In low-voltage switchgear applications, the width of aluminum flat busbar is usually selected in the range of 30mm to 120mm, and the thickness is selected in the range of 4mm to 10mm according to the current-carrying capacity requirements. The busbar sizing calculator determines the required busbar dimensions based on the continuous current rating, short circuit withstand, and thermal limits for switchgear assemblies. The current rating is calculated from the conductor cross-sectional area, material (copper or aluminium), and maximum. Engineers often rely on a busbar size chart in mm to match current demand with proper copper or aluminium bar dimensions.