IPv6 Subnet & Prefix Calculator

Calculate IPv6 prefixes, ranges, address forms, reverse DNS names, and child subnets locally.

Local browser processing

Addresses and calculation inputs stay in this browser. They are not uploaded, resolved, scanned, or sent to analytics.

Address or network

Child prefix to preview

Result

Enter values and run the tool to see the local result.

What this IPv6 calculator shows

Enter an IPv6 address with a CIDR prefix to find its normalized network, first and last address, exact address count, address type, reverse-DNS name, and child prefixes. IPv6 uses prefix lengths rather than dotted subnet masks and has no broadcast address.

How to calculate an IPv6 subnet

Enter a compressed or expanded IPv6 address followed by a prefix from /0 to /128.
Optionally choose a longer child prefix to preview how the network can be divided.
Review and copy the canonical address, network range, reverse name, or child-prefix list.

IPv6 calculation boundaries

The calculator performs address arithmetic only. It does not query DNS, test reachability, discover assigned hosts, or claim that every address in a prefix is configured. A reverse-DNS zone is shown only for nibble-aligned prefixes.

Related network tools

IPv4 Subnet Calculator IPv4 to IPv6 Converter

IPv6 subnet questions

Does IPv6 have a subnet mask?: IPv6 networks use a CIDR prefix length such as /48 or /64. They do not use IPv4-style dotted subnet masks.
What is the broadcast address of an IPv6 subnet?: IPv6 has no broadcast address. Multicast replaces broadcast for the relevant protocol functions.
Why are IPv6 address counts so large?: An IPv6 address has 128 bits, so a prefix contains 2 raised to the number of remaining host bits.
What is an ip6.arpa reverse name?: It is the nibble-reversed DNS name used for IPv6 PTR lookups. The tool calculates the name but does not perform a DNS query.

IPv6 subnet questions

Does IPv6 have a subnet mask?

IPv6 networks use a CIDR prefix length such as /48 or /64. They do not use IPv4-style dotted subnet masks.

What is the broadcast address of an IPv6 subnet?

IPv6 has no broadcast address. Multicast replaces broadcast for the relevant protocol functions.

Why are IPv6 address counts so large?

An IPv6 address has 128 bits, so a prefix contains 2 raised to the number of remaining host bits.

What is an ip6.arpa reverse name?

It is the nibble-reversed DNS name used for IPv6 PTR lookups. The tool calculates the name but does not perform a DNS query.