SubnetCalculator
 
Releases
1.0 Feb 26 2002
1.1 Mar 26 2004
1.2 May 2 2005

/28 - is that 16 or 32 addresses?
255.255.255.248 - is that /29 ?

This little utility answers those questions and more.

Screenshot

From an IPv4 address and subnet mask
see:

  • network-, broadcast-, host-addresses
  • CIDR, / and 1s-and-0s bitmasks
  • non-routeable blocks and other info
  •  

    Freeware

    SubnetCalc.dmg
    196 K

     

    Mac OS X 10.2
    or higher
    (including Tiger)