Load width is a calculation measure to determine the amount of load experienced by the beam. Many loads are commonly given in area loads or pressures such as kPa (kilopascals) and psf (pounds per square foot). Load widths imply a tributary area over which the pressure load is applied (i.e. Load Width * Pressure = Line Load). If you wish to input kN/m or lb/ft line loads instead of pressure, you can simply set a load width of 1000mm or 1ft for the relevant load width entry.