Subnetting bench

IP tools

A small kit for the everyday network math: calculate, split, reverse and aggregate across IPv4 and IPv6. Everything runs in your browser, and Copy link shares whatever you have on screen.

IP / CIDR calculator

Network, usable range, netmask and broadcast for any prefix.

Address / CIDR

Subnet splitter

Click a block to divide it in half; click a header to join it back. Colour tracks the tree.

Starting CIDR

Subnet list

Divide a prefix into fixed-size subnets. Lists the first 2000 and counts the rest.

Parent CIDR

New size

IP range → CIDR

The smallest set of prefixes that exactly covers a first–last address range.

First address

Last address

CIDR aggregator

Merge a list of prefixes into the minimal set of covering supernets. One entry per line.

Prefixes / addresses

Reverse DNS (PTR)

The in-addr.arpa / ip6.arpa name for an address, plus the zone origin for a prefix.

Address / CIDR

IPv6 expand / compress

Full and compressed (RFC 5952) forms of an IPv6 address.

IPv6 address

IP format converter

The same address as dotted/colon, integer, hex and binary, in any direction.

Value

Interpret as

Bandwidth → transfer

Sustained link rate turned into data moved per day and per month.

Rate

Unit

Utilisation %