The running-time problem behind most appliance tables
Nearly every appliance table online is built from two ingredients: a nameplate wattage and a guess at hours of use. Both are usually wrong, in the same direction.
Take the refrigerator. The Department of Energy's wattage table lists 725 W for a 16 cubic foot frost-free unit. That figure is real, but it is peak draw — compressor, condenser fan and defrost heater at once. Multiply it by 24 hours, because the fridge is never unplugged, and you get over 6,000 kWh a year, which would make it the largest load in most houses. It overstates a modern refrigerator roughly tenfold.
The missing idea is duty cycle: the share of time a thermostatically controlled appliance actually draws power rather than coasting. A fridge is energised 24 hours a day, but its compressor runs about 8 of them, in short cycles fired when the interior warms. Averaged out it behaves like 150 W continuous — 36.5 kWh a month, not 500.
The same error runs through the category. A clothes dryer draws 3,000 W but runs about 0.6 hours a day across a week's five loads: idle 97% of the time. An oven at 2,400 W is on for roughly 20 minutes. Hours plugged in is not hours running, and confusing the two is the commonest mistake in consumer energy arithmetic.
How these figures were derived and checked
Every number in the table above comes from one formula: running watts × effective hours per day × 30.4 days ÷ 1,000, giving kilowatt-hours a month. The 30.4 is the average length of a month; the hours are duty-cycle hours. Seasonal equipment — central and window air conditioning, electric heat, dehumidifiers, pool pumps — is shown at in-season hours, so annualise it by the months it actually runs, never by 12.
The outputs were then checked against metered and modelled consumption from EIA's Residential Energy Consumption Survey for 2020. The dryer figure of 54.7 kWh a month annualises to roughly 657 kWh a year against a measured 680. Central air conditioning at 638.4 kWh a month in season matches the 2,318 kWh a year measured for households that use it, over about four months. Electric space heating lands the same way against a measured 2,484 kWh.
Where a wattage table and a metered survey disagreed, the metered figure won and the disagreement is described on the appliance's own page rather than averaged away. Refrigerators are the sharpest case: a new EnergyGuide label promises 350–450 kWh a year while the survey metered 839 kWh for all refrigeration in the average home. Both are true; the gap is second fridges in hot garages and ageing primary units.
What draws the most watts is not what uses the most electricity
Watts measure draw at an instant; kilowatt-hours measure energy over time, and time is where the money is. Two appliances of identical wattage can differ twenty-five-fold on the bill.
An air fryer draws 1,500 W and uses about 9.1 kWh a month, because it runs twelve minutes a day. A space heater draws the same 1,500 W and uses 228 kWh a month, because in a cold room it runs for hours. A vacuum cleaner pulling 1,100 W costs less per month than a WiFi router pulling 8 W — 5.0 kWh against 5.8 — because the router never switches off.
The reverse trap is just as common. A tankless electric water heater has a startling 24,000 W nameplate, but it runs only while hot water flows, about 0.3 hours a day, for 218.9 kWh a month. A conventional tank at 4,500 W runs 1.7 hours a day reheating standing water and lands at 232.6. The scary number is attached to the more efficient appliance.
The rule: before worrying about wattage, ask how many hours a day it genuinely runs. If the answer is minutes, stop worrying. The appliance energy cost calculator does the arithmetic at your own rate rather than the national average.
The unpopular conclusion: heat, cold and hot water
Rank the table by consumption and the top is monotonous. Central air conditioning at 638.4 kWh a month in season. An electric furnace or heat pump at 532. An electric water heater at 232.6, all year. A space heater at 228. Anything that changes the temperature of air or water dominates the rest, and EIA puts air conditioning alone at roughly 19% of the average home's electricity, its single largest end use.
Now the electronics people worry about. A television uses 9.1 kWh a month. A laptop, 9.1. A games console, 9.7. A router, 5.8. A phone charger uses 0.5 kWh a month — about nine cents at the national average of 18.44¢ per kWh. Unplugging chargers is not an energy strategy. It is a ritual.
The biggest single decision in the table is a technology choice, not a habit. An air-source heat pump moves heat and draws 3,000–5,000 W to warm a house; an electric-resistance furnace makes heat and draws 10,000–25,000 W of strip elements for identical comfort. Heat pumps fall back on those strips in severe cold or on Emergency Heat, which is why a January bill can triple with no change in behaviour.
Spend your attention proportionally: the thermostat setpoint, the age and type of the heating and cooling equipment, the water heater, the envelope. If a bill has jumped without explanation, the diagnosis walkthrough takes the causes in the order worth checking.