IPv6 calculator

Subnet details, /127 and /128 planning, splitting, compress/expand, overlap check.

What it is for

Enter any IPv6/CIDR and see the aligned network, address range, size and expanded form.

Why it helps

Quick check before configuring interfaces, ACLs or BGP — no manual bit math.

Subnet

E.g. 2a0f:85c1:334::/64 or 2a0f:85c1:334::1/128

Results

/64 — typical SLAAC / LAN segment (2⁶⁴ addresses).

Network2a0f:85c1:334::/64
Prefix length/64
Compressed2a0f:85c1:334::
Expanded2a0f:85c1:0334:0000:0000:0000:0000:0000
First address2a0f:85c1:334::
Last address2a0f:85c1:334:0:ffff:ffff:ffff:ffff
Addresses18446744073709551616
ip6.arpa0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.4.3.3.0.1.c.5.8.f.0.a.2.ip6.arpa