Power Bill

How much does it cost to run a kettle, a TV or a fridge? Choose how long each appliance is used every day and watch the meter spin.

Appliance
Kettle power
3.0 kW
Energy per day
2.56 kWh
Energy per month
77 kWh
Cost per month
19.20

The maths, live

Energy E = P × tE = 3.000 kW × 0.25 h = 0.75 kWh a day
Month E = energy per day × 30E = 2.56 × 30 = 76.8 kWh
Cost = energy × priceCost = 76.8 × 0.25 = 19.20

A kettle is 375 times more powerful than an LED bulb. Which costs more over a month: boiling the kettle for 15 minutes a day or leaving a bulb on all evening?

How it works

Power (P) is how fast an appliance uses energy, measured in watts (W) or kilowatts (kW, 1000 W). Things that heat, like kettles, ovens and hair dryers, are the most powerful. LED bulbs and phone chargers use very little.

The energy used depends on the power and how long it is on: E = P × t. Electricity companies measure energy in kilowatt-hours (kWh): 1 kWh is a 1 kW appliance running for 1 hour. Your bill is the number of kWh times the price of each kWh.

Try this

  1. Which costs more each month: the kettle for 15 minutes a day or an LED bulb for 5 hours a day?
  2. Swap the LED bulb for an old filament bulb. How much more does the light cost?
  3. Find out the real price per kWh where you live and set it. What would your family's bill be?