ECT Visual IPv6 Subnet Calculator Network Address Prefix length / Show columns: Prefix Range of addresses Addresses Range of /64s /64s Label Divide Join Allow prefixes longer than /64 (point-to-point links and loopbacks only) Click Divide or a /prefix bracket below to split and join networks. Give each block a label to build up an allocation plan. Copy to Clipboard copies the ticked data columns above, with headings, leaving out Divide and Join — paste into Excel, Word or a ticket. If you wish to save this plan for later, bookmark this hyperlink — it carries your divisions and labels.

In IPv6 every address in a prefix is useable — there is no network address or broadcast address to reserve, so the whole Range of addresses is available. That is the main thing that changes coming from IPv4. Plan in /64s: a /64 is the unit SLAAC requires (RFC 4291), so it is the smallest network you normally need, and you hand them out whole rather than counting hosts.

Source: OHIO-ECT/ipcalc6. Forked from davidc/subnets.