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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.

Network103.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
103.0.0.0
Broadcast address
103.255.255.255
First usable
103.0.0.1
Last usable
103.255.255.254
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 67000000 · Integer 1728053248 to 1744830463
Reverse DNS zone
103.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01100111..00000000.00000000.00000000103.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network01100111..00000000.00000000.00000000103.0.0.0
Broadcast01100111..11111111.11111111.11111111103.255.255.255
Split into smaller subnets/18
/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)

103.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1103.0.0.0/18103.0.0.1 to 103.0.63.254103.0.63.25516,382
2103.0.64.0/18103.0.64.1 to 103.0.127.254103.0.127.25516,382
3103.0.128.0/18103.0.128.1 to 103.0.191.254103.0.191.25516,382
4103.0.192.0/18103.0.192.1 to 103.0.255.254103.0.255.25516,382
5103.1.0.0/18103.1.0.1 to 103.1.63.254103.1.63.25516,382
6103.1.64.0/18103.1.64.1 to 103.1.127.254103.1.127.25516,382
7103.1.128.0/18103.1.128.1 to 103.1.191.254103.1.191.25516,382
8103.1.192.0/18103.1.192.1 to 103.1.255.254103.1.255.25516,382
9103.2.0.0/18103.2.0.1 to 103.2.63.254103.2.63.25516,382
10103.2.64.0/18103.2.64.1 to 103.2.127.254103.2.127.25516,382
11103.2.128.0/18103.2.128.1 to 103.2.191.254103.2.191.25516,382
12103.2.192.0/18103.2.192.1 to 103.2.255.254103.2.255.25516,382
13103.3.0.0/18103.3.0.1 to 103.3.63.254103.3.63.25516,382
14103.3.64.0/18103.3.64.1 to 103.3.127.254103.3.127.25516,382
15103.3.128.0/18103.3.128.1 to 103.3.191.254103.3.191.25516,382
16103.3.192.0/18103.3.192.1 to 103.3.255.254103.3.255.25516,382
17103.4.0.0/18103.4.0.1 to 103.4.63.254103.4.63.25516,382
18103.4.64.0/18103.4.64.1 to 103.4.127.254103.4.127.25516,382
19103.4.128.0/18103.4.128.1 to 103.4.191.254103.4.191.25516,382
20103.4.192.0/18103.4.192.1 to 103.4.255.254103.4.255.25516,382
21103.5.0.0/18103.5.0.1 to 103.5.63.254103.5.63.25516,382
22103.5.64.0/18103.5.64.1 to 103.5.127.254103.5.127.25516,382
23103.5.128.0/18103.5.128.1 to 103.5.191.254103.5.191.25516,382
24103.5.192.0/18103.5.192.1 to 103.5.255.254103.5.255.25516,382
25103.6.0.0/18103.6.0.1 to 103.6.63.254103.6.63.25516,382
26103.6.64.0/18103.6.64.1 to 103.6.127.254103.6.127.25516,382
27103.6.128.0/18103.6.128.1 to 103.6.191.254103.6.191.25516,382
28103.6.192.0/18103.6.192.1 to 103.6.255.254103.6.255.25516,382
29103.7.0.0/18103.7.0.1 to 103.7.63.254103.7.63.25516,382
30103.7.64.0/18103.7.64.1 to 103.7.127.254103.7.127.25516,382
31103.7.128.0/18103.7.128.1 to 103.7.191.254103.7.191.25516,382
32103.7.192.0/18103.7.192.1 to 103.7.255.254103.7.255.25516,382
33103.8.0.0/18103.8.0.1 to 103.8.63.254103.8.63.25516,382
34103.8.64.0/18103.8.64.1 to 103.8.127.254103.8.127.25516,382
35103.8.128.0/18103.8.128.1 to 103.8.191.254103.8.191.25516,382
36103.8.192.0/18103.8.192.1 to 103.8.255.254103.8.255.25516,382
37103.9.0.0/18103.9.0.1 to 103.9.63.254103.9.63.25516,382
38103.9.64.0/18103.9.64.1 to 103.9.127.254103.9.127.25516,382
39103.9.128.0/18103.9.128.1 to 103.9.191.254103.9.191.25516,382
40103.9.192.0/18103.9.192.1 to 103.9.255.254103.9.255.25516,382
41103.10.0.0/18103.10.0.1 to 103.10.63.254103.10.63.25516,382
42103.10.64.0/18103.10.64.1 to 103.10.127.254103.10.127.25516,382
43103.10.128.0/18103.10.128.1 to 103.10.191.254103.10.191.25516,382
44103.10.192.0/18103.10.192.1 to 103.10.255.254103.10.255.25516,382
45103.11.0.0/18103.11.0.1 to 103.11.63.254103.11.63.25516,382
46103.11.64.0/18103.11.64.1 to 103.11.127.254103.11.127.25516,382
47103.11.128.0/18103.11.128.1 to 103.11.191.254103.11.191.25516,382
48103.11.192.0/18103.11.192.1 to 103.11.255.254103.11.255.25516,382
49103.12.0.0/18103.12.0.1 to 103.12.63.254103.12.63.25516,382
50103.12.64.0/18103.12.64.1 to 103.12.127.254103.12.127.25516,382
51103.12.128.0/18103.12.128.1 to 103.12.191.254103.12.191.25516,382
52103.12.192.0/18103.12.192.1 to 103.12.255.254103.12.255.25516,382
53103.13.0.0/18103.13.0.1 to 103.13.63.254103.13.63.25516,382
54103.13.64.0/18103.13.64.1 to 103.13.127.254103.13.127.25516,382
55103.13.128.0/18103.13.128.1 to 103.13.191.254103.13.191.25516,382
56103.13.192.0/18103.13.192.1 to 103.13.255.254103.13.255.25516,382
57103.14.0.0/18103.14.0.1 to 103.14.63.254103.14.63.25516,382
58103.14.64.0/18103.14.64.1 to 103.14.127.254103.14.127.25516,382
59103.14.128.0/18103.14.128.1 to 103.14.191.254103.14.191.25516,382
60103.14.192.0/18103.14.192.1 to 103.14.255.254103.14.255.25516,382
61103.15.0.0/18103.15.0.1 to 103.15.63.254103.15.63.25516,382
62103.15.64.0/18103.15.64.1 to 103.15.127.254103.15.127.25516,382
63103.15.128.0/18103.15.128.1 to 103.15.191.254103.15.191.25516,382
64103.15.192.0/18103.15.192.1 to 103.15.255.254103.15.255.25516,382
65103.16.0.0/18103.16.0.1 to 103.16.63.254103.16.63.25516,382
66103.16.64.0/18103.16.64.1 to 103.16.127.254103.16.127.25516,382
67103.16.128.0/18103.16.128.1 to 103.16.191.254103.16.191.25516,382
68103.16.192.0/18103.16.192.1 to 103.16.255.254103.16.255.25516,382
69103.17.0.0/18103.17.0.1 to 103.17.63.254103.17.63.25516,382
70103.17.64.0/18103.17.64.1 to 103.17.127.254103.17.127.25516,382
71103.17.128.0/18103.17.128.1 to 103.17.191.254103.17.191.25516,382
72103.17.192.0/18103.17.192.1 to 103.17.255.254103.17.255.25516,382
73103.18.0.0/18103.18.0.1 to 103.18.63.254103.18.63.25516,382
74103.18.64.0/18103.18.64.1 to 103.18.127.254103.18.127.25516,382
75103.18.128.0/18103.18.128.1 to 103.18.191.254103.18.191.25516,382
76103.18.192.0/18103.18.192.1 to 103.18.255.254103.18.255.25516,382
77103.19.0.0/18103.19.0.1 to 103.19.63.254103.19.63.25516,382
78103.19.64.0/18103.19.64.1 to 103.19.127.254103.19.127.25516,382
79103.19.128.0/18103.19.128.1 to 103.19.191.254103.19.191.25516,382
80103.19.192.0/18103.19.192.1 to 103.19.255.254103.19.255.25516,382
81103.20.0.0/18103.20.0.1 to 103.20.63.254103.20.63.25516,382
82103.20.64.0/18103.20.64.1 to 103.20.127.254103.20.127.25516,382
83103.20.128.0/18103.20.128.1 to 103.20.191.254103.20.191.25516,382
84103.20.192.0/18103.20.192.1 to 103.20.255.254103.20.255.25516,382
85103.21.0.0/18103.21.0.1 to 103.21.63.254103.21.63.25516,382
86103.21.64.0/18103.21.64.1 to 103.21.127.254103.21.127.25516,382
87103.21.128.0/18103.21.128.1 to 103.21.191.254103.21.191.25516,382
88103.21.192.0/18103.21.192.1 to 103.21.255.254103.21.255.25516,382
89103.22.0.0/18103.22.0.1 to 103.22.63.254103.22.63.25516,382
90103.22.64.0/18103.22.64.1 to 103.22.127.254103.22.127.25516,382
91103.22.128.0/18103.22.128.1 to 103.22.191.254103.22.191.25516,382
92103.22.192.0/18103.22.192.1 to 103.22.255.254103.22.255.25516,382
93103.23.0.0/18103.23.0.1 to 103.23.63.254103.23.63.25516,382
94103.23.64.0/18103.23.64.1 to 103.23.127.254103.23.127.25516,382
95103.23.128.0/18103.23.128.1 to 103.23.191.254103.23.191.25516,382
96103.23.192.0/18103.23.192.1 to 103.23.255.254103.23.255.25516,382
97103.24.0.0/18103.24.0.1 to 103.24.63.254103.24.63.25516,382
98103.24.64.0/18103.24.64.1 to 103.24.127.254103.24.127.25516,382
99103.24.128.0/18103.24.128.1 to 103.24.191.254103.24.191.25516,382
100103.24.192.0/18103.24.192.1 to 103.24.255.254103.24.255.25516,382
101103.25.0.0/18103.25.0.1 to 103.25.63.254103.25.63.25516,382
102103.25.64.0/18103.25.64.1 to 103.25.127.254103.25.127.25516,382
103103.25.128.0/18103.25.128.1 to 103.25.191.254103.25.191.25516,382
104103.25.192.0/18103.25.192.1 to 103.25.255.254103.25.255.25516,382
105103.26.0.0/18103.26.0.1 to 103.26.63.254103.26.63.25516,382
106103.26.64.0/18103.26.64.1 to 103.26.127.254103.26.127.25516,382
107103.26.128.0/18103.26.128.1 to 103.26.191.254103.26.191.25516,382
108103.26.192.0/18103.26.192.1 to 103.26.255.254103.26.255.25516,382
109103.27.0.0/18103.27.0.1 to 103.27.63.254103.27.63.25516,382
110103.27.64.0/18103.27.64.1 to 103.27.127.254103.27.127.25516,382
111103.27.128.0/18103.27.128.1 to 103.27.191.254103.27.191.25516,382
112103.27.192.0/18103.27.192.1 to 103.27.255.254103.27.255.25516,382
113103.28.0.0/18103.28.0.1 to 103.28.63.254103.28.63.25516,382
114103.28.64.0/18103.28.64.1 to 103.28.127.254103.28.127.25516,382
115103.28.128.0/18103.28.128.1 to 103.28.191.254103.28.191.25516,382
116103.28.192.0/18103.28.192.1 to 103.28.255.254103.28.255.25516,382
117103.29.0.0/18103.29.0.1 to 103.29.63.254103.29.63.25516,382
118103.29.64.0/18103.29.64.1 to 103.29.127.254103.29.127.25516,382
119103.29.128.0/18103.29.128.1 to 103.29.191.254103.29.191.25516,382
120103.29.192.0/18103.29.192.1 to 103.29.255.254103.29.255.25516,382
121103.30.0.0/18103.30.0.1 to 103.30.63.254103.30.63.25516,382
122103.30.64.0/18103.30.64.1 to 103.30.127.254103.30.127.25516,382
123103.30.128.0/18103.30.128.1 to 103.30.191.254103.30.191.25516,382
124103.30.192.0/18103.30.192.1 to 103.30.255.254103.30.255.25516,382
125103.31.0.0/18103.31.0.1 to 103.31.63.254103.31.63.25516,382
126103.31.64.0/18103.31.64.1 to 103.31.127.254103.31.127.25516,382
127103.31.128.0/18103.31.128.1 to 103.31.191.254103.31.191.25516,382
128103.31.192.0/18103.31.192.1 to 103.31.255.254103.31.255.25516,382
129103.32.0.0/18103.32.0.1 to 103.32.63.254103.32.63.25516,382
130103.32.64.0/18103.32.64.1 to 103.32.127.254103.32.127.25516,382
131103.32.128.0/18103.32.128.1 to 103.32.191.254103.32.191.25516,382
132103.32.192.0/18103.32.192.1 to 103.32.255.254103.32.255.25516,382
133103.33.0.0/18103.33.0.1 to 103.33.63.254103.33.63.25516,382
134103.33.64.0/18103.33.64.1 to 103.33.127.254103.33.127.25516,382
135103.33.128.0/18103.33.128.1 to 103.33.191.254103.33.191.25516,382
136103.33.192.0/18103.33.192.1 to 103.33.255.254103.33.255.25516,382
137103.34.0.0/18103.34.0.1 to 103.34.63.254103.34.63.25516,382
138103.34.64.0/18103.34.64.1 to 103.34.127.254103.34.127.25516,382
139103.34.128.0/18103.34.128.1 to 103.34.191.254103.34.191.25516,382
140103.34.192.0/18103.34.192.1 to 103.34.255.254103.34.255.25516,382
141103.35.0.0/18103.35.0.1 to 103.35.63.254103.35.63.25516,382
142103.35.64.0/18103.35.64.1 to 103.35.127.254103.35.127.25516,382
143103.35.128.0/18103.35.128.1 to 103.35.191.254103.35.191.25516,382
144103.35.192.0/18103.35.192.1 to 103.35.255.254103.35.255.25516,382
145103.36.0.0/18103.36.0.1 to 103.36.63.254103.36.63.25516,382
146103.36.64.0/18103.36.64.1 to 103.36.127.254103.36.127.25516,382
147103.36.128.0/18103.36.128.1 to 103.36.191.254103.36.191.25516,382
148103.36.192.0/18103.36.192.1 to 103.36.255.254103.36.255.25516,382
149103.37.0.0/18103.37.0.1 to 103.37.63.254103.37.63.25516,382
150103.37.64.0/18103.37.64.1 to 103.37.127.254103.37.127.25516,382
151103.37.128.0/18103.37.128.1 to 103.37.191.254103.37.191.25516,382
152103.37.192.0/18103.37.192.1 to 103.37.255.254103.37.255.25516,382
153103.38.0.0/18103.38.0.1 to 103.38.63.254103.38.63.25516,382
154103.38.64.0/18103.38.64.1 to 103.38.127.254103.38.127.25516,382
155103.38.128.0/18103.38.128.1 to 103.38.191.254103.38.191.25516,382
156103.38.192.0/18103.38.192.1 to 103.38.255.254103.38.255.25516,382
157103.39.0.0/18103.39.0.1 to 103.39.63.254103.39.63.25516,382
158103.39.64.0/18103.39.64.1 to 103.39.127.254103.39.127.25516,382
159103.39.128.0/18103.39.128.1 to 103.39.191.254103.39.191.25516,382
160103.39.192.0/18103.39.192.1 to 103.39.255.254103.39.255.25516,382
161103.40.0.0/18103.40.0.1 to 103.40.63.254103.40.63.25516,382
162103.40.64.0/18103.40.64.1 to 103.40.127.254103.40.127.25516,382
163103.40.128.0/18103.40.128.1 to 103.40.191.254103.40.191.25516,382
164103.40.192.0/18103.40.192.1 to 103.40.255.254103.40.255.25516,382
165103.41.0.0/18103.41.0.1 to 103.41.63.254103.41.63.25516,382
166103.41.64.0/18103.41.64.1 to 103.41.127.254103.41.127.25516,382
167103.41.128.0/18103.41.128.1 to 103.41.191.254103.41.191.25516,382
168103.41.192.0/18103.41.192.1 to 103.41.255.254103.41.255.25516,382
169103.42.0.0/18103.42.0.1 to 103.42.63.254103.42.63.25516,382
170103.42.64.0/18103.42.64.1 to 103.42.127.254103.42.127.25516,382
171103.42.128.0/18103.42.128.1 to 103.42.191.254103.42.191.25516,382
172103.42.192.0/18103.42.192.1 to 103.42.255.254103.42.255.25516,382
173103.43.0.0/18103.43.0.1 to 103.43.63.254103.43.63.25516,382
174103.43.64.0/18103.43.64.1 to 103.43.127.254103.43.127.25516,382
175103.43.128.0/18103.43.128.1 to 103.43.191.254103.43.191.25516,382
176103.43.192.0/18103.43.192.1 to 103.43.255.254103.43.255.25516,382
177103.44.0.0/18103.44.0.1 to 103.44.63.254103.44.63.25516,382
178103.44.64.0/18103.44.64.1 to 103.44.127.254103.44.127.25516,382
179103.44.128.0/18103.44.128.1 to 103.44.191.254103.44.191.25516,382
180103.44.192.0/18103.44.192.1 to 103.44.255.254103.44.255.25516,382
181103.45.0.0/18103.45.0.1 to 103.45.63.254103.45.63.25516,382
182103.45.64.0/18103.45.64.1 to 103.45.127.254103.45.127.25516,382
183103.45.128.0/18103.45.128.1 to 103.45.191.254103.45.191.25516,382
184103.45.192.0/18103.45.192.1 to 103.45.255.254103.45.255.25516,382
185103.46.0.0/18103.46.0.1 to 103.46.63.254103.46.63.25516,382
186103.46.64.0/18103.46.64.1 to 103.46.127.254103.46.127.25516,382
187103.46.128.0/18103.46.128.1 to 103.46.191.254103.46.191.25516,382
188103.46.192.0/18103.46.192.1 to 103.46.255.254103.46.255.25516,382
189103.47.0.0/18103.47.0.1 to 103.47.63.254103.47.63.25516,382
190103.47.64.0/18103.47.64.1 to 103.47.127.254103.47.127.25516,382
191103.47.128.0/18103.47.128.1 to 103.47.191.254103.47.191.25516,382
192103.47.192.0/18103.47.192.1 to 103.47.255.254103.47.255.25516,382
193103.48.0.0/18103.48.0.1 to 103.48.63.254103.48.63.25516,382
194103.48.64.0/18103.48.64.1 to 103.48.127.254103.48.127.25516,382
195103.48.128.0/18103.48.128.1 to 103.48.191.254103.48.191.25516,382
196103.48.192.0/18103.48.192.1 to 103.48.255.254103.48.255.25516,382
197103.49.0.0/18103.49.0.1 to 103.49.63.254103.49.63.25516,382
198103.49.64.0/18103.49.64.1 to 103.49.127.254103.49.127.25516,382
199103.49.128.0/18103.49.128.1 to 103.49.191.254103.49.191.25516,382
200103.49.192.0/18103.49.192.1 to 103.49.255.254103.49.255.25516,382
201103.50.0.0/18103.50.0.1 to 103.50.63.254103.50.63.25516,382
202103.50.64.0/18103.50.64.1 to 103.50.127.254103.50.127.25516,382
203103.50.128.0/18103.50.128.1 to 103.50.191.254103.50.191.25516,382
204103.50.192.0/18103.50.192.1 to 103.50.255.254103.50.255.25516,382
205103.51.0.0/18103.51.0.1 to 103.51.63.254103.51.63.25516,382
206103.51.64.0/18103.51.64.1 to 103.51.127.254103.51.127.25516,382
207103.51.128.0/18103.51.128.1 to 103.51.191.254103.51.191.25516,382
208103.51.192.0/18103.51.192.1 to 103.51.255.254103.51.255.25516,382
209103.52.0.0/18103.52.0.1 to 103.52.63.254103.52.63.25516,382
210103.52.64.0/18103.52.64.1 to 103.52.127.254103.52.127.25516,382
211103.52.128.0/18103.52.128.1 to 103.52.191.254103.52.191.25516,382
212103.52.192.0/18103.52.192.1 to 103.52.255.254103.52.255.25516,382
213103.53.0.0/18103.53.0.1 to 103.53.63.254103.53.63.25516,382
214103.53.64.0/18103.53.64.1 to 103.53.127.254103.53.127.25516,382
215103.53.128.0/18103.53.128.1 to 103.53.191.254103.53.191.25516,382
216103.53.192.0/18103.53.192.1 to 103.53.255.254103.53.255.25516,382
217103.54.0.0/18103.54.0.1 to 103.54.63.254103.54.63.25516,382
218103.54.64.0/18103.54.64.1 to 103.54.127.254103.54.127.25516,382
219103.54.128.0/18103.54.128.1 to 103.54.191.254103.54.191.25516,382
220103.54.192.0/18103.54.192.1 to 103.54.255.254103.54.255.25516,382
221103.55.0.0/18103.55.0.1 to 103.55.63.254103.55.63.25516,382
222103.55.64.0/18103.55.64.1 to 103.55.127.254103.55.127.25516,382
223103.55.128.0/18103.55.128.1 to 103.55.191.254103.55.191.25516,382
224103.55.192.0/18103.55.192.1 to 103.55.255.254103.55.255.25516,382
225103.56.0.0/18103.56.0.1 to 103.56.63.254103.56.63.25516,382
226103.56.64.0/18103.56.64.1 to 103.56.127.254103.56.127.25516,382
227103.56.128.0/18103.56.128.1 to 103.56.191.254103.56.191.25516,382
228103.56.192.0/18103.56.192.1 to 103.56.255.254103.56.255.25516,382
229103.57.0.0/18103.57.0.1 to 103.57.63.254103.57.63.25516,382
230103.57.64.0/18103.57.64.1 to 103.57.127.254103.57.127.25516,382
231103.57.128.0/18103.57.128.1 to 103.57.191.254103.57.191.25516,382
232103.57.192.0/18103.57.192.1 to 103.57.255.254103.57.255.25516,382
233103.58.0.0/18103.58.0.1 to 103.58.63.254103.58.63.25516,382
234103.58.64.0/18103.58.64.1 to 103.58.127.254103.58.127.25516,382
235103.58.128.0/18103.58.128.1 to 103.58.191.254103.58.191.25516,382
236103.58.192.0/18103.58.192.1 to 103.58.255.254103.58.255.25516,382
237103.59.0.0/18103.59.0.1 to 103.59.63.254103.59.63.25516,382
238103.59.64.0/18103.59.64.1 to 103.59.127.254103.59.127.25516,382
239103.59.128.0/18103.59.128.1 to 103.59.191.254103.59.191.25516,382
240103.59.192.0/18103.59.192.1 to 103.59.255.254103.59.255.25516,382
241103.60.0.0/18103.60.0.1 to 103.60.63.254103.60.63.25516,382
242103.60.64.0/18103.60.64.1 to 103.60.127.254103.60.127.25516,382
243103.60.128.0/18103.60.128.1 to 103.60.191.254103.60.191.25516,382
244103.60.192.0/18103.60.192.1 to 103.60.255.254103.60.255.25516,382
245103.61.0.0/18103.61.0.1 to 103.61.63.254103.61.63.25516,382
246103.61.64.0/18103.61.64.1 to 103.61.127.254103.61.127.25516,382
247103.61.128.0/18103.61.128.1 to 103.61.191.254103.61.191.25516,382
248103.61.192.0/18103.61.192.1 to 103.61.255.254103.61.255.25516,382
249103.62.0.0/18103.62.0.1 to 103.62.63.254103.62.63.25516,382
250103.62.64.0/18103.62.64.1 to 103.62.127.254103.62.127.25516,382
251103.62.128.0/18103.62.128.1 to 103.62.191.254103.62.191.25516,382
252103.62.192.0/18103.62.192.1 to 103.62.255.254103.62.255.25516,382
253103.63.0.0/18103.63.0.1 to 103.63.63.254103.63.63.25516,382
254103.63.64.0/18103.63.64.1 to 103.63.127.254103.63.127.25516,382
255103.63.128.0/18103.63.128.1 to 103.63.191.254103.63.191.25516,382
256103.63.192.0/18103.63.192.1 to 103.63.255.254103.63.255.25516,382

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.