VLSM Planner
Enter a base network and a list of subnets with the hosts each one needs. I compute the optimal VLSM allocation (aligned blocks, largest first) with mask, range, broadcast and utilization. All in your browser.
Base network utilization
0 of 0 addresses 0%
Base network
—
total addresses
Allocated
0
in blocks
Free
0
unused addresses
Utilization
0%
0 subnets
VLSM allocation
| Subnet | CIDR | Mask | Network | First host | Last host | Broadcast | Usable | Req. |
|---|
VLSM gives each subnet the smallest block that fits it and places them
largest first from the base network, so they stay
aligned with no overlap. No subnet with hosts uses
/31 or /32 (it always keeps a network and broadcast).
Runs locally in your browser · no sign-up · nothing leaves your browser