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The below CIDR table lists all 32 subnet masks for IPv4 addresses, including the number of IP addresses that can be used for hosts.

BitsCIDRSubnet MaskIP Addresses
0/32255.255.255.2551
1/31255.255.255.2542
2/30255.255.255.2524
3/29255.255.255.2488
4/28255.255.255.24016
5/27255.255.255.22432
6/26255.255.255.19264
7/25255.255.255.128128
8/24255.255.255.0256
9/23255.255.254.0512
10/22255.255.252.01,024
11/21255.255.248.02,048
12/20255.255.240.04,096
13/19255.255.224.08,192
14/18255.255.192.016,384
15/17255.255.128.032,768
16/16255.255.0.065,536
17/15255.254.0.0131,072
18/14255.252.0.0262,144
19/13255.248.0.0524,288
20/12255.240.0.01,048,576
21/11255.224.0.02,097,152
22/10255.192.0.04,194,304
23/9255.128.0.08,388,608
24/8255.0.0.016,777,216
25/7254.0.0.033,554,432
26/6252.0.0.067,108,864
27/5248.0.0.0134,217,728
28/4240.0.0.0268,435,456
29/3224.0.0.0536,870,912
30/2192.0.0.01,073,741,824
31/1128.0.0.02,147,483,648
32/00.0.0.04,294,967,296

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.