Subnetting Cheat Sheet

This is a quick reference for IPv4 and IPv6 Subnetting and Subnet masks. If you don't feel like doing the calculations or just forget them, this will save you some time.

IPv4 Subnets Sheet

CIDR

Subnet Mask

Total IPs

Usable IPs
/32 255.255.255.255 1 1
/31 255.255.255.254 2 2
/30 255.255.255.252 4 2
/29 255.255.255.248 8 6
/28 255.255.255.240 16 14
/27 255.255.255.224 32 30
/26 255.255.255.192 64 62
/25 255.255.255.128 128 126
/24 255.255.255.0 256 254
/23 255.255.254.0 512 510
/22 255.255.252.0 1024 1022
/21 255.255.248.0 2048 2046
/20 255.255.240.0 4096 4094
/19 255.255.224.0 8192 8190
/18 255.255.192.0 16,384 16,382
/17 255.255.128.0 32,768 32,766
/16 255.255.0.0 65,536 65,534
/15 255.254.0.0 131,072 131,070
/14 255.252.0.0 262,144 262,142
/13 255.248.0.0 524,288 524,286
/12 255.240.0.0 1,048,576 1,048,574
/11 255.224.0.0 2,097,152 2,097,150
/10 255.192.0.0 4,194,304 4,194,302
/9 255.128.0.0 8,388,608 8,388,606
/8 255.0.0.0 16,777,216 16,777,214
/7 254.0.0.0 33,554,432 33,554,430
/6 252.0.0.0 67,108,864 67,108,862
/5 248.0.0.0 134,217,728 134,217,726
/4 240.0.0.0 268,435,456 268,435,454
/3 224.0.0.0 536,870,912 536,870,910
/2 192.0.0.0 1,073,741,824 1,073,741,822
/1 128.0.0.0 2,147,483,648 2,147,483,646
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Private IPv4 address ranges

Range

Subnet Mask

Range of IPs
10.0.0.0/8 255.0.0.0 10.0.0.0 - 10.255.255.255
172.16.0.0/12 255.240.0.0 172.16.0.0 - 172.31.255.255
192.168.0.0/16 255.255.0.0 192.168.0.0 - 192.168.255.255

Mask/Widlcard Decimal and Binary

Subnet Mask

Binary Rep

WildCard

Binary
255 1111 1111 0 0000 0000
254 1111 1110 1 1000 0000
252 1111 1100 3 1100 0000
248 1111 1000 7 1110 0000
240 1111 0000 15 1111 0000
224 1110 0000 31 1111 1000
192 1100 0000 63 1111 1100
128 1000 0000 127 1111 1110
0 0000 0000 255 1111 1111
VLSM is a process of dividing an IP space into the subnets of different sizes without wasting IP addresses. When we perform subnetting, all subnets have the same number of hosts, this is known as FLSM ( Fixed length subnet mask).
CIDR notation is a compact representation of an IP address and its associated routing prefix. The notation is constructed from an IP address, a slash ('/') character, and a decimal number. The number is the count of leading 1 bits in the routing mask, traditionally called the network mask.

IPv6 Subnets sheet

Prefix

/48s

/56s

/64s
/24 16M 4G 1T
/25 8M 2G 512G
/26 4M 1G 256G
/27 2M 512M 128G
/28 1M 256M 64G
/29 512K 128M 32G
/30 256K 64M 16G
/31 128K 32M 8G
/32 64K 16M 4G
/33 32K 8M 2G
/34 16K 4M 1G
/35 8K 2M 512M
/36 4K 1M 256M
/37 2K 512K 128M
/38 1K 256K 64M
/39 512 128K 32M
/40 256 64K 16M
/41 128 32K 8M
/42 64 16K 4M
/43 32 8K 2M
/44 16 4K 1M
/45 8 2K 512K
/46 4 1K 256K
/47 2 512 128K
/48 1 256 64K
/49 128 32K
/50 64 16K
/51 32 8K
/52 16 4K
/53 8 2K
/54 4 1K
/55 2 512
/56 1 256
/57 128
/58 64
/59 32
/60 16
/61 8
/62 4
/63 2
/64 1