What is a BTU & Why It's Important

As you explore our site and radiators, you will see ‘BTU’ used frequently on our product pages. It is something that is important to know when it comes to shopping for home heating. A radiator with insufficient output may never raise the temperature to the required level. Outdoor temperatures, external walls, insulation, and heated adjacent rooms (i.e. above, below, and to the side) all have a contributing effect. The boiler should have sufficient capacity to supply all connected radiators to the sum of their maximum demand. Larger rooms such as living rooms may require more than one radiator, positioned evenly throughout the room. If this is the case, divide the required output by the number of radiators needed.

Use our BTU calculator to easily work out what level of BTU and Watt output will sufficiently heat your room, in turn allowing you to decide what size radiator you will need:

What does ‘BTU’ Stand For?

BTU stands for 'British Thermal Unit' and is a measurement of thermal energy and is the standard output (heat) measurement for radiators and towel rails (except electric heat sources).

What Does BTU Mean For Radiators?

Fundamentally, the BTU attributed to a radiator is a simple way of numerically displaying how much heat the radiator emits, so you can make an informed decision when buying radiators and ensuring they will heat your space effectively. Whilst style, colour and design are important, knowing how many BTUs are required will allow you to choose a radiator (s) that will heat the room efficiently - taking the time to calculate the BTU requirements of the room you’re looking to heat is integral.

How effective the radiator will be though depends on factors such as the size of the room and how well-insulated it is. A radiator’s ability to transfer heat will depend on its material, size and surface area as well as the water temperature within the system.

Calculating BTU

Whilst many factors will affect BTU, it can be daunting to try and work this out. However, the good news is that we have developed our own BTU Calculator to take care of the calculations for you. Our calculator is completely free to use and will make working out the required BTU amount nice and simple.

Once you’ve entered your measurements and specifications, our BTU Calculator will tell you the combined BTUs (Heat Output) your room requires to be heated effectively. Our BTU Calculator also provides its’ calculation results in Watts, for reference against electric radiators and towel rails.

Once you've worked out your heat output requirements, make a note of the results and keep them on hand. From here you can view our range of radiators and/or heated towel rails whilst referencing the output displayed on each against your calculations, this way you can ensure that you're choosing the perfect radiator/towel rail for you.

Important to Remember

Our calculator will show you the combined output required for the provided room measurements; in the case of larger rooms that require more than 1 radiator, divide the calculated output by how many you need.

All of our BTU ratings are displayed at Delta T50. Delta T50 is the UK standard for all domestic gas boilers and is set to allow professionals, end-users and consumers alike, to make a fair and reasonable comparison of radiator and towel rail outputs from various suppliers and across a mix of product types. Many newer boilers will operate at a lower Delta T rating, which will affect the BTUs being output, and subsequently, the size of the radiator required.