Work out ip address plan for sites instantly with clear inputs, formula shown and shareable results.
A multi-site plan reserves host bits for the largest site and site bits for the number of locations. Rounding both up to powers of two keeps every site summarisable behind one prefix, which is what makes WAN routing tables small. Utilisation above 100 percent means the parent block cannot hold the plan and you need a shorter base prefix.
Site plan
host bits = ceil(log2(hosts + 2)); site bits = ceil(log2(sites)); required prefix = 32 - (host bits + site bits)
Contiguous power-of-two allocation is what allows a single summary route per region. Nine sites need four site bits, giving room for sixteen and future growth.
A uniform prefix is simpler to operate and document. Use VLSM only where a handful of sites are dramatically larger than the rest.