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IPv6 Subnet Calculator
Expand an IPv6 address, split it into network and interface parts and build its EUI-64 link-local form.
Parse an IPv6 subnet
Expanded: —
Compressed: —
Network: —
Interface identifier: —
Range: —
Addresses: —
Subnets of this size: —
EUI-64 link-local: —
How to use the IPv6 Subnet Calculator
- Paste an IPv6 address in compressed or expanded notation.
- Set the prefix length, from zero to one hundred and twenty eight.
- Read the network, interface identifier, range and EUI-64 link-local values.
Features
- Expanded and compressed address forms
- Network and interface identifiers
- Address count and /64 subnet count
- EUI-64 link-local construction
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Frequently Asked Questions
Common questions about the free online ipv6 subnet calculator.
An IPv6 address is one hundred and twenty eight bits written as eight hexadecimal groups of
sixteen bits, and a double colon replaces the longest run.
The prefix length counts the leading bits that identify the network. A /64 leaves sixty four
bits for the interface identifier.
A /64 is the standard LAN size in IPv6 because it leaves exactly sixty four bits for
interface identifiers and stateless address configuration.
A /64 contains about eighteen quintillion addresses, which is why running out of addresses
inside a subnet is not a concern.
It is the part of the address after the prefix, used to identify the individual host on the
subnet.
The interface identifier has its universal or local bit flipped, the bytes ff and fe are
inserted in the middle, and the result is joined to the fe80.
The network address is the first address in the subnet, while the range lists that first
address and the final address together.
Either form works. Compressed addresses with a double colon and fully expanded addresses are
both accepted.
No. The parsing and all of the arithmetic happen locally in your browser, so nothing is sent
anywhere.
Last updated: October 10, 2026