IPv6 Planner
Enter your assigned IPv6 prefix (e.g. /48 or /56) and the target subnet size (typically /64). I compute how many subnets fit, the subnet bits, a suggested hierarchy and example prefixes. Fully local.
Subnets —
Bits —
/64 —
Assigned prefix
—
source block
Target subnets
—
/— blocks
Subnet bits
—
nibble-aligned
Total /64s
—
/64 networks in the block
Suggested hierarchy
| Level | Prefix | Count | Bits | Holds |
|---|
Classic rule: /48 per site → /56 per building (256 per site) → /64 per VLAN (256 per building). The nibble (4 bits) keeps every level readable in hexadecimal.
Example subnets
| # | Prefix | Compressed |
|---|
Subnets are numbered by incrementing the subnet field of the prefix. With
nibble alignment, each hex digit of the prefix maps to a level of the hierarchy,
so 2001:db8:0:0000, 0001,
0002… read at a glance.
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