Subnet Calculator
Calculate IP subnets, network ranges, CIDR notation, broadcast addresses, and available hosts.
Subnet Mask / CIDR Converter
CIDR
/24
Subnet Mask
255.255.255.0
Wildcard
0.0.0.255
CIDR Reference Table
| Prefix | Subnet Mask | Total IPs | Usable Hosts |
|---|---|---|---|
| /8 | 255.0.0.0 | 16,777,216 | 16,777,214 |
| /9 | 255.128.0.0 | 8,388,608 | 8,388,606 |
| /10 | 255.192.0.0 | 4,194,304 | 4,194,302 |
| /11 | 255.224.0.0 | 2,097,152 | 2,097,150 |
| /12 | 255.240.0.0 | 1,048,576 | 1,048,574 |
| /13 | 255.248.0.0 | 524,288 | 524,286 |
| /14 | 255.252.0.0 | 262,144 | 262,142 |
| /15 | 255.254.0.0 | 131,072 | 131,070 |
| /16 | 255.255.0.0 | 65,536 | 65,534 |
| /17 | 255.255.128.0 | 32,768 | 32,766 |
| /18 | 255.255.192.0 | 16,384 | 16,382 |
| /19 | 255.255.224.0 | 8,192 | 8,190 |
| /20 | 255.255.240.0 | 4,096 | 4,094 |
| /21 | 255.255.248.0 | 2,048 | 2,046 |
| /22 | 255.255.252.0 | 1,024 | 1,022 |
| /23 | 255.255.254.0 | 512 | 510 |
| /24 | 255.255.255.0 | 256 | 254 |
| /25 | 255.255.255.128 | 128 | 126 |
| /26 | 255.255.255.192 | 64 | 62 |
| /27 | 255.255.255.224 | 32 | 30 |
| /28 | 255.255.255.240 | 16 | 14 |
| /29 | 255.255.255.248 | 8 | 6 |
| /30 | 255.255.255.252 | 4 | 2 |
| /31 | 255.255.255.254 | 2 | 2 |
| /32 | 255.255.255.255 | 1 | 1 |
Frequently Asked Questions
What is a subnet mask?
A subnet mask is a 32-bit number that divides an IP address into the network portion and the host portion. It uses consecutive 1-bits to mark the network part and 0-bits for the host part. For example, 255.255.255.0 (/24) means the first 24 bits are the network address and the last 8 bits identify individual hosts, allowing up to 254 usable host addresses.
How do I calculate the number of hosts in a subnet?
The formula is 2^(32 - prefix length) - 2. You subtract 2 because the first address is reserved for the network address and the last for the broadcast address. For example, a /24 subnet has 2^8 - 2 = 254 usable hosts. A /30 subnet has 2^2 - 2 = 2 usable hosts, commonly used for point-to-point links.
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation represents an IP address and its subnet mask in a compact format: IP/prefix. The prefix number indicates how many leading bits of the address are the network part. For example, 192.168.1.0/24 means the first 24 bits define the network, equivalent to a subnet mask of 255.255.255.0. CIDR replaced the older classful addressing system.