IPv6 Subnet Calculator

Calcualte host IPv6 address range, subnet mask, network, broadcast address.

What is an IPv6 address?

A 16-byte IPv6 address is normally represented hexadecimal digits and divided into 8 groups separated by colons (:). For example, "2001:0cb8:0000:0000:0000:ff00:0246:7348" IPv6 address.

An IPv6 address is a unique identifier assigned to devices connected to an Internet Protocol version 6 (IPv6) network. IPv6 is the latest version of the Internet Protocol, designed to replace IPv4 due to the depletion of available IPv4 addresses.

An IPv6 address consists of 128 bits, compared to 32-bit IPv4 addresses. It is represented as eight groups of four hexadecimal digits, separated by colons. For example, a typical IPv6 address might look like this: 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

IPv6 addresses provide a significantly larger address space than IPv4, allowing for a virtually unlimited number of unique addresses. This expansion supports the growing number of devices connecting to the internet, including computers, smartphones, tablets, IoT devices, and more. IPv6 also offers additional features, such as improved security, auto-configuration, and better support for multicast communications.

IPv6 Examples

2002:c000:022a::/29
Address:     2002:c000:022a:0000:0000:0000:0000:0000/29
Netmask:     ffff:fff8:0000:0000:0000:0000:0000:0000 = 29
Network:     2002:c000:0000:0000:0000:0000:0000:0000/29
HostMin:     2002:c000:0000:0000:0000:0000:0000:0001
HostMax:     2002:c007:ffff:ffff:ffff:ffff:ffff:fffe
Hosts/Net:   633825300114114700748351602688 UNKNOWN
IPv4 repr:   192.0.2.42
PTR RR name: 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.a.2.2.0.0.0.0.c.2.0.0.2.ip6.arpa
IP version:  6

More IPv6 Addresses

2001:0db8:1234:5678:9abc:def0:1234:5678
fd12:3456:789a:1::2
2001:0:9d38:6abd:0:0:0:1
2409:8a61:3c0c:85::abcd:5678
2001:0db8::1:0:0:0:1
fe80::1
2001:db8::
2a02:120b:2c0d:0010:0000:0000:0a0b:0304

IPv6 Subnet Chart

A quick reference for IPv6 Subnetting and Subnet masks.

Prefix	/48	/56	/64	/127	# Addresses
/24	16M	4G	1T	8388608Y	16777216Y
/25	8M	2G	512G	4194304Y	8388608Y
/26	4M	1G	256G	2097152Y	4194304Y
/27	2M	512M	128G	1048576Y	2097152Y
/28	1M	256M	64G	524288Y	1048576Y
/29	512K	128M	32G	262144Y	524288Y
/30	256K	64M	16G	131072Y	262144Y
/31	128K	32M	8G	65536Y	131072Y
/32	64K	16M	4G	32768Y	65536Y
/33	32K	8M	2G	16384Y	32768Y
/34	16K	4M	1G	8192Y	16384Y
/35	8K	2M	512M	4096Y	8192Y
/36	4K	1M	256M	2048Y	4096Y
/37	2K	512K	128M	1024Y	2048Y
/38	1K	256K	64M	512Y	1024Y
/39	512	128K	32M	256Y	512Y
/40	256	64K	16M	128Y	256Y
/41	128	32K	8M	64Y	128Y
/42	64	16K	4M	32Y	64Y
/43	32	8K	2M	16Y	32Y
/44	16	4K	1M	8Y	16Y
/45	8	2K	512K	4Y	8Y
/46	4	1K	256K	2Y	4Y
/47	2	512	128K	1Y	2Y
/48	1	256	64K	512Z	1Y
/49		128	32K	256Z	512Z
/50		64	16K	128Z	256Z
/51		32	8K	64Z	128Z
/52		16	4K	32Z	64Z
/53		8	2K	16Z	32Z
/54		4	1K	8Z	16Z
/55		2	512	4Z	8Z
/56		1	256	2Z	4Z
/57			128	1Z	2Z
/58			64	512E	1Z
/59			32	256E	512E
/60			16	128E	256E
/61			8	64E	128E
/62			4	32E	64E
/63			2	16E	32E
/64			1	8E	16E

What is CIDR?

CIDR, or Classless Inter Domain Routing, was created to help large routers minimize the size of their routing tables, which was complex with classful routing.

Classful routing consumes a lot of memory, resulting in prohibitively expensive hardware. However, performance was hampered because enormous tables had to be looked up without using a more dynamic IP interval technique, such as CIDR. Another issue with a classful system is that bandwidth utilization is rather significant when routers communicate routing information.

Simply put, CIDR with address aggregation allows numerous networks to be addressed with a single routing entry.

IPv6 Addresses Explained

Less than 10% of the code has to do with the ostensible purpose of the system; the rest deals with input-output, data validation, data structure maintenance, and other housekeeping.
Mary Shaw