fuels.

❓Electricity cost FAQ