Appliance Running Cost Calculator

Every appliance that draws power costs money to run, and the amounts surprise people in both directions. A desktop computer at 200 watts, 8 hours a day, costs about $7.70 a month at the current US average of roughly $0.16/kWh. A 1,500-watt space heater over the same hours costs about $58. Identical hours, seven and a half times the bill, because cost tracks wattage and nothing else.

The formula

kWh per day = (watts / 1000) x hours per day

Monthly cost = kWh per day x days per month x rate per kWh

Annual cost = monthly cost x 12

The kilowatt-hour (kWh) is the unit utilities use for billing. One kWh means 1,000 watts running for one hour, or equally a 100-watt bulb running for ten.

Typical wattages

Refrigerator: 100-200 W (runs roughly 8-10 effective hours per day cycling on and off). Electric oven: 2,000-5,000 W during preheat and active cooking. Window AC: 500-1,500 W by BTU rating. Clothes dryer: 4,000-6,000 W. Dishwasher: 1,200-2,400 W per cycle. LED TV (55 inch): 70-100 W. Desktop with monitor: 150-300 W. Laptop: 30-70 W. For appliances with cycles (fridge, AC), the nameplate wattage is peak draw, and the effective average is usually 40 to 60% of it.

U.S. electricity rates average somewhere around $0.16/kWh nationally and climb most years, with roughly $0.12 in Louisiana at one end and north of $0.40 in Hawaii at the other. Use your own figure rather than any average: it is on the last utility bill, usually as cents per kWh. If your utility bills in tiers, the number that matters here is the marginal rate, meaning what the next kWh costs, which is often higher than the average printed on the bill.

Many utilities also charge a flat monthly service fee on top of usage. This calculator shows only the variable usage cost — your full bill will be higher.