How many usable IP addresses are in a /16 subnet?

A /16 subnet contains 65,536 total IP addresses. In standard networking, 2 addresses are reserved (the Network ID and Broadcast address), leaving 65,534 usable host IP addresses.

What is the wildcard mask for /16?

The wildcard mask for /16 (255.255.0.0) is 0.0.255.255. Wildcard masks are commonly used in Cisco IOS Access Control Lists (ACLs) and OSPF routing configurations.

Home/Subnet Calculator//16 CIDR

/15 /17

IPv4 CIDR Reference

/16 Subnet Mask — 255.255.0.0 Netmask & Host Calculator

A /16 subnet prefix allocates 255.255.0.0 as its subnet mask. It provides 65,536 total IPv4 addresses and 65,534 usable host addresses with a wildcard mask of 0.0.255.255.

Subnet Mask

255.255.0.0

Usable Hosts

65,534

Total Addresses

65,536

Wildcard Mask

0.0.255.255

Interactive /16 Subnet Calculator

Binary Architecture of a /16 Mask

An IPv4 address consists of 32 bits. In a /16 prefix, the first 16 bits are locked as binary 1s (representing the network prefix), while the remaining 16 bits are binary 0s (reserved for host assignment).

Prefix Length: /16

Binary Mask: 11111111.11111111.00000000.00000000

Dotted Decimal: 255.255.0.0

Formula: 2^(32 - 16) = 65,536 IPs

When Should You Use a /16 Subnet?

Large enterprise private network or standard AWS VPC default block.

Optimized for low-waste routing and efficient IP allocation.

Frequently Asked Questions about /16 Subnets

The subnet mask for a /16 CIDR prefix is 255.255.0.0. In binary notation, this is 11111111.11111111.00000000.00000000 (16 contiguous network bits and 16 host bits).