CALCULATE / IP60BPS / MODULE
IPV6 CIDR
Normalize an IPv6 address and inspect the exact 128-bit range covered by a CIDR prefix. All arithmetic stays in this browser.
COMMON PREFIXES
IPv6 does not use an IPv4-style broadcast address. This calculator supports standard hexadecimal IPv6 notation with :: compression; interface zone IDs and dotted IPv4-mapped notation are intentionally not accepted.
REFERENCE / FAQ
COMMON QUESTIONS
How many addresses are in an IPv6 /64?
An IPv6 /64 leaves 64 host bits, so it contains 2^64 addresses: 18,446,744,073,709,551,616.
Does IPv6 have a broadcast address?
No. IPv6 does not use the IPv4 broadcast model. This calculator shows the first and last addresses covered by the selected prefix instead.
Why does the tool use BigInt?
IPv6 addresses are 128 bits wide. JavaScript BigInt lets the browser perform exact integer arithmetic without losing address bits to floating-point rounding.
IPv6 subnet math uses browser BigInt arithmetic to preserve all 128 address bits without floating-point rounding.
IPv6 normally does not use broadcast addresses; the tool reports the first and last addresses covered by the selected prefix.
PRACTICAL / EXAMPLES
PUT THE NUMBER IN CONTEXT.
Short examples using the same units and assumptions as this module.
The network prefix becomes 2001:db8::/64 and the prefix contains 2^64 addresses.
Addresses inside fc00::/7 are Unique Local Addresses rather than globally routable public space.