⚡ Electricity Cost Calculator

How the Electricity Cost Calculator Works

Electricity is billed by the kilowatt-hour (kWh): one kWh is the energy used by a 1,000-watt device running for one hour. Enter the power rating of an appliance (usually printed on a label, in the manual, or on the plug adapter), how many hours a day it runs, and the price you pay per kWh (shown on your electricity bill, in your own currency). The calculator shows energy use and cost per day, month, and year.

Devices with a thermostat or compressor — fridges, freezers, air conditioners, and heaters — cycle on and off, so they rarely draw their full rated power all the time. For those, the optional duty-cycle setting gives a more realistic estimate.

Formula

Energy per day (kWh) = watts × quantity × hours per day × duty cycle ÷ 1,000
Cost per day         = kWh per day × price per kWh
Cost per month       = cost per day × 30.42        Cost per year = cost per day × 365

How to Use It

1. Enter the appliance power in watts (or kilowatts).
2. Enter how many hours per day it runs and how many of them you have.
3. Enter your electricity price per kWh from your bill.
4. For fridges, heaters, or AC, lower the duty cycle to reflect on/off cycling.

Frequently Asked Questions

How do I calculate the electricity cost of an appliance?

Multiply the power in kilowatts by the hours used to get kWh, then multiply by your price per kWh. A 1,500 W heater used 4 hours a day uses 6 kWh a day; at 0.20 per kWh that costs 1.20 a day, or about 438 a year.

Where do I find my electricity price per kWh?

Your electricity bill lists the unit rate per kWh. If your tariff has several rates (for example day and night), use the rate for the time the appliance usually runs, or an average.

What is a duty cycle?

It is the share of time a device actually draws full power. A fridge compressor might run about a third to half of the time, so its duty cycle is roughly 33–50%. Devices without cycling, like a TV or lamp, run at 100% while switched on.

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Formula and content last reviewed: September 2026. All calculations run in your browser — nothing you enter is sent to or stored on our servers.