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best radiator size

How to Calculate the Best Radiator Size for Your Home

Investing in new radiators is one of the best ways to improve your central heating efficiency and comfort but also give your home a fresher look. Choosing between different radiator types, styles and sizes can be quite baffling though. You need radiators powerful enough to heat your space properly but also those that won’t overheat the room and massively increase your energy bills. That’s why we’ve put together this radiator sizing guide to help you find the best radiator fit for your home.

How to Calculate Radiator Size?

A radiator power and size are calculated in British Thermal Units (BTUs). The higher the BTU output, the quicker the radiator will heat the space. Radiator sizing goes from 600 to 10,000 BTUs, and here are the factors you should consider when choosing between sizes:

  • The size of the room in square metres,
  • The number of radiators (for large rooms, you’ll need 2 to 3 radiators if you want to achieve a high level of comfort),
  • The number of windows,
  • Surrounding floors and walls.

Radiator Sizing per Room

  • For a living room of 17 m², a radiator 5,700 to 6,825 BTUs (or a few smaller ones);
  • For a kitchen of 13 m², the ideal radiator size would be 3,757 to 4,300 BTUs;
  • For a bathroom (3.7 m²) 1,225 to 1,475 BTUs;
  • And for a master bedroom (13-14 m²) 3,550 to 4,275 BTUs.

Larger rooms may require more radiators (and higher BTU, of course), especially if there are several windows and if the room is not properly insulated.

Common Types of Radiators – Which One to Choose?

1. Electrically powered or plumbed?

Electric radiators are simple to install and operate as you can individually control each and fine-tune the temperature in every room in your home. Plumbed-in radiators require professional installation so make sure to contact a heating engineer or a plumber. This type of radiator connects to your hot water system, so the water circulates through the pipes and radiators and warms up your rooms.

2. Steel panel radiators

Steel panel radiators are fairly cheap and super energy efficient for their construction (wavy or corrugated panels). You can choose between single, double, and triple panel models and easily find the best size for any room in your home.

3. Column radiators

A column radiator features a mid-level of heating efficiency and makes a good choice for period and traditional homes. Depending on the heat you want it to emit, you can choose between 2, 3, or 4 column radiators. Note that column radiators trap dust easily so you should brush them once in a while to keep them in good condition.

4. Designer Radiators

As you can already guess, designer radiators are meant to enhance the look of your premises. Attractive and efficient, this type of radiator comes in a variety of finishes, colours and sizes. Also, you can find those with magnetic memo boards, mirrors or customise them to fit your home design.


If you want to ensure an ideal temperature in your home, you should choose radiators of the correct size. Rooms such as bedrooms and living rooms may require installing 2 to 3 radiators, especially if they are spacious. You won’t need more than one radiator for your bathroom but make sure it’s powerful enough to heat up the whole space. The ideal temperature for kitchens and stairs is around 16-18 degrees, which means a mid-sized radiator would do. Contact us anytime if you need any help choosing the ideal radiator size for your home or get a quote for a new boiler today if you would like to boost your central heating efficiency.

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