Netmask to usable addresses

Specify the netmask (CIDR)


Usable amount of addresses

Total number of addresses

Netmaks in dotted decimal format


What's a netmask?

All devices on a local network have a unique IP address, but each address is inherently divided into two parts, a shared network part, and a unique host part, and this information is used by the TCP/IP stack for routing. When sending traffic to a machine with a different network part, it must be sent through a router for final delivery.

The dividing line between the network and host parts is determined by the subnet mask, and it's often seen in notation. It looks like an IP address, and it uses a "1" bit to select, or "mask" the network part.

Netmask to usable addresses [Tool]

In this case, the netmask of represents 29 bits of network and 3 bits of host (totalling 32 bits, of course), and this give 8 possible IP addresses in this range. The first and last of the range are reserved addresses, giving 6 usable addresses that may be assigned to a device.