IPv6 Subnet Calculator
Enter an IPv6 address with a prefix length from 0 to 128 to calculate its complete address range in your browser.
A QUICK WALKTHROUGH
How to use this tool
- Enter an IPv6 address and CIDR prefix, such as 2001:db8::1/64.
- Calculate the subnet and review any input error.
- Read the normalized prefix, first and last address, and total address count.
Exact range calculation
Formula: count = 2^(128 − prefix); network = (address >> host bits) << host bits; last = network + count − 1.
Accepted notation
Accepts :: compression and a final IPv4 dotted decimal tail (four octets, 0–255, no leading zeroes). Zone identifiers (%) are not supported: they describe an interface scope, not the 128-bit address.
Local calculation and scope
Calculated locally. This range does not establish routing, allocation, or security.
GOOD TO KNOW
Common questions
What happens at /0 and /128?
All addresses are counted. /0 covers the entire 128-bit range; /128 contains exactly one address.