CIDR calculator

Enter an IPv4 address with CIDR prefix (e.g. 192.168.1.0/24) or dotted subnet mask.

Examples
IP address192.168.1.0
CIDR prefix/24
Subnet mask255.255.255.0
Wildcard mask0.0.0.255
Network address192.168.1.0
Broadcast address192.168.1.255
First host192.168.1.1
Last host192.168.1.254
Total addresses256
Usable hosts254
Address classPrivate (RFC 1918)
Network (binary)11000000.10101000.00000001.00000000

For /31 and /32, all addresses in the block may be usable (point-to-point links).