IPv6 Subnet Calculator

Input an IPv6 address and the subnet size in slash notation:

Compressed Address:
Expanded Address:
Number of /64s:

Select a number of subnets or a subnet size to divide the above into:

subnets or

This calculator can be used for IPv6 in the same way as our VLSM calculator is used to plan an IPv4 network.

Note that best practice is to always use a /64 subnet mask for simplicity on real world IPv6 subnets with hosts. This can lead to a lot of ‘wasted’ addresses, but the IPv6 address space is so large that it isn’t a concern.

This IPv6 subnetting calculator is provided to help you understand the IPv6 address space better and to study for exams – you should always use a /64 subnet mask on real networks.

Remember, the IPv6 address space can be huge. Because of this, only up to the first 999 subnets are displayed.

Download our Subnet Cheat Sheet for all the essential information you need to quickly perform subnet calculations in your head.

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