Subnet Calc is a handy little app that allows you to determine various aspects of a given subnet defined by an IP address and CIDR netmask. It will tell you the base IP, net mask, wildcard, network address, broadcast address, minimum & maximum host addresses, the total number of hosts available and even the class of the subnet including if it's a private range or not.

In due course, various aspects of the highly successful iOS app will be being ported over so stay tuned for future updates!