Energy cost calculator

Enter the power of the load, its daily operating hours and the unit price of electricity, and we show the consumption and the cost per day, per month and per year.

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How do we calculate the energy cost?

Energy consumption in kilowatt-hours (kWh) is the product of power and operating time: kWh = P (W) · operating hours / 1000. From this the calculator gives the daily, monthly (one twelfth of the annual value) and annual consumption, then, with the unit price you enter, the cost in the currency you choose, rounded to that currency's usual decimals.

What do you need to enter?

• The power of the load in watts.
• The daily operating hours: how long it runs per day (0.01–24 hours).
• The operating days per year: 365 by default; if it only runs on certain days of the week, you can reduce it.
• The unit price per kWh, in the currency you choose. We do not store or suggest the price: you find it on your supplier's bill, and it changes from time to time.

What to watch out for

The calculation assumes constant power and continuous operation during the operating hours. For a thermostat-controlled or intermittently running appliance (fridge, heating, boiler) the actual consumption is lower, because the appliance draws rated power only for part of the operating time; in that case the "operating hours" should be the effective full-load time. The calculation is informative.

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