This radiator calculator will provide a guide to the output required both in BTUs and Watts, for a specified room.

The calculator requires measurements to be entered in metres so we've included a handy imperial to metric converter if required - simply enter your dimensions in feet and inches (or just inches) and click the CALCULATE button.

The main radiator calculator is easy to use - just complete the form including room dimensions, window area (multiply height x width of window frame) and select the floor, ceiling and wall details that best match your home. The results are given at the bottom of the page and include BTU (British Thermal Units) and Watts for your convenience.

Please note that this radiator calculator uses industry standard formulas, however, the results are for guidance only and we make no guarantees as to the accuracy of individual results.