Appliance Wattage Calculator: Annual Cost Estimator
This appliance wattage calculator goes from the power figure on the label to a dollar amount on your bill. Enter the running watts (or the amps and voltage if that is all the nameplate lists), how many hours it runs each day, and your electricity rate, and it returns daily and yearly kilowatt-hours plus the operating cost. Optional duty-cycle and standby settings handle cycling appliances like refrigerators and phantom loads. It estimates one appliance at a time; for generator planning, use the running-watt result as one input and check surge watts separately.
Turn one nameplate into a yearly cost you can trust
The number you get is only as good as the four things you feed it: the power draw, the daily runtime, the rate, and whether the appliance cycles or idles. Get those right and the yearly figure is close enough to compare two models, settle a bill argument, or budget a new device. Here is how to enter each one cleanly.
If the nameplate lists watts, use wattage mode. If it lists only amps and a voltage, switch to amps-and-voltage mode and the calculator multiplies them for you (120 V for standard outlets, 240 V for dryers and ranges).
For a refrigerator or freezer, leave hours at 24 and use a measured or manufacturer-backed duty-cycle factor when you have one. For example, 0.33 means the compressor draws full power for about one-third of the day.
If the device sits plugged in but idle, enter its standby watts. The calculator charges that phantom load for the hours the appliance is not actively running and reports it as a separate line.
Pull the all-in price per kWh off a recent bill rather than the default. The prefilled $0.16/kWh is roughly the EIA U.S. average residential price, but state rates vary widely, and the rate drives the entire cost output.
Example: a refrigerator that cycles all day
A fridge rated at 150 W does not run flat out around the clock. Leave hours at 24 and set a duty-cycle factor of 0.33, so the effective wattage is 150 x 0.33 = 49.5 W. Daily energy is 49.5 x 24 / 1000 = 1.19 kWh. Over a full year that is 1.19 x 365 = 434 kWh, and at $0.16/kWh the operating cost lands near $69 a year. Change only the rate to your own and the yearly number moves with it.
Where to read the power figure
Most appliances print their draw on a data plate or nameplate stamped on the back, bottom, side, or inside a door, and the same numbers appear in the owner's manual specifications. Look for watts first. If the plate shows only amps and volts, you do not need to convert anything by hand: enter both values in amps-and-voltage mode and the calculator returns the watts it carries into the energy math.
When the duty-cycle factor matters
Refrigerators, freezers, and some heaters and pumps switch their compressor or element on and off rather than running steadily. Treating that as 24 hours at full power overstates the bill badly. The duty-cycle factor is the fraction of on-time the appliance actually draws rated power; the calculator scales the wattage down by it before computing energy. Leave it at 1 for steady loads like a TV or a lamp, where the device draws roughly constant power whenever it is on.
Active cost versus standby cost
Many electronics keep drawing 1 to 10 W while plugged in and idle, for an indicator light, a clock, or a standby radio. The calculator splits the day into active hours at running power and the remaining hours at standby power, then reports the active and standby shares of the yearly cost separately. That split tells you whether unplugging a device or using a switched strip is worth the bother, or whether the real money is in the active runtime.
Where this estimate stops being exact
The math assumes a flat rate per kWh, a constant voltage, and the same hours every day, so tiered or time-of-use pricing and seasonal swings in runtime will pull the real bill away from the estimate. It also uses running watts only. Motors and compressors briefly spike to a higher starting (surge) draw, which this tool does not model, so do not use the yearly figure to size a generator for an appliance at startup.