IPv6 subnet calculator

IPv6 CIDR range for abcd:efab:cd00::/40

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 abcd:efab:cd00::/40

The prefix identifies a network with 88 host bits. Every address from the first address through the last address belongs to this range.

CIDR prefix

abcd:efab:cd00::/40

Network mask

ffff:ffff:ff00::

Prefix length

/40

Host bits

88

First address

abcd:efab:cd00::

Last address

abcd:efab:cdff:ffff:ffff:ffff:ffff:ffff

Total addresses

309485009821345068724781056

Total addresses (human readable)

2^88 addresses (309,485,009,821,345,068,724,781,056; about 309.48 septillion)

How this range is calculated

  1. 1The /40 prefix keeps the first 40 network bits fixed.
  2. 2Setting all 88 host bits to zero produces abcd:efab:cd00::.
  3. 3Setting those host bits to one produces abcd:efab:cdff:ffff: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

abcd:efab:cd00:0000:0000:0000:0000:0000

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