Electricity Cost Calculator

This electricity cost calculator estimates the running costs of electrical appliances based on their rated power and how long they are used. Enter the power, daily operating hours, number of days per week it is operated, and price per kilowatt hour (kWh).

You can see the cost per day, week, month and year of using an electrical appliance as well as how much energy it uses. You can also compare more efficient alternatives and find out their carbon footprint.

How are electricity costs calculated?

Electricity costs are calculated based on energy consumption, with the energy being measured in kilowatt hours (kWh). A kilowatt hour is the amount of energy used by a 1,000W electrical appliance running for one hour.

The amount of energy is the product of power and time, while cost is obtained by multiplying the amount of energy by the price per kWh:

The power is usually stated on the device or a label and is measured in watts (W) or kilowatts (kW). As 1 kW equals 1,000 W, a 60 W light bulb would be equivalent to 0.06 kW.

Example calculation:

An electrical appliance with a power of 1,000 W (1 kW) is operated for 5 hours daily. The electricity price is 0.15 per kWh.

5kWh is consumed daily by multiplying the power of 1kW with time of 5. The daily cost comes from the product of 5 and 0.15 which gives 0.75.

Over the course of a year this will be about 1820 kWh and cost around 273. This calculator can be used with any inputs for power, operating time and electricity price.

Performance and part-load operation:

Many appliances do not use their rated power throughout the entire time they are in operation. Refrigerators only run their compressor intermittently, air conditioners reduce output when a room is cooled and cooktops rarely operate at full capacity.

In the "Capacity" field you can reduce the performance in percent to reflect this situation. Devices that are always run at maximum capacity should be left at 100% or, if possible, set slightly lower to estimate average power consumption.

Performance units:

Watts and kilowatts are units commonly used in everyday life but other units may be listed on the labels of electrical appliances. This tool supports watts, kilowatts, British thermal units (BTUs), and horsepower and will automatically convert between them.

The table below shows a comparison of common units of power.

For example a window air conditioner with the rating of 12,000 BTUs has an output capacity of about 3.5 kW but since it does not generate heat, only transfers it, the actual power consumed is lower.

Common electrical appliances' power rating:

Actual power consumption can vary widely depending on the model of device, and values listed on the label are usually maximums rather than typical averages. Use these ranges as a starting point and adjust them to match the specifications on your particular device's label.

Here's how to save money:

If you know the annual values, small changes over time can make a big difference. If brightness is kept constant, replacing a 60W incandescent bulb with a 9W LED light bulb will reduce that lamp's energy consumption by about 85%.

Instead of leaving appliances on standby, turn them off. By fully loading washing machines and dishwashers, as well as using programmable thermostats, you can reduce the running time and therefore the load in the above formula.

When buying new appliances, don't just consider the price tag - calculate the running costs over the life of the appliance. This comparison tool will show you how much money a more energy efficient model can save you each year or over ten years.

These figures are estimates and for planning purposes only. The actual cost of electricity will depend on your actual usage, tariffs, standing charges and taxes which are not taken into account by this tool.