Electricity Calculator
Estimate the daily, monthly, and annual cost of running any appliance, from its wattage, hours of use, and your electricity price per kWh.
Estimated Monthly Cost
$20.25
Example
Running 1500W for 3 hours a day uses 4.5 kWh/day — at $0.15/kWh, that's $0.68/day, $20.25/month, or $246.38/year.
Daily Energy Use
4.5 kWh
Daily Cost
$0.68
Estimated Annual Cost
$246.38
How Is Electricity Cost Calculated?
A kilowatt-hour (kWh) — the standard unit on every electric bill — is the energy used to maintain one kilowatt of power for one hour. To find the cost of running any device, convert its wattage to kilowatts, multiply by the hours it runs, then multiply by your utility's price per kilowatt-hour.
Keep in mind that the wattage printed on an appliance's label is usually its maximum rated power draw, not its typical running wattage — many devices (refrigerators, air conditioners) cycle on and off or draw less than their maximum rating during normal operation, so actual costs are often somewhat lower than a worst-case estimate.
Annual Cost of Common Appliances
Estimated yearly cost for common household devices, using your hours-per-day and price inputs.
The Electricity Cost Formula
This calculator applies that formula per day, then scales it to monthly (×30) and annual (×365) totals, multiplied by the quantity of identical devices if you're calculating for more than one.
Why Small Devices Add Up
A single LED bulb costs pennies a day, but a household running 20 bulbs, a refrigerator, and various electronics continuously accumulates real monthly cost — this is why "phantom load" from always-on devices is a common target for household energy savings.
High-Wattage Devices Dominate the Bill
Heating and cooling equipment, water heaters, and clothes dryers typically use far more wattage than lighting or electronics, so even modest daily usage of these appliances often accounts for the largest share of a typical electric bill.
Time-of-Use Electricity Rates
Some utilities charge different rates depending on the time of day, with peak afternoon and evening hours often costing significantly more per kWh than overnight rates — shifting high-wattage tasks like laundry or EV charging to off-peak hours can meaningfully lower costs under these plans.
Example — Your Current Inputs
Running 1500W for 3 hours a day uses 4.5 kWh/day — at $0.15/kWh, that's $0.68/day, $20.25/month, or $246.38/year.
Additional Example — A Window AC Unit
A 1,000W window AC unit run 8 hours a day at $0.15/kWh uses 8 kWh/day — about $1.20/day, $36/month, or $438/year if run every day of the summer season equivalent.
About These Parameters
- Appliance Wattage
- Usually printed on a label, nameplate, or in the product manual — often listed as "W" or calculable from listed volts × amps if only those are given.
- Hours Used Per Day & Quantity
- Realistic average daily usage, not just the hours the device is plugged in. Quantity multiplies the total for identical devices, like a set of light bulbs.
- Electricity Price per kWh
- Found on your utility bill, usually listed per kWh. The US average is around $0.15/kWh but varies significantly by state and utility provider.
Frequently Asked Questions
What's the difference between watts and kilowatt-hours?
Watts measure instantaneous power — how much energy a device draws at any moment. Kilowatt-hours measure energy used over time — the actual quantity billed by your utility, found by multiplying power (in kW) by hours of use.
Does this account for standby/phantom power?
No — this calculator only estimates cost while a device is actively running at its stated wattage. Many electronics also draw a small amount of "phantom" power even when off or in standby mode, which isn't included here.
Why is my actual bill different from this estimate?
Actual appliance wattage often varies from the maximum rated wattage on the label — for example, refrigerators and AC units cycle on and off rather than running continuously at full power, which typically makes real-world costs lower than a worst-case estimate.