Every appliance listing shows a wattage number, and almost nobody converts it to money. The formula takes ten seconds and regularly overturns “energy hog” reputations — high-wattage appliances that run minutes cost less than low-wattage ones that run all day.

The formula

Watts × hours used ÷ 1000 × your electricity rate = cost.

US average residential rate is around 16–17¢ per kWh (check your bill — coastal states run 25–40¢, some southern states 11–13¢). Examples at 16¢:

  • 1500W air fryer, 20 min/day: 0.5 kWh/day → about $2.40/month
  • 900W dehydrator, one 8-hour batch/week: 7.2 kWh/month → $1.15/month
  • 60W wine fridge compressor, cycling ~8h/day: 14.4 kWh/month → $2.30/month
  • 5 cu ft chest freezer (modern, ~215 kWh/year): → $2.90/month
  • 1200W space heater, 8h/day all winter: 9.6 kWh/day → $46/month — this is the one that actually shows up on a bill

The pattern: duty cycle beats wattage. Burst appliances (kettles, air fryers, microwaves) are cheap no matter their watts. Always-on and long-running appliances (freezers, heaters, dehumidifiers) are where efficiency specs pay.

Reading the two different “watt” numbers

Listings mix two figures. Rated wattage is the peak draw (compressor start, heating element on). Annual kWh — on refrigeration EnergyGuide labels — already accounts for cycling and is the number to compare across freezers and fridges. When a freezer says 300W but 215 kWh/year, the second number is your bill; the first is your circuit-planning number.

Where efficiency premiums pay back — and where they don’t

  • Worth paying for: chest freezers and refrigerators (run 24/7 for a decade — a 100 kWh/year difference is ~$160 over ten years), dehumidifiers, anything with a compressor that lives plugged in.
  • Rarely worth paying for: kettles, toasters, air fryers, popcorn machines. A 20% efficiency edge on $2.40/month is 48 cents. Buy those on capacity, build quality, and cleanup instead.

Phantom load, the quiet line item

Anything with a clock, remote standby, or warm power brick draws 1–10W around the clock. One device is pennies; the average home runs 20–40 of them, totaling 5–10% of the bill. Appliances with a physical off switch or a display-off mode genuinely save more than most “eco mode” marketing.

The short version

Convert watts to dollars before letting a spec scare you: watts × hours ÷ 1000 × your rate. Sweat the annual-kWh number on anything that runs continuously, ignore small efficiency deltas on burst appliances, and put the always-on gadgets on a switch.