6connect on Twitter: "Our IPv6 Subnet Calculator can be used to work within your IP block range and estimate the structure of your IPv6 allocation. Or you can just generate CSV files
Subnetting Calculator on the App Store
IP Calculator / IP Workshop Professional
FREE: SolarWinds Advanced Subnet Calculator – IP subnet calculation made easy – 4sysops
Download Subnet Calculator 1.1
networking - Is there a subnet calculator that computes the *complement* of a subnet? - Stack Overflow