How is the cost calculated?

Energy per day equals watts divided by 1000 times hours used, giving kWh. Multiply by your price per kWh for the daily cost, then scale to a month (about 30.4 days) and a year (365.25 days).

What is the standing charge?

Some tariffs add a fixed daily charge regardless of usage. Enter it if you want the totals to include it, or leave it at 0 for the appliance's running cost alone.

Does this work in any currency?

Yes. Enter the price per kWh in your own currency and every total is shown in that same currency. All maths runs locally in your browser.

Where do I find an appliance's wattage?

It is usually printed on a label on the device, on its power supply, or in the manual, shown as W or watts. If only amps and volts are given, multiply them (watts = volts × amps) to get the wattage.

How do I convert watts to kWh?

A kilowatt-hour is 1,000 watts running for one hour. So energy per day = wattage ÷ 1000 × hours per day. A 1500 W heater used 3 hours a day uses 1500 ÷ 1000 × 3 = 4.5 kWh per day.

How are the monthly and yearly figures worked out?

The daily cost is multiplied by 30.44 for a month (the average Gregorian month) and 365.25 for a year (allowing for leap years), so the annual figure is not just the monthly cost times twelve.

Should I include the standing charge in an appliance estimate?

Usually no. The standing charge is a fixed daily fee for being connected to the grid, not for running one device. Leave it at 0 to see a single appliance's running cost, or add it when estimating a whole tariff.

Electricity Bill Estimator

Estimate any appliance’s running cost

How much does that space heater, fridge or gaming PC actually cost to run? The price isn’t on the device — it depends on its power draw, how long you use it, and your electricity tariff. This estimator turns those three numbers into a clear cost per day, month and year, plus the energy used in kilowatt-hours (kWh).

How it works

The calculation is the standard energy-cost formula. First it converts power and time into energy: kWh per day = wattage ÷ 1000 × hours per day. Then it multiplies by your price per kWh to get the daily energy cost and adds any daily standing charge. Finally it scales the daily total: × 30.44 for a month and × 365.25 for a year, both being calendar averages that account for varying month lengths and leap years.

Example

A 1500 W heater run 3 hours a day at 0.28 per kWh, with no standing charge:

Step	Value
Energy per day	1500 ÷ 1000 × 3 = 4.5 kWh
Cost per day	4.5 × 0.28 = 1.26
Cost per month	1.26 × 30.44 ≈ 38.35
Cost per year	1.26 × 365.25 ≈ 460.22

Works in any currency — enter the price in yours and every total is shown in it. Everything runs in your browser, with nothing sent anywhere.