IP Calculator

Netmask
Network
Broadcast
First
Last
Hosts

Private ranges

networkfromto
10.0.0.0/810.0.0.010.255.255.255
172.16.0.0/12172.16.0.0172.31.255.255
192.168.0.0/16192.168.0.0192.168.255.255

These addresses can be savely used on your private and/or corporate lan, 192.168.1.0/24 is most used by dsl and cable modems.

Special addresses

networkfromtopurpose
127.0.0.0/8127.0.0.0127.255.255.255Loopback addresses, 127.0.0.1 is default
169.254.0.0/16169.254.0.0169.254.255.255Link local addresses
192.0.2.0/24192.0.2.0192.0.2.255Test net addresses
224.0.0.0/4224.0.0.0239.255.255.255Multicast