WattThe / Homeowner / Electricity costs
Pick an appliance, set how long it runs, and see the real cost — with duty cycle handled honestly and your state's rate filled in automatically. Add items to build a whole-home total.
The wattage printed on an appliance is its maximum draw, not its average. Compressor-driven devices — refrigerators, air conditioners, dehumidifiers — cycle on and off, so a 150 W refrigerator actually running a third of the time averages 50 W. That is the duty cycle, and it is the single biggest reason naive calculators overstate appliance costs. This tool makes it an explicit slider with realistic defaults per appliance instead of a footnote.
The other half of the estimate is your rate, which varies by nearly 4× across states — from around 11¢/kWh in Washington to over 40¢ in Hawaii. The state selector fills in the current average residential rate so the dollar figures reflect where you actually live, and the whole-home list lets you stack appliances into a bill you can sanity-check against your utility statement.
Attack in order of magnitude: HVAC first (usually 40–50% of the bill — thermostat schedules, filters, and sealing beat everything else), then water heating, then find your always-on load by reading your meter with everything "off" — routers, standby electronics, and old freezers quietly burn 100–300 W around the clock. When replacing equipment, heat pumps beat resistive heating three-to-one on efficiency, and LED lighting is a fraction of the wattage of what it replaced. Chasing phone chargers is theater; chasing compressors and heaters is money.
Multiply wattage by hours used, divide by 1,000 to get kWh, then multiply by your electricity rate. A 1,500 W space heater running 4 hours a day uses 6 kWh — about $1.02/day at the U.S. average rate of roughly 17¢/kWh.
Because of duty cycle: the compressor only runs part of the time. A refrigerator rated 150 W typically averages 40–60 W across the day, so it might use 1–1.5 kWh daily rather than 3.6.
Heating and cooling dominate, typically 40–50% of the bill, followed by water heating (~15%), then dryers, ovens, refrigeration, and pool pumps. Electronics and lighting are usually smaller than people expect.
Estimates are for planning and education, not engineering design or financial advice. Verify rates with your utility and confirm electrical work with a licensed engineer or electrician.
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