IPv6 subnet calculator

IPv6 CIDR range for 2a01:4f8:173:e8e::/66

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 2a01:4f8:173:e8e::/66

The prefix identifies a network with 62 host bits. Every address from the first address through the last address belongs to this range.

CIDR prefix

2a01:4f8:173:e8e::/66

Network mask

ffff:ffff:ffff:ffff:c000::

Prefix length

/66

Host bits

62

First address

2a01:4f8:173:e8e::

Last address

2a01:4f8:173:e8e:3fff:ffff:ffff:ffff

Total addresses

4611686018427387904

Total addresses (human readable)

2^62 addresses (4,611,686,018,427,387,904; about 4.61 quintillion)

How this range is calculated

  1. 1The /66 prefix keeps the first 66 network bits fixed.
  2. 2Setting all 62 host bits to zero produces 2a01:4f8:173:e8e::.
  3. 3Setting those host bits to one produces 2a01:4f8:173:e8e:3fff: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

2a01:04f8:0173:0e8e:0000:0000:0000:0000

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