The 255.255.224.0 subnet mask.

The /19 subnet uses 255.255.224.0 as its subnet mask — meaning the first 19 bits of every address identify the network, and the remaining 13 bits identify the host within that network. That gives you 8,192 total addresses (8,190 usable on standard RFC math, after subtracting the network and broadcast addresses).

The wildcard mask — the bitwise inverse of the subnet mask — is 0.0.31.255. Wildcards are what Cisco access-control lists and OSPF area definitions use instead of subnet masks; the "1" bits mark "don't care" positions. For a /19, that leaves 13 don't-care host bits.

To find the network address for any IP in a /19 block, perform a bitwise AND between the IP and the subnet mask. To find the broadcast, OR the network address with the wildcard. Modern tools — like our subnet calculator — do this in microseconds, but the underlying mechanics are straightforward binary arithmetic.

A /19 has 8,192 addresses. Frequently used as the parent CIDR for a department or business unit, then split into /24 LANs per VLAN. Also a common allocation from ISPs to mid-sized customers.

Cloud-provider quirks matter at every prefix size: AWS and Azure reserve 5 IPs per subnet, GCP reserves 4, and OCI reserves 3. So a /19 on standard RFC math gives you 8,190 usable hosts, but on AWS or Azure that drops to 8,187. The capacity-planning gap bites hardest at small prefixes (a /28 has 14 usable on paper, only 11 on AWS) but exists at every size. Our cloud-aware calculator applies the right math automatically.