The /24 subnet
A /24 subnet uses the mask 255.255.255.0 and holds 256 addresses, 254 of them usable.
A /24 is the most familiar subnet size on the internet: 256 addresses, 254 of them usable, with the mask 255.255.255.0. It maps to one classic class C network and to a single "third octet" of an address plan.
Home routers, office LANs, and lab networks default to a /24 because it is large enough for most segments yet small enough to reason about. The wildcard mask 0.0.0.255 is what you type into an access list to match the same range.
Below you can see the exact network, broadcast, and host range for any /24 you enter, calculated instantly in your browser.
Calculate a /24 network
Accepts CIDR (192.0.2.0/24), IP + mask (192.0.2.0 255.255.255.0), or a bare IP (defaults to /24).
11000000.00000000.00000010.0000000011111111.11111111.11111111.00000000Example: 192.0.2.0/24
Taking 192.0.2.0/24 as a worked example, the block breaks down like this:
| Network address | 192.0.2.0 |
|---|---|
| Usable range | 192.0.2.1 - 192.0.2.254 |
| Broadcast address | 192.0.2.255 |
| Total addresses | 256 |
| Usable hosts | 254 |
| Size | 1 class C block (a /24) |
Frequently asked questions
What is the subnet mask for a /24?
A /24 uses the subnet mask 255.255.255.0. Its wildcard mask, used in access lists, is 0.0.0.255.
How many hosts are in a /24 subnet?
A /24 has 256 total addresses and 254 usable hosts (the total minus the network and broadcast addresses, except for /31 and /32).
What is a /24 used for?
Standard LAN size. It is equivalent to 1 class C block (a /24).
How do I calculate a /24 network?
Set the host bits to zero for the network address and to one for the broadcast address. The calculator on this page does it for any /24 block you enter.