IPv6 CIDR to Range Converter

Turn an IPv6 prefix into its address range. Enter a CIDR block such as 2001:db8::/48 and the tool returns the first and last address in the block and the total number of addresses it holds. Free and instant in your browser.

Total addresses
1,208,925,819,614,629,174,706,176 (2^80)
Every address in the block, including the first and last.
First address2001:db8::
Last address2001:db8:0:ffff:ffff:ffff:ffff:ffff
Total addresses1,208,925,819,614,629,174,706,176 (2^80)

How it works

  1. 1

    Enter the CIDR block

    Type an IPv6 prefix such as 2001:db8::/48 or fd00::/8.

  2. 2

    Read the range

    See the first and last address the prefix covers, in compressed form.

  3. 3

    Check the count

    See the total number of addresses, shown as a grouped number and a power of two.

Instant & 100% private — nothing is uploaded

Everything runs locally in your browser. Your code, text and files are processed on your own device and are never sent to a server — so there are no upload waits, no size limits from us, and nothing is ever stored or logged.

Frequently asked questions

How many addresses are in an IPv6 /48?
A /48 leaves 80 host bits, so it holds 2^80 addresses, which is 1,208,925,819,614,629,174,706,176. The first address is the prefix with all host bits zero and the last is the prefix with all host bits one. A /64, the usual subnet size, holds 2^64 addresses.
What are the first and last addresses of a prefix?
The first address is the network address: the prefix with every host bit set to 0. The last is the prefix with every host bit set to 1. Unlike IPv4, IPv6 has no broadcast address, so both ends are usable. The tool masks whatever you enter down to the network address first.
Can I enter any prefix length?
Yes, from /0 to /128. A /128 describes a single address, where the first and last are the same and the count is 1. A /0 covers the entire IPv6 space of 2^128 addresses.
Does this run on a server?
No. The range and count are computed in your browser using 128-bit integer maths, so the prefix you enter is never sent anywhere and the tool works offline.

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