IPv6 subnet calculator

IPv6 CIDR range for 2100:db8:acad:1::/65

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 2100:db8:acad:1::/65

The prefix identifies a network with 63 host bits. Every address from the first address through the last address belongs to this range.

CIDR prefix

2100:db8:acad:1::/65

Network mask

ffff:ffff:ffff:ffff:8000::

Prefix length

/65

Host bits

63

First address

2100:db8:acad:1::

Last address

2100:db8:acad:1:7fff:ffff:ffff:ffff

Total addresses

9223372036854775808

Total addresses (human readable)

2^63 addresses (9,223,372,036,854,775,808; about 9.22 quintillion)

How this range is calculated

  1. 1The /65 prefix keeps the first 65 network bits fixed.
  2. 2Setting all 63 host bits to zero produces 2100:db8:acad:1::.
  3. 3Setting those host bits to one produces 2100:db8:acad:1:7fff: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

2100:0db8:acad:0001:0000:0000:0000:0000

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