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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.

Network128.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
128.0.0.0
Broadcast address
129.255.255.255
First usable
128.0.0.1
Last usable
129.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
B (default /16)
As numbers
Hex 80000000 · Integer 2147483648 to 2181038079
Reverse DNS zones
128.in-addr.arpa
129.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10000000.00000000.00000000.00000000128.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10000000.00000000.00000000.00000000128.0.0.0
Broadcast10000001.11111111.11111111.11111111129.255.255.255
Split into smaller subnets/19
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

128.0.0.0/7 makes 4,096 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1128.0.0.0/19128.0.0.1 to 128.0.31.254128.0.31.2558,190
2128.0.32.0/19128.0.32.1 to 128.0.63.254128.0.63.2558,190
3128.0.64.0/19128.0.64.1 to 128.0.95.254128.0.95.2558,190
4128.0.96.0/19128.0.96.1 to 128.0.127.254128.0.127.2558,190
5128.0.128.0/19128.0.128.1 to 128.0.159.254128.0.159.2558,190
6128.0.160.0/19128.0.160.1 to 128.0.191.254128.0.191.2558,190
7128.0.192.0/19128.0.192.1 to 128.0.223.254128.0.223.2558,190
8128.0.224.0/19128.0.224.1 to 128.0.255.254128.0.255.2558,190
9128.1.0.0/19128.1.0.1 to 128.1.31.254128.1.31.2558,190
10128.1.32.0/19128.1.32.1 to 128.1.63.254128.1.63.2558,190
11128.1.64.0/19128.1.64.1 to 128.1.95.254128.1.95.2558,190
12128.1.96.0/19128.1.96.1 to 128.1.127.254128.1.127.2558,190
13128.1.128.0/19128.1.128.1 to 128.1.159.254128.1.159.2558,190
14128.1.160.0/19128.1.160.1 to 128.1.191.254128.1.191.2558,190
15128.1.192.0/19128.1.192.1 to 128.1.223.254128.1.223.2558,190
16128.1.224.0/19128.1.224.1 to 128.1.255.254128.1.255.2558,190
17128.2.0.0/19128.2.0.1 to 128.2.31.254128.2.31.2558,190
18128.2.32.0/19128.2.32.1 to 128.2.63.254128.2.63.2558,190
19128.2.64.0/19128.2.64.1 to 128.2.95.254128.2.95.2558,190
20128.2.96.0/19128.2.96.1 to 128.2.127.254128.2.127.2558,190
21128.2.128.0/19128.2.128.1 to 128.2.159.254128.2.159.2558,190
22128.2.160.0/19128.2.160.1 to 128.2.191.254128.2.191.2558,190
23128.2.192.0/19128.2.192.1 to 128.2.223.254128.2.223.2558,190
24128.2.224.0/19128.2.224.1 to 128.2.255.254128.2.255.2558,190
25128.3.0.0/19128.3.0.1 to 128.3.31.254128.3.31.2558,190
26128.3.32.0/19128.3.32.1 to 128.3.63.254128.3.63.2558,190
27128.3.64.0/19128.3.64.1 to 128.3.95.254128.3.95.2558,190
28128.3.96.0/19128.3.96.1 to 128.3.127.254128.3.127.2558,190
29128.3.128.0/19128.3.128.1 to 128.3.159.254128.3.159.2558,190
30128.3.160.0/19128.3.160.1 to 128.3.191.254128.3.191.2558,190
31128.3.192.0/19128.3.192.1 to 128.3.223.254128.3.223.2558,190
32128.3.224.0/19128.3.224.1 to 128.3.255.254128.3.255.2558,190
33128.4.0.0/19128.4.0.1 to 128.4.31.254128.4.31.2558,190
34128.4.32.0/19128.4.32.1 to 128.4.63.254128.4.63.2558,190
35128.4.64.0/19128.4.64.1 to 128.4.95.254128.4.95.2558,190
36128.4.96.0/19128.4.96.1 to 128.4.127.254128.4.127.2558,190
37128.4.128.0/19128.4.128.1 to 128.4.159.254128.4.159.2558,190
38128.4.160.0/19128.4.160.1 to 128.4.191.254128.4.191.2558,190
39128.4.192.0/19128.4.192.1 to 128.4.223.254128.4.223.2558,190
40128.4.224.0/19128.4.224.1 to 128.4.255.254128.4.255.2558,190
41128.5.0.0/19128.5.0.1 to 128.5.31.254128.5.31.2558,190
42128.5.32.0/19128.5.32.1 to 128.5.63.254128.5.63.2558,190
43128.5.64.0/19128.5.64.1 to 128.5.95.254128.5.95.2558,190
44128.5.96.0/19128.5.96.1 to 128.5.127.254128.5.127.2558,190
45128.5.128.0/19128.5.128.1 to 128.5.159.254128.5.159.2558,190
46128.5.160.0/19128.5.160.1 to 128.5.191.254128.5.191.2558,190
47128.5.192.0/19128.5.192.1 to 128.5.223.254128.5.223.2558,190
48128.5.224.0/19128.5.224.1 to 128.5.255.254128.5.255.2558,190
49128.6.0.0/19128.6.0.1 to 128.6.31.254128.6.31.2558,190
50128.6.32.0/19128.6.32.1 to 128.6.63.254128.6.63.2558,190
51128.6.64.0/19128.6.64.1 to 128.6.95.254128.6.95.2558,190
52128.6.96.0/19128.6.96.1 to 128.6.127.254128.6.127.2558,190
53128.6.128.0/19128.6.128.1 to 128.6.159.254128.6.159.2558,190
54128.6.160.0/19128.6.160.1 to 128.6.191.254128.6.191.2558,190
55128.6.192.0/19128.6.192.1 to 128.6.223.254128.6.223.2558,190
56128.6.224.0/19128.6.224.1 to 128.6.255.254128.6.255.2558,190
57128.7.0.0/19128.7.0.1 to 128.7.31.254128.7.31.2558,190
58128.7.32.0/19128.7.32.1 to 128.7.63.254128.7.63.2558,190
59128.7.64.0/19128.7.64.1 to 128.7.95.254128.7.95.2558,190
60128.7.96.0/19128.7.96.1 to 128.7.127.254128.7.127.2558,190
61128.7.128.0/19128.7.128.1 to 128.7.159.254128.7.159.2558,190
62128.7.160.0/19128.7.160.1 to 128.7.191.254128.7.191.2558,190
63128.7.192.0/19128.7.192.1 to 128.7.223.254128.7.223.2558,190
64128.7.224.0/19128.7.224.1 to 128.7.255.254128.7.255.2558,190
65128.8.0.0/19128.8.0.1 to 128.8.31.254128.8.31.2558,190
66128.8.32.0/19128.8.32.1 to 128.8.63.254128.8.63.2558,190
67128.8.64.0/19128.8.64.1 to 128.8.95.254128.8.95.2558,190
68128.8.96.0/19128.8.96.1 to 128.8.127.254128.8.127.2558,190
69128.8.128.0/19128.8.128.1 to 128.8.159.254128.8.159.2558,190
70128.8.160.0/19128.8.160.1 to 128.8.191.254128.8.191.2558,190
71128.8.192.0/19128.8.192.1 to 128.8.223.254128.8.223.2558,190
72128.8.224.0/19128.8.224.1 to 128.8.255.254128.8.255.2558,190
73128.9.0.0/19128.9.0.1 to 128.9.31.254128.9.31.2558,190
74128.9.32.0/19128.9.32.1 to 128.9.63.254128.9.63.2558,190
75128.9.64.0/19128.9.64.1 to 128.9.95.254128.9.95.2558,190
76128.9.96.0/19128.9.96.1 to 128.9.127.254128.9.127.2558,190
77128.9.128.0/19128.9.128.1 to 128.9.159.254128.9.159.2558,190
78128.9.160.0/19128.9.160.1 to 128.9.191.254128.9.191.2558,190
79128.9.192.0/19128.9.192.1 to 128.9.223.254128.9.223.2558,190
80128.9.224.0/19128.9.224.1 to 128.9.255.254128.9.255.2558,190
81128.10.0.0/19128.10.0.1 to 128.10.31.254128.10.31.2558,190
82128.10.32.0/19128.10.32.1 to 128.10.63.254128.10.63.2558,190
83128.10.64.0/19128.10.64.1 to 128.10.95.254128.10.95.2558,190
84128.10.96.0/19128.10.96.1 to 128.10.127.254128.10.127.2558,190
85128.10.128.0/19128.10.128.1 to 128.10.159.254128.10.159.2558,190
86128.10.160.0/19128.10.160.1 to 128.10.191.254128.10.191.2558,190
87128.10.192.0/19128.10.192.1 to 128.10.223.254128.10.223.2558,190
88128.10.224.0/19128.10.224.1 to 128.10.255.254128.10.255.2558,190
89128.11.0.0/19128.11.0.1 to 128.11.31.254128.11.31.2558,190
90128.11.32.0/19128.11.32.1 to 128.11.63.254128.11.63.2558,190
91128.11.64.0/19128.11.64.1 to 128.11.95.254128.11.95.2558,190
92128.11.96.0/19128.11.96.1 to 128.11.127.254128.11.127.2558,190
93128.11.128.0/19128.11.128.1 to 128.11.159.254128.11.159.2558,190
94128.11.160.0/19128.11.160.1 to 128.11.191.254128.11.191.2558,190
95128.11.192.0/19128.11.192.1 to 128.11.223.254128.11.223.2558,190
96128.11.224.0/19128.11.224.1 to 128.11.255.254128.11.255.2558,190
97128.12.0.0/19128.12.0.1 to 128.12.31.254128.12.31.2558,190
98128.12.32.0/19128.12.32.1 to 128.12.63.254128.12.63.2558,190
99128.12.64.0/19128.12.64.1 to 128.12.95.254128.12.95.2558,190
100128.12.96.0/19128.12.96.1 to 128.12.127.254128.12.127.2558,190
101128.12.128.0/19128.12.128.1 to 128.12.159.254128.12.159.2558,190
102128.12.160.0/19128.12.160.1 to 128.12.191.254128.12.191.2558,190
103128.12.192.0/19128.12.192.1 to 128.12.223.254128.12.223.2558,190
104128.12.224.0/19128.12.224.1 to 128.12.255.254128.12.255.2558,190
105128.13.0.0/19128.13.0.1 to 128.13.31.254128.13.31.2558,190
106128.13.32.0/19128.13.32.1 to 128.13.63.254128.13.63.2558,190
107128.13.64.0/19128.13.64.1 to 128.13.95.254128.13.95.2558,190
108128.13.96.0/19128.13.96.1 to 128.13.127.254128.13.127.2558,190
109128.13.128.0/19128.13.128.1 to 128.13.159.254128.13.159.2558,190
110128.13.160.0/19128.13.160.1 to 128.13.191.254128.13.191.2558,190
111128.13.192.0/19128.13.192.1 to 128.13.223.254128.13.223.2558,190
112128.13.224.0/19128.13.224.1 to 128.13.255.254128.13.255.2558,190
113128.14.0.0/19128.14.0.1 to 128.14.31.254128.14.31.2558,190
114128.14.32.0/19128.14.32.1 to 128.14.63.254128.14.63.2558,190
115128.14.64.0/19128.14.64.1 to 128.14.95.254128.14.95.2558,190
116128.14.96.0/19128.14.96.1 to 128.14.127.254128.14.127.2558,190
117128.14.128.0/19128.14.128.1 to 128.14.159.254128.14.159.2558,190
118128.14.160.0/19128.14.160.1 to 128.14.191.254128.14.191.2558,190
119128.14.192.0/19128.14.192.1 to 128.14.223.254128.14.223.2558,190
120128.14.224.0/19128.14.224.1 to 128.14.255.254128.14.255.2558,190
121128.15.0.0/19128.15.0.1 to 128.15.31.254128.15.31.2558,190
122128.15.32.0/19128.15.32.1 to 128.15.63.254128.15.63.2558,190
123128.15.64.0/19128.15.64.1 to 128.15.95.254128.15.95.2558,190
124128.15.96.0/19128.15.96.1 to 128.15.127.254128.15.127.2558,190
125128.15.128.0/19128.15.128.1 to 128.15.159.254128.15.159.2558,190
126128.15.160.0/19128.15.160.1 to 128.15.191.254128.15.191.2558,190
127128.15.192.0/19128.15.192.1 to 128.15.223.254128.15.223.2558,190
128128.15.224.0/19128.15.224.1 to 128.15.255.254128.15.255.2558,190
129128.16.0.0/19128.16.0.1 to 128.16.31.254128.16.31.2558,190
130128.16.32.0/19128.16.32.1 to 128.16.63.254128.16.63.2558,190
131128.16.64.0/19128.16.64.1 to 128.16.95.254128.16.95.2558,190
132128.16.96.0/19128.16.96.1 to 128.16.127.254128.16.127.2558,190
133128.16.128.0/19128.16.128.1 to 128.16.159.254128.16.159.2558,190
134128.16.160.0/19128.16.160.1 to 128.16.191.254128.16.191.2558,190
135128.16.192.0/19128.16.192.1 to 128.16.223.254128.16.223.2558,190
136128.16.224.0/19128.16.224.1 to 128.16.255.254128.16.255.2558,190
137128.17.0.0/19128.17.0.1 to 128.17.31.254128.17.31.2558,190
138128.17.32.0/19128.17.32.1 to 128.17.63.254128.17.63.2558,190
139128.17.64.0/19128.17.64.1 to 128.17.95.254128.17.95.2558,190
140128.17.96.0/19128.17.96.1 to 128.17.127.254128.17.127.2558,190
141128.17.128.0/19128.17.128.1 to 128.17.159.254128.17.159.2558,190
142128.17.160.0/19128.17.160.1 to 128.17.191.254128.17.191.2558,190
143128.17.192.0/19128.17.192.1 to 128.17.223.254128.17.223.2558,190
144128.17.224.0/19128.17.224.1 to 128.17.255.254128.17.255.2558,190
145128.18.0.0/19128.18.0.1 to 128.18.31.254128.18.31.2558,190
146128.18.32.0/19128.18.32.1 to 128.18.63.254128.18.63.2558,190
147128.18.64.0/19128.18.64.1 to 128.18.95.254128.18.95.2558,190
148128.18.96.0/19128.18.96.1 to 128.18.127.254128.18.127.2558,190
149128.18.128.0/19128.18.128.1 to 128.18.159.254128.18.159.2558,190
150128.18.160.0/19128.18.160.1 to 128.18.191.254128.18.191.2558,190
151128.18.192.0/19128.18.192.1 to 128.18.223.254128.18.223.2558,190
152128.18.224.0/19128.18.224.1 to 128.18.255.254128.18.255.2558,190
153128.19.0.0/19128.19.0.1 to 128.19.31.254128.19.31.2558,190
154128.19.32.0/19128.19.32.1 to 128.19.63.254128.19.63.2558,190
155128.19.64.0/19128.19.64.1 to 128.19.95.254128.19.95.2558,190
156128.19.96.0/19128.19.96.1 to 128.19.127.254128.19.127.2558,190
157128.19.128.0/19128.19.128.1 to 128.19.159.254128.19.159.2558,190
158128.19.160.0/19128.19.160.1 to 128.19.191.254128.19.191.2558,190
159128.19.192.0/19128.19.192.1 to 128.19.223.254128.19.223.2558,190
160128.19.224.0/19128.19.224.1 to 128.19.255.254128.19.255.2558,190
161128.20.0.0/19128.20.0.1 to 128.20.31.254128.20.31.2558,190
162128.20.32.0/19128.20.32.1 to 128.20.63.254128.20.63.2558,190
163128.20.64.0/19128.20.64.1 to 128.20.95.254128.20.95.2558,190
164128.20.96.0/19128.20.96.1 to 128.20.127.254128.20.127.2558,190
165128.20.128.0/19128.20.128.1 to 128.20.159.254128.20.159.2558,190
166128.20.160.0/19128.20.160.1 to 128.20.191.254128.20.191.2558,190
167128.20.192.0/19128.20.192.1 to 128.20.223.254128.20.223.2558,190
168128.20.224.0/19128.20.224.1 to 128.20.255.254128.20.255.2558,190
169128.21.0.0/19128.21.0.1 to 128.21.31.254128.21.31.2558,190
170128.21.32.0/19128.21.32.1 to 128.21.63.254128.21.63.2558,190
171128.21.64.0/19128.21.64.1 to 128.21.95.254128.21.95.2558,190
172128.21.96.0/19128.21.96.1 to 128.21.127.254128.21.127.2558,190
173128.21.128.0/19128.21.128.1 to 128.21.159.254128.21.159.2558,190
174128.21.160.0/19128.21.160.1 to 128.21.191.254128.21.191.2558,190
175128.21.192.0/19128.21.192.1 to 128.21.223.254128.21.223.2558,190
176128.21.224.0/19128.21.224.1 to 128.21.255.254128.21.255.2558,190
177128.22.0.0/19128.22.0.1 to 128.22.31.254128.22.31.2558,190
178128.22.32.0/19128.22.32.1 to 128.22.63.254128.22.63.2558,190
179128.22.64.0/19128.22.64.1 to 128.22.95.254128.22.95.2558,190
180128.22.96.0/19128.22.96.1 to 128.22.127.254128.22.127.2558,190
181128.22.128.0/19128.22.128.1 to 128.22.159.254128.22.159.2558,190
182128.22.160.0/19128.22.160.1 to 128.22.191.254128.22.191.2558,190
183128.22.192.0/19128.22.192.1 to 128.22.223.254128.22.223.2558,190
184128.22.224.0/19128.22.224.1 to 128.22.255.254128.22.255.2558,190
185128.23.0.0/19128.23.0.1 to 128.23.31.254128.23.31.2558,190
186128.23.32.0/19128.23.32.1 to 128.23.63.254128.23.63.2558,190
187128.23.64.0/19128.23.64.1 to 128.23.95.254128.23.95.2558,190
188128.23.96.0/19128.23.96.1 to 128.23.127.254128.23.127.2558,190
189128.23.128.0/19128.23.128.1 to 128.23.159.254128.23.159.2558,190
190128.23.160.0/19128.23.160.1 to 128.23.191.254128.23.191.2558,190
191128.23.192.0/19128.23.192.1 to 128.23.223.254128.23.223.2558,190
192128.23.224.0/19128.23.224.1 to 128.23.255.254128.23.255.2558,190
193128.24.0.0/19128.24.0.1 to 128.24.31.254128.24.31.2558,190
194128.24.32.0/19128.24.32.1 to 128.24.63.254128.24.63.2558,190
195128.24.64.0/19128.24.64.1 to 128.24.95.254128.24.95.2558,190
196128.24.96.0/19128.24.96.1 to 128.24.127.254128.24.127.2558,190
197128.24.128.0/19128.24.128.1 to 128.24.159.254128.24.159.2558,190
198128.24.160.0/19128.24.160.1 to 128.24.191.254128.24.191.2558,190
199128.24.192.0/19128.24.192.1 to 128.24.223.254128.24.223.2558,190
200128.24.224.0/19128.24.224.1 to 128.24.255.254128.24.255.2558,190
201128.25.0.0/19128.25.0.1 to 128.25.31.254128.25.31.2558,190
202128.25.32.0/19128.25.32.1 to 128.25.63.254128.25.63.2558,190
203128.25.64.0/19128.25.64.1 to 128.25.95.254128.25.95.2558,190
204128.25.96.0/19128.25.96.1 to 128.25.127.254128.25.127.2558,190
205128.25.128.0/19128.25.128.1 to 128.25.159.254128.25.159.2558,190
206128.25.160.0/19128.25.160.1 to 128.25.191.254128.25.191.2558,190
207128.25.192.0/19128.25.192.1 to 128.25.223.254128.25.223.2558,190
208128.25.224.0/19128.25.224.1 to 128.25.255.254128.25.255.2558,190
209128.26.0.0/19128.26.0.1 to 128.26.31.254128.26.31.2558,190
210128.26.32.0/19128.26.32.1 to 128.26.63.254128.26.63.2558,190
211128.26.64.0/19128.26.64.1 to 128.26.95.254128.26.95.2558,190
212128.26.96.0/19128.26.96.1 to 128.26.127.254128.26.127.2558,190
213128.26.128.0/19128.26.128.1 to 128.26.159.254128.26.159.2558,190
214128.26.160.0/19128.26.160.1 to 128.26.191.254128.26.191.2558,190
215128.26.192.0/19128.26.192.1 to 128.26.223.254128.26.223.2558,190
216128.26.224.0/19128.26.224.1 to 128.26.255.254128.26.255.2558,190
217128.27.0.0/19128.27.0.1 to 128.27.31.254128.27.31.2558,190
218128.27.32.0/19128.27.32.1 to 128.27.63.254128.27.63.2558,190
219128.27.64.0/19128.27.64.1 to 128.27.95.254128.27.95.2558,190
220128.27.96.0/19128.27.96.1 to 128.27.127.254128.27.127.2558,190
221128.27.128.0/19128.27.128.1 to 128.27.159.254128.27.159.2558,190
222128.27.160.0/19128.27.160.1 to 128.27.191.254128.27.191.2558,190
223128.27.192.0/19128.27.192.1 to 128.27.223.254128.27.223.2558,190
224128.27.224.0/19128.27.224.1 to 128.27.255.254128.27.255.2558,190
225128.28.0.0/19128.28.0.1 to 128.28.31.254128.28.31.2558,190
226128.28.32.0/19128.28.32.1 to 128.28.63.254128.28.63.2558,190
227128.28.64.0/19128.28.64.1 to 128.28.95.254128.28.95.2558,190
228128.28.96.0/19128.28.96.1 to 128.28.127.254128.28.127.2558,190
229128.28.128.0/19128.28.128.1 to 128.28.159.254128.28.159.2558,190
230128.28.160.0/19128.28.160.1 to 128.28.191.254128.28.191.2558,190
231128.28.192.0/19128.28.192.1 to 128.28.223.254128.28.223.2558,190
232128.28.224.0/19128.28.224.1 to 128.28.255.254128.28.255.2558,190
233128.29.0.0/19128.29.0.1 to 128.29.31.254128.29.31.2558,190
234128.29.32.0/19128.29.32.1 to 128.29.63.254128.29.63.2558,190
235128.29.64.0/19128.29.64.1 to 128.29.95.254128.29.95.2558,190
236128.29.96.0/19128.29.96.1 to 128.29.127.254128.29.127.2558,190
237128.29.128.0/19128.29.128.1 to 128.29.159.254128.29.159.2558,190
238128.29.160.0/19128.29.160.1 to 128.29.191.254128.29.191.2558,190
239128.29.192.0/19128.29.192.1 to 128.29.223.254128.29.223.2558,190
240128.29.224.0/19128.29.224.1 to 128.29.255.254128.29.255.2558,190
241128.30.0.0/19128.30.0.1 to 128.30.31.254128.30.31.2558,190
242128.30.32.0/19128.30.32.1 to 128.30.63.254128.30.63.2558,190
243128.30.64.0/19128.30.64.1 to 128.30.95.254128.30.95.2558,190
244128.30.96.0/19128.30.96.1 to 128.30.127.254128.30.127.2558,190
245128.30.128.0/19128.30.128.1 to 128.30.159.254128.30.159.2558,190
246128.30.160.0/19128.30.160.1 to 128.30.191.254128.30.191.2558,190
247128.30.192.0/19128.30.192.1 to 128.30.223.254128.30.223.2558,190
248128.30.224.0/19128.30.224.1 to 128.30.255.254128.30.255.2558,190
249128.31.0.0/19128.31.0.1 to 128.31.31.254128.31.31.2558,190
250128.31.32.0/19128.31.32.1 to 128.31.63.254128.31.63.2558,190
251128.31.64.0/19128.31.64.1 to 128.31.95.254128.31.95.2558,190
252128.31.96.0/19128.31.96.1 to 128.31.127.254128.31.127.2558,190
253128.31.128.0/19128.31.128.1 to 128.31.159.254128.31.159.2558,190
254128.31.160.0/19128.31.160.1 to 128.31.191.254128.31.191.2558,190
255128.31.192.0/19128.31.192.1 to 128.31.223.254128.31.223.2558,190
256128.31.224.0/19128.31.224.1 to 128.31.255.254128.31.255.2558,190

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.