IPv6 subnet calculator

IPv6 CIDR range for fdb5:b785:12cf:7777::aa8:1007/128

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 fdb5:b785:12cf:7777::aa8:1007/128

The prefix identifies a network with 0 host bits. Every address from the first address through the last address belongs to this range.

CIDR prefix

fdb5:b785:12cf:7777::aa8:1007/128

Network mask

ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff

Prefix length

/128

Host bits

0

First address

fdb5:b785:12cf:7777::aa8:1007

Last address

fdb5:b785:12cf:7777::aa8:1007

Total addresses

1

Total addresses (human readable)

2^0 addresses (1)

How this range is calculated

  1. 1The /128 prefix keeps the first 128 network bits fixed.
  2. 2Setting all 0 host bits to zero produces fdb5:b785:12cf:7777::aa8:1007.
  3. 3Setting those host bits to one produces fdb5:b785:12cf:7777::aa8:1007.

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

fdb5:b785:12cf:7777:0000:0000:0aa8:1007

Recent network calculations

Recent IPv6 CIDR Ranges

Open recent IPv6 prefixes to inspect their normalized range, mask, and address capacity.

Learn how IPv6 CIDR notation and subnet ranges work