IPv4 calculator

Subnet details, /30·/31·/32 planning, splitting, masks, private IPs, overlap check.

What it is for

Interactively split a block in half (Split) and join adjacent siblings back (Join).

Why it helps

Plan LAN / customer segments visually — see ranges, host counts and hierarchy without manual math.

Block split / join

Accepts /24 or /255.255.255.0 — or paste a full prefix into the address field (e.g. 10.0.0.0/16).

Show columns:
Root network—
Leaf subnets—
Last action—
Subnet Netmask IP range Usable IPs Hosts Split Join