Electricity Cost Calculator
Work out the running cost of any device from three numbers: its power draw (watts or kilowatts), how many hours a day it runs, and your electricity rate per kilowatt-hour. The calculator converts power to energy (kWh = kW × hours) and multiplies by your rate, then projects the daily figure across a week, a 30-day month and a 365-day year. Useful for budgeting appliances, comparing an old fridge to a new one, sizing solar savings, or settling who-left-the-heater-on debates. Everything runs locally in your browser — your numbers are never sent anywhere.
Estimated monthly cost
$2.25
| Period | Energy | Cost |
|---|---|---|
| Day | 0.5 kWh | $0.07 |
| Week | 3.5 kWh | $0.53 |
| Month | 15 kWh | $2.25 |
| Year | 182.5 kWh | $27.38 |
Based on 30-day months and 365-day years. All math runs in your browser.
How to use
- Enter the appliance's power and pick the unit (W or kW). A label on the device or its manual usually lists it.
- Set how many hours a day it runs and your electricity rate per kWh (from your bill).
- Read the estimated monthly cost, plus the full day/week/month/year breakdown of energy and cost. Change the currency symbol if you like.
Frequently asked questions
- Where do I find an appliance's wattage?
- Check the rating label (often on the back or base) or the manual. It's usually shown in watts (W); some list amps and volts, where watts = amps × volts.
- What rate per kWh should I use?
- Use the per-kWh price from your electricity bill. If you have tiered or time-of-use pricing, use an average or the rate for the time the device runs.
- Why are months 30 days and years 365 days?
- They're simple, standard approximations for estimates. For an exact bill period, multiply the daily cost by the number of days you care about.
- Does standby power count?
- This assumes the device draws its rated power only while running. Devices that idle on standby use a smaller amount around the clock, which you'd model separately.
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