Subnet calculator

Server side

Work out network, broadcast, usable range, mask and host count for any IPv4 or IPv6 block

Input

Network

IPv4 or IPv6. Accepts 10.20.0.0/22, 10.20.0.5/22 or 10.20.0.0 255.255.252.0.

Split into /

Optional. Divides the network into equal subnets of this prefix length.

Show first

How many subnets to list when splitting.

This tool runs on the AdminForge server, which needs to reach the target you enter. Nothing is stored or logged. Do not paste secrets into a server-side tool on an instance you do not control.

Fill in the form and run the tool. Results appear here.

Pure arithmetic — the server does no network access for this tool, and nothing you enter leaves the instance. A /31 is treated as an RFC 3021 point-to-point link and a /32 as a single host, so neither reports a broadcast address.