A /24 subnet is a block of 256 IPv4 addresses that share the same first three octets, such as 192.168.1.0 through 192.168.1.255. It uses the subnet mask 255.255.255.0 and provides 254 usable host addresses. It’s the most common subnet size in business networks, and the one most people picture when they think of “a subnet.”
This guide explains what the /24 means, how to calculate its range, and how to split or combine /24 networks when one isn’t the right size.
/24 at a Glance
| Property | Value |
|---|---|
| CIDR notation | /24 |
| Subnet mask | 255.255.255.0 |
| Wildcard mask | 0.0.0.255 |
| Network bits | 24 |
| Host bits | 8 |
| Total addresses | 256 |
| Usable hosts | 254 |
| Historical equivalent | Class C network |
What Does the “/24” Mean?
An IPv4 address is 32 bits long, written as four 8-bit numbers (octets) separated by dots. The number after the slash—the prefix length—tells you how many of those 32 bits identify the network. The remaining bits identify individual hosts on that network.
In a /24, the first 24 bits (the first three octets) are the network portion and the last 8 bits (the final octet) are the host portion:
Address: 192 .168 .1 .100
Binary: 11000000 .10101000 .00000001 .01100100
Mask: 11111111 .11111111 .11111111 .00000000 = 255.255.255.0
|<------- network (24 bits) ------->|<- host ->|Because only the last octet changes, every device on a /24 shares the same first three numbers. That’s what makes /24 networks so easy to read: 192.168.1.x is one network, 192.168.2.x is another.
How Many Hosts Are in a /24?
A /24 leaves 8 bits for hosts, and 28 = 256 addresses. Two of those are reserved:
- Network address — the first address (for example, 192.168.1.0) identifies the subnet itself.
- Broadcast address — the last address (for example, 192.168.1.255) reaches every host on the subnet.
That leaves 254 usable addresses for devices: 192.168.1.1 through 192.168.1.254. In practice, one of those usually goes to the default gateway (often .1 or .254), leaving 253 for everything else.
The general formula works for any prefix length:
Usable hosts = 2(32 − prefix) − 2
Example: 192.168.1.0/24
| Field | Value |
|---|---|
| Network address | 192.168.1.0 |
| First usable host | 192.168.1.1 |
| Last usable host | 192.168.1.254 |
| Broadcast address | 192.168.1.255 |
| Subnet mask | 255.255.255.0 |
You can check any address instantly with our free IPv4 Subnet Calculator—enter an IP and /24 to see the full range.
Why /24 Is So Popular
- It’s easy to read. Network boundaries line up with the dots, so anyone can tell at a glance which devices share a subnet.
- It’s the right size for many segments. 254 hosts comfortably fits a department, a floor, a VLAN, or a small office.
- It’s the default almost everywhere. Home routers, small-business firewalls, and many templates default to a /24 such as 192.168.0.0/24 or 192.168.1.0/24.
- It’s the standard unit on the internet. A /24 is generally the smallest block of public IPv4 space that is widely accepted in global BGP routing, so it’s the common unit for public address allocations.
That popularity has a downside. Because so many devices default to the same /24 ranges, overlapping subnets are a frequent problem when offices connect over VPN or when companies merge. Our guide to multi-site IP address management covers how to avoid them.
Splitting a /24 into Smaller Subnets
When 254 hosts is more than a segment needs—or you want to separate device types—you can divide a /24 into smaller subnets. Each additional prefix bit halves the size:
| Prefix | Subnets per /24 | Addresses each | Usable hosts each | Typical use |
|---|---|---|---|---|
| /25 | 2 | 128 | 126 | Splitting a floor or department |
| /26 | 4 | 64 | 62 | Small departments, IoT groups |
| /27 | 8 | 32 | 30 | Branch offices, small VLANs |
| /28 | 16 | 16 | 14 | Server groups, DMZs |
| /29 | 32 | 8 | 6 | Small device clusters |
| /30 | 64 | 4 | 2 | Point-to-point links |
For example, 192.168.1.0/24 splits into four /26 subnets:
- 192.168.1.0/26 (hosts .1–.62)
- 192.168.1.64/26 (hosts .65–.126)
- 192.168.1.128/26 (hosts .129–.190)
- 192.168.1.192/26 (hosts .193–.254)
Combining /24s into Larger Networks
When a segment outgrows 254 hosts, you can combine contiguous /24 blocks into a larger subnet (sometimes called a supernet):
| Prefix | /24s combined | Usable hosts | Example |
|---|---|---|---|
| /23 | 2 | 510 | 10.0.0.0 – 10.0.1.255 |
| /22 | 4 | 1,022 | 10.0.0.0 – 10.0.3.255 |
| /21 | 8 | 2,046 | 10.0.0.0 – 10.0.7.255 |
| /20 | 16 | 4,094 | 10.0.0.0 – 10.0.15.255 |
The blocks must be aligned: a /23 has to start on an even third octet (10.0.0.0/23 or 10.0.2.0/23, not 10.0.1.0/23). Bigger isn’t always better, though—very large flat subnets increase broadcast traffic and make problems harder to isolate. See our subnet planning best practices for guidance on choosing sizes.
/24 vs. Class C
You’ll often hear a /24 called a “Class C network.” Before CIDR was introduced in 1993, IPv4 addresses were divided into fixed classes, and Class C networks (192.0.0.0 through 223.255.255.255) always used a 255.255.255.0 mask.
CIDR replaced that system so any prefix length can be used with any address range. Today, “Class C” is just informal shorthand for “a /24”—and a /24 can be carved out of any range, including 10.0.0.0/8 or 172.16.0.0/12.
When a /24 Isn’t the Right Choice
- Point-to-point links only need two addresses; use a /30 or /31.
- Guest Wi-Fi or large campuses may need more than 254 addresses; consider a /23 or /22.
- IoT and camera networks can grow quickly; plan capacity before you run out. Our guide to IP address capacity planning shows how to forecast growth.
- IPv6 networks don’t use /24 subnets at all—the standard IPv6 subnet is a /64. Try the IPv6 Subnet Calculator to explore IPv6 prefixes.
Frequently Asked Questions
How many IP addresses are in a /24?
256 in total, of which 254 can be assigned to devices.
What subnet mask is /24?
255.255.255.0.
Is 192.168.1.0/24 a private network?
Yes. 192.168.1.0/24 falls inside 192.168.0.0/16, one of the private ranges reserved by RFC 1918. It is not routed on the public internet.
How many /24 subnets are in a /16?
- A /16 such as 10.1.0.0/16 contains 10.1.0.0/24 through 10.1.255.0/24.
What’s the difference between /24 and /16?
A /24 has 256 addresses; a /16 has 65,536—256 times larger. A /16 uses the mask 255.255.0.0, so only the first two octets identify the network.
Keep Track of Every /24
Subnetting math is the easy part. The hard part is remembering which /24s are in use, what’s inside each one, and which ones are about to fill up. The free Network Planner helps you lay out subnets and catch overlaps, and Subnet24 tracks every subnet and IP address for your whole team with real-time scanning.
Get your free Subnet24 account — 4 /24 subnets free forever, no credit card required.