CIDR Calculator is a simple to use utility. Not loaded with a bunch of bells and whistles, CIDR Calculator concentrates on the job at hand.
Requesting IPs using CIDR notation
If you need to request a net block from your ISP, you can determine the right CIDR block size by simply checking the handy ‘IPv4 CIDRs’ quick reference sheet:
Understanding a CIDR
If you already have a CIDR assigned for your network, or simply desire to understand the IP ranging for any IPv4 CIDR block, simply punch the value into the input box, and you will receive the starting IP, ending IP, common network settings, and for those that deal in the world of IP blocklists, and data warehousing, a base10 integer representation of the IP addresses (start and finish).
Help at your Fingertips
Along with the CIDR Calculator, new to the MAC OSX desktop version is a handy Apple Help Book containing all the information you need to make the most out of CIDR Calculator.