What Does It Cost to Run Each of Your Devices?
See the exact cost to run any single device by the hour, day, or year, then compare multiple devices side by side to find your home's biggest power users.
Common conversions
| Input | Result |
|---|---|
| Phone charger, 5 W, 3 h/day | $0.88/yr |
| Hair dryer, 1,500 W, 6 min/day | $8.76/yr |
| Electric kettle, 1,500 W, 9 min/day | $13.14/yr |
| WiFi router, 10 W, 24 h/day | $14.02/yr |
| Treadmill, 600 W, 30 min/day | $17.52/yr |
| Game console, 150 W, 3 h/day | $26.28/yr |
| Box fan, 100 W, 8 h/day | $46.72/yr |
| Space heater, 1,500 W, 5 h/day | $438.00/yr |
The math behind it
- Heater: kWh/day = 1,500 × 5 / 1000 = 7.5
- Heater: cost/day = 7.5 × 0.16 = $1.20, cost/year = $438.00
- Fan: kWh/day = 100 × 8 / 1000 = 0.8
- Fan: cost/day = 0.8 × 0.16 = $0.128, cost/year = $46.72
Everything you need to know
Two devices can cost about the same to run even when their wattages are far apart, because cost depends on how long something runs, not just how much power it draws at any instant. This calculator isolates one device's running cost so you can see it on its own, then set it next to any other appliance in the house.
Cost per hour, day, and year for one device
The calculator multiplies a device's wattage by the hours it runs each day to get kWh used, then multiplies that by your electricity rate. Divide watts by 1,000 first to convert to kilowatts, since utility rates are quoted per kilowatt-hour. The result above is the annual figure; divide it by 365 for a daily number or by 8,760 for an hourly one, or use the per-hour and per-day formulas directly if you only need a short-run estimate, such as pricing out a single load of laundry or one evening of gaming.
Comparing devices side by side
Wattage alone is a poor guide to which device actually costs more, because runtime moves the total just as much as power draw does. A 10 W WiFi router left on 24 hours a day costs about $14 a year, more than a 1,500 W hair dryer used for 6 minutes a day, which costs about $8.76 a year, even though the dryer draws 150 times more power while it's running. To compare fairly, run the calculator once per device with its own wattage and hours, write down the annual figure, and rank the results. That ranking, not the wattage rating on the box, tells you which device is actually worth targeting first.
Where the wattage and hours numbers come from
Start with the number on the appliance's nameplate or in its manual, or check the appliance wattage reference for typical figures by device type. Nameplate values are usually a maximum, so for anything with a compressor or motor, such as a fridge or an AC unit, the true average running wattage is lower than the plate rating. For hours per day, use actual observed usage rather than how long the device is plugged in; a plug-in power meter that logs both wattage and runtime over a few days gives the most accurate inputs for both fields.
Common applications
Run every major device through the calculator and sort by annual cost. A 1,500 W space heater run 5 h/day ($438/yr) will dwarf a 10 W router run all day ($14/yr), even though the router runs far longer.
Compare the annual running cost of an aging space heater or window AC against a newer, more efficient model's wattage before spending money on a replacement.
Calculate the running cost of a dedicated space heater, gaming PC, or mini-fridge in one person's room to work out a fair share of a shared electric bill.
If cutting a device's daily runtime in half saves more per year than a $15 smart plug costs, the purchase pays for itself within months.
Common mistakes
A microwave rated at 1,500 W often draws closer to 1,000-1,200 W while cooking. Using the nameplate figure can overstate the true running cost by 20% or more.
A game console or TV left in standby can draw 1 to 5 W continuously. It looks negligible per device but adds up when several electronics sit in standby all day.
A 1,500 W hair dryer used for 6 minutes a day costs less per year than a 10 W router left on 24 hours a day. Compare the annual cost, not the wattage rating.
Rates range from about $0.11/kWh in Idaho to $0.40/kWh in Hawaii. Using $0.16/kWh when your actual rate is $0.30/kWh understates every device's true cost by close to half.
Frequently asked questions
How much does it cost to run a 1,500 W device for one hour?+
About 24 cents at the US average rate of $0.16/kWh. A 1,500 W device draws 1.5 kWh in an hour, and 1.5 × 0.16 = $0.24.
Does a higher-wattage device always cost more to run?+
No, runtime matters as much as wattage. A 10 W WiFi router left on 24 hours a day costs about $14 a year, more than a 1,500 W hair dryer used only 6 minutes a day, which costs about $8.76 a year.
How do I compare the running cost of two different devices?+
Run the calculator once for each device with its own wattage and daily hours, then compare the annual cost figures side by side rather than comparing wattage ratings alone.
Is standby or phantom power included in this calculator?+
No, this tool only prices the active-use hours you enter. Add a separate estimate for standby draw, commonly 1 to 5 W per device, for anything left plugged in the rest of the day.
What electricity rate should I use for this calculator?+
Use your own utility's per-kWh rate for the most accurate result. The US residential average was about $0.16/kWh in 2025, ranging from roughly $0.11 in Idaho to $0.40 in Hawaii.
How much does it cost to run a space heater all winter?+
About $438 a year for a 1,500 W heater run 5 hours a day at $0.16/kWh. Cost scales directly with however many hours a day it actually runs.
Does this calculator show cost per hour or per year?+
The main result above is the annual cost. Divide by 365 for a daily figure, by 8,760 for an hourly figure, or use the per-hour and per-day formulas listed above directly.
Why does my device seem to cost more than this calculator says?+
The most common reason is that its true running wattage is higher than the nameplate figure, or it runs more hours a day than assumed. A plug-in power meter gives the most accurate inputs.
Which household devices are usually the most expensive to run?+
Anything that generates heat, such as space heaters, water heaters, and clothes dryers, since these draw 1,000 to 5,000 W compared to under 200 W for most electronics.
Should I compare devices by wattage or by annual cost?+
By annual cost, since it accounts for both power draw and daily runtime together, which the wattage rating on its own does not capture.