Tom, As someone previously mentioned have a look at whatmask. The source can be found here http://www.laffeycomputer.com/whatmask.html An online demo can be found here http://grox.net/utils/whatmask/ ------------------------------------------------ TCP/IP NETWORK INFORMATION ------------------------------------------------ IP Entered = ..................: 192.168.1.0 CIDR = ........................: /24 Netmask = .....................: 255.255.255.0 Wildcard Bits = ...............: 0.0.0.255 ------------------------------------------------ Network Address = .............: 192.168.1.0 Broadcast Address = ...........: 192.168.1.255 Usable IP Addresses = .........: 254 First Usable IP Address = .....: 192.168.1.1 Last Usable IP Address = ......: 192.168.1.254 -- Regards, Graham Smith ---------------------------------------------------------