/11 subnet mask (255.224.0.0)

A /11 network has 21 host bits, 2,097,152 addresses and 2,097,150 usable hosts. It is 8,192 /24 networks.

/11 at a glance

Netmask: 255.224.0.0
Wildcard mask: 0.31.255.255
Hex mask: 0xFFE00000
Binary mask: 11111111.11100000.00000000.00000000
Host bits: 21
Total addresses: 2,097,152
Usable hosts: 2,097,150 (minus network and broadcast)
Compared with a /24: 8,192 /24 networks

Calculate a /11 in the subnet calculator

Typical uses of a /11

A /11 is commonly used as a regional summary inside a 10.0.0.0/8 plan, for example 10.0.0.0/11 for one region, 10.32.0.0/11 for the next, giving eight regions of 2 million addresses each.

Example /11 ranges

Network	Network address	First usable	Last usable	Broadcast	Next /11
10.0.0.0/11	10.0.0.0	10.0.0.1	10.31.255.254	10.31.255.255	10.32.0.0/11	calculate

The /11 boundary falls in the second octet, so /11 networks start every 32 in that octet (8 per /8): 0, 32, 64, 96, 128, 160, 192, 224.

How many /11s fit

In a	Number of /11 subnets
/8	8

What a /11 contains

Smaller block	How many
/16	32
/24	8,192
/26	32,768
/28	131,072
/29	262,144
/30	524,288
/32	2,097,152

Splitting a /11

Into	Subnets	Usable hosts each
/12	2	1,048,574
/13	4	524,286
/14	8	262,142
/15	16	131,070

/11 in AWS, Azure and Google Cloud

Platform	Allowed subnet sizes	/11 allowed?	Usable after reservation
AWS VPC	/16 to /28	No	-
Azure VNet	/2 to /29	Yes	2,097,147 (5 reserved)
Google Cloud VPC	/4 to /29	Yes	2,097,148 (4 reserved)

Cloud providers reserve addresses in every subnet (first four and the last address (network, VPC router, DNS, future use, broadcast) on AWS), so the usable count there differs from the classic 2^n - 2.