/11 Subnet: Mask 255.224.0.0, 2,097,150 Usable Hosts

A /11 subnet has a subnet mask of 255.224.0.0 and contains 2,097,152 total IP addresses, of which 2,097,150 are usable host addresses (the network and broadcast addresses are reserved). A /11 contains 8,192 /24 networks.

Usable hosts in a /11 by platform

Cloud providers reserve more than the usual two addresses per subnet, so the same /11 gives you fewer usable IPs in the cloud than on a standard LAN.

Good to know

A /11 subnet has a 255.224.0.0 mask and 2,097,152 total addresses (2,097,150 usable). Each step from /11 to /12 halves the block; each step back to /10 doubles it.

How a /11 is calculated

• The /11 means the first 11 bits are the network portion, leaving 21 host bits.
• Total addresses = 2^(32 - 11) = 2^21 = 2,097,152.
• Usable hosts (standard) = 2,097,152 - 2 (network + broadcast) = 2,097,150.
• Subnet mask = 255.224.0.0; wildcard mask = 0.31.255.255.