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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.

Network216.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
216.0.0.0
Broadcast address
219.255.255.255
First usable
216.0.0.1
Last usable
219.255.255.254
Usable hosts
67,108,862 (67,108,864 less the network and broadcast addresses)
Subnet mask
252.0.0.0
Wildcard mask
3.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/6
Type
Public public
Old class
C (default /24)
As numbers
Hex D8000000 · Integer 3623878656 to 3690987519
Reverse DNS zones
216.in-addr.arpa
217.in-addr.arpa
218.in-addr.arpa
219.in-addr.arpa
/6 is not on a 8-bit boundary, so it takes 4 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011000.00000000.00000000.00000000216.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network11011000.00000000.00000000.00000000216.0.0.0
Broadcast11011011.11111111.11111111.11111111219.255.255.255
Split into smaller subnets/18
/7 (2)/8 (4)/9 (8)/10 (16)/11 (32)/12 (64)/13 (128)/14 (256)/15 (512)/16 (1,024)/17 (2,048)/18 (4,096)

216.0.0.0/6 makes 4,096 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1216.0.0.0/18216.0.0.1 to 216.0.63.254216.0.63.25516,382
2216.0.64.0/18216.0.64.1 to 216.0.127.254216.0.127.25516,382
3216.0.128.0/18216.0.128.1 to 216.0.191.254216.0.191.25516,382
4216.0.192.0/18216.0.192.1 to 216.0.255.254216.0.255.25516,382
5216.1.0.0/18216.1.0.1 to 216.1.63.254216.1.63.25516,382
6216.1.64.0/18216.1.64.1 to 216.1.127.254216.1.127.25516,382
7216.1.128.0/18216.1.128.1 to 216.1.191.254216.1.191.25516,382
8216.1.192.0/18216.1.192.1 to 216.1.255.254216.1.255.25516,382
9216.2.0.0/18216.2.0.1 to 216.2.63.254216.2.63.25516,382
10216.2.64.0/18216.2.64.1 to 216.2.127.254216.2.127.25516,382
11216.2.128.0/18216.2.128.1 to 216.2.191.254216.2.191.25516,382
12216.2.192.0/18216.2.192.1 to 216.2.255.254216.2.255.25516,382
13216.3.0.0/18216.3.0.1 to 216.3.63.254216.3.63.25516,382
14216.3.64.0/18216.3.64.1 to 216.3.127.254216.3.127.25516,382
15216.3.128.0/18216.3.128.1 to 216.3.191.254216.3.191.25516,382
16216.3.192.0/18216.3.192.1 to 216.3.255.254216.3.255.25516,382
17216.4.0.0/18216.4.0.1 to 216.4.63.254216.4.63.25516,382
18216.4.64.0/18216.4.64.1 to 216.4.127.254216.4.127.25516,382
19216.4.128.0/18216.4.128.1 to 216.4.191.254216.4.191.25516,382
20216.4.192.0/18216.4.192.1 to 216.4.255.254216.4.255.25516,382
21216.5.0.0/18216.5.0.1 to 216.5.63.254216.5.63.25516,382
22216.5.64.0/18216.5.64.1 to 216.5.127.254216.5.127.25516,382
23216.5.128.0/18216.5.128.1 to 216.5.191.254216.5.191.25516,382
24216.5.192.0/18216.5.192.1 to 216.5.255.254216.5.255.25516,382
25216.6.0.0/18216.6.0.1 to 216.6.63.254216.6.63.25516,382
26216.6.64.0/18216.6.64.1 to 216.6.127.254216.6.127.25516,382
27216.6.128.0/18216.6.128.1 to 216.6.191.254216.6.191.25516,382
28216.6.192.0/18216.6.192.1 to 216.6.255.254216.6.255.25516,382
29216.7.0.0/18216.7.0.1 to 216.7.63.254216.7.63.25516,382
30216.7.64.0/18216.7.64.1 to 216.7.127.254216.7.127.25516,382
31216.7.128.0/18216.7.128.1 to 216.7.191.254216.7.191.25516,382
32216.7.192.0/18216.7.192.1 to 216.7.255.254216.7.255.25516,382
33216.8.0.0/18216.8.0.1 to 216.8.63.254216.8.63.25516,382
34216.8.64.0/18216.8.64.1 to 216.8.127.254216.8.127.25516,382
35216.8.128.0/18216.8.128.1 to 216.8.191.254216.8.191.25516,382
36216.8.192.0/18216.8.192.1 to 216.8.255.254216.8.255.25516,382
37216.9.0.0/18216.9.0.1 to 216.9.63.254216.9.63.25516,382
38216.9.64.0/18216.9.64.1 to 216.9.127.254216.9.127.25516,382
39216.9.128.0/18216.9.128.1 to 216.9.191.254216.9.191.25516,382
40216.9.192.0/18216.9.192.1 to 216.9.255.254216.9.255.25516,382
41216.10.0.0/18216.10.0.1 to 216.10.63.254216.10.63.25516,382
42216.10.64.0/18216.10.64.1 to 216.10.127.254216.10.127.25516,382
43216.10.128.0/18216.10.128.1 to 216.10.191.254216.10.191.25516,382
44216.10.192.0/18216.10.192.1 to 216.10.255.254216.10.255.25516,382
45216.11.0.0/18216.11.0.1 to 216.11.63.254216.11.63.25516,382
46216.11.64.0/18216.11.64.1 to 216.11.127.254216.11.127.25516,382
47216.11.128.0/18216.11.128.1 to 216.11.191.254216.11.191.25516,382
48216.11.192.0/18216.11.192.1 to 216.11.255.254216.11.255.25516,382
49216.12.0.0/18216.12.0.1 to 216.12.63.254216.12.63.25516,382
50216.12.64.0/18216.12.64.1 to 216.12.127.254216.12.127.25516,382
51216.12.128.0/18216.12.128.1 to 216.12.191.254216.12.191.25516,382
52216.12.192.0/18216.12.192.1 to 216.12.255.254216.12.255.25516,382
53216.13.0.0/18216.13.0.1 to 216.13.63.254216.13.63.25516,382
54216.13.64.0/18216.13.64.1 to 216.13.127.254216.13.127.25516,382
55216.13.128.0/18216.13.128.1 to 216.13.191.254216.13.191.25516,382
56216.13.192.0/18216.13.192.1 to 216.13.255.254216.13.255.25516,382
57216.14.0.0/18216.14.0.1 to 216.14.63.254216.14.63.25516,382
58216.14.64.0/18216.14.64.1 to 216.14.127.254216.14.127.25516,382
59216.14.128.0/18216.14.128.1 to 216.14.191.254216.14.191.25516,382
60216.14.192.0/18216.14.192.1 to 216.14.255.254216.14.255.25516,382
61216.15.0.0/18216.15.0.1 to 216.15.63.254216.15.63.25516,382
62216.15.64.0/18216.15.64.1 to 216.15.127.254216.15.127.25516,382
63216.15.128.0/18216.15.128.1 to 216.15.191.254216.15.191.25516,382
64216.15.192.0/18216.15.192.1 to 216.15.255.254216.15.255.25516,382
65216.16.0.0/18216.16.0.1 to 216.16.63.254216.16.63.25516,382
66216.16.64.0/18216.16.64.1 to 216.16.127.254216.16.127.25516,382
67216.16.128.0/18216.16.128.1 to 216.16.191.254216.16.191.25516,382
68216.16.192.0/18216.16.192.1 to 216.16.255.254216.16.255.25516,382
69216.17.0.0/18216.17.0.1 to 216.17.63.254216.17.63.25516,382
70216.17.64.0/18216.17.64.1 to 216.17.127.254216.17.127.25516,382
71216.17.128.0/18216.17.128.1 to 216.17.191.254216.17.191.25516,382
72216.17.192.0/18216.17.192.1 to 216.17.255.254216.17.255.25516,382
73216.18.0.0/18216.18.0.1 to 216.18.63.254216.18.63.25516,382
74216.18.64.0/18216.18.64.1 to 216.18.127.254216.18.127.25516,382
75216.18.128.0/18216.18.128.1 to 216.18.191.254216.18.191.25516,382
76216.18.192.0/18216.18.192.1 to 216.18.255.254216.18.255.25516,382
77216.19.0.0/18216.19.0.1 to 216.19.63.254216.19.63.25516,382
78216.19.64.0/18216.19.64.1 to 216.19.127.254216.19.127.25516,382
79216.19.128.0/18216.19.128.1 to 216.19.191.254216.19.191.25516,382
80216.19.192.0/18216.19.192.1 to 216.19.255.254216.19.255.25516,382
81216.20.0.0/18216.20.0.1 to 216.20.63.254216.20.63.25516,382
82216.20.64.0/18216.20.64.1 to 216.20.127.254216.20.127.25516,382
83216.20.128.0/18216.20.128.1 to 216.20.191.254216.20.191.25516,382
84216.20.192.0/18216.20.192.1 to 216.20.255.254216.20.255.25516,382
85216.21.0.0/18216.21.0.1 to 216.21.63.254216.21.63.25516,382
86216.21.64.0/18216.21.64.1 to 216.21.127.254216.21.127.25516,382
87216.21.128.0/18216.21.128.1 to 216.21.191.254216.21.191.25516,382
88216.21.192.0/18216.21.192.1 to 216.21.255.254216.21.255.25516,382
89216.22.0.0/18216.22.0.1 to 216.22.63.254216.22.63.25516,382
90216.22.64.0/18216.22.64.1 to 216.22.127.254216.22.127.25516,382
91216.22.128.0/18216.22.128.1 to 216.22.191.254216.22.191.25516,382
92216.22.192.0/18216.22.192.1 to 216.22.255.254216.22.255.25516,382
93216.23.0.0/18216.23.0.1 to 216.23.63.254216.23.63.25516,382
94216.23.64.0/18216.23.64.1 to 216.23.127.254216.23.127.25516,382
95216.23.128.0/18216.23.128.1 to 216.23.191.254216.23.191.25516,382
96216.23.192.0/18216.23.192.1 to 216.23.255.254216.23.255.25516,382
97216.24.0.0/18216.24.0.1 to 216.24.63.254216.24.63.25516,382
98216.24.64.0/18216.24.64.1 to 216.24.127.254216.24.127.25516,382
99216.24.128.0/18216.24.128.1 to 216.24.191.254216.24.191.25516,382
100216.24.192.0/18216.24.192.1 to 216.24.255.254216.24.255.25516,382
101216.25.0.0/18216.25.0.1 to 216.25.63.254216.25.63.25516,382
102216.25.64.0/18216.25.64.1 to 216.25.127.254216.25.127.25516,382
103216.25.128.0/18216.25.128.1 to 216.25.191.254216.25.191.25516,382
104216.25.192.0/18216.25.192.1 to 216.25.255.254216.25.255.25516,382
105216.26.0.0/18216.26.0.1 to 216.26.63.254216.26.63.25516,382
106216.26.64.0/18216.26.64.1 to 216.26.127.254216.26.127.25516,382
107216.26.128.0/18216.26.128.1 to 216.26.191.254216.26.191.25516,382
108216.26.192.0/18216.26.192.1 to 216.26.255.254216.26.255.25516,382
109216.27.0.0/18216.27.0.1 to 216.27.63.254216.27.63.25516,382
110216.27.64.0/18216.27.64.1 to 216.27.127.254216.27.127.25516,382
111216.27.128.0/18216.27.128.1 to 216.27.191.254216.27.191.25516,382
112216.27.192.0/18216.27.192.1 to 216.27.255.254216.27.255.25516,382
113216.28.0.0/18216.28.0.1 to 216.28.63.254216.28.63.25516,382
114216.28.64.0/18216.28.64.1 to 216.28.127.254216.28.127.25516,382
115216.28.128.0/18216.28.128.1 to 216.28.191.254216.28.191.25516,382
116216.28.192.0/18216.28.192.1 to 216.28.255.254216.28.255.25516,382
117216.29.0.0/18216.29.0.1 to 216.29.63.254216.29.63.25516,382
118216.29.64.0/18216.29.64.1 to 216.29.127.254216.29.127.25516,382
119216.29.128.0/18216.29.128.1 to 216.29.191.254216.29.191.25516,382
120216.29.192.0/18216.29.192.1 to 216.29.255.254216.29.255.25516,382
121216.30.0.0/18216.30.0.1 to 216.30.63.254216.30.63.25516,382
122216.30.64.0/18216.30.64.1 to 216.30.127.254216.30.127.25516,382
123216.30.128.0/18216.30.128.1 to 216.30.191.254216.30.191.25516,382
124216.30.192.0/18216.30.192.1 to 216.30.255.254216.30.255.25516,382
125216.31.0.0/18216.31.0.1 to 216.31.63.254216.31.63.25516,382
126216.31.64.0/18216.31.64.1 to 216.31.127.254216.31.127.25516,382
127216.31.128.0/18216.31.128.1 to 216.31.191.254216.31.191.25516,382
128216.31.192.0/18216.31.192.1 to 216.31.255.254216.31.255.25516,382
129216.32.0.0/18216.32.0.1 to 216.32.63.254216.32.63.25516,382
130216.32.64.0/18216.32.64.1 to 216.32.127.254216.32.127.25516,382
131216.32.128.0/18216.32.128.1 to 216.32.191.254216.32.191.25516,382
132216.32.192.0/18216.32.192.1 to 216.32.255.254216.32.255.25516,382
133216.33.0.0/18216.33.0.1 to 216.33.63.254216.33.63.25516,382
134216.33.64.0/18216.33.64.1 to 216.33.127.254216.33.127.25516,382
135216.33.128.0/18216.33.128.1 to 216.33.191.254216.33.191.25516,382
136216.33.192.0/18216.33.192.1 to 216.33.255.254216.33.255.25516,382
137216.34.0.0/18216.34.0.1 to 216.34.63.254216.34.63.25516,382
138216.34.64.0/18216.34.64.1 to 216.34.127.254216.34.127.25516,382
139216.34.128.0/18216.34.128.1 to 216.34.191.254216.34.191.25516,382
140216.34.192.0/18216.34.192.1 to 216.34.255.254216.34.255.25516,382
141216.35.0.0/18216.35.0.1 to 216.35.63.254216.35.63.25516,382
142216.35.64.0/18216.35.64.1 to 216.35.127.254216.35.127.25516,382
143216.35.128.0/18216.35.128.1 to 216.35.191.254216.35.191.25516,382
144216.35.192.0/18216.35.192.1 to 216.35.255.254216.35.255.25516,382
145216.36.0.0/18216.36.0.1 to 216.36.63.254216.36.63.25516,382
146216.36.64.0/18216.36.64.1 to 216.36.127.254216.36.127.25516,382
147216.36.128.0/18216.36.128.1 to 216.36.191.254216.36.191.25516,382
148216.36.192.0/18216.36.192.1 to 216.36.255.254216.36.255.25516,382
149216.37.0.0/18216.37.0.1 to 216.37.63.254216.37.63.25516,382
150216.37.64.0/18216.37.64.1 to 216.37.127.254216.37.127.25516,382
151216.37.128.0/18216.37.128.1 to 216.37.191.254216.37.191.25516,382
152216.37.192.0/18216.37.192.1 to 216.37.255.254216.37.255.25516,382
153216.38.0.0/18216.38.0.1 to 216.38.63.254216.38.63.25516,382
154216.38.64.0/18216.38.64.1 to 216.38.127.254216.38.127.25516,382
155216.38.128.0/18216.38.128.1 to 216.38.191.254216.38.191.25516,382
156216.38.192.0/18216.38.192.1 to 216.38.255.254216.38.255.25516,382
157216.39.0.0/18216.39.0.1 to 216.39.63.254216.39.63.25516,382
158216.39.64.0/18216.39.64.1 to 216.39.127.254216.39.127.25516,382
159216.39.128.0/18216.39.128.1 to 216.39.191.254216.39.191.25516,382
160216.39.192.0/18216.39.192.1 to 216.39.255.254216.39.255.25516,382
161216.40.0.0/18216.40.0.1 to 216.40.63.254216.40.63.25516,382
162216.40.64.0/18216.40.64.1 to 216.40.127.254216.40.127.25516,382
163216.40.128.0/18216.40.128.1 to 216.40.191.254216.40.191.25516,382
164216.40.192.0/18216.40.192.1 to 216.40.255.254216.40.255.25516,382
165216.41.0.0/18216.41.0.1 to 216.41.63.254216.41.63.25516,382
166216.41.64.0/18216.41.64.1 to 216.41.127.254216.41.127.25516,382
167216.41.128.0/18216.41.128.1 to 216.41.191.254216.41.191.25516,382
168216.41.192.0/18216.41.192.1 to 216.41.255.254216.41.255.25516,382
169216.42.0.0/18216.42.0.1 to 216.42.63.254216.42.63.25516,382
170216.42.64.0/18216.42.64.1 to 216.42.127.254216.42.127.25516,382
171216.42.128.0/18216.42.128.1 to 216.42.191.254216.42.191.25516,382
172216.42.192.0/18216.42.192.1 to 216.42.255.254216.42.255.25516,382
173216.43.0.0/18216.43.0.1 to 216.43.63.254216.43.63.25516,382
174216.43.64.0/18216.43.64.1 to 216.43.127.254216.43.127.25516,382
175216.43.128.0/18216.43.128.1 to 216.43.191.254216.43.191.25516,382
176216.43.192.0/18216.43.192.1 to 216.43.255.254216.43.255.25516,382
177216.44.0.0/18216.44.0.1 to 216.44.63.254216.44.63.25516,382
178216.44.64.0/18216.44.64.1 to 216.44.127.254216.44.127.25516,382
179216.44.128.0/18216.44.128.1 to 216.44.191.254216.44.191.25516,382
180216.44.192.0/18216.44.192.1 to 216.44.255.254216.44.255.25516,382
181216.45.0.0/18216.45.0.1 to 216.45.63.254216.45.63.25516,382
182216.45.64.0/18216.45.64.1 to 216.45.127.254216.45.127.25516,382
183216.45.128.0/18216.45.128.1 to 216.45.191.254216.45.191.25516,382
184216.45.192.0/18216.45.192.1 to 216.45.255.254216.45.255.25516,382
185216.46.0.0/18216.46.0.1 to 216.46.63.254216.46.63.25516,382
186216.46.64.0/18216.46.64.1 to 216.46.127.254216.46.127.25516,382
187216.46.128.0/18216.46.128.1 to 216.46.191.254216.46.191.25516,382
188216.46.192.0/18216.46.192.1 to 216.46.255.254216.46.255.25516,382
189216.47.0.0/18216.47.0.1 to 216.47.63.254216.47.63.25516,382
190216.47.64.0/18216.47.64.1 to 216.47.127.254216.47.127.25516,382
191216.47.128.0/18216.47.128.1 to 216.47.191.254216.47.191.25516,382
192216.47.192.0/18216.47.192.1 to 216.47.255.254216.47.255.25516,382
193216.48.0.0/18216.48.0.1 to 216.48.63.254216.48.63.25516,382
194216.48.64.0/18216.48.64.1 to 216.48.127.254216.48.127.25516,382
195216.48.128.0/18216.48.128.1 to 216.48.191.254216.48.191.25516,382
196216.48.192.0/18216.48.192.1 to 216.48.255.254216.48.255.25516,382
197216.49.0.0/18216.49.0.1 to 216.49.63.254216.49.63.25516,382
198216.49.64.0/18216.49.64.1 to 216.49.127.254216.49.127.25516,382
199216.49.128.0/18216.49.128.1 to 216.49.191.254216.49.191.25516,382
200216.49.192.0/18216.49.192.1 to 216.49.255.254216.49.255.25516,382
201216.50.0.0/18216.50.0.1 to 216.50.63.254216.50.63.25516,382
202216.50.64.0/18216.50.64.1 to 216.50.127.254216.50.127.25516,382
203216.50.128.0/18216.50.128.1 to 216.50.191.254216.50.191.25516,382
204216.50.192.0/18216.50.192.1 to 216.50.255.254216.50.255.25516,382
205216.51.0.0/18216.51.0.1 to 216.51.63.254216.51.63.25516,382
206216.51.64.0/18216.51.64.1 to 216.51.127.254216.51.127.25516,382
207216.51.128.0/18216.51.128.1 to 216.51.191.254216.51.191.25516,382
208216.51.192.0/18216.51.192.1 to 216.51.255.254216.51.255.25516,382
209216.52.0.0/18216.52.0.1 to 216.52.63.254216.52.63.25516,382
210216.52.64.0/18216.52.64.1 to 216.52.127.254216.52.127.25516,382
211216.52.128.0/18216.52.128.1 to 216.52.191.254216.52.191.25516,382
212216.52.192.0/18216.52.192.1 to 216.52.255.254216.52.255.25516,382
213216.53.0.0/18216.53.0.1 to 216.53.63.254216.53.63.25516,382
214216.53.64.0/18216.53.64.1 to 216.53.127.254216.53.127.25516,382
215216.53.128.0/18216.53.128.1 to 216.53.191.254216.53.191.25516,382
216216.53.192.0/18216.53.192.1 to 216.53.255.254216.53.255.25516,382
217216.54.0.0/18216.54.0.1 to 216.54.63.254216.54.63.25516,382
218216.54.64.0/18216.54.64.1 to 216.54.127.254216.54.127.25516,382
219216.54.128.0/18216.54.128.1 to 216.54.191.254216.54.191.25516,382
220216.54.192.0/18216.54.192.1 to 216.54.255.254216.54.255.25516,382
221216.55.0.0/18216.55.0.1 to 216.55.63.254216.55.63.25516,382
222216.55.64.0/18216.55.64.1 to 216.55.127.254216.55.127.25516,382
223216.55.128.0/18216.55.128.1 to 216.55.191.254216.55.191.25516,382
224216.55.192.0/18216.55.192.1 to 216.55.255.254216.55.255.25516,382
225216.56.0.0/18216.56.0.1 to 216.56.63.254216.56.63.25516,382
226216.56.64.0/18216.56.64.1 to 216.56.127.254216.56.127.25516,382
227216.56.128.0/18216.56.128.1 to 216.56.191.254216.56.191.25516,382
228216.56.192.0/18216.56.192.1 to 216.56.255.254216.56.255.25516,382
229216.57.0.0/18216.57.0.1 to 216.57.63.254216.57.63.25516,382
230216.57.64.0/18216.57.64.1 to 216.57.127.254216.57.127.25516,382
231216.57.128.0/18216.57.128.1 to 216.57.191.254216.57.191.25516,382
232216.57.192.0/18216.57.192.1 to 216.57.255.254216.57.255.25516,382
233216.58.0.0/18216.58.0.1 to 216.58.63.254216.58.63.25516,382
234216.58.64.0/18216.58.64.1 to 216.58.127.254216.58.127.25516,382
235216.58.128.0/18216.58.128.1 to 216.58.191.254216.58.191.25516,382
236216.58.192.0/18216.58.192.1 to 216.58.255.254216.58.255.25516,382
237216.59.0.0/18216.59.0.1 to 216.59.63.254216.59.63.25516,382
238216.59.64.0/18216.59.64.1 to 216.59.127.254216.59.127.25516,382
239216.59.128.0/18216.59.128.1 to 216.59.191.254216.59.191.25516,382
240216.59.192.0/18216.59.192.1 to 216.59.255.254216.59.255.25516,382
241216.60.0.0/18216.60.0.1 to 216.60.63.254216.60.63.25516,382
242216.60.64.0/18216.60.64.1 to 216.60.127.254216.60.127.25516,382
243216.60.128.0/18216.60.128.1 to 216.60.191.254216.60.191.25516,382
244216.60.192.0/18216.60.192.1 to 216.60.255.254216.60.255.25516,382
245216.61.0.0/18216.61.0.1 to 216.61.63.254216.61.63.25516,382
246216.61.64.0/18216.61.64.1 to 216.61.127.254216.61.127.25516,382
247216.61.128.0/18216.61.128.1 to 216.61.191.254216.61.191.25516,382
248216.61.192.0/18216.61.192.1 to 216.61.255.254216.61.255.25516,382
249216.62.0.0/18216.62.0.1 to 216.62.63.254216.62.63.25516,382
250216.62.64.0/18216.62.64.1 to 216.62.127.254216.62.127.25516,382
251216.62.128.0/18216.62.128.1 to 216.62.191.254216.62.191.25516,382
252216.62.192.0/18216.62.192.1 to 216.62.255.254216.62.255.25516,382
253216.63.0.0/18216.63.0.1 to 216.63.63.254216.63.63.25516,382
254216.63.64.0/18216.63.64.1 to 216.63.127.254216.63.127.25516,382
255216.63.128.0/18216.63.128.1 to 216.63.191.254216.63.191.25516,382
256216.63.192.0/18216.63.192.1 to 216.63.255.254216.63.255.25516,382

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.