IPv6 calculator

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

What it is for

Divide a larger prefix into equal smaller ones (e.g. /48 → /56 or /64, /64 → /127).

Why it helps

Know the exact subnet count and first rows — allocate your whole /48 without gaps or guessing.

Subnet splitter

From prefix

To length

From #

Count

E.g. /48 → /64 = 65536 × /64 · /64 → /127 = 2⁶³ pairs.

Quick templates

/48→/64 /48→/56 /64→/127 /64→/128

Split result

From2001:db8:1:ffff::/64

To/127

Subnets9223372036854775808

#	Prefix	Network
0	`2001:db8:1:ffff::/127`	`2001:db8:1:ffff::`
1	`2001:db8:1:ffff::2/127`	`2001:db8:1:ffff::2`
2	`2001:db8:1:ffff::4/127`	`2001:db8:1:ffff::4`
3	`2001:db8:1:ffff::6/127`	`2001:db8:1:ffff::6`
4	`2001:db8:1:ffff::8/127`	`2001:db8:1:ffff::8`
5	`2001:db8:1:ffff::a/127`	`2001:db8:1:ffff::a`
6	`2001:db8:1:ffff::c/127`	`2001:db8:1:ffff::c`
7	`2001:db8:1:ffff::e/127`	`2001:db8:1:ffff::e`
8	`2001:db8:1:ffff::10/127`	`2001:db8:1:ffff::10`
9	`2001:db8:1:ffff::12/127`	`2001:db8:1:ffff::12`
10	`2001:db8:1:ffff::14/127`	`2001:db8:1:ffff::14`
11	`2001:db8:1:ffff::16/127`	`2001:db8:1:ffff::16`
12	`2001:db8:1:ffff::18/127`	`2001:db8:1:ffff::18`
13	`2001:db8:1:ffff::1a/127`	`2001:db8:1:ffff::1a`
14	`2001:db8:1:ffff::1c/127`	`2001:db8:1:ffff::1c`
15	`2001:db8:1:ffff::1e/127`	`2001:db8:1:ffff::1e`