Our electric radiator calculator takes the guesswork out of choosing a radiator size - making it quick and easy to finalise your purchase and keep your home warm. Simply tell us your room dimensions and some basic information about your property and the calculator will do the rest - providing the total wattage you need to heat your space. Whether you buy one radiator that equals that total, or a combination of different radiators, is entirely up to you! If the wattage provided is in between sizes, it’s better to round up rather than down as this allows your radiators to use less energy to maintain temperatures.