ipv6 subnet calculator
An IPv6 address has 128 bits, four times an IPv4 address, and this calculator takes an address plus a prefix to return the network, first and last address of the block in seconds.
2001:db8::/32 is the only block RFC 3849 reserves for written examples, so no real internet router ever forwards traffic for it.
The leading byte in fd00 falls inside fc00::/7, the IPv6 counterpart of a private network, functionally similar to IPv4 10.0.0.0/8 but without the global collision risk.
Every address here comes from the reserved fe80::/10 block, assigned automatically to each interface for neighbor discovery, and it is never routed past the local link.
Yes. It helps visualize the main subnetting outputs for both IPv4 and IPv6, including split scenarios and more detailed planning workflows.
Because writing all 8 groups of 4 digits out in full could make an address up to 39 characters long; the `::` compression replaces the longest run of consecutive zero groups in one shot, always once per address so the reader never has to guess how many zeros are missing.
The protocol replaces broadcast with segmented multicast, and uses the link-local address from the fe80::/10 prefix, present on every interface by itself, for local tasks like neighbor and default router discovery, without flooding the entire network with traffic.
A /64 is a single LAN subnet with 64 host bits, the minimum SLAAC requires; a /48 reserves 16 extra network bits over a /64, so one /48 delegated to a customer already contains 65536 full /64 blocks to split across branches or VLANs.
All calculations run locally in your browser. Nothing is sent to the network or to external services.