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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network101.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
101.0.0.0
Broadcast address
101.127.255.255
First usable
101.0.0.1
Last usable
101.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 65000000 · Integer 1694498816 to 1702887423
Reverse DNS zones
0.101.in-addr.arpa
1.101.in-addr.arpa
2.101.in-addr.arpa
3.101.in-addr.arpa
4.101.in-addr.arpa
5.101.in-addr.arpa
6.101.in-addr.arpa
7.101.in-addr.arpa
8.101.in-addr.arpa
9.101.in-addr.arpa
10.101.in-addr.arpa
11.101.in-addr.arpa
12.101.in-addr.arpa
13.101.in-addr.arpa
14.101.in-addr.arpa
15.101.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01100101.00000000.00000000.00000000101.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01100101.00000000.00000000.00000000101.0.0.0
Broadcast01100101.01111111.11111111.11111111101.127.255.255
Split into smaller subnets/19
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

101.0.0.0/9 makes 1,024 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1101.0.0.0/19101.0.0.1 to 101.0.31.254101.0.31.2558,190
2101.0.32.0/19101.0.32.1 to 101.0.63.254101.0.63.2558,190
3101.0.64.0/19101.0.64.1 to 101.0.95.254101.0.95.2558,190
4101.0.96.0/19101.0.96.1 to 101.0.127.254101.0.127.2558,190
5101.0.128.0/19101.0.128.1 to 101.0.159.254101.0.159.2558,190
6101.0.160.0/19101.0.160.1 to 101.0.191.254101.0.191.2558,190
7101.0.192.0/19101.0.192.1 to 101.0.223.254101.0.223.2558,190
8101.0.224.0/19101.0.224.1 to 101.0.255.254101.0.255.2558,190
9101.1.0.0/19101.1.0.1 to 101.1.31.254101.1.31.2558,190
10101.1.32.0/19101.1.32.1 to 101.1.63.254101.1.63.2558,190
11101.1.64.0/19101.1.64.1 to 101.1.95.254101.1.95.2558,190
12101.1.96.0/19101.1.96.1 to 101.1.127.254101.1.127.2558,190
13101.1.128.0/19101.1.128.1 to 101.1.159.254101.1.159.2558,190
14101.1.160.0/19101.1.160.1 to 101.1.191.254101.1.191.2558,190
15101.1.192.0/19101.1.192.1 to 101.1.223.254101.1.223.2558,190
16101.1.224.0/19101.1.224.1 to 101.1.255.254101.1.255.2558,190
17101.2.0.0/19101.2.0.1 to 101.2.31.254101.2.31.2558,190
18101.2.32.0/19101.2.32.1 to 101.2.63.254101.2.63.2558,190
19101.2.64.0/19101.2.64.1 to 101.2.95.254101.2.95.2558,190
20101.2.96.0/19101.2.96.1 to 101.2.127.254101.2.127.2558,190
21101.2.128.0/19101.2.128.1 to 101.2.159.254101.2.159.2558,190
22101.2.160.0/19101.2.160.1 to 101.2.191.254101.2.191.2558,190
23101.2.192.0/19101.2.192.1 to 101.2.223.254101.2.223.2558,190
24101.2.224.0/19101.2.224.1 to 101.2.255.254101.2.255.2558,190
25101.3.0.0/19101.3.0.1 to 101.3.31.254101.3.31.2558,190
26101.3.32.0/19101.3.32.1 to 101.3.63.254101.3.63.2558,190
27101.3.64.0/19101.3.64.1 to 101.3.95.254101.3.95.2558,190
28101.3.96.0/19101.3.96.1 to 101.3.127.254101.3.127.2558,190
29101.3.128.0/19101.3.128.1 to 101.3.159.254101.3.159.2558,190
30101.3.160.0/19101.3.160.1 to 101.3.191.254101.3.191.2558,190
31101.3.192.0/19101.3.192.1 to 101.3.223.254101.3.223.2558,190
32101.3.224.0/19101.3.224.1 to 101.3.255.254101.3.255.2558,190
33101.4.0.0/19101.4.0.1 to 101.4.31.254101.4.31.2558,190
34101.4.32.0/19101.4.32.1 to 101.4.63.254101.4.63.2558,190
35101.4.64.0/19101.4.64.1 to 101.4.95.254101.4.95.2558,190
36101.4.96.0/19101.4.96.1 to 101.4.127.254101.4.127.2558,190
37101.4.128.0/19101.4.128.1 to 101.4.159.254101.4.159.2558,190
38101.4.160.0/19101.4.160.1 to 101.4.191.254101.4.191.2558,190
39101.4.192.0/19101.4.192.1 to 101.4.223.254101.4.223.2558,190
40101.4.224.0/19101.4.224.1 to 101.4.255.254101.4.255.2558,190
41101.5.0.0/19101.5.0.1 to 101.5.31.254101.5.31.2558,190
42101.5.32.0/19101.5.32.1 to 101.5.63.254101.5.63.2558,190
43101.5.64.0/19101.5.64.1 to 101.5.95.254101.5.95.2558,190
44101.5.96.0/19101.5.96.1 to 101.5.127.254101.5.127.2558,190
45101.5.128.0/19101.5.128.1 to 101.5.159.254101.5.159.2558,190
46101.5.160.0/19101.5.160.1 to 101.5.191.254101.5.191.2558,190
47101.5.192.0/19101.5.192.1 to 101.5.223.254101.5.223.2558,190
48101.5.224.0/19101.5.224.1 to 101.5.255.254101.5.255.2558,190
49101.6.0.0/19101.6.0.1 to 101.6.31.254101.6.31.2558,190
50101.6.32.0/19101.6.32.1 to 101.6.63.254101.6.63.2558,190
51101.6.64.0/19101.6.64.1 to 101.6.95.254101.6.95.2558,190
52101.6.96.0/19101.6.96.1 to 101.6.127.254101.6.127.2558,190
53101.6.128.0/19101.6.128.1 to 101.6.159.254101.6.159.2558,190
54101.6.160.0/19101.6.160.1 to 101.6.191.254101.6.191.2558,190
55101.6.192.0/19101.6.192.1 to 101.6.223.254101.6.223.2558,190
56101.6.224.0/19101.6.224.1 to 101.6.255.254101.6.255.2558,190
57101.7.0.0/19101.7.0.1 to 101.7.31.254101.7.31.2558,190
58101.7.32.0/19101.7.32.1 to 101.7.63.254101.7.63.2558,190
59101.7.64.0/19101.7.64.1 to 101.7.95.254101.7.95.2558,190
60101.7.96.0/19101.7.96.1 to 101.7.127.254101.7.127.2558,190
61101.7.128.0/19101.7.128.1 to 101.7.159.254101.7.159.2558,190
62101.7.160.0/19101.7.160.1 to 101.7.191.254101.7.191.2558,190
63101.7.192.0/19101.7.192.1 to 101.7.223.254101.7.223.2558,190
64101.7.224.0/19101.7.224.1 to 101.7.255.254101.7.255.2558,190
65101.8.0.0/19101.8.0.1 to 101.8.31.254101.8.31.2558,190
66101.8.32.0/19101.8.32.1 to 101.8.63.254101.8.63.2558,190
67101.8.64.0/19101.8.64.1 to 101.8.95.254101.8.95.2558,190
68101.8.96.0/19101.8.96.1 to 101.8.127.254101.8.127.2558,190
69101.8.128.0/19101.8.128.1 to 101.8.159.254101.8.159.2558,190
70101.8.160.0/19101.8.160.1 to 101.8.191.254101.8.191.2558,190
71101.8.192.0/19101.8.192.1 to 101.8.223.254101.8.223.2558,190
72101.8.224.0/19101.8.224.1 to 101.8.255.254101.8.255.2558,190
73101.9.0.0/19101.9.0.1 to 101.9.31.254101.9.31.2558,190
74101.9.32.0/19101.9.32.1 to 101.9.63.254101.9.63.2558,190
75101.9.64.0/19101.9.64.1 to 101.9.95.254101.9.95.2558,190
76101.9.96.0/19101.9.96.1 to 101.9.127.254101.9.127.2558,190
77101.9.128.0/19101.9.128.1 to 101.9.159.254101.9.159.2558,190
78101.9.160.0/19101.9.160.1 to 101.9.191.254101.9.191.2558,190
79101.9.192.0/19101.9.192.1 to 101.9.223.254101.9.223.2558,190
80101.9.224.0/19101.9.224.1 to 101.9.255.254101.9.255.2558,190
81101.10.0.0/19101.10.0.1 to 101.10.31.254101.10.31.2558,190
82101.10.32.0/19101.10.32.1 to 101.10.63.254101.10.63.2558,190
83101.10.64.0/19101.10.64.1 to 101.10.95.254101.10.95.2558,190
84101.10.96.0/19101.10.96.1 to 101.10.127.254101.10.127.2558,190
85101.10.128.0/19101.10.128.1 to 101.10.159.254101.10.159.2558,190
86101.10.160.0/19101.10.160.1 to 101.10.191.254101.10.191.2558,190
87101.10.192.0/19101.10.192.1 to 101.10.223.254101.10.223.2558,190
88101.10.224.0/19101.10.224.1 to 101.10.255.254101.10.255.2558,190
89101.11.0.0/19101.11.0.1 to 101.11.31.254101.11.31.2558,190
90101.11.32.0/19101.11.32.1 to 101.11.63.254101.11.63.2558,190
91101.11.64.0/19101.11.64.1 to 101.11.95.254101.11.95.2558,190
92101.11.96.0/19101.11.96.1 to 101.11.127.254101.11.127.2558,190
93101.11.128.0/19101.11.128.1 to 101.11.159.254101.11.159.2558,190
94101.11.160.0/19101.11.160.1 to 101.11.191.254101.11.191.2558,190
95101.11.192.0/19101.11.192.1 to 101.11.223.254101.11.223.2558,190
96101.11.224.0/19101.11.224.1 to 101.11.255.254101.11.255.2558,190
97101.12.0.0/19101.12.0.1 to 101.12.31.254101.12.31.2558,190
98101.12.32.0/19101.12.32.1 to 101.12.63.254101.12.63.2558,190
99101.12.64.0/19101.12.64.1 to 101.12.95.254101.12.95.2558,190
100101.12.96.0/19101.12.96.1 to 101.12.127.254101.12.127.2558,190
101101.12.128.0/19101.12.128.1 to 101.12.159.254101.12.159.2558,190
102101.12.160.0/19101.12.160.1 to 101.12.191.254101.12.191.2558,190
103101.12.192.0/19101.12.192.1 to 101.12.223.254101.12.223.2558,190
104101.12.224.0/19101.12.224.1 to 101.12.255.254101.12.255.2558,190
105101.13.0.0/19101.13.0.1 to 101.13.31.254101.13.31.2558,190
106101.13.32.0/19101.13.32.1 to 101.13.63.254101.13.63.2558,190
107101.13.64.0/19101.13.64.1 to 101.13.95.254101.13.95.2558,190
108101.13.96.0/19101.13.96.1 to 101.13.127.254101.13.127.2558,190
109101.13.128.0/19101.13.128.1 to 101.13.159.254101.13.159.2558,190
110101.13.160.0/19101.13.160.1 to 101.13.191.254101.13.191.2558,190
111101.13.192.0/19101.13.192.1 to 101.13.223.254101.13.223.2558,190
112101.13.224.0/19101.13.224.1 to 101.13.255.254101.13.255.2558,190
113101.14.0.0/19101.14.0.1 to 101.14.31.254101.14.31.2558,190
114101.14.32.0/19101.14.32.1 to 101.14.63.254101.14.63.2558,190
115101.14.64.0/19101.14.64.1 to 101.14.95.254101.14.95.2558,190
116101.14.96.0/19101.14.96.1 to 101.14.127.254101.14.127.2558,190
117101.14.128.0/19101.14.128.1 to 101.14.159.254101.14.159.2558,190
118101.14.160.0/19101.14.160.1 to 101.14.191.254101.14.191.2558,190
119101.14.192.0/19101.14.192.1 to 101.14.223.254101.14.223.2558,190
120101.14.224.0/19101.14.224.1 to 101.14.255.254101.14.255.2558,190
121101.15.0.0/19101.15.0.1 to 101.15.31.254101.15.31.2558,190
122101.15.32.0/19101.15.32.1 to 101.15.63.254101.15.63.2558,190
123101.15.64.0/19101.15.64.1 to 101.15.95.254101.15.95.2558,190
124101.15.96.0/19101.15.96.1 to 101.15.127.254101.15.127.2558,190
125101.15.128.0/19101.15.128.1 to 101.15.159.254101.15.159.2558,190
126101.15.160.0/19101.15.160.1 to 101.15.191.254101.15.191.2558,190
127101.15.192.0/19101.15.192.1 to 101.15.223.254101.15.223.2558,190
128101.15.224.0/19101.15.224.1 to 101.15.255.254101.15.255.2558,190
129101.16.0.0/19101.16.0.1 to 101.16.31.254101.16.31.2558,190
130101.16.32.0/19101.16.32.1 to 101.16.63.254101.16.63.2558,190
131101.16.64.0/19101.16.64.1 to 101.16.95.254101.16.95.2558,190
132101.16.96.0/19101.16.96.1 to 101.16.127.254101.16.127.2558,190
133101.16.128.0/19101.16.128.1 to 101.16.159.254101.16.159.2558,190
134101.16.160.0/19101.16.160.1 to 101.16.191.254101.16.191.2558,190
135101.16.192.0/19101.16.192.1 to 101.16.223.254101.16.223.2558,190
136101.16.224.0/19101.16.224.1 to 101.16.255.254101.16.255.2558,190
137101.17.0.0/19101.17.0.1 to 101.17.31.254101.17.31.2558,190
138101.17.32.0/19101.17.32.1 to 101.17.63.254101.17.63.2558,190
139101.17.64.0/19101.17.64.1 to 101.17.95.254101.17.95.2558,190
140101.17.96.0/19101.17.96.1 to 101.17.127.254101.17.127.2558,190
141101.17.128.0/19101.17.128.1 to 101.17.159.254101.17.159.2558,190
142101.17.160.0/19101.17.160.1 to 101.17.191.254101.17.191.2558,190
143101.17.192.0/19101.17.192.1 to 101.17.223.254101.17.223.2558,190
144101.17.224.0/19101.17.224.1 to 101.17.255.254101.17.255.2558,190
145101.18.0.0/19101.18.0.1 to 101.18.31.254101.18.31.2558,190
146101.18.32.0/19101.18.32.1 to 101.18.63.254101.18.63.2558,190
147101.18.64.0/19101.18.64.1 to 101.18.95.254101.18.95.2558,190
148101.18.96.0/19101.18.96.1 to 101.18.127.254101.18.127.2558,190
149101.18.128.0/19101.18.128.1 to 101.18.159.254101.18.159.2558,190
150101.18.160.0/19101.18.160.1 to 101.18.191.254101.18.191.2558,190
151101.18.192.0/19101.18.192.1 to 101.18.223.254101.18.223.2558,190
152101.18.224.0/19101.18.224.1 to 101.18.255.254101.18.255.2558,190
153101.19.0.0/19101.19.0.1 to 101.19.31.254101.19.31.2558,190
154101.19.32.0/19101.19.32.1 to 101.19.63.254101.19.63.2558,190
155101.19.64.0/19101.19.64.1 to 101.19.95.254101.19.95.2558,190
156101.19.96.0/19101.19.96.1 to 101.19.127.254101.19.127.2558,190
157101.19.128.0/19101.19.128.1 to 101.19.159.254101.19.159.2558,190
158101.19.160.0/19101.19.160.1 to 101.19.191.254101.19.191.2558,190
159101.19.192.0/19101.19.192.1 to 101.19.223.254101.19.223.2558,190
160101.19.224.0/19101.19.224.1 to 101.19.255.254101.19.255.2558,190
161101.20.0.0/19101.20.0.1 to 101.20.31.254101.20.31.2558,190
162101.20.32.0/19101.20.32.1 to 101.20.63.254101.20.63.2558,190
163101.20.64.0/19101.20.64.1 to 101.20.95.254101.20.95.2558,190
164101.20.96.0/19101.20.96.1 to 101.20.127.254101.20.127.2558,190
165101.20.128.0/19101.20.128.1 to 101.20.159.254101.20.159.2558,190
166101.20.160.0/19101.20.160.1 to 101.20.191.254101.20.191.2558,190
167101.20.192.0/19101.20.192.1 to 101.20.223.254101.20.223.2558,190
168101.20.224.0/19101.20.224.1 to 101.20.255.254101.20.255.2558,190
169101.21.0.0/19101.21.0.1 to 101.21.31.254101.21.31.2558,190
170101.21.32.0/19101.21.32.1 to 101.21.63.254101.21.63.2558,190
171101.21.64.0/19101.21.64.1 to 101.21.95.254101.21.95.2558,190
172101.21.96.0/19101.21.96.1 to 101.21.127.254101.21.127.2558,190
173101.21.128.0/19101.21.128.1 to 101.21.159.254101.21.159.2558,190
174101.21.160.0/19101.21.160.1 to 101.21.191.254101.21.191.2558,190
175101.21.192.0/19101.21.192.1 to 101.21.223.254101.21.223.2558,190
176101.21.224.0/19101.21.224.1 to 101.21.255.254101.21.255.2558,190
177101.22.0.0/19101.22.0.1 to 101.22.31.254101.22.31.2558,190
178101.22.32.0/19101.22.32.1 to 101.22.63.254101.22.63.2558,190
179101.22.64.0/19101.22.64.1 to 101.22.95.254101.22.95.2558,190
180101.22.96.0/19101.22.96.1 to 101.22.127.254101.22.127.2558,190
181101.22.128.0/19101.22.128.1 to 101.22.159.254101.22.159.2558,190
182101.22.160.0/19101.22.160.1 to 101.22.191.254101.22.191.2558,190
183101.22.192.0/19101.22.192.1 to 101.22.223.254101.22.223.2558,190
184101.22.224.0/19101.22.224.1 to 101.22.255.254101.22.255.2558,190
185101.23.0.0/19101.23.0.1 to 101.23.31.254101.23.31.2558,190
186101.23.32.0/19101.23.32.1 to 101.23.63.254101.23.63.2558,190
187101.23.64.0/19101.23.64.1 to 101.23.95.254101.23.95.2558,190
188101.23.96.0/19101.23.96.1 to 101.23.127.254101.23.127.2558,190
189101.23.128.0/19101.23.128.1 to 101.23.159.254101.23.159.2558,190
190101.23.160.0/19101.23.160.1 to 101.23.191.254101.23.191.2558,190
191101.23.192.0/19101.23.192.1 to 101.23.223.254101.23.223.2558,190
192101.23.224.0/19101.23.224.1 to 101.23.255.254101.23.255.2558,190
193101.24.0.0/19101.24.0.1 to 101.24.31.254101.24.31.2558,190
194101.24.32.0/19101.24.32.1 to 101.24.63.254101.24.63.2558,190
195101.24.64.0/19101.24.64.1 to 101.24.95.254101.24.95.2558,190
196101.24.96.0/19101.24.96.1 to 101.24.127.254101.24.127.2558,190
197101.24.128.0/19101.24.128.1 to 101.24.159.254101.24.159.2558,190
198101.24.160.0/19101.24.160.1 to 101.24.191.254101.24.191.2558,190
199101.24.192.0/19101.24.192.1 to 101.24.223.254101.24.223.2558,190
200101.24.224.0/19101.24.224.1 to 101.24.255.254101.24.255.2558,190
201101.25.0.0/19101.25.0.1 to 101.25.31.254101.25.31.2558,190
202101.25.32.0/19101.25.32.1 to 101.25.63.254101.25.63.2558,190
203101.25.64.0/19101.25.64.1 to 101.25.95.254101.25.95.2558,190
204101.25.96.0/19101.25.96.1 to 101.25.127.254101.25.127.2558,190
205101.25.128.0/19101.25.128.1 to 101.25.159.254101.25.159.2558,190
206101.25.160.0/19101.25.160.1 to 101.25.191.254101.25.191.2558,190
207101.25.192.0/19101.25.192.1 to 101.25.223.254101.25.223.2558,190
208101.25.224.0/19101.25.224.1 to 101.25.255.254101.25.255.2558,190
209101.26.0.0/19101.26.0.1 to 101.26.31.254101.26.31.2558,190
210101.26.32.0/19101.26.32.1 to 101.26.63.254101.26.63.2558,190
211101.26.64.0/19101.26.64.1 to 101.26.95.254101.26.95.2558,190
212101.26.96.0/19101.26.96.1 to 101.26.127.254101.26.127.2558,190
213101.26.128.0/19101.26.128.1 to 101.26.159.254101.26.159.2558,190
214101.26.160.0/19101.26.160.1 to 101.26.191.254101.26.191.2558,190
215101.26.192.0/19101.26.192.1 to 101.26.223.254101.26.223.2558,190
216101.26.224.0/19101.26.224.1 to 101.26.255.254101.26.255.2558,190
217101.27.0.0/19101.27.0.1 to 101.27.31.254101.27.31.2558,190
218101.27.32.0/19101.27.32.1 to 101.27.63.254101.27.63.2558,190
219101.27.64.0/19101.27.64.1 to 101.27.95.254101.27.95.2558,190
220101.27.96.0/19101.27.96.1 to 101.27.127.254101.27.127.2558,190
221101.27.128.0/19101.27.128.1 to 101.27.159.254101.27.159.2558,190
222101.27.160.0/19101.27.160.1 to 101.27.191.254101.27.191.2558,190
223101.27.192.0/19101.27.192.1 to 101.27.223.254101.27.223.2558,190
224101.27.224.0/19101.27.224.1 to 101.27.255.254101.27.255.2558,190
225101.28.0.0/19101.28.0.1 to 101.28.31.254101.28.31.2558,190
226101.28.32.0/19101.28.32.1 to 101.28.63.254101.28.63.2558,190
227101.28.64.0/19101.28.64.1 to 101.28.95.254101.28.95.2558,190
228101.28.96.0/19101.28.96.1 to 101.28.127.254101.28.127.2558,190
229101.28.128.0/19101.28.128.1 to 101.28.159.254101.28.159.2558,190
230101.28.160.0/19101.28.160.1 to 101.28.191.254101.28.191.2558,190
231101.28.192.0/19101.28.192.1 to 101.28.223.254101.28.223.2558,190
232101.28.224.0/19101.28.224.1 to 101.28.255.254101.28.255.2558,190
233101.29.0.0/19101.29.0.1 to 101.29.31.254101.29.31.2558,190
234101.29.32.0/19101.29.32.1 to 101.29.63.254101.29.63.2558,190
235101.29.64.0/19101.29.64.1 to 101.29.95.254101.29.95.2558,190
236101.29.96.0/19101.29.96.1 to 101.29.127.254101.29.127.2558,190
237101.29.128.0/19101.29.128.1 to 101.29.159.254101.29.159.2558,190
238101.29.160.0/19101.29.160.1 to 101.29.191.254101.29.191.2558,190
239101.29.192.0/19101.29.192.1 to 101.29.223.254101.29.223.2558,190
240101.29.224.0/19101.29.224.1 to 101.29.255.254101.29.255.2558,190
241101.30.0.0/19101.30.0.1 to 101.30.31.254101.30.31.2558,190
242101.30.32.0/19101.30.32.1 to 101.30.63.254101.30.63.2558,190
243101.30.64.0/19101.30.64.1 to 101.30.95.254101.30.95.2558,190
244101.30.96.0/19101.30.96.1 to 101.30.127.254101.30.127.2558,190
245101.30.128.0/19101.30.128.1 to 101.30.159.254101.30.159.2558,190
246101.30.160.0/19101.30.160.1 to 101.30.191.254101.30.191.2558,190
247101.30.192.0/19101.30.192.1 to 101.30.223.254101.30.223.2558,190
248101.30.224.0/19101.30.224.1 to 101.30.255.254101.30.255.2558,190
249101.31.0.0/19101.31.0.1 to 101.31.31.254101.31.31.2558,190
250101.31.32.0/19101.31.32.1 to 101.31.63.254101.31.63.2558,190
251101.31.64.0/19101.31.64.1 to 101.31.95.254101.31.95.2558,190
252101.31.96.0/19101.31.96.1 to 101.31.127.254101.31.127.2558,190
253101.31.128.0/19101.31.128.1 to 101.31.159.254101.31.159.2558,190
254101.31.160.0/19101.31.160.1 to 101.31.191.254101.31.191.2558,190
255101.31.192.0/19101.31.192.1 to 101.31.223.254101.31.223.2558,190
256101.31.224.0/19101.31.224.1 to 101.31.255.254101.31.255.2558,190

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.