Subnet calculator
Hosts, ranges and split counts for an IPv4 prefix, plus how many VLANs a block gives you before you commit to a numbering scheme.
256
Addresses in the block
254
Usable hosts
4
Subnets when split
Zero means the split prefix is larger than the block itself.
| Addresses in each | 64 |
|---|---|
| Usable hosts in each | 62 |
| Each subnet fits your host count 1 means yes, 0 means the split is too aggressive. | 1 |
| 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.