Electricity Bill Calculator
Estimate your electricity cost from an appliance's power consumption. Enter the power in watts (W) or kilowatts (kW), the hours of use per day and the price of one kilowatt-hour (kWh), then press Calculate to get the cost per day, per month and per year. Everything runs locally in your browser.
Set the power consumption
Type the device power in watts (W) or kilowatts (kW), or pick a typical appliance from the selector to prefill a common wattage. The country selector only switches the cost unit (pence for the UK, rupee for India, peso for the Philippines, cent elsewhere) — it never changes the arithmetic.
Enter hours per day and the kWh price
Type how many hours per day the device runs and the price of 1 kWh in the selected unit (cent, pence, rupee or peso). Zero is allowed for any field; negative values are rejected because consumption and price are magnitudes.
Press Calculate, read day / month / year
The calculator shows the energy use in kWh per day internally and returns the electricity cost per day, per month (30 days) and per year (365 days), each with two decimals. Press Reset at any time to clear everything and start over.
Electricity bill calculation
- How do you calculate electricity cost per day?
- The energy E in kilowatt-hours (kWh) per day equals the power P in watts (W) times the usage hours per day t, divided by 1000: E(kWh/day) = P(W) × t(h/day) / 1000. The cost per day is that energy times the price of 1 kWh, divided by 100 to turn the subunit price (cent, pence, rupee, peso) into the major currency unit: Cost/day = E(kWh/day) × cost / 100.
- How are the monthly and yearly costs computed?
- This calculator multiplies the daily cost by 30 for the month and by 365 for the year. Real bills vary with tariff tiers, standing charges and the number of days in the billing period, so treat these as clean estimates.
- Watts or kilowatts — which unit should I enter?
- Either works: 1 kW = 1000 W, so 1500 W and 1.5 kW give exactly the same result. Device nameplates usually print watts; utility literature often uses kilowatts. The unit selector only renames your number — it never double-counts.
- What goes in the "1 kWh cost" field?
- Your electricity tariff per kilowatt-hour, entered in the unit you select: US cents for cent, pence for pence, rupees for rupee, pesos for peso. For example, a 12 ¢/kWh plan means entering 12 with the unit set to cent. The result is shown in dollars (or pounds, rupees, pesos) with the matching symbol.
- Worked example
- A 100 W LED lighting setup running 8 hours a day on a 10 ¢/kWh plan uses E = 100 × 8 / 1000 = 0.8 kWh per day and costs 0.8 × 10 / 100 = $0.08 per day — $2.40 per month (30 days) and $29.20 per year (365 days).
Privacy: every calculation runs in your browser tab — no value you type is sent anywhere, and this tool does not use the clipboard, storage, or the network. Results are ideal flat-tariff estimates; check your actual bill for tiered rates and fixed charges.