# /24 Subnet Mask (255.255.255.0) – Hosts, Range & FAQ

> The /24 subnet mask is 255.255.255.0. A /24 block holds 256 addresses with 254 usable hosts — ranges, wildcard, binary math and FAQs.

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# /24 Subnet Mask ReferenceIPv4

The workhorse of the Internet: a /24 is 256 addresses with mask 255.255.255.0, small enough to manage and large enough for most LANs. When someone says 'a Class C' or 'one subnet', odds are they picture a /24.

The /24 subnet mask is 255.255.255.0, equivalent to 0.0.0.255 as a wildcard. A /24 block contains 256 IP addresses (254 usable hosts).

## /24 facts at a glance

- **Subnet mask:** 255.255.255.0
- **Wildcard mask:** 0.0.0.255
- **Binary mask:** 11111111.11111111.11111111.00000000
- **Total addresses:** 256
- **Usable hosts:** 254 (excludes network & broadcast)
- **Block size:** 256 addresses (28)
- **Typical role:** Standard LAN subnet

## Example /24 networks

Three consecutive /24 blocks, starting at the /24 boundary that contains 198.51.100.0:

| Network | Usable range | Usable hosts |
| --- | --- | --- |
| 198.51.100.0/24 | 198.51.100.1 – 198.51.100.254 | 254 |
| 198.51.101.0/24 | 198.51.101.1 – 198.51.101.254 | 254 |
| 198.51.102.0/24 | 198.51.102.1 – 198.51.102.254 | 254 |

## How to calculate a /24 mask

A /24 mask sets the first 24 bits of a 32-bit number to 1 and leaves the remaining 8 bits as 0. In binary that reads `11111111.11111111.11111111.00000000`, which converts to dotted decimal `255.255.255.0`. Each block covers a contiguous run of 28 = 256 addresses, and every block starts at a multiple of that size. The wildcard simply flips every bit, giving `0.0.0.255`.

## Where /24 is used

- Standard office and home LANs, including Wi-Fi segments such as the ubiquitous 192.168.1.0/24.
- Per-VLAN addressing in enterprise designs, one /24 per department or floor.
- The smallest prefix generally accepted across the global routing table; announcements longer than /24 are routinely filtered.
- Reverse DNS delegation happens on this boundary, as an x.y.z.in-addr.arpa zone maps to exactly one /24.

Why only 254 usable hosts: the lowest address identifies the network itself and the highest is reserved for broadcast, leaving 254 for real devices.

All three RFC 5737 documentation ranges are /24s: 192.0.2.0/24, 198.51.100.0/24, and 203.0.113.0/24.

One /24 splits into two /25s, four /26s, eight /27s, sixteen /28s, or sixty-four /30s.

## Frequently asked questions

**How many usable hosts are in a /24?**

Exactly 254. The block holds 256 addresses, minus the network address at the bottom and the broadcast address at the top.

**What is the subnet mask for a /24?**

255.255.255.0, with wildcard 0.0.0.255. Twenty-four fixed bits leave the entire last octet for host numbering.

**Why does a /24 have 254 hosts instead of 256?**

Two addresses carry structural roles rather than device roles: the all-zero host byte names the network and the all-ones host byte broadcasts to everyone on it.

**How many /24s are in a /16?**

256. Each occupies one value of the third octet, which is why /16-to-/24 planning feels so natural.

**Is /24 the smallest routable subnet on the Internet?**

In practice, yes: operators worldwide filter prefixes longer than /24, so anything smaller stays behind NAT or within a provider's network.

## Open this block in a calculator

[Open the /24 block in the subnet calculator](https://itinsighthub.com/subnet-calculator/?q=198.51.100.0%2F24)

[Get the /24 wildcard mask →](https://itinsighthub.com/wildcard-mask-calculator/?q=%2F24)

### Related prefixes

[/23](https://itinsighthub.com/subnet/23/)[/25](https://itinsighthub.com/subnet/25/)[/26](https://itinsighthub.com/subnet/26/)[/28](https://itinsighthub.com/subnet/28/)[/30](https://itinsighthub.com/subnet/30/)

← /23 subnet mask
/25 subnet mask →

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