What is an electricity cost calculator?
An electricity cost calculator estimates how much it costs to run an appliance based on its power draw, how long you use it, and your electricity rate. Enter the wattage, daily hours of use, and a rate per kilowatt-hour, and it returns the cost broken down by day, month, and year.
This is useful for comparing appliances before you buy, checking whether a space heater or window AC unit is driving up a bill, or simply understanding where electricity costs in a home are coming from. Pages for individual states pre-fill the rate with a real average so you do not need to look it up yourself.
Key inputs
Four numbers drive every estimate. Most can be found on an appliance's nameplate or a recent utility bill.
| Input | What to enter |
|---|---|
| Appliance power | Wattage from the appliance label or manual, in watts or kilowatts |
| Hours per day | How many hours the appliance actually runs each day, not just how long it is plugged in |
| Billing days per month | Typically 28 to 31, matched to your utility billing cycle |
| Electricity rate | Cost per kilowatt-hour, in cents or dollars, pre-filled with your state's average |
What the calculator returns
Once your inputs are entered, the calculator produces a full cost and energy-use breakdown.
Cost per day, per month, and per year, so you can see the impact of a single appliance at a glance.
Energy use in kilowatt-hours (kWh) per day, month, and year, the same unit your utility bill uses.
The effective rate used in the calculation, so you can confirm it matches your actual utility plan.
How to use this calculator
- 1
Find the appliance's power rating
Check the nameplate, sticker, or manual for a wattage value. If only amps and volts are listed, multiply them together to get watts.
- 2
Estimate realistic daily use
Enter how many hours the appliance is actually running, not just plugged in. A refrigerator runs continuously but cycles on and off, so its true average draw is lower than its peak wattage.
- 3
Confirm the electricity rate
The rate is pre-filled with your state's average. Edit it if your utility bill shows a different rate, especially if you're on a time-of-use plan.
- 4
Review the cost and energy breakdown
Check the daily, monthly, and yearly cost alongside the kWh figures to see how the appliance compares to others in the home.
Common appliance wattage reference
Don't have a nameplate handy? These typical ranges can get you a reasonable starting estimate. Actual draw varies by model, size, and age.
| Appliance | Typical wattage |
|---|---|
| Refrigerator | 100 – 800 W (cycles on and off; average draw is lower than peak) |
| Central air conditioner | 2,000 – 5,000 W |
| Window AC unit | 500 – 1,500 W |
| Electric water heater | 3,000 – 4,500 W |
| Space heater | 750 – 1,500 W |
| Clothes dryer | 2,000 – 5,000 W |
| Washing machine | 350 – 1,200 W |
| Dishwasher | 1,200 – 1,800 W |
| Microwave | 600 – 1,200 W |
| Television (LED) | 30 – 150 W |
| Desktop computer | 200 – 600 W |
| LED light bulb | 5 – 15 W |
Practical tips and limitations
Peak wattage isn't average wattage
Appliances with compressors or heating elements, like refrigerators and water heaters, cycle on and off. The nameplate wattage is the peak draw, not a constant rate, so real-world costs are often lower than a naive calculation suggests.
Rates vary by plan, not just by state
State averages are a useful starting point, but many utilities offer tiered or time-of-use pricing where rates change by season or time of day. Your bill is always the most accurate source.
Taxes and fees aren't included
This calculator estimates energy cost only. Utility bills often include fixed delivery charges, taxes, and fees on top of the per-kWh energy rate, so your actual bill impact may be higher.
Use it to compare, not just to total
The most practical use is often comparing two appliances or two usage patterns side by side, rather than relying on the absolute number as a precise bill prediction.
Frequently asked questions
How do I calculate electricity cost for an appliance?
▾
Convert the appliance's wattage to kilowatts, multiply by the hours used per day to get daily kWh, then multiply by your electricity rate. This calculator does that automatically and extends the result to monthly and yearly totals.
Where do I find an appliance's wattage?
▾
Check the nameplate or sticker, usually on the back or bottom of the unit, or the product manual. If only amps and volts are listed, multiply them together to estimate watts.
Why does my actual bill differ from this estimate?
▾
Bills include fixed delivery charges, taxes, and fees beyond the energy rate, and many appliances draw less than their peak wattage on average. Time-of-use or tiered rate plans can also change the effective price per kWh.
Where does the default electricity rate come from?
▾
State pages are pre-filled with the average residential electricity rate reported by the U.S. Energy Information Administration (EIA). You can always overwrite it with the rate from your own utility bill.
Can I use this for kilowatts instead of watts?
▾
Yes. Switch the power unit to kilowatts if that's how your appliance or equipment is rated, and the calculation adjusts automatically.