# /5 Subnet Mask (248.0.0.0) – Hosts, Range & FAQ

> The /5 subnet mask is 248.0.0.0. A /5 block holds 134,217,728 addresses with 134,217,726 usable hosts — ranges, wildcard, binary math and FAQs.

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# /5 Subnet Mask ReferenceIPv4

A /5, masked 248.0.0.0, is an eight-lane slice of IPv4: 134,217,728 addresses, or eight consecutive /8-sized networks under one summary. Outside aggregation exercises, deployments are vanishingly rare.

The /5 subnet mask is 248.0.0.0, equivalent to 7.255.255.255 as a wildcard. A /5 block contains 134,217,728 IP addresses (134,217,726 usable hosts).

## /5 facts at a glance

- **Subnet mask:** 248.0.0.0
- **Wildcard mask:** 7.255.255.255
- **Binary mask:** 11111000.00000000.00000000.00000000
- **Total addresses:** 134,217,728
- **Usable hosts:** 134,217,726 (excludes network & broadcast)
- **Block size:** 134,217,728 addresses (227)
- **Typical role:** Aggregation and supernetting

## Example /5 networks

A /5 spans a large share of the address space, so one aligned example says it all.

| Network | Usable range | Usable hosts |
| --- | --- | --- |
| 192.0.0.0/5 | 192.0.0.1 – 199.255.255.254 | 134,217,726 |

## How to calculate a /5 mask

A /5 mask sets the first 5 bits of a 32-bit number to 1 and leaves the remaining 27 bits as 0. In binary that reads `11111000.00000000.00000000.00000000`, which converts to dotted decimal `248.0.0.0`. Each block covers a contiguous run of 227 = 134,217,728 addresses, and every block starts at a multiple of that size. The wildcard simply flips every bit, giving `7.255.255.255`.

## Where /5 is used

- Supernetting practice on five-bit boundaries.
- Mapping broad regions of the space, such as the fully reserved top slice 248.0.0.0/5 (248-255).
- Certification coursework on variable-length masking.

Worked example: 72.0.0.0/5 stretches from 72.0.0.0 to 79.255.255.255. Every /5 aligns on a first-octet multiple of eight.

## Frequently asked questions

**What is the mask for a /5?**

248.0.0.0, wildcard 7.255.255.255. Five one-bits fix the top of the first octet in steps of eight.

**How many addresses are in a /5?**

134,217,728 total and 134,217,726 usable by convention: twice a /6 and half a /4.

**How many /8s are inside a /5?**

Eight. For instance, 72.0.0.0/5 contains the /8 networks beginning 72, 73, 74, 75, 76, 77, 78, and 79.

## Open this block in a calculator

[Open the /5 block in the subnet calculator](https://itinsighthub.com/subnet-calculator/?q=192.0.0.0%2F5)

[Get the /5 wildcard mask →](https://itinsighthub.com/wildcard-mask-calculator/?q=%2F5)

### Related prefixes

[/4](https://itinsighthub.com/subnet/4/)[/6](https://itinsighthub.com/subnet/6/)[/24](https://itinsighthub.com/subnet/24/)[/26](https://itinsighthub.com/subnet/26/)[/28](https://itinsighthub.com/subnet/28/)[/30](https://itinsighthub.com/subnet/30/)

← /4 subnet mask
/6 subnet mask →

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