For a square room enter the measurements in the boxes below in meters. For example 3.45 for (3mtr 45cm). The calculation will give you the m² of the room. In fact you need a kit about 10% less than the size of the room. This is due to the none heated area around the edge of the room and also when laying the mat you need to leave a gap between each run. Remember if our design team see anything that could be a potential issue they will contact you before going ahead with the order, it is not in our or your interest to get anything wrong.