IPv6 Subnet Calculator

Type any IPv6 address with a prefix length and see the whole subnet: the network in canonical RFC 5952 form and fully expanded, the first and last address, the exact number of addresses, which special block it belongs to, and the ip6.arpa reverse zone. Give a longer prefix to split the network, for example a /48 into /64s. All of the 128-bit arithmetic runs on this page.

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How to use

Enter an IPv6 address followed by a slash and the prefix length, for example 2001:db8:abcd:12::1/48. Without a prefix, /64 is assumed.
Read the network in short (RFC 5952) and full form, the first and last address, the total number of addresses and the address type.
Use the reverse zone line when you set up PTR records: it is the ip6.arpa name of the network, cut at a 4-bit (nibble) boundary.
To plan smaller subnets, enter a longer prefix in Split into /n (such as 64). The first 256 subnets are listed, with the total count above them.
Copy the summary, or copy or download the subnet list as a text file.

Examples

Input

2001:db8:abcd:12::1/48

Network · range

2001:db8:abcd::/48 · 2001:db8:abcd:: – 2001:db8:abcd:ffff:ffff:ffff:ffff:ffff

Total addresses

1,208,925,819,614,629,174,706,176 (2^80) · 65,536 /64 subnets

Reverse zone

d.c.b.a.8.b.d.0.1.0.0.2.ip6.arpa

Compression

2001:0db8:0000:0000:0001:0000:0000:0001 → 2001:db8::1:0:0:1 (first of two equal zero runs)

Supported formats

IPv6 addresses in any valid text form: full (2001:0db8:0000:0000:0000:0000:0000:0001), compressed with :: (2001:db8::1), upper or lower case, with leading zeros dropped or kept.
Embedded IPv4 in the last 32 bits (::ffff:192.0.2.1, 64:ff9b::198.51.100.7), a zone index (fe80::1%eth0) and square brackets ([2001:db8::1]/64).
Prefix lengths /0 to /128. Results are exact for every length, including the 2^128 addresses of ::/0.

Privacy

This tool runs entirely in your browser. Nothing you enter or open is sent anywhere. Privacy policy.

Limitations

IPv6 only. For IPv4 networks use the IPv4 subnet calculator.
The address type comes from the well-known blocks listed in the FAQ. It does not look up which provider or registry holds a global prefix.
Splitting lists at most the first 256 subnets; the total is always shown. To see a later part of the range, enter a smaller network further in, such as 2001:db8:abcd:100::/56.
IPv6 has no broadcast address, so the first and last addresses are both shown as part of the range. Whether a router accepts them on a host (for example the all-zero Subnet-Router anycast address) depends on its configuration.

FAQ

How is an IPv6 address shortened?

RFC 5952 sets one canonical form: lower-case hex, no leading zeros in a group, and the longest run of two or more all-zero groups replaced by ::. If two runs are equally long, the first one is shortened. A single zero group stays as 0, so 2001:db8:0:1:1:1:1:1 is not shortened. IPv4-mapped addresses keep the dotted form, as in ::ffff:192.0.2.1.

How many addresses are in a /64 or a /48?

A /64 has 2^64 = 18,446,744,073,709,551,616 addresses. A /48 holds 65,536 /64 subnets. Each step of 4 bits in the prefix multiplies or divides the count by 16, and each single bit by 2.

Which address types does it recognise?

Unspecified (::), loopback (::1), IPv4-mapped (::ffff:0:0/96), documentation (2001:db8::/32), multicast (ff00::/8), link-local (fe80::/10), unique local (fc00::/7, in practice fd00::/8) and global unicast (2000::/3). Anything else is reported as reserved or other. A prefix shorter than these blocks, such as ::/0, is shown as mixed.

Why does a /50 show two or more reverse zones?

ip6.arpa names have one label per hex digit, so a reverse zone can only end on a 4-bit boundary. A /50 is delegated as the /52 zones it contains: 2^(52−50) = 4 zones. Prefixes that are a multiple of 4, such as /48 or /64, need exactly one.

Is anything sent to a server?

No. Parsing and the 128-bit arithmetic use JavaScript BigInt in your browser, so the addresses you type never leave this page.