This is determined by the speed capability of one individual port on your switch. If each port supports 1 Gbps, then each port's capacity is simply that – 1 Gbps. To estimate the switch's overall capacity, multiply the per-port speed by the total number of ports on the. Well, understanding how to calculate the switching capacity of your switches is the first step! What is Switching Capacity? Let's start from square one. Switching capacity, often known as fabric capacity, is the total amount of data a switch can process and transfer in a given second.