/19 Subnet Mask ReferenceIPv4
Thirty-two /24s and 8,190 usable hosts: the /19 (mask <code>255.255.224.0</code>) is the quiet favorite of designers carving a /16 into departmental chunks without fragmenting the summary.
/19 facts at a glance
- Subnet mask
- 255.255.224.0
- Wildcard mask
- 0.0.31.255
- Binary mask
- 11111111.11111111.11100000.00000000
- Total addresses
- 8,192
- Usable hosts
- 8,190 (excludes network & broadcast)
- Block size
- 8,192 addresses (213)
- Typical role
- Mid-size networks and ISP allocations
Example /19 networks
Three consecutive /19 blocks, starting at the /19 boundary that contains 198.51.100.0:
| Network | Usable range | Usable hosts |
|---|---|---|
| 198.51.96.0/19 | 198.51.96.1 – 198.51.127.254 | 8,190 |
| 198.51.128.0/19 | 198.51.128.1 – 198.51.159.254 | 8,190 |
| 198.51.160.0/19 | 198.51.160.1 – 198.51.191.254 | 8,190 |
How to calculate a /19 mask
A /19 mask sets the first 19 bits of a 32-bit number to 1 and leaves the remaining 13 bits as 0. In binary that reads 11111111.11111111.11100000.00000000, which converts to dotted decimal 255.255.224.0. Each block covers a contiguous run of 213 = 8,192 addresses, and every block starts at a multiple of that size. The wildcard simply flips every bit, giving 0.0.31.255.
Where /19 is used
- Department-level VLAN blocks inside a corporate /16.
- Master subnets for medium businesses planning years of growth.
- Public allocation slices that still aggregate cleanly upstream.
Example: <code>192.168.32.0/19</code> covers 192.168.32.0 through 192.168.63.255. The third octet moves in multiples of 32, so eight /19s tile a /16 exactly.
Frequently asked questions
What is the subnet mask for a /19?
<code>255.255.224.0</code>, wildcard <code>0.0.31.255</code>.
How many hosts are in a /19?
8,190 usable of 8,192 total.
How many /19s are in a /16?
Eight. Their third octets start at 0, 32, 64, 96, 128, 160, 192, and 224.
Open this block in a calculator
Open the /19 block in the subnet calculator