IPv6 Network Calculator
Derive the IPv6 network address, prefix boundary and subnet identifier for any address and prefix length.
About IPv6 Network Calculator
Each 16-bit group keeps only the bits that fall inside the prefix. With the common /48 site prefix and /64 subnets, the fourth group is the subnet identifier you increment per VLAN. Getting the network address wrong in IPv6 is easy because the boundaries are invisible in compressed notation, and a wrong prefix means neighbour discovery never resolves.
Formula
IPv6 Network
network = address AND prefix mask, applied 16 bits at a time across the eight groups.
- p
- Prefix length in bits
- subnetId
- Fourth group, conventionally the site subnet field
Worked example
With the default values below, IPv6 Network Calculator returns Network Address of 2001:db8:acad:1234::/64. Change any input above and every figure here is recalculated in your browser.
Inputs used
- IPv6 address
- 2001:db8:acad:1234:5678::1
- Prefix lengthaccepts 0–128 bits
- 64 bits
Results
- Network Address
- 2001:db8:acad:1234::/64
- Subnet ID (hex)
- 1234
- Prefix on Nibble Boundary
- Yes
- Host Bits
- 64
Step by step
- 1Values used
- 2IPv6 Network
- 3Network Address= 2001:db8:acad:1234::/64
- 4Subnet ID (hex)= 1234
- 5Prefix on Nibble Boundary= Yes
- 6Host Bits= 64
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is IPv6 Network calculated?
network = address AND prefix mask, applied 16 bits at a time across the eight groups. Each 16-bit group keeps only the bits that fall inside the prefix. With the common /48 site prefix and /64 subnets, the fourth group is the subnet identifier you increment per VLAN.
Why does IPv6 Network matter?
Getting the network address wrong in IPv6 is easy because the boundaries are invisible in compressed notation, and a wrong prefix means neighbour discovery never resolves.
What values do I need to enter?
This calculator takes 2 inputs: IPv6 address, Prefix length. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.