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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.

Network102.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
102.0.0.0
Broadcast address
102.255.255.255
First usable
102.0.0.1
Last usable
102.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 66000000 · Integer 1711276032 to 1728053247
Reverse DNS zone
102.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01100110..00000000.00000000.00000000102.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network01100110..00000000.00000000.00000000102.0.0.0
Broadcast01100110..11111111.11111111.11111111102.255.255.255
Split into smaller subnets/19
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

102.0.0.0/8 makes 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1102.0.0.0/19102.0.0.1 to 102.0.31.254102.0.31.2558,190
2102.0.32.0/19102.0.32.1 to 102.0.63.254102.0.63.2558,190
3102.0.64.0/19102.0.64.1 to 102.0.95.254102.0.95.2558,190
4102.0.96.0/19102.0.96.1 to 102.0.127.254102.0.127.2558,190
5102.0.128.0/19102.0.128.1 to 102.0.159.254102.0.159.2558,190
6102.0.160.0/19102.0.160.1 to 102.0.191.254102.0.191.2558,190
7102.0.192.0/19102.0.192.1 to 102.0.223.254102.0.223.2558,190
8102.0.224.0/19102.0.224.1 to 102.0.255.254102.0.255.2558,190
9102.1.0.0/19102.1.0.1 to 102.1.31.254102.1.31.2558,190
10102.1.32.0/19102.1.32.1 to 102.1.63.254102.1.63.2558,190
11102.1.64.0/19102.1.64.1 to 102.1.95.254102.1.95.2558,190
12102.1.96.0/19102.1.96.1 to 102.1.127.254102.1.127.2558,190
13102.1.128.0/19102.1.128.1 to 102.1.159.254102.1.159.2558,190
14102.1.160.0/19102.1.160.1 to 102.1.191.254102.1.191.2558,190
15102.1.192.0/19102.1.192.1 to 102.1.223.254102.1.223.2558,190
16102.1.224.0/19102.1.224.1 to 102.1.255.254102.1.255.2558,190
17102.2.0.0/19102.2.0.1 to 102.2.31.254102.2.31.2558,190
18102.2.32.0/19102.2.32.1 to 102.2.63.254102.2.63.2558,190
19102.2.64.0/19102.2.64.1 to 102.2.95.254102.2.95.2558,190
20102.2.96.0/19102.2.96.1 to 102.2.127.254102.2.127.2558,190
21102.2.128.0/19102.2.128.1 to 102.2.159.254102.2.159.2558,190
22102.2.160.0/19102.2.160.1 to 102.2.191.254102.2.191.2558,190
23102.2.192.0/19102.2.192.1 to 102.2.223.254102.2.223.2558,190
24102.2.224.0/19102.2.224.1 to 102.2.255.254102.2.255.2558,190
25102.3.0.0/19102.3.0.1 to 102.3.31.254102.3.31.2558,190
26102.3.32.0/19102.3.32.1 to 102.3.63.254102.3.63.2558,190
27102.3.64.0/19102.3.64.1 to 102.3.95.254102.3.95.2558,190
28102.3.96.0/19102.3.96.1 to 102.3.127.254102.3.127.2558,190
29102.3.128.0/19102.3.128.1 to 102.3.159.254102.3.159.2558,190
30102.3.160.0/19102.3.160.1 to 102.3.191.254102.3.191.2558,190
31102.3.192.0/19102.3.192.1 to 102.3.223.254102.3.223.2558,190
32102.3.224.0/19102.3.224.1 to 102.3.255.254102.3.255.2558,190
33102.4.0.0/19102.4.0.1 to 102.4.31.254102.4.31.2558,190
34102.4.32.0/19102.4.32.1 to 102.4.63.254102.4.63.2558,190
35102.4.64.0/19102.4.64.1 to 102.4.95.254102.4.95.2558,190
36102.4.96.0/19102.4.96.1 to 102.4.127.254102.4.127.2558,190
37102.4.128.0/19102.4.128.1 to 102.4.159.254102.4.159.2558,190
38102.4.160.0/19102.4.160.1 to 102.4.191.254102.4.191.2558,190
39102.4.192.0/19102.4.192.1 to 102.4.223.254102.4.223.2558,190
40102.4.224.0/19102.4.224.1 to 102.4.255.254102.4.255.2558,190
41102.5.0.0/19102.5.0.1 to 102.5.31.254102.5.31.2558,190
42102.5.32.0/19102.5.32.1 to 102.5.63.254102.5.63.2558,190
43102.5.64.0/19102.5.64.1 to 102.5.95.254102.5.95.2558,190
44102.5.96.0/19102.5.96.1 to 102.5.127.254102.5.127.2558,190
45102.5.128.0/19102.5.128.1 to 102.5.159.254102.5.159.2558,190
46102.5.160.0/19102.5.160.1 to 102.5.191.254102.5.191.2558,190
47102.5.192.0/19102.5.192.1 to 102.5.223.254102.5.223.2558,190
48102.5.224.0/19102.5.224.1 to 102.5.255.254102.5.255.2558,190
49102.6.0.0/19102.6.0.1 to 102.6.31.254102.6.31.2558,190
50102.6.32.0/19102.6.32.1 to 102.6.63.254102.6.63.2558,190
51102.6.64.0/19102.6.64.1 to 102.6.95.254102.6.95.2558,190
52102.6.96.0/19102.6.96.1 to 102.6.127.254102.6.127.2558,190
53102.6.128.0/19102.6.128.1 to 102.6.159.254102.6.159.2558,190
54102.6.160.0/19102.6.160.1 to 102.6.191.254102.6.191.2558,190
55102.6.192.0/19102.6.192.1 to 102.6.223.254102.6.223.2558,190
56102.6.224.0/19102.6.224.1 to 102.6.255.254102.6.255.2558,190
57102.7.0.0/19102.7.0.1 to 102.7.31.254102.7.31.2558,190
58102.7.32.0/19102.7.32.1 to 102.7.63.254102.7.63.2558,190
59102.7.64.0/19102.7.64.1 to 102.7.95.254102.7.95.2558,190
60102.7.96.0/19102.7.96.1 to 102.7.127.254102.7.127.2558,190
61102.7.128.0/19102.7.128.1 to 102.7.159.254102.7.159.2558,190
62102.7.160.0/19102.7.160.1 to 102.7.191.254102.7.191.2558,190
63102.7.192.0/19102.7.192.1 to 102.7.223.254102.7.223.2558,190
64102.7.224.0/19102.7.224.1 to 102.7.255.254102.7.255.2558,190
65102.8.0.0/19102.8.0.1 to 102.8.31.254102.8.31.2558,190
66102.8.32.0/19102.8.32.1 to 102.8.63.254102.8.63.2558,190
67102.8.64.0/19102.8.64.1 to 102.8.95.254102.8.95.2558,190
68102.8.96.0/19102.8.96.1 to 102.8.127.254102.8.127.2558,190
69102.8.128.0/19102.8.128.1 to 102.8.159.254102.8.159.2558,190
70102.8.160.0/19102.8.160.1 to 102.8.191.254102.8.191.2558,190
71102.8.192.0/19102.8.192.1 to 102.8.223.254102.8.223.2558,190
72102.8.224.0/19102.8.224.1 to 102.8.255.254102.8.255.2558,190
73102.9.0.0/19102.9.0.1 to 102.9.31.254102.9.31.2558,190
74102.9.32.0/19102.9.32.1 to 102.9.63.254102.9.63.2558,190
75102.9.64.0/19102.9.64.1 to 102.9.95.254102.9.95.2558,190
76102.9.96.0/19102.9.96.1 to 102.9.127.254102.9.127.2558,190
77102.9.128.0/19102.9.128.1 to 102.9.159.254102.9.159.2558,190
78102.9.160.0/19102.9.160.1 to 102.9.191.254102.9.191.2558,190
79102.9.192.0/19102.9.192.1 to 102.9.223.254102.9.223.2558,190
80102.9.224.0/19102.9.224.1 to 102.9.255.254102.9.255.2558,190
81102.10.0.0/19102.10.0.1 to 102.10.31.254102.10.31.2558,190
82102.10.32.0/19102.10.32.1 to 102.10.63.254102.10.63.2558,190
83102.10.64.0/19102.10.64.1 to 102.10.95.254102.10.95.2558,190
84102.10.96.0/19102.10.96.1 to 102.10.127.254102.10.127.2558,190
85102.10.128.0/19102.10.128.1 to 102.10.159.254102.10.159.2558,190
86102.10.160.0/19102.10.160.1 to 102.10.191.254102.10.191.2558,190
87102.10.192.0/19102.10.192.1 to 102.10.223.254102.10.223.2558,190
88102.10.224.0/19102.10.224.1 to 102.10.255.254102.10.255.2558,190
89102.11.0.0/19102.11.0.1 to 102.11.31.254102.11.31.2558,190
90102.11.32.0/19102.11.32.1 to 102.11.63.254102.11.63.2558,190
91102.11.64.0/19102.11.64.1 to 102.11.95.254102.11.95.2558,190
92102.11.96.0/19102.11.96.1 to 102.11.127.254102.11.127.2558,190
93102.11.128.0/19102.11.128.1 to 102.11.159.254102.11.159.2558,190
94102.11.160.0/19102.11.160.1 to 102.11.191.254102.11.191.2558,190
95102.11.192.0/19102.11.192.1 to 102.11.223.254102.11.223.2558,190
96102.11.224.0/19102.11.224.1 to 102.11.255.254102.11.255.2558,190
97102.12.0.0/19102.12.0.1 to 102.12.31.254102.12.31.2558,190
98102.12.32.0/19102.12.32.1 to 102.12.63.254102.12.63.2558,190
99102.12.64.0/19102.12.64.1 to 102.12.95.254102.12.95.2558,190
100102.12.96.0/19102.12.96.1 to 102.12.127.254102.12.127.2558,190
101102.12.128.0/19102.12.128.1 to 102.12.159.254102.12.159.2558,190
102102.12.160.0/19102.12.160.1 to 102.12.191.254102.12.191.2558,190
103102.12.192.0/19102.12.192.1 to 102.12.223.254102.12.223.2558,190
104102.12.224.0/19102.12.224.1 to 102.12.255.254102.12.255.2558,190
105102.13.0.0/19102.13.0.1 to 102.13.31.254102.13.31.2558,190
106102.13.32.0/19102.13.32.1 to 102.13.63.254102.13.63.2558,190
107102.13.64.0/19102.13.64.1 to 102.13.95.254102.13.95.2558,190
108102.13.96.0/19102.13.96.1 to 102.13.127.254102.13.127.2558,190
109102.13.128.0/19102.13.128.1 to 102.13.159.254102.13.159.2558,190
110102.13.160.0/19102.13.160.1 to 102.13.191.254102.13.191.2558,190
111102.13.192.0/19102.13.192.1 to 102.13.223.254102.13.223.2558,190
112102.13.224.0/19102.13.224.1 to 102.13.255.254102.13.255.2558,190
113102.14.0.0/19102.14.0.1 to 102.14.31.254102.14.31.2558,190
114102.14.32.0/19102.14.32.1 to 102.14.63.254102.14.63.2558,190
115102.14.64.0/19102.14.64.1 to 102.14.95.254102.14.95.2558,190
116102.14.96.0/19102.14.96.1 to 102.14.127.254102.14.127.2558,190
117102.14.128.0/19102.14.128.1 to 102.14.159.254102.14.159.2558,190
118102.14.160.0/19102.14.160.1 to 102.14.191.254102.14.191.2558,190
119102.14.192.0/19102.14.192.1 to 102.14.223.254102.14.223.2558,190
120102.14.224.0/19102.14.224.1 to 102.14.255.254102.14.255.2558,190
121102.15.0.0/19102.15.0.1 to 102.15.31.254102.15.31.2558,190
122102.15.32.0/19102.15.32.1 to 102.15.63.254102.15.63.2558,190
123102.15.64.0/19102.15.64.1 to 102.15.95.254102.15.95.2558,190
124102.15.96.0/19102.15.96.1 to 102.15.127.254102.15.127.2558,190
125102.15.128.0/19102.15.128.1 to 102.15.159.254102.15.159.2558,190
126102.15.160.0/19102.15.160.1 to 102.15.191.254102.15.191.2558,190
127102.15.192.0/19102.15.192.1 to 102.15.223.254102.15.223.2558,190
128102.15.224.0/19102.15.224.1 to 102.15.255.254102.15.255.2558,190
129102.16.0.0/19102.16.0.1 to 102.16.31.254102.16.31.2558,190
130102.16.32.0/19102.16.32.1 to 102.16.63.254102.16.63.2558,190
131102.16.64.0/19102.16.64.1 to 102.16.95.254102.16.95.2558,190
132102.16.96.0/19102.16.96.1 to 102.16.127.254102.16.127.2558,190
133102.16.128.0/19102.16.128.1 to 102.16.159.254102.16.159.2558,190
134102.16.160.0/19102.16.160.1 to 102.16.191.254102.16.191.2558,190
135102.16.192.0/19102.16.192.1 to 102.16.223.254102.16.223.2558,190
136102.16.224.0/19102.16.224.1 to 102.16.255.254102.16.255.2558,190
137102.17.0.0/19102.17.0.1 to 102.17.31.254102.17.31.2558,190
138102.17.32.0/19102.17.32.1 to 102.17.63.254102.17.63.2558,190
139102.17.64.0/19102.17.64.1 to 102.17.95.254102.17.95.2558,190
140102.17.96.0/19102.17.96.1 to 102.17.127.254102.17.127.2558,190
141102.17.128.0/19102.17.128.1 to 102.17.159.254102.17.159.2558,190
142102.17.160.0/19102.17.160.1 to 102.17.191.254102.17.191.2558,190
143102.17.192.0/19102.17.192.1 to 102.17.223.254102.17.223.2558,190
144102.17.224.0/19102.17.224.1 to 102.17.255.254102.17.255.2558,190
145102.18.0.0/19102.18.0.1 to 102.18.31.254102.18.31.2558,190
146102.18.32.0/19102.18.32.1 to 102.18.63.254102.18.63.2558,190
147102.18.64.0/19102.18.64.1 to 102.18.95.254102.18.95.2558,190
148102.18.96.0/19102.18.96.1 to 102.18.127.254102.18.127.2558,190
149102.18.128.0/19102.18.128.1 to 102.18.159.254102.18.159.2558,190
150102.18.160.0/19102.18.160.1 to 102.18.191.254102.18.191.2558,190
151102.18.192.0/19102.18.192.1 to 102.18.223.254102.18.223.2558,190
152102.18.224.0/19102.18.224.1 to 102.18.255.254102.18.255.2558,190
153102.19.0.0/19102.19.0.1 to 102.19.31.254102.19.31.2558,190
154102.19.32.0/19102.19.32.1 to 102.19.63.254102.19.63.2558,190
155102.19.64.0/19102.19.64.1 to 102.19.95.254102.19.95.2558,190
156102.19.96.0/19102.19.96.1 to 102.19.127.254102.19.127.2558,190
157102.19.128.0/19102.19.128.1 to 102.19.159.254102.19.159.2558,190
158102.19.160.0/19102.19.160.1 to 102.19.191.254102.19.191.2558,190
159102.19.192.0/19102.19.192.1 to 102.19.223.254102.19.223.2558,190
160102.19.224.0/19102.19.224.1 to 102.19.255.254102.19.255.2558,190
161102.20.0.0/19102.20.0.1 to 102.20.31.254102.20.31.2558,190
162102.20.32.0/19102.20.32.1 to 102.20.63.254102.20.63.2558,190
163102.20.64.0/19102.20.64.1 to 102.20.95.254102.20.95.2558,190
164102.20.96.0/19102.20.96.1 to 102.20.127.254102.20.127.2558,190
165102.20.128.0/19102.20.128.1 to 102.20.159.254102.20.159.2558,190
166102.20.160.0/19102.20.160.1 to 102.20.191.254102.20.191.2558,190
167102.20.192.0/19102.20.192.1 to 102.20.223.254102.20.223.2558,190
168102.20.224.0/19102.20.224.1 to 102.20.255.254102.20.255.2558,190
169102.21.0.0/19102.21.0.1 to 102.21.31.254102.21.31.2558,190
170102.21.32.0/19102.21.32.1 to 102.21.63.254102.21.63.2558,190
171102.21.64.0/19102.21.64.1 to 102.21.95.254102.21.95.2558,190
172102.21.96.0/19102.21.96.1 to 102.21.127.254102.21.127.2558,190
173102.21.128.0/19102.21.128.1 to 102.21.159.254102.21.159.2558,190
174102.21.160.0/19102.21.160.1 to 102.21.191.254102.21.191.2558,190
175102.21.192.0/19102.21.192.1 to 102.21.223.254102.21.223.2558,190
176102.21.224.0/19102.21.224.1 to 102.21.255.254102.21.255.2558,190
177102.22.0.0/19102.22.0.1 to 102.22.31.254102.22.31.2558,190
178102.22.32.0/19102.22.32.1 to 102.22.63.254102.22.63.2558,190
179102.22.64.0/19102.22.64.1 to 102.22.95.254102.22.95.2558,190
180102.22.96.0/19102.22.96.1 to 102.22.127.254102.22.127.2558,190
181102.22.128.0/19102.22.128.1 to 102.22.159.254102.22.159.2558,190
182102.22.160.0/19102.22.160.1 to 102.22.191.254102.22.191.2558,190
183102.22.192.0/19102.22.192.1 to 102.22.223.254102.22.223.2558,190
184102.22.224.0/19102.22.224.1 to 102.22.255.254102.22.255.2558,190
185102.23.0.0/19102.23.0.1 to 102.23.31.254102.23.31.2558,190
186102.23.32.0/19102.23.32.1 to 102.23.63.254102.23.63.2558,190
187102.23.64.0/19102.23.64.1 to 102.23.95.254102.23.95.2558,190
188102.23.96.0/19102.23.96.1 to 102.23.127.254102.23.127.2558,190
189102.23.128.0/19102.23.128.1 to 102.23.159.254102.23.159.2558,190
190102.23.160.0/19102.23.160.1 to 102.23.191.254102.23.191.2558,190
191102.23.192.0/19102.23.192.1 to 102.23.223.254102.23.223.2558,190
192102.23.224.0/19102.23.224.1 to 102.23.255.254102.23.255.2558,190
193102.24.0.0/19102.24.0.1 to 102.24.31.254102.24.31.2558,190
194102.24.32.0/19102.24.32.1 to 102.24.63.254102.24.63.2558,190
195102.24.64.0/19102.24.64.1 to 102.24.95.254102.24.95.2558,190
196102.24.96.0/19102.24.96.1 to 102.24.127.254102.24.127.2558,190
197102.24.128.0/19102.24.128.1 to 102.24.159.254102.24.159.2558,190
198102.24.160.0/19102.24.160.1 to 102.24.191.254102.24.191.2558,190
199102.24.192.0/19102.24.192.1 to 102.24.223.254102.24.223.2558,190
200102.24.224.0/19102.24.224.1 to 102.24.255.254102.24.255.2558,190
201102.25.0.0/19102.25.0.1 to 102.25.31.254102.25.31.2558,190
202102.25.32.0/19102.25.32.1 to 102.25.63.254102.25.63.2558,190
203102.25.64.0/19102.25.64.1 to 102.25.95.254102.25.95.2558,190
204102.25.96.0/19102.25.96.1 to 102.25.127.254102.25.127.2558,190
205102.25.128.0/19102.25.128.1 to 102.25.159.254102.25.159.2558,190
206102.25.160.0/19102.25.160.1 to 102.25.191.254102.25.191.2558,190
207102.25.192.0/19102.25.192.1 to 102.25.223.254102.25.223.2558,190
208102.25.224.0/19102.25.224.1 to 102.25.255.254102.25.255.2558,190
209102.26.0.0/19102.26.0.1 to 102.26.31.254102.26.31.2558,190
210102.26.32.0/19102.26.32.1 to 102.26.63.254102.26.63.2558,190
211102.26.64.0/19102.26.64.1 to 102.26.95.254102.26.95.2558,190
212102.26.96.0/19102.26.96.1 to 102.26.127.254102.26.127.2558,190
213102.26.128.0/19102.26.128.1 to 102.26.159.254102.26.159.2558,190
214102.26.160.0/19102.26.160.1 to 102.26.191.254102.26.191.2558,190
215102.26.192.0/19102.26.192.1 to 102.26.223.254102.26.223.2558,190
216102.26.224.0/19102.26.224.1 to 102.26.255.254102.26.255.2558,190
217102.27.0.0/19102.27.0.1 to 102.27.31.254102.27.31.2558,190
218102.27.32.0/19102.27.32.1 to 102.27.63.254102.27.63.2558,190
219102.27.64.0/19102.27.64.1 to 102.27.95.254102.27.95.2558,190
220102.27.96.0/19102.27.96.1 to 102.27.127.254102.27.127.2558,190
221102.27.128.0/19102.27.128.1 to 102.27.159.254102.27.159.2558,190
222102.27.160.0/19102.27.160.1 to 102.27.191.254102.27.191.2558,190
223102.27.192.0/19102.27.192.1 to 102.27.223.254102.27.223.2558,190
224102.27.224.0/19102.27.224.1 to 102.27.255.254102.27.255.2558,190
225102.28.0.0/19102.28.0.1 to 102.28.31.254102.28.31.2558,190
226102.28.32.0/19102.28.32.1 to 102.28.63.254102.28.63.2558,190
227102.28.64.0/19102.28.64.1 to 102.28.95.254102.28.95.2558,190
228102.28.96.0/19102.28.96.1 to 102.28.127.254102.28.127.2558,190
229102.28.128.0/19102.28.128.1 to 102.28.159.254102.28.159.2558,190
230102.28.160.0/19102.28.160.1 to 102.28.191.254102.28.191.2558,190
231102.28.192.0/19102.28.192.1 to 102.28.223.254102.28.223.2558,190
232102.28.224.0/19102.28.224.1 to 102.28.255.254102.28.255.2558,190
233102.29.0.0/19102.29.0.1 to 102.29.31.254102.29.31.2558,190
234102.29.32.0/19102.29.32.1 to 102.29.63.254102.29.63.2558,190
235102.29.64.0/19102.29.64.1 to 102.29.95.254102.29.95.2558,190
236102.29.96.0/19102.29.96.1 to 102.29.127.254102.29.127.2558,190
237102.29.128.0/19102.29.128.1 to 102.29.159.254102.29.159.2558,190
238102.29.160.0/19102.29.160.1 to 102.29.191.254102.29.191.2558,190
239102.29.192.0/19102.29.192.1 to 102.29.223.254102.29.223.2558,190
240102.29.224.0/19102.29.224.1 to 102.29.255.254102.29.255.2558,190
241102.30.0.0/19102.30.0.1 to 102.30.31.254102.30.31.2558,190
242102.30.32.0/19102.30.32.1 to 102.30.63.254102.30.63.2558,190
243102.30.64.0/19102.30.64.1 to 102.30.95.254102.30.95.2558,190
244102.30.96.0/19102.30.96.1 to 102.30.127.254102.30.127.2558,190
245102.30.128.0/19102.30.128.1 to 102.30.159.254102.30.159.2558,190
246102.30.160.0/19102.30.160.1 to 102.30.191.254102.30.191.2558,190
247102.30.192.0/19102.30.192.1 to 102.30.223.254102.30.223.2558,190
248102.30.224.0/19102.30.224.1 to 102.30.255.254102.30.255.2558,190
249102.31.0.0/19102.31.0.1 to 102.31.31.254102.31.31.2558,190
250102.31.32.0/19102.31.32.1 to 102.31.63.254102.31.63.2558,190
251102.31.64.0/19102.31.64.1 to 102.31.95.254102.31.95.2558,190
252102.31.96.0/19102.31.96.1 to 102.31.127.254102.31.127.2558,190
253102.31.128.0/19102.31.128.1 to 102.31.159.254102.31.159.2558,190
254102.31.160.0/19102.31.160.1 to 102.31.191.254102.31.191.2558,190
255102.31.192.0/19102.31.192.1 to 102.31.223.254102.31.223.2558,190
256102.31.224.0/19102.31.224.1 to 102.31.255.254102.31.255.2558,190

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.