# /11 Subnet Mask (255.224.0.0) – Hosts, Range & FAQ

> The /11 subnet mask is 255.224.0.0. A /11 block holds 2,097,152 addresses with 2,097,150 usable hosts — ranges, wildcard, binary math and FAQs.

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# /11 Subnet Mask ReferenceIPv4

Eight equal wedges tile a /8, and each wedge is a /11: mask 255.224.0.0, 2,097,152 addresses. Architects reach for one when they want a generous internal region without committing a full /10.

The /11 subnet mask is 255.224.0.0, equivalent to 0.31.255.255 as a wildcard. A /11 block contains 2,097,152 IP addresses (2,097,150 usable hosts).

## /11 facts at a glance

- **Subnet mask:** 255.224.0.0
- **Wildcard mask:** 0.31.255.255
- **Binary mask:** 11111111.11100000.00000000.00000000
- **Total addresses:** 2,097,152
- **Usable hosts:** 2,097,150 (excludes network & broadcast)
- **Block size:** 2,097,152 addresses (221)
- **Typical role:** Large enterprise and carrier aggregation

## Example /11 networks

Three consecutive /11 blocks, starting at the /11 boundary that contains 198.51.100.0:

| Network | Usable range | Usable hosts |
| --- | --- | --- |
| 198.32.0.0/11 | 198.32.0.1 – 198.63.255.254 | 2,097,150 |
| 198.64.0.0/11 | 198.64.0.1 – 198.95.255.254 | 2,097,150 |
| 198.96.0.0/11 | 198.96.0.1 – 198.127.255.254 | 2,097,150 |

## How to calculate a /11 mask

A /11 mask sets the first 11 bits of a 32-bit number to 1 and leaves the remaining 21 bits as 0. In binary that reads `11111111.11100000.00000000.00000000`, which converts to dotted decimal `255.224.0.0`. Each block covers a contiguous run of 221 = 2,097,152 addresses, and every block starts at a multiple of that size. The wildcard simply flips every bit, giving `0.31.255.255`.

## Where /11 is used

- Dividing a corporate /8 among data centers, regions, or subsidiaries.
- Summary lines in design documents that keep high-level maps readable.
- Lab topologies sized between the familiar /10 and /12 landmarks.

Handy landmark: the RFC 1918 private block 172.16.0.0/12 occupies exactly the upper half of 172.0.0.0/11, which spans 172.0.0.0 through 172.31.255.255.

## Frequently asked questions

**What is the subnet mask for /11?**

255.224.0.0, wildcard 0.31.255.255. Eleven fixed bits means the second octet advances in steps of 32.

**How many addresses are in a /11?**

2,097,152 total; 2,097,150 usable after the standard deduction.

**How many /11s fit in a /8?**

Eight. Their networks begin at second-octet values 0, 32, 64, 96, 128, 160, 192, and 224.

## Open this block in a calculator

[Open the /11 block in the subnet calculator](https://itinsighthub.com/subnet-calculator/?q=198.32.0.0%2F11)

[Get the /11 wildcard mask →](https://itinsighthub.com/wildcard-mask-calculator/?q=%2F11)

### Related prefixes

[/10](https://itinsighthub.com/subnet/10/)[/12](https://itinsighthub.com/subnet/12/)[/24](https://itinsighthub.com/subnet/24/)[/26](https://itinsighthub.com/subnet/26/)[/28](https://itinsighthub.com/subnet/28/)[/30](https://itinsighthub.com/subnet/30/)

← /10 subnet mask
/12 subnet mask →

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