IP Subnet Calculator - Version 3.2.1 The IP Subnet Calculator™ is a popular freeware Windows 95/98/NT/2000 utility for computing information about IP addresses. The IP Subnet Calculator is also part of our commercial product, the multi-purpose Network Calculator. Given an IP class A, B or C address, the IP Subnet Calculator can display several pieces of information about that address by selecting one of four tabs: the Address Info, Subnet Info, Subnet/Hosts or CIDR tab.