IPv6 Subnet Calculator – Prefix and Address Range
Calculate IPv6 subnet information from prefix length.
About This Calculator
Calculate IPv6 subnet information from prefix length. Use the calculator above for instant results.
Worked Examples
- 2^64 = 18,446,744,073,709,551,616 addresses per subnet
- Standard for SLAAC (auto-configuration)
Answer: /64 = 2^64 addresses
- 2^80 addresses | 65,536 /64 subnets
Answer: 65,536 subnets of /64
- 1 address only | Like IPv4 /32
Answer: Single host route
Who Uses This Calculator?
IPv6 subnetting and planning.
IPv6 network design.
IPv6 exam preparation.
IPv6 networking study.
Common Mistakes to Avoid
❌ IPv6 subnetting is different from IPv4
IPv6 uses a standard /64 for most subnets. No need to conserve addresses — the space is astronomically large.
❌ SLAAC requires /64
Stateless Address Autoconfiguration (SLAAC) requires exactly a /64 prefix. Don't use longer prefixes if you need SLAAC.
Frequently Asked Questions
IPv6 address types?
Global unicast: 2000::/3 (internet routable). Link-local: fe80::/10 (auto-configured). Unique local: fc00::/7 (like RFC 1918). Multicast: ff00::/8.
Standard allocation sizes?
/32: typical ISP allocation. /48: end organization (65,536 /64 subnets). /64: single subnet. /128: single host (loopback, point-to-point).
IPv4 vs IPv6 addressing?
IPv4: 4.3 billion addresses (exhausted). IPv6: 340 undecillion (3.4×10^38). More IPv6 addresses than atoms in a cubic meter of sand.