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IPv6 CIDR to range

Enter an IPv6 prefix to get its first and last address and how many addresses and /64 networks it holds. Paste a list to convert many at once.

One per line, or separated by commas. Netmasks work too: 10.0.0.0 255.255.0.0.

Try:

Range

2001:db8:abcd::/48

Example: type your own block above.

First address2001:db8:abcd::
Last address2001:db8:abcd:ffff:ffff:ffff:ffff:ffff
Addresses2^801.2 septillion
CIDR
2001:db8:abcd::/48
/64 networks
65,536
First (full form)
2001:0db8:abcd:0000:0000:0000:0000:0000
Last (full form)
2001:0db8:abcd:ffff:ffff:ffff:ffff:ffff

How it works

A CIDR block is an address followed by a prefix length, like 192.168.0.0/22. The prefix length says how many of the address's leading bits are fixed. The rest can be anything, so a block holds 2(32 − prefix) IPv4 addresses, or 2(128 − prefix) IPv6 addresses.

The first address has all the free bits set to 0, and the last has them all set to 1. For 192.168.0.0/22 that's 192.168.0.0 to 192.168.3.255: 1,024 addresses.

On an IPv4 LAN, the first address names the network and the last is the broadcast address, so hosts use the ones in between. Use the subnet calculator for usable hosts, netmasks and more. To go the other way, use IP range to CIDR.