IP Subnet Calculator
Enter an IPv4 address and prefix length to inspect the containing subnet and common routing values.
Network192.168.1.0/24
Subnet mask255.255.255.0
Broadcast192.168.1.255
Usable hosts254
First host192.168.1.1
Last host192.168.1.254
Wildcard mask0.0.0.255
Total addresses256
For /31 point-to-point and /32 host routes, usable-address conventions differ from traditional subnet host ranges; this tool reports all addresses as usable for those prefixes.
How this tool works
A CIDR prefix creates a 32-bit network mask. Bitwise AND gives the network address; applying the inverse mask gives the broadcast address.
Example
192.168.1.42/24 resolves to network 192.168.1.0, mask 255.255.255.0 and broadcast 192.168.1.255.
Common questions
Does this support IPv6?
This version focuses on IPv4 CIDR calculations.
Why are /31 and /32 different?
Modern point-to-point /31 networks and /32 host routes do not follow the traditional “network and broadcast are unusable hosts” convention.