IPv4 Subnet & CIDR Calculator
Determine IP network addresses, broadcast boundaries, usable host ranges, and binary representations across any CIDR prefix (/8 to /32).
Frequently Asked Questions
How many usable hosts are in a /24 subnet?
A /24 subnet has 256 total IP addresses (2^(32-24) = 2^8 = 256). Subtracting the Network ID (.0) and the Broadcast IP (.255), there are 254 usable host IP addresses.
What is the subnet mask for a /16 network?
A /16 prefix corresponds to a subnet mask of 255.255.0.0, providing 65,536 total addresses and 65,534 usable hosts.
What is a wildcard mask and how is it calculated?
A wildcard mask is the inverted representation of a subnet mask, commonly used in Cisco ACLs (Access Control Lists) and OSPF routing. It is calculated by subtracting each octet of the subnet mask from 255 (e.g. 255.255.255.0 has a wildcard mask of 0.0.0.255).