Electricity Cost Calculator — Appliance Running Cost
Work out what an appliance costs to run per day, month and year from its wattage, hours of use and your electricity rate. Free, 100% in your browser.
🔒 Calculated in your browser — nothing is uploaded. You enter your own tariff, so no live-rate lookup is needed. Month = ×30, year = ×365.
What an appliance costs to run
Enter a device's power in watts, how many hours a day you use it, and your electricity rate per kWh. The tool multiplies them into daily, monthly and yearly cost, plus the kWh it uses per day. Useful for space heaters, air conditioners, PCs, fridges, EV charging and more.
Why it needs no live data
You enter your own tariff, so there's no need to look up live rates — the result stays accurate for your bill and everything runs in your browser. Monthly figures use 30 days and yearly use 365; adjust the hours to model seasonal use.
Frequently asked questions
How do I calculate the cost to run an appliance?
kWh = watts ÷ 1000 × hours per day, then cost = kWh × your rate. A 100 W device for 5 h/day at $0.15/kWh is about $2.25 a month.
Where do I find an appliance's wattage?
Check the label on the device or its power supply, or the manual — it's usually printed in watts (W) or amps × volts.