How to use the Electricity Cost Calculator
- Pick an appliance or enter its wattage (on the label or charger).
- Enter hours of use per day.
- Enter your electricity price per kWh from your bill.
Watts to cost
Energy (kWh) = watts × hours ÷ 1,000. A 400 W PC used 4 hours a day uses 1.6 kWh, which at $0.17/kWh costs about $0.27 a day or $99 a year. Devices like fridges cycle on and off, so use their average draw rather than the peak.
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Tools that pair well with the Electricity Cost Calculator
- Fuel Cost Calculator — Work out how much gas a trip will cost from the distance, your car’s fuel economy and the fuel price — one-way or round trip, split between passengers.
- Unit Converter — Convert between metric, imperial and technical units in ten categories — with a two-way converter and a table of every unit at once.
- Percentage Calculator — Seven everyday percentage calculations on one page.
- Savings Goal Calculator — Find out how much to save each month to reach a goal — a house deposit, a car, a trip or an emergency fund — including interest on your savings.
Frequently asked questions
Where do I find my price per kWh?
On your electricity bill: divide the energy charge by the kWh used, or look for the unit rate.
Does standby power matter?
A few watts each across many devices add up — 10 W in standby all year is about 88 kWh.
Is anything I enter saved or sent?
No. The calculation runs in your browser. Your last inputs are remembered on this device only, so the page opens where you left off.
Can I install Electricity Cost Calculator as a web app and use it offline?
Yes. Electricity Cost Calculator is an installable web app (PWA) — installed from your browser, not downloaded from an app store. Click Install app at the top of this page in Chrome or Edge (Windows, macOS, Linux, ChromeOS) or on Android, use Share → Add to Home Screen on iPhone and iPad, or File → Add to Dock in Safari 17+ on a Mac. It then opens in its own window with its own icon, and because it runs entirely in your browser it keeps working offline. Firefox on desktop can’t install web apps. How installing works.