Electricity Cost Calculator — Appliance Running Cost
Work out what an appliance costs to run per day, month and year from its wattage, hours of use and your electricity rate.
100 % takes the rating at its word. A fridge or an air conditioner on a thermostat is off part of the time, so its average draw is lower — put that share here.
The starting 0.15 is a round example, not an average — the rate per kWh on your own bill is the one to use.
For a bill’s own period, or any stretch that is not a 30-day month: type the days, or pick the two meter-reading dates and the days between them are counted (the end date is not).
Typical wattage of common appliances
| Appliance | Typical power |
|---|---|
| Portable heater | – W |
| Dehumidifier | W |
| Ceiling fan | – W |
| Window fan | – W |
| Water heater (40 gallon) | – W |
| Refrigerator (frost-free, 16 cu ft) | W |
| Microwave oven | – W |
| Dishwasher (drying uses much more) | – W |
| Coffee maker | – W |
| Toaster | – W |
| Toaster oven | W |
| Washing machine | – W |
| Clothes dryer | – W |
| Clothes iron | – W |
| Hair dryer | – W |
| Vacuum cleaner | – W |
| Electric blanket (single–double) | – W |
| Flat-screen TV | W |
| Desktop computer (awake) | W |
| Computer monitor (awake) | W |
| Laptop computer | W |
| Water pump (deep well) | – W |
Nameplate figures from Virginia Cooperative Extension’s “Estimating Appliance and Home Electronic Energy Use” (2020). The watts on your own appliance’s rating label are the figure to use — and a fridge, heater or air conditioner cycles on and off, so it draws its full power for fewer hours than it is switched on. Press a figure to put it in Power, in watts.
You enter your own tariff, so no live-rate lookup is needed. Month = ×30, year = ×365.
What an appliance costs to run
Enter a device's power in watts — or, with “Power unit”, in kilowatts, BTU/h, horsepower, metric horsepower or tons of refrigeration, the way air conditioners and motors are often rated — how many hours a day you use it, and your electricity rate per kWh. The tool multiplies them into daily, monthly and yearly cost, plus the kWh it uses per day. Useful for space heaters, air conditioners, PCs, fridges, EV charging and more.
Why it needs no live data
You enter your own tariff, so there's no need to look up live rates, and everything runs in your browser. Monthly figures use 30 days and yearly use 365; adjust the hours to model seasonal use.
Watts, kilowatt-hours and the tariff
Watts are a rate — how fast a device draws power. A kilowatt-hour is an amount: one kilowatt drawn for one hour, and the unit your bill is priced in. The conversion is the whole calculation: watts ÷ 1000 × hours gives kilowatt-hours, and that times your rate gives the cost. A 2,000 W heater run for three hours is 6 kWh; the same 6 kWh is a 100 W fridge compressor running for sixty. The tariff is yours to enter because rates differ by supplier, region, time of day and season, and a calculator that guessed one would be wrong for almost everybody.
Nameplate watts are not what it draws
The figure on the label is usually maximum draw, and most appliances spend most of their time well below it. A fridge is rated for its compressor but the compressor cycles; a washing machine's peak is the heating element, which runs for a fraction of the cycle; a laptop charger rated 65 W draws that only while charging hard. For anything that cycles, an energy label's annual kWh figure divided by 365 is a better daily figure than the nameplate: set “Power unit” to kilowatts and enter it with one hour a day — a label of 438 kWh a year is 1.2 kW for an hour a day. Or keep the nameplate figure and set “Runs at (% of rated power)” to the share of it the appliance really averages. Standby matters more than it looks: a few watts left on all year is tens of kilowatt-hours. This page treats a month as 30 days and a year as 365, so the monthly figure is a level month rather than a calendar one.
Frequently asked questions
How do I calculate the cost to run an appliance?
kWh = watts ÷ 1000 × hours per day, then cost = kWh × your rate. A 100 W device for 5 h/day at $0.15/kWh is about $2.25 a month.
Where do I find an appliance's wattage?
On the rating plate — the sticker on the back or underside — or in the manual, printed in watts (W) or as amps × volts. For anything that cycles on and off, prefer the annual kWh figure from the energy label: divide it by 365, set “Power unit” to kilowatts and enter the result with one hour a day — typed in watts it would read a thousand times too low. When the label is missing, the table of typical wattages on the page gives a figure, and pressing one puts it into Power, in watts.
Is a month 30 days here?
Yes, and a year is 365. The monthly figure is a level month so that twelve of them and one year agree closely, rather than tracking the calendar. For a bill or any other stretch, type its days in “Days in the period”, or pick its two dates, and the cost for exactly those days is shown beside the month.
Why is my bill higher than this?
A bill is every appliance plus standing charges, taxes and often a tiered rate where later units cost more. This tool prices each appliance, and any list of them you add up, at one flat rate with no standing charges — useful for comparing two appliances or deciding whether something is worth switching off, not for predicting a bill.
What if the appliance is not used every day?
Choose the usage period that fits — minutes or hours a day, hours a week, a month or a year — and the most you can enter changes to match that period.
Can I add up several appliances, or see what an hour of use costs?
Yes. “+ Add this appliance to a list” keeps each appliance in a running list — carried in the page link — with its monthly cost at the rate above and a button to remove it, and a “List total” per month and per year underneath. The first figure in the answer, “Per hour of use”, is what an hour of running costs, the useful number for anything used in short bursts.
What if the appliance is rated in BTU or horsepower, or never runs at full power?
Pick its unit in “Power unit” — kilowatts, BTU/h, horsepower, metric horsepower or tons of refrigeration — and the figure is shown in watts under the box. For something that cycles or runs below its rating, “Runs at (% of rated power)” scales the watts down: leave it at full to take the rating at its word, or put in the share of the rating it really averages. Appliances added to the list keep the watts they actually draw.