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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.

Network217.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
217.0.0.0
Broadcast address
217.255.255.255
First usable
217.0.0.1
Last usable
217.255.255.254
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
C (default /24)
As numbers
Hex D9000000 · Integer 3640655872 to 3657433087
Reverse DNS zone
217.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011001..00000000.00000000.00000000217.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11011001..00000000.00000000.00000000217.0.0.0
Broadcast11011001..11111111.11111111.11111111217.255.255.255
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)

217.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1217.0.0.0/18217.0.0.1 to 217.0.63.254217.0.63.25516,382
2217.0.64.0/18217.0.64.1 to 217.0.127.254217.0.127.25516,382
3217.0.128.0/18217.0.128.1 to 217.0.191.254217.0.191.25516,382
4217.0.192.0/18217.0.192.1 to 217.0.255.254217.0.255.25516,382
5217.1.0.0/18217.1.0.1 to 217.1.63.254217.1.63.25516,382
6217.1.64.0/18217.1.64.1 to 217.1.127.254217.1.127.25516,382
7217.1.128.0/18217.1.128.1 to 217.1.191.254217.1.191.25516,382
8217.1.192.0/18217.1.192.1 to 217.1.255.254217.1.255.25516,382
9217.2.0.0/18217.2.0.1 to 217.2.63.254217.2.63.25516,382
10217.2.64.0/18217.2.64.1 to 217.2.127.254217.2.127.25516,382
11217.2.128.0/18217.2.128.1 to 217.2.191.254217.2.191.25516,382
12217.2.192.0/18217.2.192.1 to 217.2.255.254217.2.255.25516,382
13217.3.0.0/18217.3.0.1 to 217.3.63.254217.3.63.25516,382
14217.3.64.0/18217.3.64.1 to 217.3.127.254217.3.127.25516,382
15217.3.128.0/18217.3.128.1 to 217.3.191.254217.3.191.25516,382
16217.3.192.0/18217.3.192.1 to 217.3.255.254217.3.255.25516,382
17217.4.0.0/18217.4.0.1 to 217.4.63.254217.4.63.25516,382
18217.4.64.0/18217.4.64.1 to 217.4.127.254217.4.127.25516,382
19217.4.128.0/18217.4.128.1 to 217.4.191.254217.4.191.25516,382
20217.4.192.0/18217.4.192.1 to 217.4.255.254217.4.255.25516,382
21217.5.0.0/18217.5.0.1 to 217.5.63.254217.5.63.25516,382
22217.5.64.0/18217.5.64.1 to 217.5.127.254217.5.127.25516,382
23217.5.128.0/18217.5.128.1 to 217.5.191.254217.5.191.25516,382
24217.5.192.0/18217.5.192.1 to 217.5.255.254217.5.255.25516,382
25217.6.0.0/18217.6.0.1 to 217.6.63.254217.6.63.25516,382
26217.6.64.0/18217.6.64.1 to 217.6.127.254217.6.127.25516,382
27217.6.128.0/18217.6.128.1 to 217.6.191.254217.6.191.25516,382
28217.6.192.0/18217.6.192.1 to 217.6.255.254217.6.255.25516,382
29217.7.0.0/18217.7.0.1 to 217.7.63.254217.7.63.25516,382
30217.7.64.0/18217.7.64.1 to 217.7.127.254217.7.127.25516,382
31217.7.128.0/18217.7.128.1 to 217.7.191.254217.7.191.25516,382
32217.7.192.0/18217.7.192.1 to 217.7.255.254217.7.255.25516,382
33217.8.0.0/18217.8.0.1 to 217.8.63.254217.8.63.25516,382
34217.8.64.0/18217.8.64.1 to 217.8.127.254217.8.127.25516,382
35217.8.128.0/18217.8.128.1 to 217.8.191.254217.8.191.25516,382
36217.8.192.0/18217.8.192.1 to 217.8.255.254217.8.255.25516,382
37217.9.0.0/18217.9.0.1 to 217.9.63.254217.9.63.25516,382
38217.9.64.0/18217.9.64.1 to 217.9.127.254217.9.127.25516,382
39217.9.128.0/18217.9.128.1 to 217.9.191.254217.9.191.25516,382
40217.9.192.0/18217.9.192.1 to 217.9.255.254217.9.255.25516,382
41217.10.0.0/18217.10.0.1 to 217.10.63.254217.10.63.25516,382
42217.10.64.0/18217.10.64.1 to 217.10.127.254217.10.127.25516,382
43217.10.128.0/18217.10.128.1 to 217.10.191.254217.10.191.25516,382
44217.10.192.0/18217.10.192.1 to 217.10.255.254217.10.255.25516,382
45217.11.0.0/18217.11.0.1 to 217.11.63.254217.11.63.25516,382
46217.11.64.0/18217.11.64.1 to 217.11.127.254217.11.127.25516,382
47217.11.128.0/18217.11.128.1 to 217.11.191.254217.11.191.25516,382
48217.11.192.0/18217.11.192.1 to 217.11.255.254217.11.255.25516,382
49217.12.0.0/18217.12.0.1 to 217.12.63.254217.12.63.25516,382
50217.12.64.0/18217.12.64.1 to 217.12.127.254217.12.127.25516,382
51217.12.128.0/18217.12.128.1 to 217.12.191.254217.12.191.25516,382
52217.12.192.0/18217.12.192.1 to 217.12.255.254217.12.255.25516,382
53217.13.0.0/18217.13.0.1 to 217.13.63.254217.13.63.25516,382
54217.13.64.0/18217.13.64.1 to 217.13.127.254217.13.127.25516,382
55217.13.128.0/18217.13.128.1 to 217.13.191.254217.13.191.25516,382
56217.13.192.0/18217.13.192.1 to 217.13.255.254217.13.255.25516,382
57217.14.0.0/18217.14.0.1 to 217.14.63.254217.14.63.25516,382
58217.14.64.0/18217.14.64.1 to 217.14.127.254217.14.127.25516,382
59217.14.128.0/18217.14.128.1 to 217.14.191.254217.14.191.25516,382
60217.14.192.0/18217.14.192.1 to 217.14.255.254217.14.255.25516,382
61217.15.0.0/18217.15.0.1 to 217.15.63.254217.15.63.25516,382
62217.15.64.0/18217.15.64.1 to 217.15.127.254217.15.127.25516,382
63217.15.128.0/18217.15.128.1 to 217.15.191.254217.15.191.25516,382
64217.15.192.0/18217.15.192.1 to 217.15.255.254217.15.255.25516,382
65217.16.0.0/18217.16.0.1 to 217.16.63.254217.16.63.25516,382
66217.16.64.0/18217.16.64.1 to 217.16.127.254217.16.127.25516,382
67217.16.128.0/18217.16.128.1 to 217.16.191.254217.16.191.25516,382
68217.16.192.0/18217.16.192.1 to 217.16.255.254217.16.255.25516,382
69217.17.0.0/18217.17.0.1 to 217.17.63.254217.17.63.25516,382
70217.17.64.0/18217.17.64.1 to 217.17.127.254217.17.127.25516,382
71217.17.128.0/18217.17.128.1 to 217.17.191.254217.17.191.25516,382
72217.17.192.0/18217.17.192.1 to 217.17.255.254217.17.255.25516,382
73217.18.0.0/18217.18.0.1 to 217.18.63.254217.18.63.25516,382
74217.18.64.0/18217.18.64.1 to 217.18.127.254217.18.127.25516,382
75217.18.128.0/18217.18.128.1 to 217.18.191.254217.18.191.25516,382
76217.18.192.0/18217.18.192.1 to 217.18.255.254217.18.255.25516,382
77217.19.0.0/18217.19.0.1 to 217.19.63.254217.19.63.25516,382
78217.19.64.0/18217.19.64.1 to 217.19.127.254217.19.127.25516,382
79217.19.128.0/18217.19.128.1 to 217.19.191.254217.19.191.25516,382
80217.19.192.0/18217.19.192.1 to 217.19.255.254217.19.255.25516,382
81217.20.0.0/18217.20.0.1 to 217.20.63.254217.20.63.25516,382
82217.20.64.0/18217.20.64.1 to 217.20.127.254217.20.127.25516,382
83217.20.128.0/18217.20.128.1 to 217.20.191.254217.20.191.25516,382
84217.20.192.0/18217.20.192.1 to 217.20.255.254217.20.255.25516,382
85217.21.0.0/18217.21.0.1 to 217.21.63.254217.21.63.25516,382
86217.21.64.0/18217.21.64.1 to 217.21.127.254217.21.127.25516,382
87217.21.128.0/18217.21.128.1 to 217.21.191.254217.21.191.25516,382
88217.21.192.0/18217.21.192.1 to 217.21.255.254217.21.255.25516,382
89217.22.0.0/18217.22.0.1 to 217.22.63.254217.22.63.25516,382
90217.22.64.0/18217.22.64.1 to 217.22.127.254217.22.127.25516,382
91217.22.128.0/18217.22.128.1 to 217.22.191.254217.22.191.25516,382
92217.22.192.0/18217.22.192.1 to 217.22.255.254217.22.255.25516,382
93217.23.0.0/18217.23.0.1 to 217.23.63.254217.23.63.25516,382
94217.23.64.0/18217.23.64.1 to 217.23.127.254217.23.127.25516,382
95217.23.128.0/18217.23.128.1 to 217.23.191.254217.23.191.25516,382
96217.23.192.0/18217.23.192.1 to 217.23.255.254217.23.255.25516,382
97217.24.0.0/18217.24.0.1 to 217.24.63.254217.24.63.25516,382
98217.24.64.0/18217.24.64.1 to 217.24.127.254217.24.127.25516,382
99217.24.128.0/18217.24.128.1 to 217.24.191.254217.24.191.25516,382
100217.24.192.0/18217.24.192.1 to 217.24.255.254217.24.255.25516,382
101217.25.0.0/18217.25.0.1 to 217.25.63.254217.25.63.25516,382
102217.25.64.0/18217.25.64.1 to 217.25.127.254217.25.127.25516,382
103217.25.128.0/18217.25.128.1 to 217.25.191.254217.25.191.25516,382
104217.25.192.0/18217.25.192.1 to 217.25.255.254217.25.255.25516,382
105217.26.0.0/18217.26.0.1 to 217.26.63.254217.26.63.25516,382
106217.26.64.0/18217.26.64.1 to 217.26.127.254217.26.127.25516,382
107217.26.128.0/18217.26.128.1 to 217.26.191.254217.26.191.25516,382
108217.26.192.0/18217.26.192.1 to 217.26.255.254217.26.255.25516,382
109217.27.0.0/18217.27.0.1 to 217.27.63.254217.27.63.25516,382
110217.27.64.0/18217.27.64.1 to 217.27.127.254217.27.127.25516,382
111217.27.128.0/18217.27.128.1 to 217.27.191.254217.27.191.25516,382
112217.27.192.0/18217.27.192.1 to 217.27.255.254217.27.255.25516,382
113217.28.0.0/18217.28.0.1 to 217.28.63.254217.28.63.25516,382
114217.28.64.0/18217.28.64.1 to 217.28.127.254217.28.127.25516,382
115217.28.128.0/18217.28.128.1 to 217.28.191.254217.28.191.25516,382
116217.28.192.0/18217.28.192.1 to 217.28.255.254217.28.255.25516,382
117217.29.0.0/18217.29.0.1 to 217.29.63.254217.29.63.25516,382
118217.29.64.0/18217.29.64.1 to 217.29.127.254217.29.127.25516,382
119217.29.128.0/18217.29.128.1 to 217.29.191.254217.29.191.25516,382
120217.29.192.0/18217.29.192.1 to 217.29.255.254217.29.255.25516,382
121217.30.0.0/18217.30.0.1 to 217.30.63.254217.30.63.25516,382
122217.30.64.0/18217.30.64.1 to 217.30.127.254217.30.127.25516,382
123217.30.128.0/18217.30.128.1 to 217.30.191.254217.30.191.25516,382
124217.30.192.0/18217.30.192.1 to 217.30.255.254217.30.255.25516,382
125217.31.0.0/18217.31.0.1 to 217.31.63.254217.31.63.25516,382
126217.31.64.0/18217.31.64.1 to 217.31.127.254217.31.127.25516,382
127217.31.128.0/18217.31.128.1 to 217.31.191.254217.31.191.25516,382
128217.31.192.0/18217.31.192.1 to 217.31.255.254217.31.255.25516,382
129217.32.0.0/18217.32.0.1 to 217.32.63.254217.32.63.25516,382
130217.32.64.0/18217.32.64.1 to 217.32.127.254217.32.127.25516,382
131217.32.128.0/18217.32.128.1 to 217.32.191.254217.32.191.25516,382
132217.32.192.0/18217.32.192.1 to 217.32.255.254217.32.255.25516,382
133217.33.0.0/18217.33.0.1 to 217.33.63.254217.33.63.25516,382
134217.33.64.0/18217.33.64.1 to 217.33.127.254217.33.127.25516,382
135217.33.128.0/18217.33.128.1 to 217.33.191.254217.33.191.25516,382
136217.33.192.0/18217.33.192.1 to 217.33.255.254217.33.255.25516,382
137217.34.0.0/18217.34.0.1 to 217.34.63.254217.34.63.25516,382
138217.34.64.0/18217.34.64.1 to 217.34.127.254217.34.127.25516,382
139217.34.128.0/18217.34.128.1 to 217.34.191.254217.34.191.25516,382
140217.34.192.0/18217.34.192.1 to 217.34.255.254217.34.255.25516,382
141217.35.0.0/18217.35.0.1 to 217.35.63.254217.35.63.25516,382
142217.35.64.0/18217.35.64.1 to 217.35.127.254217.35.127.25516,382
143217.35.128.0/18217.35.128.1 to 217.35.191.254217.35.191.25516,382
144217.35.192.0/18217.35.192.1 to 217.35.255.254217.35.255.25516,382
145217.36.0.0/18217.36.0.1 to 217.36.63.254217.36.63.25516,382
146217.36.64.0/18217.36.64.1 to 217.36.127.254217.36.127.25516,382
147217.36.128.0/18217.36.128.1 to 217.36.191.254217.36.191.25516,382
148217.36.192.0/18217.36.192.1 to 217.36.255.254217.36.255.25516,382
149217.37.0.0/18217.37.0.1 to 217.37.63.254217.37.63.25516,382
150217.37.64.0/18217.37.64.1 to 217.37.127.254217.37.127.25516,382
151217.37.128.0/18217.37.128.1 to 217.37.191.254217.37.191.25516,382
152217.37.192.0/18217.37.192.1 to 217.37.255.254217.37.255.25516,382
153217.38.0.0/18217.38.0.1 to 217.38.63.254217.38.63.25516,382
154217.38.64.0/18217.38.64.1 to 217.38.127.254217.38.127.25516,382
155217.38.128.0/18217.38.128.1 to 217.38.191.254217.38.191.25516,382
156217.38.192.0/18217.38.192.1 to 217.38.255.254217.38.255.25516,382
157217.39.0.0/18217.39.0.1 to 217.39.63.254217.39.63.25516,382
158217.39.64.0/18217.39.64.1 to 217.39.127.254217.39.127.25516,382
159217.39.128.0/18217.39.128.1 to 217.39.191.254217.39.191.25516,382
160217.39.192.0/18217.39.192.1 to 217.39.255.254217.39.255.25516,382
161217.40.0.0/18217.40.0.1 to 217.40.63.254217.40.63.25516,382
162217.40.64.0/18217.40.64.1 to 217.40.127.254217.40.127.25516,382
163217.40.128.0/18217.40.128.1 to 217.40.191.254217.40.191.25516,382
164217.40.192.0/18217.40.192.1 to 217.40.255.254217.40.255.25516,382
165217.41.0.0/18217.41.0.1 to 217.41.63.254217.41.63.25516,382
166217.41.64.0/18217.41.64.1 to 217.41.127.254217.41.127.25516,382
167217.41.128.0/18217.41.128.1 to 217.41.191.254217.41.191.25516,382
168217.41.192.0/18217.41.192.1 to 217.41.255.254217.41.255.25516,382
169217.42.0.0/18217.42.0.1 to 217.42.63.254217.42.63.25516,382
170217.42.64.0/18217.42.64.1 to 217.42.127.254217.42.127.25516,382
171217.42.128.0/18217.42.128.1 to 217.42.191.254217.42.191.25516,382
172217.42.192.0/18217.42.192.1 to 217.42.255.254217.42.255.25516,382
173217.43.0.0/18217.43.0.1 to 217.43.63.254217.43.63.25516,382
174217.43.64.0/18217.43.64.1 to 217.43.127.254217.43.127.25516,382
175217.43.128.0/18217.43.128.1 to 217.43.191.254217.43.191.25516,382
176217.43.192.0/18217.43.192.1 to 217.43.255.254217.43.255.25516,382
177217.44.0.0/18217.44.0.1 to 217.44.63.254217.44.63.25516,382
178217.44.64.0/18217.44.64.1 to 217.44.127.254217.44.127.25516,382
179217.44.128.0/18217.44.128.1 to 217.44.191.254217.44.191.25516,382
180217.44.192.0/18217.44.192.1 to 217.44.255.254217.44.255.25516,382
181217.45.0.0/18217.45.0.1 to 217.45.63.254217.45.63.25516,382
182217.45.64.0/18217.45.64.1 to 217.45.127.254217.45.127.25516,382
183217.45.128.0/18217.45.128.1 to 217.45.191.254217.45.191.25516,382
184217.45.192.0/18217.45.192.1 to 217.45.255.254217.45.255.25516,382
185217.46.0.0/18217.46.0.1 to 217.46.63.254217.46.63.25516,382
186217.46.64.0/18217.46.64.1 to 217.46.127.254217.46.127.25516,382
187217.46.128.0/18217.46.128.1 to 217.46.191.254217.46.191.25516,382
188217.46.192.0/18217.46.192.1 to 217.46.255.254217.46.255.25516,382
189217.47.0.0/18217.47.0.1 to 217.47.63.254217.47.63.25516,382
190217.47.64.0/18217.47.64.1 to 217.47.127.254217.47.127.25516,382
191217.47.128.0/18217.47.128.1 to 217.47.191.254217.47.191.25516,382
192217.47.192.0/18217.47.192.1 to 217.47.255.254217.47.255.25516,382
193217.48.0.0/18217.48.0.1 to 217.48.63.254217.48.63.25516,382
194217.48.64.0/18217.48.64.1 to 217.48.127.254217.48.127.25516,382
195217.48.128.0/18217.48.128.1 to 217.48.191.254217.48.191.25516,382
196217.48.192.0/18217.48.192.1 to 217.48.255.254217.48.255.25516,382
197217.49.0.0/18217.49.0.1 to 217.49.63.254217.49.63.25516,382
198217.49.64.0/18217.49.64.1 to 217.49.127.254217.49.127.25516,382
199217.49.128.0/18217.49.128.1 to 217.49.191.254217.49.191.25516,382
200217.49.192.0/18217.49.192.1 to 217.49.255.254217.49.255.25516,382
201217.50.0.0/18217.50.0.1 to 217.50.63.254217.50.63.25516,382
202217.50.64.0/18217.50.64.1 to 217.50.127.254217.50.127.25516,382
203217.50.128.0/18217.50.128.1 to 217.50.191.254217.50.191.25516,382
204217.50.192.0/18217.50.192.1 to 217.50.255.254217.50.255.25516,382
205217.51.0.0/18217.51.0.1 to 217.51.63.254217.51.63.25516,382
206217.51.64.0/18217.51.64.1 to 217.51.127.254217.51.127.25516,382
207217.51.128.0/18217.51.128.1 to 217.51.191.254217.51.191.25516,382
208217.51.192.0/18217.51.192.1 to 217.51.255.254217.51.255.25516,382
209217.52.0.0/18217.52.0.1 to 217.52.63.254217.52.63.25516,382
210217.52.64.0/18217.52.64.1 to 217.52.127.254217.52.127.25516,382
211217.52.128.0/18217.52.128.1 to 217.52.191.254217.52.191.25516,382
212217.52.192.0/18217.52.192.1 to 217.52.255.254217.52.255.25516,382
213217.53.0.0/18217.53.0.1 to 217.53.63.254217.53.63.25516,382
214217.53.64.0/18217.53.64.1 to 217.53.127.254217.53.127.25516,382
215217.53.128.0/18217.53.128.1 to 217.53.191.254217.53.191.25516,382
216217.53.192.0/18217.53.192.1 to 217.53.255.254217.53.255.25516,382
217217.54.0.0/18217.54.0.1 to 217.54.63.254217.54.63.25516,382
218217.54.64.0/18217.54.64.1 to 217.54.127.254217.54.127.25516,382
219217.54.128.0/18217.54.128.1 to 217.54.191.254217.54.191.25516,382
220217.54.192.0/18217.54.192.1 to 217.54.255.254217.54.255.25516,382
221217.55.0.0/18217.55.0.1 to 217.55.63.254217.55.63.25516,382
222217.55.64.0/18217.55.64.1 to 217.55.127.254217.55.127.25516,382
223217.55.128.0/18217.55.128.1 to 217.55.191.254217.55.191.25516,382
224217.55.192.0/18217.55.192.1 to 217.55.255.254217.55.255.25516,382
225217.56.0.0/18217.56.0.1 to 217.56.63.254217.56.63.25516,382
226217.56.64.0/18217.56.64.1 to 217.56.127.254217.56.127.25516,382
227217.56.128.0/18217.56.128.1 to 217.56.191.254217.56.191.25516,382
228217.56.192.0/18217.56.192.1 to 217.56.255.254217.56.255.25516,382
229217.57.0.0/18217.57.0.1 to 217.57.63.254217.57.63.25516,382
230217.57.64.0/18217.57.64.1 to 217.57.127.254217.57.127.25516,382
231217.57.128.0/18217.57.128.1 to 217.57.191.254217.57.191.25516,382
232217.57.192.0/18217.57.192.1 to 217.57.255.254217.57.255.25516,382
233217.58.0.0/18217.58.0.1 to 217.58.63.254217.58.63.25516,382
234217.58.64.0/18217.58.64.1 to 217.58.127.254217.58.127.25516,382
235217.58.128.0/18217.58.128.1 to 217.58.191.254217.58.191.25516,382
236217.58.192.0/18217.58.192.1 to 217.58.255.254217.58.255.25516,382
237217.59.0.0/18217.59.0.1 to 217.59.63.254217.59.63.25516,382
238217.59.64.0/18217.59.64.1 to 217.59.127.254217.59.127.25516,382
239217.59.128.0/18217.59.128.1 to 217.59.191.254217.59.191.25516,382
240217.59.192.0/18217.59.192.1 to 217.59.255.254217.59.255.25516,382
241217.60.0.0/18217.60.0.1 to 217.60.63.254217.60.63.25516,382
242217.60.64.0/18217.60.64.1 to 217.60.127.254217.60.127.25516,382
243217.60.128.0/18217.60.128.1 to 217.60.191.254217.60.191.25516,382
244217.60.192.0/18217.60.192.1 to 217.60.255.254217.60.255.25516,382
245217.61.0.0/18217.61.0.1 to 217.61.63.254217.61.63.25516,382
246217.61.64.0/18217.61.64.1 to 217.61.127.254217.61.127.25516,382
247217.61.128.0/18217.61.128.1 to 217.61.191.254217.61.191.25516,382
248217.61.192.0/18217.61.192.1 to 217.61.255.254217.61.255.25516,382
249217.62.0.0/18217.62.0.1 to 217.62.63.254217.62.63.25516,382
250217.62.64.0/18217.62.64.1 to 217.62.127.254217.62.127.25516,382
251217.62.128.0/18217.62.128.1 to 217.62.191.254217.62.191.25516,382
252217.62.192.0/18217.62.192.1 to 217.62.255.254217.62.255.25516,382
253217.63.0.0/18217.63.0.1 to 217.63.63.254217.63.63.25516,382
254217.63.64.0/18217.63.64.1 to 217.63.127.254217.63.127.25516,382
255217.63.128.0/18217.63.128.1 to 217.63.191.254217.63.191.25516,382
256217.63.192.0/18217.63.192.1 to 217.63.255.254217.63.255.25516,382

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.