Electricity Cost Calculator
Estimate the daily, monthly, and yearly running cost of any appliance from its wattage, usage, and your electricity rate — right in your browser.
The Electricity Cost Calculator runs entirely in your browser. The wattage, usage hours, and electricity rate you enter never leave your device and nothing is uploaded to ArrayKit.
Open the Ohm's Law Calculator
About Electricity Cost Calculator
The Electricity Cost Calculator estimates the energy use and running cost of any appliance from its wattage, how many hours a day it runs, and your price per kWh. Enter the power rating printed on the device or its label, the hours it typically runs each day, and your utility's rate, and the calculator converts watts into kilowatt-hours and multiplies by your rate to show daily, monthly, and yearly cost. It is useful for comparing space heaters, air conditioners, fridges, or gaming PCs, spotting which always-on devices add up over a year, or checking a bill against expected usage before you call your utility. Everything runs locally in your browser — the numbers you enter never leave your device.
Features
- Converts appliance wattage and daily hours into kilowatt-hours (kWh)
- Shows daily, monthly, and yearly running cost side by side
- Uses your own price per kWh so results match your actual electricity rate
- Handles small always-on loads (routers, chargers) and large appliances alike
- Copy a plain-text summary of the power, usage, and cost figures
- Clear error message when hours per day is outside the 0–24 range
- Instant recalculation as you adjust wattage, hours, or rate
- Runs entirely in your browser with no appliance or billing data uploaded
How to use the Electricity Cost Calculator
- Enter the appliance's power rating in watts
- Enter how many hours per day it typically runs
- Enter your electricity price per kilowatt-hour
- Read the daily, monthly, and yearly cost estimates
Example
Input
1000 W, 5 h/day, $0.15
Output
$0.75/day · $273.75/yr
Common errors & troubleshooting
- Estimated cost looks nothing like the actual electricity bill. — Confirm the wattage — many devices list a maximum rating that's higher than typical draw — and check whether your utility bills a flat rate or a tiered/time-of-use rate.
- Rate entered as 15 instead of 0.15. — Enter the price per kWh in dollars, e.g. 0.15 for 15 cents, not the whole cent amount as if it were dollars.
- Hours per day entered as a weekly total. — Use average hours run per single day (0–24), not hours per week — divide a weekly total by 7 first.
- Monthly and yearly totals seem too round. — This calculator assumes a fixed 30-day month and 365-day year at the same daily usage; real bills vary with the actual number of days and any change in usage.
Frequently asked questions
- What does the Electricity Cost Calculator actually compute?
- It converts an appliance's wattage and daily hours of use into kilowatt-hours (kWh = watts ÷ 1000 × hours), then multiplies by your price per kWh to estimate daily, monthly, and yearly running cost.
- Where do I find an appliance's wattage for this calculator?
- Check the label or nameplate on the device, its manual, or the box it came in — most appliances list a wattage or amps × volts rating you can convert to watts.
- Does the Electricity Cost Calculator account for tiered or time-of-use electricity rates?
- No. It uses a single flat price per kWh that you enter. If your utility bills different rates by usage tier or time of day, run the calculator separately for each rate band and add the results.
- How does the calculator work out the monthly and yearly cost?
- It multiplies the daily cost by 30 for the monthly figure and by 365 for the yearly figure, assuming the same daily usage every day — real bills will vary with the exact number of days and any change in habits.
- Is this electricity cost estimate accurate enough to budget with?
- It's a close estimate based on the wattage and hours you provide, not an exact bill. Actual devices often draw less than their maximum rating, and utilities add taxes and fees — verify against your meter or bill before relying on it.
- Does the Electricity Cost Calculator upload my appliance or billing details?
- No. All calculations happen locally in your browser. The wattage, hours, and rate you enter are never sent to ArrayKit or anywhere else.
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