IPv6 subnet calculator

IPv6 CIDR range for fc00:ffff:ffff:ffff:ffff:ffff::/120

Calculate the network address, final address, mask, and exact address capacity of any IPv6 CIDR prefix.

Example: 2606:4700::/32

Host bits are normalized to the network address before the range is calculated.

CIDR calculation

Network details for fc00:ffff:ffff:ffff:ffff:ffff::/120

The prefix identifies a network with 8 host bits. Every address from the first address through the last address belongs to this range.

CIDR prefix

fc00:ffff:ffff:ffff:ffff:ffff::/120

Network mask

ffff:ffff:ffff:ffff:ffff:ffff:ffff:ff00

Prefix length

/120

Host bits

8

First address

fc00:ffff:ffff:ffff:ffff:ffff::

Last address

fc00:ffff:ffff:ffff:ffff:ffff:0:ff

Total addresses

256

Total addresses (human readable)

2^8 addresses (256)

How this range is calculated

  1. 1The /120 prefix keeps the first 120 network bits fixed.
  2. 2Setting all 8 host bits to zero produces fc00:ffff:ffff:ffff:ffff:ffff::.
  3. 3Setting those host bits to one produces fc00:ffff:ffff:ffff:ffff:ffff:0:ff.

Network address

The normalized prefix base

CIDR notation describes a network, not a single host. If an address with host bits set is entered, this calculator normalizes it to the network base before calculating the range.

Expanded network address

fc00:ffff:ffff:ffff:ffff:ffff:0000:0000

Recent network calculations

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Learn how IPv6 CIDR notation and subnet ranges work