IPv6 subnet calculator

IPv6 CIDR range for 2001:db8::/87

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 2001:db8::/87

The prefix identifies a network with 41 host bits. Every address from the first address through the last address belongs to this range.

CIDR prefix

2001:db8::/87

Network mask

ffff:ffff:ffff:ffff:ffff:fe00::

Prefix length

/87

Host bits

41

First address

2001:db8::

Last address

2001:db8::1ff:ffff:ffff

Total addresses

2199023255552

Total addresses (human readable)

2^41 addresses (2,199,023,255,552; about 2.19 trillion)

How this range is calculated

  1. 1The /87 prefix keeps the first 87 network bits fixed.
  2. 2Setting all 41 host bits to zero produces 2001:db8::.
  3. 3Setting those host bits to one produces 2001:db8::1ff: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

2001:0db8:0000:0000:0000:0000:0000:0000

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