IPTool
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IPv6 calculator
Calculate IPv6 network blocks, address ranges and CIDR prefixes. Supports abbreviated and expanded notation, helping you plan and document IPv6 allocations.
Supports compressed (::), full and IPv4-embedded formats (e.g., ::ffff:192.0.2.1).
/
| IP/Prefix | — |
|---|---|
| Compressed representation | — |
| Expanded (full) representation | — |
| Network block | — |
| First address in subnet | — |
| Last address in subnet | — |
| Addresses in subnet | — |
| Type/class of address | — |
Reference: reserved blocks
| ::/128 | :: (unspecified) |
|---|---|
| ::1/128 | Loopback, address of the current device. |
| ::/96 | Embedded IPv4 (IPv4-compatible, obsolete) |
| ::ffff:0:0/96 | IPv4-mapped address (::ffff:0:0/96) |
| 64:ff9b::/96 | NAT64 well-known prefix |
| 2001::/32 | Teredo (2001::/32) |
| 2001:db8::/32 | For documentation examples |
| 2002::/16 | 6to4 (2002::/16) |
| fe80::/10 | Link-local addresses are often used for automatic network address configuration when external sources are unavailable. |
| fec0::/10 | Site-local (deprecated) |
| fc00::/7 | Private (internal) networks |
| ff00::/8 | For multicast |
| 3fff::/20 | For documentation examples |
What it is
The IPv6 calculator derives the network block, first/last address in the subnet and multiple address representations (compressed/expanded) from an IP and prefix.
How it works
Enter an IPv6 in any valid form (e.g., 2001:db8::1 or ::ffff:192.0.2.1) and prefix length (/64). The tool computes the network and range.
Examples
2001:db8::1/64→ network2001:db8::/64, range2001:db8::–2001:db8::ffff:ffff:ffff:ffff.fc00::/7→ unique local address (ULA) range.
Limitations & notes
There is no broadcast in IPv6; we show the last address in the subnet. Calculations follow standard CIDR rules.
FAQ
- Why show 2^N instead of an exact number? IPv6 subnets can contain astronomically large numbers of addresses. A /64 subnet has 2^64 (about 18.4 quintillion) addresses - writing that as a decimal would be unreadable. Powers of two make subnet sizes immediately comparable and easier to work with in network planning.
- Is IPv4-embedded form supported? Yes. The calculator handles IPv4-mapped addresses like
::ffff:192.0.2.1and IPv4-compatible addresses. These transition mechanisms allow IPv6 networks to reference IPv4 addresses, which is useful during the ongoing migration between the two protocol versions. - What is the most common IPv6 prefix length? /64 is the standard prefix for a single LAN segment - it is recommended by RFC 4291 and required for SLAAC (Stateless Address Autoconfiguration) to work. ISPs typically assign /48 (65,536 subnets) or /56 (256 subnets) to end customers, giving them plenty of room to create internal /64 networks.
- How does IPv6 address abbreviation work? IPv6 addresses can be shortened by removing leading zeros in each group (2001:0db8 becomes 2001:db8) and replacing the longest consecutive sequence of all-zero groups with :: (once per address). For example, 2001:0db8:0000:0000:0000:0000:0000:0001 becomes 2001:db8::1.