IPv4 CIDR table
5 October 2021
The below CIDR table lists all 32 subnet masks for IPv4 addresses, including the number of IP addresses that can be used for hosts.
| Bits | CIDR | Subnet Mask | IP Addresses |
|---|---|---|---|
| 0 | /32 | 255.255.255.255 | 1 |
| 1 | /31 | 255.255.255.254 | 2 |
| 2 | /30 | 255.255.255.252 | 4 |
| 3 | /29 | 255.255.255.248 | 8 |
| 4 | /28 | 255.255.255.240 | 16 |
| 5 | /27 | 255.255.255.224 | 32 |
| 6 | /26 | 255.255.255.192 | 64 |
| 7 | /25 | 255.255.255.128 | 128 |
| 8 | /24 | 255.255.255.0 | 256 |
| 9 | /23 | 255.255.254.0 | 512 |
| 10 | /22 | 255.255.252.0 | 1,024 |
| 11 | /21 | 255.255.248.0 | 2,048 |
| 12 | /20 | 255.255.240.0 | 4,096 |
| 13 | /19 | 255.255.224.0 | 8,192 |
| 14 | /18 | 255.255.192.0 | 16,384 |
| 15 | /17 | 255.255.128.0 | 32,768 |
| 16 | /16 | 255.255.0.0 | 65,536 |
| 17 | /15 | 255.254.0.0 | 131,072 |
| 18 | /14 | 255.252.0.0 | 262,144 |
| 19 | /13 | 255.248.0.0 | 524,288 |
| 20 | /12 | 255.240.0.0 | 1,048,576 |
| 21 | /11 | 255.224.0.0 | 2,097,152 |
| 22 | /10 | 255.192.0.0 | 4,194,304 |
| 23 | /9 | 255.128.0.0 | 8,388,608 |
| 24 | /8 | 255.0.0.0 | 16,777,216 |
| 25 | /7 | 254.0.0.0 | 33,554,432 |
| 26 | /6 | 252.0.0.0 | 67,108,864 |
| 27 | /5 | 248.0.0.0 | 134,217,728 |
| 28 | /4 | 240.0.0.0 | 268,435,456 |
| 29 | /3 | 224.0.0.0 | 536,870,912 |
| 30 | /2 | 192.0.0.0 | 1,073,741,824 |
| 31 | /1 | 128.0.0.0 | 2,147,483,648 |
| 32 | /0 | 0.0.0.0 | 4,294,967,296 |
Notes
- Bits is the number of bits used for nodes.
- CIDR is the CIDR notation.
- Subnet mask is the corresponding mask.
- IP Addresses lists the number of host IP addresses.
Example
The subnet mask 255.255.255.0 translates to /24 in CIDR-speak, as 24 bits are used for the network. That leaves 8 bits / 256 IPs for nodes.
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