Work out broadcast domain size instantly with clear inputs, formula shown and shareable results.
Every broadcast is delivered to every host in the VLAN, so aggregate broadcast traffic grows linearly with host count while the load on each individual NIC grows at the same rate. That is why flat networks degrade: at a few thousand hosts, ARP, NetBIOS, mDNS and DHCP chatter alone consume noticeable CPU on every device. Frame overhead of 20 bytes covers the preamble and inter-frame gap on Ethernet.
Broadcast load
pps = hosts x broadcasts per host; bandwidth = pps x (frame bytes + 20) x 8; every host receives the full pps
Design guidance usually caps a broadcast domain around 500 to 1000 hosts, which typically corresponds to a /23 or /22. Beyond that, split the VLAN and route between segments.
No. Switches flood broadcasts to every port in the VLAN. Only a router or a VLAN boundary stops them.