Local network utility
Calculate an IPv6 prefix range and validate an address
Calculate inclusive IPv6 prefix bounds and total address count locally, then see normalized and expanded address forms. No lookup or network scan.
Calculate an IPv6 prefix range
Enter an IPv6 address and prefix length from 0 through 128. The range and address count are calculated in this browser; the address is not looked up or sent anywhere.
Use eight hexadecimal groups or compress one or more zero groups with ::. A final dotted-decimal IPv4 part is accepted. Enter the prefix length separately; do not include brackets or a zone identifier.
What the outputs mean
The first and last addresses are the inclusive numeric bounds of the selected prefix, and the count includes every address in that range. The count does not tell you how many addresses a network convention treats as assignable. IPv6 allocation and interface-ID conventions depend on context; check the plan and requirements for the network you are configuring.
The expanded form shows all eight 16-bit groups. The normalized form uses lowercase, omits leading zeros in groups, and compresses the longest run of zero groups when that run has at least two groups. Equal-length runs use the first run.
This performs address and prefix arithmetic only. It does not check whether a prefix is allocated, routed, available on a network, or safe to use. It is not a network scan.
Sources
- IETF RFC 4291: IP Version 6 Addressing Architecture (2006-02), sections 2.2–2.3. Defines IPv6 text forms and prefix notation.
- IETF RFC 5952: A Recommendation for IPv6 Address Text Representation (2010-08), sections 4–5. Recommends lowercase, suppressed leading zeros, and compression of the longest zero run, with first-run tie breaking.
Related: IPv4 subnet calculator, IP and DNS checks, the IP geolocation accuracy guide, and how to check IPv6 behavior with a VPN. This validator checks address text only; it does not test VPN routing.
How it works
Enter an IPv6 address and a whole-number prefix from 0 through 128. The page calculates the inclusive range and count locally; it does not check allocation, routing, or network availability.
Good to know
Does this tool look up or transmit the address?
No. It parses the text and calculates the prefix range in your browser. It does not perform a DNS lookup, contact an address, or send the value to a server.
What does the address count mean?
It is the total number of numeric IPv6 addresses in the inclusive prefix range. It does not say how many addresses a network convention treats as assignable or whether the prefix is allocated.
What syntax does it accept?
Enter an IPv6 address using eight hexadecimal groups, one :: compression for one or more zero groups, or a final IPv4 dotted-decimal part. Enter the prefix length separately as a whole number from 0 through 128.
Does a valid range mean the prefix is assigned or reachable?
No. The result is address arithmetic only. It does not check allocation, routing, device configuration, or reachability.
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