IPv6 subnet calculator

IPv6 CIDR range for fc00::/55

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::/55

The prefix identifies a network with 73 host bits. Every address from the first address through the last address belongs to this range.

CIDR prefix

fc00::/55

Network mask

ffff:ffff:ffff:fe00::

Prefix length

/55

Host bits

73

First address

fc00::

Last address

fc00::1ff:ffff:ffff:ffff:ffff

Total addresses

9444732965739290427392

Total addresses (human readable)

2^73 addresses (9,444,732,965,739,290,427,392; about 9.44 sextillion)

How this range is calculated

  1. 1The /55 prefix keeps the first 55 network bits fixed.
  2. 2Setting all 73 host bits to zero produces fc00::.
  3. 3Setting those host bits to one produces fc00::1ff:ffff:ffff:ffff:ffff.

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

fc00:0000:0000:0000:0000:0000:0000:0000

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