Pick an appliance (or enter custom wattage), choose how long it runs, and WattWise shows the hourly, daily, monthly and yearly electricity cost using estimated 2026 residential rates for all 50 states + DC. Compare appliances side by side and hunt down vampire standby loads.
Add the appliances you actually run and WattWise totals your real monthly & yearly cost, ranks the biggest energy hogs, estimates your carbon footprint, and finds your fastest savings. All on-device — nothing leaves your browser.
Devices sip power 24/7 even when “off.” Tick what lives in your home — costs use your selected rate. Wattages are typical estimates.
The exact walk-through we use to find $200–600/year of silent waste in a typical home — meter readings, vampire hunt order, and the three settings that matter most.
Every electricity bill comes down to one unit: the kilowatt-hour (kWh) — 1,000 watts running for one hour. The math WattWise does for you is simple and worth knowing by heart:
Cost = (watts ÷ 1,000) × hours used × rate per kWh.
A 1,500-watt space heater running 8 hours uses 1.5 kW × 8 h = 12 kWh. At an estimated 2026 U.S. average residential rate of about 18¢/kWh, that single day costs roughly $2.16 — about $66 a month if it runs daily. The same arithmetic works for everything from a 9 W LED bulb (around a dollar a year) to a Level 2 EV charger that can move $50–120 of electricity in a month.
Two things trip people up. First, nameplate watts are a maximum, not an average: a refrigerator's compressor cycles on and off, so a “150 W” fridge really averages far less across the day — that's why our fridge preset uses compressor run-hours rather than 24 h. Second, your rate is probably not the national average. Hawaii households pay roughly four times what households in North Dakota pay, and time-of-use plans can double the price of the same kWh at 6 p.m. versus 2 a.m. Always sanity-check the ¢/kWh field against the “supply + delivery” total on your actual bill, not just the supply line.
They are estimates of average residential rates per state, modeled on recent federal data and typical year-over-year escalation. Your utility's tariff — including delivery charges, fixed fees and time-of-use windows — will differ. For precise results, divide your bill's total dollars by total kWh and type that number into the rate field.
Many appliances cycle (fridges, AC compressors, water heaters) or modulate (induction hobs, modern heat pumps), so average draw is below nameplate. Use the lower end of the typical range shown under the watts field, or measure with a plug-in power meter and enter the real number.
In most U.S. homes the ranking is: heating/cooling first, then the electric water heater, then EV charging (if you have one), then the dryer and fridge. A single space heater used 8 h/day all winter can out-cost everything else in the house combined.
Heating one occupied room with a space heater can beat heating the whole house — but heating several rooms with space heaters is almost always more expensive than a heat pump, which moves about 3 units of heat per unit of electricity. Use the comparison tray above to see the gap at your rate.
Typical U.S. homes waste 40–90 W of continuous standby draw — roughly $60–150 per year at 2026 rates. Cable boxes, instant-on consoles and idle desktops are the usual top offenders. A $15 smart power strip eliminates most of it.
Barely — a modern phone charger idles at ~0.3 W, under 50¢/year. Focus on the big standby items (set-top boxes, consoles, AV receivers) instead of charger guilt.
Yes — use the whole-home builder above. Add each appliance with a quantity (or start from a preset), and WattWise totals your monthly and yearly electricity cost, ranks the biggest energy users, estimates your yearly CO₂, and lists the swaps that save you the most.
Yes. Choose your country at the top and every cost is shown in your local currency using estimated 2026 national-average rates (US results go down to the state). Prefer your exact tariff? Type your own price per kWh and everything recalculates instantly.
More free AppVitamins tools: SolarPayback (will rooftop solar pay off at your rate?), Auto TCO (EV vs petrol total running cost) and Rent vs Buy. Want WattWise to run offline, with one-click CSV and a printable home report? Get WattWise Pro in the store →.