Subnet Masks Reference Table
Class A Class B
Network Number of Number of Network Number of Number of
Subnet Mask Subnet Mask
Bits Subnets Hosts Bits Subnets Hosts
/8 255.0.0.0 0 16777214 /16 255.255.0.0 0 65534
/9 255.128.0.0 2 (0) 8388606 /17 255.255.128.0 2 (0) 32766
/10 255.192.0.0 4 (2) 4194302 /18 255.255.192.0 4 (2) 16382
/11 255.224.0.0 8 (6) 2097150 /19 255.255.224.0 8 (6) 8190
/12 255.240.0.0 16 (14) 1048574 /20 255.255.240.0 16 (14) 4094
/13 255.248.0.0 32 (30) 524286 /21 255.255.248.0 32 (30) 2046
/14 255.252.0.0 64 (62) 262142 /22 255.255.252.0 64 (62) 1022
/15 255.254.0.0 128 (126) 131070 /23 255.255.254.0 128 (126) 510
/16 255.255.0.0 256 (254) 65534 /24 255.255.255.0 256 (254) 254
/17 255.255.128.0 512 (510) 32766 255.255.255.12
/25 512 (510) 126
8
/18 255.255.192.0 1024 (1022) 16382
255.255.255.19
/19 255.255.224.0 2048 (2046) 8190 /26 1024 (1022) 62
2
/20 255.255.240.0 4096 (4094) 4094 255.255.255.22
/27 2048 (2046) 30
4
/21 255.255.248.0 8192 (8190) 2046
255.255.255.24
16384 /28 4096 (4094) 14
/22 255.255.252.0 1022 0
(16382)
255.255.255.24
32768 /29 8192 (8190) 6
/23 255.255.254.0 510 8
(32766)
255.255.255.25 16384
65536 /30 2
/24 255.255.255.0 254 2 (16382)
(65534)
131072
/25 255.255.255.128 126
(131070)
262144
/26 255.255.255.192 62
(262142)
524288
/27 255.255.255.224 30
(524286)
1048576
/28 255.255.255.240 14
(1048574)
2097152
/29 255.255.255.248 6
(2097150)
4194304
/30 255.255.255.252 2
(4194302)
Class C
Network Number of Number of
Subnet Mask
Bits Subnets Hosts
/24 255.255.255.0 0 254
/25 255.255.255.128 2 (0) 126
/26 255.255.255.192 4 (2) 62
/27 255.255.255.224 8 (6) 30
/28 255.255.255.240 16 (14) 14
/29 255.255.255.248 32 (30) 6
/30 255.255.255.252 64 (62) 2
Network Portion
IP Address = 192.168.1.0 Host Portion
Subnet Mask: 111111111.11111111.00000000.0000000
Host Portion
Network Portion
The 1s in the subnet mask represent the network portion.
the 0s represent the host portion.
Subnetting Table
Binary 1000000 01000000 00100000 00010000 00001000 00000100 00000010 00000001
Value 128 64 32 16 8 4 2 1
Subnet 10000000 11000000 11100000 11110000 11111000 11111100 11111110 11111111
Mask
128 192 224 240 248 252 254 255
Equation of Host per Subnet
2𝑡𝑜 𝑡ℎ𝑒 𝑝𝑜𝑤𝑒𝑟 𝑜𝑓 𝑡ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 0′ 𝑠 𝑖𝑛 𝑡ℎ𝑒 𝑠𝑢𝑏𝑛𝑒𝑡 𝑚𝑎𝑠𝑘 𝑏𝑖𝑛𝑎𝑟𝑦 𝑜𝑟 𝑡ℎ𝑒 ℎ𝑜𝑠𝑡 𝑝𝑜𝑟𝑡𝑖𝑜𝑛
Equation of Subnet
2𝑡𝑜 𝑡ℎ𝑒 𝑝𝑜𝑤𝑒𝑟 𝑜𝑓 𝑡ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 ℎ𝑜𝑠𝑡 𝑏𝑖𝑡𝑠 𝑏𝑜𝑟𝑟𝑜𝑤𝑒𝑑 .
Equation Subnet Mask = Binary
20=1 255 = 11111111
21=2 254 = 11111110
22=4 252 = 11111100
23=8 248 = 11111000
24 =16 240 = 11110000
25=32 224 = 11100000
26=64 192 = 11000000
27=128 128 = 10000000
28=256 64 = 01000000
29=512 32 = 00100000
210=1024 16 = 00010000
211 =2048 8 = 00001000
212=4019 4 = 00000100
213=8192 2 = 00000010
214=16384 1 = 00000001
215=32768
216=65536
217=131072
218=262144
219=542288
220=1048576
221=2097152
222=4194304
223=8388608
224=16777216
