Technical calculator
IPv6 Subnet Calculator
Calculate an IPv6 network prefix, subnet mask, full address range, and address count from an IPv6 address and prefix length.
Calculated result
Calculating…
Results update as you change the inputs.
Methodology and assumptions
Formula: Network = address AND 128-bit prefix mask. Last address = network + 2^(128 − prefix length) − 1. Address count = 2^(128 − prefix length).
Worked example:2001:db8:1234::1/64 belongs to 2001:db8:1234::/64, containing 18,446,744,073,709,551,616 addresses.
Common mistake or edge case:IPv6 subnets do not use IPv4 broadcast-address subtraction. This tool reports the full prefix range and does not infer assignment policy, subnet reservations, or provider-specific limits.
Additional official references:
Read the supporting guide and worked examples.
For IPv4 prefixes and network/broadcast ranges, read the CIDR subnetting guide.
Frequently asked questions
How many addresses are in an IPv6 /64?
A /64 leaves 64 host bits, so it contains 2^64 (18,446,744,073,709,551,616) addresses.
Does IPv6 have network and broadcast addresses?
IPv6 does not use the IPv4 broadcast-address convention. The calculator reports all addresses in the prefix and does not subtract reserved addresses.
Can I use a compressed IPv6 address?
Yes. Standard :: zero compression and upper- or lowercase hexadecimal are accepted. The result is displayed in lowercase with leading zeros omitted and the longest zero run compressed.
Pricing last verified:
Frequently Asked Questions
What does the IPv6 Subnet Calculator calculate?
Calculate an IPv6 network prefix, subnet mask, full address range, and address count from an IPv6 address and prefix length.
How accurate is the IPv6 Subnet Calculator?
It is a planning estimate based on the inputs, formula, assumptions, and sources shown on this page. Actual prices, invoices, taxes, discounts, and outcomes can differ.
Which pricing source does the IPv6 Subnet Calculator use?
The calculator links to RFC 4291 IPv6 addressing architecture as its official source. The displayed pricing or reference data was last verified on 2026-10-01.
Are calculator inputs saved or sent to analytics?
Inputs are processed in your browser. Calculator values are not included in analytics events.