What a /24 subnet is: the classic LAN subnet
A /24 holds 256 addresses, 254 usable, and fixes the first three octets. It is the default mental model for a subnet and the size almost every home router ships with.
At a glance
- Subnet mask
- 255.255.255.0
- Wildcard mask
- 0.0.0.255
- Total addresses
- 256
- Usable hosts
- 254
- Contains
- 1 networks of /24
- Host bits
- 8 of 32
In detail
The mask is 255.255.255.0. The last octet is entirely free: .0 is the network address, .255 is the broadcast address, and .1 through .254 are assignable. The alignment with octet boundaries is exactly why it became the default.
A /24 is the right size for a normal office subnet, a rack, a virtual network tier, or anything with fewer than 254 devices. Its readability is a real feature: everyone can see at a glance which addresses are on the same network.
If you are running out of a /24, widen to a /23 rather than adding a second unrelated /24. One larger subnet is simpler than two subnets plus a route between them.
Examples
192.168.1.0/24
mask 255.255.255.0
wildcard 0.0.0.255
network 192.168.1.0
broadcast 192.168.1.255
usable 192.168.1.1 to 192.168.1.254 (254 hosts)Things that catch people out
- 192.168.1.0/24 is the most common home network on the internet, which makes it the worst possible choice for the office end of a virtual private network. Pick something less likely to collide.
- The .0 and .255 addresses are not usable in a /24, but they are perfectly usable inside a larger prefix. The rule is about the prefix, not about the last octet.
Try it: IP Subnet Calculator
Enter any IPv4 address with a prefix or a dotted mask and get the network address, broadcast address, wildcard mask, usable host range, address class, and the hex and binary forms.
IP Subnet Calculator
LOCAL · Browser-OnlyCalculate IP subnet details, network ranges, and CIDR notation
192.168.1.0192.168.1.255255.255.255.00.0.0.255192.168.1.0/24192.168.1.1 - 192.168.1.254192.168.1.1192.168.1.254256254C0xC0A8016411000000.10101000.00000001.01100100Split into two /25 subnets
Dividing 192.168.1.0/24 one prefix deeper.
Common Subnet Masks
Related IPv4 subnets
All ipv4 subnets →What a /25 subnet is: half a /24
A /25 uses the mask 255.255.255.128 and gives 126 usable addresses. What it is for and where it goes wrong.
What a /23 subnet is: two /24s
A /23 uses the mask 255.255.254.0 and gives 510 usable addresses. What it is for and where it goes wrong.
What a /16 subnet is: a full class B block
A /16 uses the mask 255.255.0.0 and gives 65,534 usable addresses. What it is for and where it goes wrong.
What a /26 subnet is: a quarter of a /24
A /26 uses the mask 255.255.255.192 and gives 62 usable addresses. What it is for and where it goes wrong.
What a /27 subnet is: an eighth of a /24
A /27 uses the mask 255.255.255.224 and gives 30 usable addresses. What it is for and where it goes wrong.
What a /28 subnet is: sixteen addresses
A /28 uses the mask 255.255.255.240 and gives 14 usable addresses. What it is for and where it goes wrong.
Tools for this
- IP Subnet Calculator Free online IP subnet calculator - calculate IP subnet details, CIDR notation, and network address ranges
- IP Address Lookup Free online IP address lookup - find your public IP address and basic network information
- Number Base Converter Free online number base converter - convert numbers between decimal, binary, octal, and hexadecimal