BTU Heat Loss Calculator
BTU Calculator (ΔT50)
Our BTU calculator helps you estimate the amount of heat needed to comfortably warm your room. Results are shown using the UK standard measurement of ΔT50 BTU/h, which reflects the output of radiators when used with a typical gas-powered central heating system.
If you’re using a heat pump, radiators operate at lower water temperatures, so we also provide an equivalent ΔT30 calculation. This allows you to easily compare outputs and choose a radiator that will perform effectively with your heating system, whatever type you use.
if you are are in a remote area, in the highlands and islands, we would recommend using conservative mode to allow for colder minimum temperatures.
BTU Calculator Disclaimer
This BTU calculator provides an estimated heat requirement based on a typical UK home at Delta ΔT50. Actual performance may vary depending on factors such as installation quality, building construction, insulation, air changes, and the overall efficiency of your heating system.
For best results, we recommend rounding your calculated BTU requirement up to ensure a comfortable heat output. If you have a complex layout, an unusual property type, or require a precise calculation, please consult a qualified heating engineer.
All radiator outputs listed on our website use Delta ΔT50 for standard UK central heating systems and Delta ΔT30 for typical domestic air-source heat pumps. If you require a different Delta T rating, please use an appropriate conversion tool.