Electricity cost calculator
Estimate what an appliance costs to run per day, month and year. Enter its wattage, how many hours a day it runs, and your electricity rate.
On this page
How to calculate appliance running cost
Electricity is billed in kilowatt-hours (kWh), a unit of energy equal to one kilowatt of power used for one hour. To find out what an appliance costs to run, you convert its power draw and usage time into kWh, then multiply by your electricity rate.
- Daily kWh = (Watts × Hours per day) ÷ 1000
- Daily cost = Daily kWh × Price per kWh
- Monthly cost = Daily cost × Days per month
- Annual cost = Monthly cost × 12
Worked example: a 1500-watt space heater run for 4 hours a day uses (1500 × 4) ÷ 1000, or 6 kWh per day. At $0.16 per kWh, that is $0.96 a day. Over a 30-day month, the heater costs about $28.80, and over a year, roughly $350 if it ran that same 4 hours every day.
This same math works for any appliance, so it is worth running through it once with your own numbers. Check the label on the device for its wattage, estimate how many hours a day it actually runs, and pull your real rate from a recent electricity bill. Swapping those three numbers into the calculator above gives you a quick sense of which appliances are actually driving your bill up, rather than guessing based on how big or how loud something seems.
Typical wattage for common appliances
These are typical, approximate ranges. Always check the label on your specific appliance for its actual wattage:
- Space heater: around 1500W
- Refrigerator: around 150W while running, higher during startup
- Window AC unit: around 1000W
- Hair dryer: around 1800W
- LED bulb: around 10W
- Laptop: around 50W
Because a refrigerator's compressor cycles on and off, its effective daily runtime is much less than 24 hours even though it appears to run continuously, so its real daily cost is lower than multiplying its wattage by 24 would suggest.
Ways to cut electricity costs
- Run high-wattage appliances less: heaters, dryers and AC units use the most energy, so trimming their hours has the biggest impact.
- Shift usage to off-peak hours: if your rate plan has time-of-use pricing, running appliances outside peak hours can lower the effective rate you pay.
- Check your actual per-kWh rate: rates vary a lot by region, provider and season, so plug in your own number from your bill rather than relying on a national average.
Small, frequent-use devices like LED bulbs and laptops cost very little individually, so the biggest savings usually come from managing high-wattage appliances rather than unplugging chargers. A single space heater run for a full winter can cost more than a laptop run all year, simply because of the gap in wattage, so it pays to focus effort where the numbers are largest.
It also helps to separate one-time habit changes from ongoing ones. Turning down a thermostat a couple of degrees or switching to a lower-wattage heater setting is a habit change that keeps paying off every day. Replacing an old appliance with a more efficient model is a one-time change that lowers the baseline wattage for good. Both matter, but the appliance swap tends to have the larger long-term effect since it reduces cost automatically without relying on remembering to change behavior.
Frequently asked questions
How do I calculate how much an appliance costs to run?
Multiply the wattage by hours used per day, then divide by 1000 to get kWh used per day. Multiply that by your price per kWh to get the daily cost, then multiply by days per month or 365 for a yearly figure.
Where do I find my electricity price per kWh?
Check your latest electricity bill or your utility's website. Rates vary a lot by region, provider and season, so use your own rate rather than a national average for an accurate estimate.
Where do I find an appliance's wattage?
Check the label on the appliance itself, the manual, or the box it came in. It is usually listed in watts (W) directly, or you can multiply volts by amps if only those are given.
Why is my refrigerator's actual usage lower than its wattage suggests?
A refrigerator's wattage rating reflects peak draw when the compressor is running, but the compressor cycles on and off throughout the day. Its average running time is much lower than 24 hours, so actual daily usage is lower than wattage times 24 would suggest.
Does this calculator give an exact bill amount?
No. It gives an estimate for a single appliance based on the numbers you enter. Your actual bill also includes other appliances, fixed utility fees, and possibly tiered or time-of-use pricing.