/15 subnet mask (255.254.0.0)

A /15 network has 17 host bits, 131,072 addresses and 131,070 usable hosts. It is 512 /24 networks.

/15 at a glance

Netmask: 255.254.0.0
Wildcard mask: 0.1.255.255
Hex mask: 0xFFFE0000
Binary mask: 11111111.11111110.00000000.00000000
Host bits: 17
Total addresses: 131,072
Usable hosts: 131,070 (minus network and broadcast)
Compared with a /24: 512 /24 networks

Calculate a /15 in the subnet calculator

Typical uses of a /15

A /15 is two /16s. 198.18.0.0/15 is reserved for network benchmarking (RFC 2544); lab traffic generators use it so test traffic never collides with real networks.

Well-known /15 blocks

198.18.0.0/15: Network device benchmarking (RFC 2544)

Example /15 ranges

Network	Network address	First usable	Last usable	Broadcast	Next /15
10.0.0.0/15	10.0.0.0	10.0.0.1	10.1.255.254	10.1.255.255	10.2.0.0/15	calculate
172.16.0.0/15	172.16.0.0	172.16.0.1	172.17.255.254	172.17.255.255	172.18.0.0/15	calculate

The /15 boundary falls in the second octet, so /15 networks start every 2 in that octet (128 per /8): 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, ....

How many /15s fit

In a	Number of /15 subnets
/8	128

What a /15 contains

Smaller block	How many
/16	2
/24	512
/26	2,048
/28	8,192
/29	16,384
/30	32,768
/32	131,072

Splitting a /15

Into	Subnets	Usable hosts each
/16	2	65,534
/17	4	32,766
/18	8	16,382
/19	16	8,190

/15 in AWS, Azure and Google Cloud

Platform	Allowed subnet sizes	/15 allowed?	Usable after reservation
AWS VPC	/16 to /28	No	-
Azure VNet	/2 to /29	Yes	131,067 (5 reserved)
Google Cloud VPC	/4 to /29	Yes	131,068 (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.