# /4 Subnet Mask (240.0.0.0) – Hosts, Range & FAQ

> The /4 subnet mask is 240.0.0.0. A /4 block holds 268,435,456 addresses with 268,435,454 usable hosts — ranges, wildcard, binary math and FAQs.

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# /4 Subnet Mask ReferenceIPv4

Networking's most famous /4 needs no introduction: 224.0.0.0/4 is multicast, the former Class D territory where one packet reaches many willing listeners at once. The mask is 240.0.0.0 and the block spans 224.0.0.0 through 239.255.255.255.

The /4 subnet mask is 240.0.0.0, equivalent to 15.255.255.255 as a wildcard. A /4 block contains 268,435,456 IP addresses (268,435,454 usable hosts).

## /4 facts at a glance

- **Subnet mask:** 240.0.0.0
- **Wildcard mask:** 15.255.255.255
- **Binary mask:** 11110000.00000000.00000000.00000000
- **Total addresses:** 268,435,456
- **Usable hosts:** 268,435,454 (excludes network & broadcast)
- **Block size:** 268,435,456 addresses (228)
- **Typical role:** Aggregation and supernetting

## Example /4 networks

A /4 spans a large share of the address space, so one aligned example says it all.

| Network | Usable range | Usable hosts |
| --- | --- | --- |
| 192.0.0.0/4 | 192.0.0.1 – 207.255.255.254 | 268,435,454 |

## How to calculate a /4 mask

A /4 mask sets the first 4 bits of a 32-bit number to 1 and leaves the remaining 28 bits as 0. In binary that reads `11110000.00000000.00000000.00000000`, which converts to dotted decimal `240.0.0.0`. Each block covers a contiguous run of 228 = 268,435,456 addresses, and every block starts at a multiple of that size. The wildcard simply flips every bit, giving `15.255.255.255`.

## Where /4 is used

- One-to-many delivery such as video distribution and market-data feeds.
- Routing protocol chatter: OSPF hello packets target 224.0.0.5 and 224.0.0.6.
- Lab work with multicast groups, IGMP, and PIM.

Well-known residents include 224.0.0.1, the all-hosts group on a link, and the OSPF pair 224.0.0.5 and 224.0.0.6. A multicast address never appears as the source of a packet.

The familiar usable-hosts arithmetic does not really apply here: multicast groups have members, not hosts, so the minus-two figure is a formality.

## Frequently asked questions

**What is 224.0.0.0/4 used for?**

IP multicast. A sender transmits once to a group address and the network delivers copies to subscribed receivers, saving bandwidth compared with unicasting to each member.

**How many addresses are in a /4?**

268,435,456, one sixteenth of IPv4. The nominal usable figure is 268,435,454, though multicast semantics make the distinction academic.

**What subnet mask corresponds to /4?**

240.0.0.0 (wildcard 15.255.255.255): the first four bits are set, matching exactly the addresses that begin with binary 1110.

## Open this block in a calculator

[Open the /4 block in the subnet calculator](https://itinsighthub.com/subnet-calculator/?q=192.0.0.0%2F4)

[Get the /4 wildcard mask →](https://itinsighthub.com/wildcard-mask-calculator/?q=%2F4)

### Related prefixes

[/3](https://itinsighthub.com/subnet/3/)[/5](https://itinsighthub.com/subnet/5/)[/24](https://itinsighthub.com/subnet/24/)[/26](https://itinsighthub.com/subnet/26/)[/28](https://itinsighthub.com/subnet/28/)[/30](https://itinsighthub.com/subnet/30/)

← /3 subnet mask
/5 subnet mask →

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