Article — Electricity Cost Calculator
Electricity cost calculator: kWh, rates and the real cost of every appliance
An electricity cost calculator takes three inputs and returns the bill: device wattage, hours per day, and the price per kilowatt-hour. Wattage divided by 1,000 is the load in kilowatts. Multiply by hours for kilowatt-hours. Multiply by your utility rate for the dollar cost. A 1,500-watt space heater running four hours a day at the US average $0.17 per kWh costs $1.02 a day, $30.60 a month, or $372 a year.
The calculator above pre-loads state-average residential rates from the US Energy Information Administration, so you can drop in a Hawaii rate (42 cents per kWh) or a Washington rate (12 cents) and see how the same appliance plays out.
What electricity cost actually measures
Electricity cost is energy used times price per unit of energy. The unit is the kilowatt-hour, defined as the energy a 1,000-watt device uses in one hour. A 100-watt bulb for 10 hours uses 1 kWh. A 2,000-watt kettle for 30 minutes uses 1 kWh. Both cost the same on the bill.
The rate is set by your utility and regulated state by state in the US. Washington households pay about a quarter of what Hawaii households pay for the same fridge running the same hours.
The average US household used 10,791 kWh in 2022 according to EIA Residential Energy Consumption Survey data — about 30 kWh per day. At the 2024-2025 national average rate, that is $5.21 per day or $1,876 per year per household. Hawaii households pay over $4,500 a year for the same consumption; Louisiana households pay around $1,342.
From watts to a kWh cost
Three steps: divide wattage by 1,000 for kilowatts; multiply by hours for kilowatt-hours; multiply by the rate per kWh for dollars. Most nameplates print wattage on a sticker on the back of the fridge, the bottom of the microwave, or inside the battery compartment.
For appliances rated in amps and volts only, multiply the two to get watts. A 5-amp US appliance on a 120-volt outlet draws 600 watts. A 15-amp UK appliance on 230 volts draws 3,450 watts.
1 kWh = 1,000 W for 1 hourUS average = $0.1738 per kWh100 W for 10 h = 1 kWh = $0.171,500 W for 4 h = 6 kWh = $1.04US electricity rates in 2026
EIA puts the early-2026 US average at $0.1738 per kWh, up about 28% from 2020. The rise tracks higher natural-gas fuel costs and grid upgrades funded by the 2021 infrastructure bill. Pacific Northwest hydro keeps Washington and Idaho below 13 cents. New England's gas-and-imports mix pushes Connecticut and Massachusetts past 30 cents. Hawaii sits above 42 cents.
Time-of-use plans now exist in most regulated markets, with peak rates during 4-9 p.m. weekdays and lower overnight rates. Households that can shift dishwasher, EV charging or pool pumps save 20-40% versus the flat rate.
Highest electricity loads in a home
Three loads dominate the US residential stock. Heating and cooling combined account for 42-48% of household electricity use. Water heating runs 17-22%. Lighting and electronics make up 20-25%. Cooking, refrigeration and laundry split the remainder.
On a per-appliance basis the order is: electric water heater, central AC, electric dryer, electric oven, refrigerator. Switching one appliance from electric resistance to heat-pump typically saves 50-70%. Heat-pump water heaters now hit Energy Star ratings near 2,500 kWh/year — half of a standard electric resistance unit.
- Electric water heater — 4,500 W, 3 h/day cycling, ~3,300 kWh/year, $573/year US average.
- Central AC (3 ton) — 3,500 W, 8 h/day summer, ~3,000 kWh/year, $521/year.
- Electric dryer — 3,000 W, 0.5 h/day, ~550 kWh/year, $96/year.
- Refrigerator (Energy Star) — 150 W cycling, ~450 kWh/year, $78/year.
- Dishwasher — 1,200 W, 1 h/day, ~270 kWh/year (heater cycle), $47/year.
- Gaming PC — 500 W, 4 h/day, ~730 kWh/year, $127/year.
- LED home lighting — ~30 bulbs at 10 W, 5 h/day, ~550 kWh/year, $96/year.
Standby and phantom electricity cost
Standby power is the draw of devices when off but plugged in. TVs and set-top boxes draw 2-15 watts each in standby. A typical US home has 25-40 devices in standby summing to 50-100 watts of continuous draw.
At 100 watts continuous the annual cost is 876 kWh = $152 at the US average. A smart power strip that cuts idle secondary outlets typically reduces this by 60-80%. Payback on a $25 smart strip is 6-9 months.
Refrigerators, freezers and AC compressors do not run continuously — they cycle on and off. A 150 W fridge nameplate does not mean 150 W continuous; the compressor runs 25-40% of each hour. To estimate fridge cost accurately, use about 8 hours of effective daily run-time rather than 24 hours.
Electricity cost by room
Different rooms drive different shares of the bill. The kitchen runs 22-28% in most US homes (fridge, dishwasher, microwave, range). HVAC is the next big block at 35-45%. Laundry contributes 5-10% (mostly the dryer). Bedrooms and living rooms account for 10-15% from TVs, computers and lighting.
Outdoor and garage loads — pool pumps, hot tubs, EV charging — have grown sharply since 2020. A 7.2 kW EV charger running two hours a night adds 5,250 kWh per year, tripling the household lighting load on its own.
Reducing electricity cost without buying anything
Five no-cost moves reduce a typical bill by 10-25%. Drop the thermostat 2°F in winter and raise it 2°F in summer (each degree shifts HVAC consumption about 3%). Set the water heater to 120°F instead of the factory 140°F. Run dishwasher and laundry only on full loads. Switch remaining incandescent bulbs to LED. Use smart strips on standby loads.
Behavioural moves matter more than people expect. American Council for an Energy-Efficient Economy studies put combined savings from smart-thermostat use plus standby-load management at $200-400 per year.
Read your last 12 months of utility bills before changing anything. Most utilities offer a 12-month consumption history graph in the online account. The summer-peak versus winter-baseline gap tells you whether your bill is dominated by AC, heating, or year-round loads — and which fix to prioritize.
Common electricity cost calculator mistakes
The most common mistake is confusing watts with kilowatts — a 1.5 kW heater is 1,500 watts, not 1.5. The second is treating wattage as continuous when the device cycles. Fridges, AC compressors and heat pumps cycle on and off, so multiplying nameplate wattage by 24 hours over-counts consumption by 2x to 4x. Use real run-hours per day instead.
The third trap is using an outdated rate. US average rates rose 28% from 2020 to 2025. A 2022 spreadsheet at $0.13 per kWh is now $0.17 — 30% higher cost. The calculator above uses current EIA Electric Power Monthly data to avoid this drift.