IPv4 Subnets
I've gotten tired of doing binary math to calculate IPv4 subnets in my head, so I created the following two reference tables. The first table is small and can be used to easily slide horizontally to look up information for a subnet within an octet. Where as the second larger table can be used to slide vertically to look up information for any possible 32 bit subnet.
- Bits
- The number of bits in the netmask, counting from the left (MSB) to the right (LSB).
- Netmask
- The doted quad netmask in decimal notation.
- Hexmask
- The doted quad netmask in hexadecimal notation.
- Wildcard
- The wildcard is a Cisco nomenclature that is a binary inversion of the netmask.
- Sub Networks
- The number of sub networks for the given netmask.
- Host IPs
- The number of usable host IPs for the given netmask. - Remember that you loose two usable IPs to network and broadcast addresses.
- Binary
- The decimal value of the given bit.
Bits |
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Netmask |
0 |
128 |
192 |
224 |
240 |
248 |
252 |
254 |
255 |
Hexmask |
0 |
80 |
C0 |
E0 |
F0 |
F8 |
FC |
FE |
FF |
Wildcard |
255 |
127 |
63 |
31 |
15 |
7 |
3 |
1 |
0 |
Sub Networks |
0 |
2 |
4 |
8 |
16 |
32 |
64 |
128 |
256 |
Host IPs |
254 |
126 |
62 |
30 |
14 |
6 |
2 |
0 |
0 |
Binary |
256 |
128 |
64 |
32 |
16 |
8 |
4 |
2 |
1 |
Bits |
Netmask |
Hexmask |
Wildcard |
Sub Networks |
Host IPs |
Binary |
0 |
0.0.0.0 |
0.0.0.0 |
255.255.255.255 |
0 |
4,294,967,294 |
4,294,967,296 |
Bits |
Netmask |
Hexmask |
Wildcard |
Sub Networks |
Host IPs |
Binary |
1 |
128.0.0.0 |
80.0.0.0 |
127.255.255.255 |
2 |
2,147,483,646 |
2,147,483,648 |
2 |
192.0.0.0 |
C0.0.0.0 |
63.255.255.255 |
4 |
1,073,741,822 |
1,073,741,824 |
3 |
224.0.0.0 |
E0.0.0.0 |
31.255.255.255 |
8 |
536,870,910 |
536,870,912 |
4 |
240.0.0.0 |
F0.0.0.0 |
15.255.255.255 |
16 |
268,435,454 |
268,435,456 |
5 |
248.0.0.0 |
F8.0.0.0 |
7.255.255.255 |
32 |
134,217,726 |
134,217,728 |
6 |
252.0.0.0 |
FC.0.0.0 |
3.255.255.255 |
64 |
67,108,862 |
67,108,864 |
7 |
254.0.0.0 |
FE.0.0.0 |
1.255.255.255 |
128 |
33,554,430 |
33,554,432 |
8 |
255.0.0.0 |
FF.0.0.0 |
0.255.255.255 |
256 |
16,777,214 |
16,777,216 |
Bits |
Netmask |
Hexmask |
Wildcard |
Sub Networks |
Host IPs |
Binary |
9 |
255.128.0.0 |
FF.80.0.0 |
0.127.255.255 |
512 |
8,388,606 |
8,388,608 |
10 |
255.192.0.0 |
FF.C0.0.0 |
0.63.255.255 |
1,024 |
4,194,302 |
4,194,304 |
11 |
255.224.0.0 |
FF.E0.0.0 |
0.31.255.255 |
2,048 |
2,097,150 |
2,097,152 |
12 |
255.240.0.0 |
FF.F0.0.0 |
0.15.255.255 |
4,096 |
1,048,574 |
1,048,576 |
13 |
255.248.0.0 |
FF.F8.0.0 |
0.7.255.255 |
8,192 |
524,286 |
524,288 |
14 |
255.252.0.0 |
FF.FC.0.0 |
0.3.255.255 |
16,384 |
262,142 |
262,144 |
15 |
255.254.0.0 |
FF.FE.0.0 |
0.1.255.255 |
32,768 |
131,070 |
131,072 |
16 |
255.255.0.0 |
FF.FF.0.0 |
0.0.255.255 |
65,536 |
65,534 |
65,536 |
Bits |
Netmask |
Hexmask |
Wildcard |
Sub Networks |
Host IPs |
Binary |
17 |
255.255.128.0 |
FF.FF.80.0 |
0.0.127.255 |
131,072 |
32,766 |
32,768 |
18 |
255.255.192.0 |
FF.FF.C0.0 |
0.0.63.255 |
262,144 |
16,382 |
16,384 |
19 |
255.255.224.0 |
FF.FF.E0.0 |
0.0.31.255 |
524,288 |
8,190 |
8,192 |
20 |
255.255.240.0 |
FF.FF.F0.0 |
0.0.15.255 |
1,048,576 |
4,094 |
4,096 |
21 |
255.255.248.0 |
FF.FF.F8.0 |
0.0.7.255 |
2,097,152 |
2,046 |
2,048 |
22 |
255.255.252.0 |
FF.FF.FC.0 |
0.0.3.255 |
4,194,304 |
1,022 |
1,024 |
23 |
255.255.254.0 |
FF.FF.FE.0 |
0.0.1.255 |
8,388,608 |
510 |
512 |
24 |
255.255.255.0 |
FF.FF.FF.0 |
0.0.0.255 |
16,777,216 |
254 |
256 |
Bits |
Netmask |
Hexmask |
Wildcard |
Sub Networks |
Host IPs |
Binary |
25 |
255.255.255.128 |
FF.FF.FF.80 |
0.0.0.127 |
33,554,432 |
126 |
128 |
26 |
255.255.255.192 |
FF.FF.FF.C0 |
0.0.0.63 |
67,108,864 |
62 |
64 |
27 |
255.255.255.224 |
FF.FF.FF.E0 |
0.0.0.31 |
134,217,728 |
30 |
32 |
28 |
255.255.255.240 |
FF.FF.FF.F0 |
0.0.0.15 |
268,435,456 |
14 |
16 |
29 |
255.255.255.248 |
FF.FF.FF.F8 |
0.0.0.7 |
536,870,912 |
6 |
8 |
30 |
255.255.255.252 |
FF.FF.FF.FC |
0.0.0.3 |
1,073,741,824 |
2 |
4 |
31 |
255.255.255.254 |
FF.FF.FF.FE |
0.0.0.1 |
‐ |
‐ |
2 |
32 |
255.255.255.255 |
FF.FF.FF.FF |
0.0.0.0 |
‐ |
‐ |
1 |
Bits |
Netmask |
Hexmask |
Wildcard |
Sub Networks |
Host IPs |
Binary |