Software & Windows Solutions - Subnet and IP Calculator One of the most important tools in the belt of a junior network engineer is an IP network calculator. These can be used
Subnet Calculator Sites for Network Admins
Subnet Calculator (IPv4)
Guide to Subnet Mask (Subnetting) & IP Subnet Calculator
WildPackets IP Subnet Calculator screenshot and download at SnapFiles.com
Subnet Calculator for IP Addresses and Subnetting ONLINE!