Address (Host or Network) Netmask (i.e. 24) Netmask for sub/supernet (optional)
/ move to:
  



Address:   192.168.0.1           11000000.10101000.000000 00.00000001
Netmask:   255.255.252.0 = 22    11111111.11111111.111111 00.00000000
Wildcard:  0.0.3.255             00000000.00000000.000000 11.11111111
=>
Network:   192.168.0.0/22        11000000.10101000.000000 00.00000000 (Class C)
Broadcast: 192.168.3.255         11000000.10101000.000000 11.11111111
HostMin:   192.168.0.1           11000000.10101000.000000 00.00000001
HostMax:   192.168.3.254         11000000.10101000.000000 11.11111110
Hosts/Net: 1022                  (Private Internet)

Thanks to http://www.netzwerkinfo.de/daemons/ for this ip calculator icon :-)
Version 0.35.2 2005/07/07
Download
07/27/2006 Security information
Screenshot (ipcalc works also at the prompt)
CGI wrapper that produced this page.
Archive
Have a look in the archives for the new version 0.41, with the capability to deaggregate network ranges
How to run this under windows
Debian users can apt-get install ipcalc
2000-2006 Krischan Jodies