Convert IPv6 CIDR blocks to address ranges with the first and last address in full and the number of addresses. Handles many prefixes at once.
About this tool
Convert an IPv6 CIDR block to its first and last address and address count.
How to use IPv6 CIDR to Range
- Enter one IPv6 CIDR block per line, such as 2001:db8::/48.
- Read the first address, last address and address count for each block.
- Copy the ranges for firewall rules or documentation.
Worked example
2001:db8:abcd:12::/64 runs from 2001:0db8:abcd:0012:0000:0000:0000:0000 to 2001:0db8:abcd:0012:ffff:ffff:ffff:ffff, 2^64 addresses.
What does the prefix length mean?
It is the number of leading bits fixed for the network; the rest vary. A /64 has 64 fixed bits and 64 host bits.
Why is /64 so common?
IPv6 automatic addressing (SLAAC) expects /64 subnets, so almost every LAN uses one.
- IPv6 CIDR to Range — Convert an IPv6 CIDR block to its first and last address and address count.
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