IPv6 Subnet Calculator
Calculate the network address, address range, and total address count for an IPv6 address and prefix length.
- Free to use
- Accurate results
- No registration required
- Works on all devices
Your result
2001:0db8:0000:0042:0000:0000:0000:0000
Network address
AI explanation
Formula
Network = Address AND Mask (128-bit); Last address = Network OR (NOT Mask); total addresses = 2^(128 − prefix length)Worked example
2001:0db8:0000:0042:0000:0000:0000:0001 / 64
| Field | Value |
|---|---|
| IPv6 address (fully expanded) | 2001:0db8:0000:0042:0000:0000:0000:0001 |
| Prefix length | 64 |
| Network address | 2001:0db8:0000:0042:0000:0000:0000:0000 |
| First address | 2001:0db8:0000:0042:0000:0000:0000:0000 |
| Last address | 2001:0db8:0000:0042:ffff:ffff:ffff:ffff |
| Total addresses in this prefix | 18446744073709551616 |
Assumptions
- Requires a fully-expanded 8-group address (no "::" zero-compression shorthand) — expand your address first if it uses shorthand notation.
- Unlike IPv4, IPv6 has no reserved network/broadcast address — every address in the range, including the first and last, is usable.
- Total address counts for small prefixes are astronomically large (e.g. a /64 has over 18 quintillion addresses) — shown as exact text, not a rounded number.
Frequently asked questions
Why doesn't IPv6 have a broadcast address like IPv4?
IPv6 replaced broadcast with multicast for one-to-many communication — every address within a subnet, including what would be the "network" and "broadcast" addresses in IPv4, is assignable to a host.
What is a typical IPv6 subnet size?
/64 is the standard subnet size for most IPv6 networks (recommended by IETF for LANs), leaving 64 bits for the interface identifier — far larger than any practical device count.
How do I expand a compressed ("::") IPv6 address?
Replace "::" with enough groups of "0000" to make 8 groups total, and pad every group to 4 hex digits — e.g. "2001:db8::1" expands to "2001:0db8:0000:0000:0000:0000:0000:0001".