How to use
- Enter an IPv4 address (e.g. 192.168.1.1 or 10.0.0.1/16).
- Choose a CIDR prefix from /0 to /32 or click a quick preset button (/24, /16, /8).
- Instantly inspect the network address, broadcast address, wildcard mask, and usable host count.
FAQ
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) specifies subnet mask lengths using a slash followed by the prefix bit count. For instance, /24 corresponds to 255.255.255.0 and leaves 8 bits for 254 assignable host addresses.
Why are there 2 fewer usable hosts than total addresses?
In traditional IPv4 subnets, the very first IP is reserved as the Network identifier, and the very last IP is designated as the broadcast address for all hosts on that wire.
What are RFC 1918 private IPv4 ranges?
Private addresses are non-routable on the public internet, defined for local area networks: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.