/16 Subnet Mask: How Many IPs?
65,536 addresses, 65,534 usable, mask 255.255.0.0.
A /16 is a common size for a whole cloud network (VPC or VCN) and holds 256 /24 networks. It is the largest subnet AWS allows.
Subnet mask for /16
The /16 subnet mask is 255.255.0.0: 16 bits for the network and 16 for hosts.
| Subnet mask | 255.255.0.0 |
|---|---|
| Mask in binary | 11111111.11111111.00000000.00000000 |
| Wildcard mask | 0.0.255.255 |
| Total addresses | 65,536 |
| Usable hosts | 65,534 |
| In /24 terms | It contains 256 /24 networks. |
| Example (10.0.0.0/16) | 10.0.0.0 - 10.0.255.255 |
Usable addresses in cloud subnets
Cloud providers reserve extra addresses in every subnet, so fewer than 65,534 are available to your machines.
| AWS | 65,531 usable |
|---|---|
| Azure | 65,531 usable |
| Google Cloud | 65,532 usable |
| Oracle Cloud | 65,533 usable |
Limits and reserved counts are commonly documented values; check your provider's current documentation before you plan around them.
Other sizes
/16 | /22 | /23 | /24 | /25 | /26 | /27 | /28 | /29 | /30
Split a block into /16 subnets with the subnet splitter, or calculate any block with the CIDR calculator.
FAQ
How many usable IP addresses are in a /16?
65,534 usable addresses out of 65,536. The network and broadcast addresses are reserved.
What is the subnet mask for /16?
255.255.0.0, with wildcard mask 0.0.255.255.
How many usable addresses does a /16 have in AWS?
65,531, because AWS reserves five addresses in every subnet.