IPv6 subnet calculator

IPv6 CIDR range for fec0::/56

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 fec0::/56

The prefix identifies a network with 72 host bits. Every address from the first address through the last address belongs to this range.

CIDR prefix

fec0::/56

Network mask

ffff:ffff:ffff:ff00::

Prefix length

/56

Host bits

72

First address

fec0::

Last address

fec0::ff:ffff:ffff:ffff:ffff

Total addresses

4722366482869645213696

Total addresses (human readable)

2^72 addresses (4,722,366,482,869,645,213,696; about 4.72 sextillion)

How this range is calculated

  1. 1The /56 prefix keeps the first 56 network bits fixed.
  2. 2Setting all 72 host bits to zero produces fec0::.
  3. 3Setting those host bits to one produces fec0::ff: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

fec0:0000:0000:0000:0000:0000:0000:0000

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