IPv6 Address Expander & Compressor

Expand or compress an IPv6 address, see its type, reverse DNS name and prefix range.

How do you compress an IPv6 address?

Drop leading zeros in each 16-bit group and replace the longest run of two or more all-zero groups with a double colon (::), once. For example 2001:0db8:0000:0000:0000:ff00:0042:8329 compresses to 2001:db8::ff00:42:8329 (RFC 5952).

IPv6 address types

Prefix	Type
2000::/3	Global unicast (public internet)
fc00::/7	Unique local (private, like 10.x.x.x)
fe80::/10	Link-local (one network segment only)
ff00::/8	Multicast
::1	Loopback
2001:db8::/32	Documentation examples

Add a prefix such as /64 to see the network, the first and last address and how many /64 subnets a larger allocation (a /48 or /56) contains.

Frequently asked questions

How long is an IPv6 address?

128 bits, written as 8 groups of 4 hex digits.

Can :: appear twice?

No, only once — otherwise the address would be ambiguous.

What is the PTR name for?

It is the ip6.arpa name used to set up reverse DNS for the address.