How this tool works
Enter an IPv4 address and a prefix length such as /24. The calculator applies the mask to find the network and broadcast addresses, the first and last usable host and the number of hosts. You can also split the network into equal smaller subnets, or enter the number of hosts you need to find the smallest prefix that fits.
Common questions
How many usable hosts are in a /24?
A /24 has 256 addresses and 254 usable hosts, because the first address is the network and the last is the broadcast.
What are the private IPv4 ranges?
10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 are reserved for private networks and are not routed on the public internet.
What are /31 and /32 used for?
A /31 has two addresses and is used on point-to-point links. A /32 is a single host address, often used for loopbacks and static routes.
