IP subnet calculator

Enter an IP address with its prefix (CIDR notation) or with its netmask and get the network address, the broadcast, the range of usable hosts and much more. Works with IPv4 and IPv6.

What is a subnet?

A subnet is a division of an IP network. The netmask tells which part of the address identifies the network and which part identifies each host. In CIDR notation the mask is written as the number of network bits after a slash: 192.168.1.0/24 is equivalent to the mask 255.255.255.0 and contains 256 addresses.

Network address, broadcast and hosts

In IPv4, the first address of a subnet is the network address and the last one is the broadcast; neither can be assigned to a host, which is why a /24 has 254 usable hosts. The /31 (point-to-point links) and /32 (a single host) subnets are exceptions. IPv6 has no broadcast and each local network is normally a /64.

What is the wildcard mask?

The wildcard is the inverted mask (0.0.0.255 for a /24). It is used in access control lists (ACLs) on Cisco routers and in OSPF configuration.

IPv4 subnet mask table