About this tool
Enter an IPv4 address with a CIDR prefix and instantly see the netmask, network and broadcast addresses, usable host range and totals. Everything is computed locally in your browser.
Frequently asked questions
Why are usable hosts two fewer than total?
The network and broadcast addresses are reserved, so a /24 has 256 total addresses but 254 usable hosts. /31 and /32 are special-cased.
What is the wildcard mask?
It is the bitwise inverse of the subnet mask, commonly used in access control lists on routers.