Class | Subnet Bits | Possible Subnets | Usuable Subnets | Host Bits | Possible Hosts | Usable Hosts | Subnet Bit Map |
---|---|---|---|---|---|---|---|
C | 2 | 4 | 2 | 6 | 64 | 62 | 110NNNNN.NNNNNNNN.NNNNNNNN.SSHHHHHH |
C | 3 | 8 | 6 | 5 | 32 | 30 | 110NNNNN.NNNNNNNN.NNNNNNNN.SSSHHHHH |
C | 4 | 16 | 14 | 4 | 16 | 14 | 110NNNNN.NNNNNNNN.NNNNNNNN.SSSSHHHH |
C | 5 | 32 | 30 | 3 | 8 | 6 | 110NNNNN.NNNNNNNN.NNNNNNNN.SSSSSHHH |
C | 6 | 64 | 62 | 2 | 4 | 2 | 110NNNNN.NNNNNNNN.NNNNNNNN.SSSSSSHH |
B | 2 | 4 | 2 | 14 | 16,384 | 16,382 | 10NNNNNN.NNNNNNNN.SSHHHHHH.HHHHHHHH |
B | 3 | 8 | 6 | 13 | 8,192 | 8,190 | 10NNNNNN.NNNNNNNN.SSSHHHHH.HHHHHHHH |
B | 4 | 16 | 14 | 12 | 4,096 | 4,094 | 10NNNNNN.NNNNNNNN.SSSSHHHH.HHHHHHHH |
B | 5 | 32 | 30 | 11 | 2,048 | 2,046 | 10NNNNNN.NNNNNNNN.SSSSSHHH.HHHHHHHH |
B | 6 | 64 | 62 | 10 | 1,024 | 1,022 | 10NNNNNN.NNNNNNNN.SSSSSSHH.HHHHHHHH |
B | 7 | 128 | 126 | 9 | 512 | 510 | 10NNNNNN.NNNNNNNN.SSSSSSSH.HHHHHHHH |
B | 8 | 256 | 254 | 8 | 256 | 254 | 10NNNNNN.NNNNNNNN.SSSSSSSS.HHHHHHHH |
B | 9 | 512 | 510 | 7 | 128 | 126 | 10NNNNNN.NNNNNNNN.SSSSSSSS.SHHHHHHH |
B | 10 | 1,024 | 1,022 | 6 | 64 | 62 | 10NNNNNN.NNNNNNNN.SSSSSSSS.SSHHHHHH |
B | 11 | 2,048 | 2,046 | 5 | 32 | 30 | 10NNNNNN.NNNNNNNN.SSSSSSSS.SSSHHHHH |
B | 12 | 4,096 | 4,094 | 4 | 16 | 14 | 10NNNNNN.NNNNNNNN.SSSSSSSS.SSSSHHHH |
B | 13 | 8,192 | 8,190 | 3 | 8 | 6 | 10NNNNNN.NNNNNNNN.SSSSSSSS.SSSSSHHH |
B | 14 | 16,384 | 16,382 | 2 | 4 | 2 | 10NNNNNN.NNNNNNNN.SSSSSSSS.SSSSSSHH |
A | 2 | 4 | 2 | 22 | 4,192,304 | 4,192,302 | 0NNNNNNN.SSHHHHHH.HHHHHHHH.HHHHHHHH |
A | 3 | 8 | 6 | 21 | 2,097,152 | 2,097,150 | 0NNNNNNN.SSSHHHHH.HHHHHHHH.HHHHHHHH |
A | 4 | 16 | 14 | 20 | 1,048,576 | 1,048,574 | 0NNNNNNN.SSSSHHHH.HHHHHHHH.HHHHHHHH |
A | 5 | 32 | 30 | 19 | 524,288 | 524,286 | 0NNNNNNN.SSSSSHHH.HHHHHHHH.HHHHHHHH |
A | 6 | 64 | 62 | 18 | 262,144 | 262,142 | 0NNNNNNN.SSSSSSHH.HHHHHHHH.HHHHHHHH |
A | 7 | 128 | 126 | 17 | 131,072 | 131,070 | 0NNNNNNN.SSSSSSSH.HHHHHHHH.HHHHHHHH |
A | 8 | 256 | 254 | 16 | 65,536 | 65,534 | 0NNNNNNN.SSSSSSSS.HHHHHHHH.HHHHHHHH |
A | 9 | 512 | 510 | 15 | 32,768 | 32,766 | 0NNNNNNN.SSSSSSSS.SHHHHHHH.HHHHHHHH |
A | 10 | 1,024 | 1,022 | 14 | 16,384 | 16,382 | 0NNNNNNN.SSSSSSSS.SSHHHHHH.HHHHHHHH |
A | 11 | 2,048 | 2,046 | 13 | 8,192 | 8,190 | 0NNNNNNN.SSSSSSSS.SSSHHHHH.HHHHHHHH |
A | 12 | 4,096 | 4,094 | 12 | 4,096 | 4,094 | 0NNNNNNN.SSSSSSSS.SSSSHHHH.HHHHHHHH |
A | 13 | 8,192 | 8,190 | 11 | 2,048 | 2,046 | 0NNNNNNN.SSSSSSSS.SSSSSHHH.HHHHHHHH |
A | 14 | 16,384 | 16,382 | 10 | 1,024 | 1,022 | 0NNNNNNN.SSSSSSSS.SSSSSSHH.HHHHHHHH |
A | 15 | 32,768 | 32,766 | 9 | 512 | 510 | 0NNNNNNN.SSSSSSSS.SSSSSSSH.HHHHHHHH |
A | 16 | 65,536 | 65,534 | 8 | 256 | 254 | 0NNNNNNN.SSSSSSSS.SSSSSSSS.HHHHHHHH |
A | 17 | 131,072 | 131,070 | 7 | 128 | 126 | 0NNNNNNN.SSSSSSSS.SSSSSSSS.SHHHHHHH |
A | 18 | 262,144 | 262,142 | 6 | 64 | 62 | 0NNNNNNN.SSSSSSSS.SSSSSSSS.SSHHHHHH |
A | 19 | 524,288 | 524,286 | 5 | 32 | 30 | 0NNNNNNN.SSSSSSSS.SSSSSSSS.SSSHHHHH |
A | 20 | 1,048,576 | 1,048,574 | 4 | 16 | 14 | 0NNNNNNN.SSSSSSSS.SSSSSSSS.SSSSHHHH |
A | 21 | 2,097,152 | 2,097,150 | 3 | 8 | 6 | 0NNNNNNN.SSSSSSSS.SSSSSSSS.SSSSSHHH |
A | 22 | 4,194,304 | 4,194,302 | 2 | 4 | 2 | 0NNNNNNN.SSSSSSSS.SSSSSSSS.SSSSsSHH |
20=1 | 28=256 | 216=65,536 | 224=16,777,216 |
21=2 | 29=512 | 217=131,072 | 225=33,554,432 |
22=4 | 210=1,024 | 218=262,144 | 226=67,108,864 |
23=8 | 211=2,048 | 219=524,288 | 227=134,217,728 |
24=16 | 212=4,096 | 220=1,048,576 | 228=268,435,456 |
25=32 | 213=8,192 | 221=2,097,152 | 229=536,870,912 |
26=64 | 214=16,384 | 222=4,194,304 | 230=1,073,741,824 |
27=128 | 215=32,768 | 223=8,388,608 | 231=2,147,483,648 |
Each bit in each octet can have a binary placement value.
The 8 bits in the first octet:
231 | 230 | 229 | 228 | 227 | 226 | 225 | 224 |
The 8 bits in the second octet:
223 | 222 | 221 | 220 | 219 | 218 | 217 | 216 |
The 8 bits in the third octet:
215 | 214 | 213 | 212 | 211 | 210 | 29 | 28 |
The 8 bits in the fourth octet:
27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 |
IP Addresses are 32 bits long.
Some subnet calculations are accomplished using all 32 bits and their corresponding binary positions: 20 - 231.
Some subnet calculations are accomplished using 4 groups of 8, each octet never increasing beyond 27.