IPv4 subnet calculator

Network, broadcast, host range and wildcard mask for any address block

Network address

Subnet mask

Hosts per subnet

Split into

IPv6 subnet calculator

Network details and a subnet plan for any IPv6 address block

Network address block

Split into

The shortest list of CIDR blocks that exactly covers an address range

First address

Last address

EUI-64 conversion in both directions, with an optional SLAAC prefix

MAC address

Link-local address

SLAAC prefix (optional)

Find the manufacturer behind a MAC address, or the prefixes assigned to a vendor

MAC address, OUI prefix or vendor name

Uses a local copy of the IEEE MA-L registry. Lookups never leave this page.

PTR record names and reverse zones for an address or prefix, and back again

Address, CIDR or .arpa name

Usable MTU and TCP MSS after stacking tunnel and encapsulation overhead

Link MTU

Outer IP version

Encapsulation

Dotted, integer, hexadecimal and binary forms of an IPv4 or IPv6 address

Address or number

Accepts 192.168.1.1, 3232235777, 0xc0a80101, 0b1100… or an IPv6 address.