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Understanding BTUs: How to Determine the Right Radiator for Your Home

Are you tired of being in a room that's always too cold or too hot, despite having the heating on? This might be due to a radiator that's not powerful enough to heat the space or one that's too powerful, resulting in higher heating bills. To prevent this, it's essential to use a BTU calculator to determine the correct radiator size for your home.

What is a  BTU?

BTU stands for British Thermal Units, which is a unit of measurement for energy. For instance, 150 British Thermal Units can raise the temperature of 150 pounds of water by one degree Fahrenheit. In terms of heating, the higher the BTU number, the more heat the radiator can emit to warm the room.


What about Watt Output?

We all call them BTU calculators, but they also give you the Watt calculation. Most radiators nowadays will talk in Watt and BTU.

  • How do I covert from Watt to BTUs? Multiply x 3.412
  • How do I covert BTU to Watt? Divide x 3.412


So how does the BTU Calculator Work?

  • To get an accurate estimate of your heating needs, you need to know your room's dimensions, including ceiling height, the number of windows and their size, type of glazing, outside wall material, and what's above and below the room.
  • This information is crucial to determine the total BTU required to heat the room adequately.
  • The number returned by the BTU calculator is the total BTUs / Watt required to heat a room.
  • You can use as many radiators as you'd like to reach this number. However, we recommend going above the BTU / Watt number if you're unsure.
  • Some homes or buildings are naturally colder than others, and you're the best judge of that.
  • Going over your total BTU / Watt number does no harm, except it could make the room too hot if you're not using a thermostat or result in unnecessarily high bills.


We always recommend working with a plumber to get an expert's opinion on-site. Still, our detailed BTU / Watt calculator works brilliantly and ensures you achieve an accurate guide as to how many BTUs and watts you need to heat your room effectively and efficiently.

To summarise, choosing the right size radiator is crucial to ensure your room's optimum temperature, and using a BTU / Watt calculator helps to achieve the perfect fit. Remember, when in doubt, always choose a radiator with a higher BTU output than your calculation, as it's always easier to turn it down than to install a new one.

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