IPv6 Subnet Calculator

Works out the extent of an IPv6 prefix.

Network

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Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.

First address —

Last address —

Network written in full —

Addresses in the block —

Number of /64 subnets —

Address type —

Reading this —

The formula

network = address AND prefix mask addresses = 2^(128 − prefix)

Compressed addresses follow RFC 5952: lower case, leading zeros dropped, and :: in place of the longest run of zero groups.

Each hexadecimal digit is four bits, so prefixes in multiples of four fall on digit boundaries and are easiest to read.

How many /64 subnets are in a /48?

65,536.

What does 2001:db8::/32 cover?

2001:db8:: to 2001:db8:ffff:ffff:ffff:ffff:ffff:ffff. This block is reserved for documentation.

How many addresses are in a /64?

18,446,744,073,709,551,616.