A managed network switch should match the devices you have and the growth you can reasonably expect. Count computers, access points, cameras, printers, and other wired equipment, then leave several ports unused.
For example, an office with 18 active connections may need a 24-port switch, but ceiling-mounted access points or planned cameras can quickly use that spare capacity. A little headroom helps. Still, buying far more ports than you need can waste budget and rack space.
Match port speed to actual traffic, not just the largest number on a product sheet. Gigabit Ethernet is often sufficient for standard office devices, while workstations moving large files may benefit from faster connections. Check network cards, cabling, and connected equipment; one slower link can limit the whole path. Faster is not always better.
Uplink capacity matters too. If many access ports send traffic to a server or another switch, a single low-speed uplink may become a bottleneck. Compare the combined traffic likely to cross that link, and check whether the switch supports the required number and type of uplinks.
Distance matters: copper is practical for short runs, while longer connections may need fiber.
I have seen port counts planned neatly on paper, then fall short once real devices are installed. Recheck the layout before ordering.