Subnet Calculator (IPv4)
Find a block that fits your hosts, then see what a valid IPv4 split gives each VLAN before committing to a numbering scheme.
254
Usable hosts
4
Subnets when split
One means no split; a larger number is the number of equal VLAN blocks.
Valid split
Split request
| Addresses in the block | 256 |
|---|
| Addresses in each | 64 |
|---|---|
| Usable hosts in each | 62 |
| Each subnet fits your host count Spare usable addresses in each subnet after your hosts. | Fits, barely |
| Smallest prefix that fits your hosts The tightest block that still leaves room for network and broadcast. | 26 |
|---|---|
| Addresses wasted at that size | 12 |
Usable-host counts assume one network address and one broadcast address per subnet, except at /31 and /32. RFC 3021 makes a /31 a valid point-to-point link with both addresses usable, and a /32 is a single host route — the minus-two rule does not apply to either.
Nothing here is sent anywhere; the numbers live in the page address.