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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/20
/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 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1217.0.0.0/20217.0.0.1 to 217.0.15.254217.0.15.2554,094
2217.0.16.0/20217.0.16.1 to 217.0.31.254217.0.31.2554,094
3217.0.32.0/20217.0.32.1 to 217.0.47.254217.0.47.2554,094
4217.0.48.0/20217.0.48.1 to 217.0.63.254217.0.63.2554,094
5217.0.64.0/20217.0.64.1 to 217.0.79.254217.0.79.2554,094
6217.0.80.0/20217.0.80.1 to 217.0.95.254217.0.95.2554,094
7217.0.96.0/20217.0.96.1 to 217.0.111.254217.0.111.2554,094
8217.0.112.0/20217.0.112.1 to 217.0.127.254217.0.127.2554,094
9217.0.128.0/20217.0.128.1 to 217.0.143.254217.0.143.2554,094
10217.0.144.0/20217.0.144.1 to 217.0.159.254217.0.159.2554,094
11217.0.160.0/20217.0.160.1 to 217.0.175.254217.0.175.2554,094
12217.0.176.0/20217.0.176.1 to 217.0.191.254217.0.191.2554,094
13217.0.192.0/20217.0.192.1 to 217.0.207.254217.0.207.2554,094
14217.0.208.0/20217.0.208.1 to 217.0.223.254217.0.223.2554,094
15217.0.224.0/20217.0.224.1 to 217.0.239.254217.0.239.2554,094
16217.0.240.0/20217.0.240.1 to 217.0.255.254217.0.255.2554,094
17217.1.0.0/20217.1.0.1 to 217.1.15.254217.1.15.2554,094
18217.1.16.0/20217.1.16.1 to 217.1.31.254217.1.31.2554,094
19217.1.32.0/20217.1.32.1 to 217.1.47.254217.1.47.2554,094
20217.1.48.0/20217.1.48.1 to 217.1.63.254217.1.63.2554,094
21217.1.64.0/20217.1.64.1 to 217.1.79.254217.1.79.2554,094
22217.1.80.0/20217.1.80.1 to 217.1.95.254217.1.95.2554,094
23217.1.96.0/20217.1.96.1 to 217.1.111.254217.1.111.2554,094
24217.1.112.0/20217.1.112.1 to 217.1.127.254217.1.127.2554,094
25217.1.128.0/20217.1.128.1 to 217.1.143.254217.1.143.2554,094
26217.1.144.0/20217.1.144.1 to 217.1.159.254217.1.159.2554,094
27217.1.160.0/20217.1.160.1 to 217.1.175.254217.1.175.2554,094
28217.1.176.0/20217.1.176.1 to 217.1.191.254217.1.191.2554,094
29217.1.192.0/20217.1.192.1 to 217.1.207.254217.1.207.2554,094
30217.1.208.0/20217.1.208.1 to 217.1.223.254217.1.223.2554,094
31217.1.224.0/20217.1.224.1 to 217.1.239.254217.1.239.2554,094
32217.1.240.0/20217.1.240.1 to 217.1.255.254217.1.255.2554,094
33217.2.0.0/20217.2.0.1 to 217.2.15.254217.2.15.2554,094
34217.2.16.0/20217.2.16.1 to 217.2.31.254217.2.31.2554,094
35217.2.32.0/20217.2.32.1 to 217.2.47.254217.2.47.2554,094
36217.2.48.0/20217.2.48.1 to 217.2.63.254217.2.63.2554,094
37217.2.64.0/20217.2.64.1 to 217.2.79.254217.2.79.2554,094
38217.2.80.0/20217.2.80.1 to 217.2.95.254217.2.95.2554,094
39217.2.96.0/20217.2.96.1 to 217.2.111.254217.2.111.2554,094
40217.2.112.0/20217.2.112.1 to 217.2.127.254217.2.127.2554,094
41217.2.128.0/20217.2.128.1 to 217.2.143.254217.2.143.2554,094
42217.2.144.0/20217.2.144.1 to 217.2.159.254217.2.159.2554,094
43217.2.160.0/20217.2.160.1 to 217.2.175.254217.2.175.2554,094
44217.2.176.0/20217.2.176.1 to 217.2.191.254217.2.191.2554,094
45217.2.192.0/20217.2.192.1 to 217.2.207.254217.2.207.2554,094
46217.2.208.0/20217.2.208.1 to 217.2.223.254217.2.223.2554,094
47217.2.224.0/20217.2.224.1 to 217.2.239.254217.2.239.2554,094
48217.2.240.0/20217.2.240.1 to 217.2.255.254217.2.255.2554,094
49217.3.0.0/20217.3.0.1 to 217.3.15.254217.3.15.2554,094
50217.3.16.0/20217.3.16.1 to 217.3.31.254217.3.31.2554,094
51217.3.32.0/20217.3.32.1 to 217.3.47.254217.3.47.2554,094
52217.3.48.0/20217.3.48.1 to 217.3.63.254217.3.63.2554,094
53217.3.64.0/20217.3.64.1 to 217.3.79.254217.3.79.2554,094
54217.3.80.0/20217.3.80.1 to 217.3.95.254217.3.95.2554,094
55217.3.96.0/20217.3.96.1 to 217.3.111.254217.3.111.2554,094
56217.3.112.0/20217.3.112.1 to 217.3.127.254217.3.127.2554,094
57217.3.128.0/20217.3.128.1 to 217.3.143.254217.3.143.2554,094
58217.3.144.0/20217.3.144.1 to 217.3.159.254217.3.159.2554,094
59217.3.160.0/20217.3.160.1 to 217.3.175.254217.3.175.2554,094
60217.3.176.0/20217.3.176.1 to 217.3.191.254217.3.191.2554,094
61217.3.192.0/20217.3.192.1 to 217.3.207.254217.3.207.2554,094
62217.3.208.0/20217.3.208.1 to 217.3.223.254217.3.223.2554,094
63217.3.224.0/20217.3.224.1 to 217.3.239.254217.3.239.2554,094
64217.3.240.0/20217.3.240.1 to 217.3.255.254217.3.255.2554,094
65217.4.0.0/20217.4.0.1 to 217.4.15.254217.4.15.2554,094
66217.4.16.0/20217.4.16.1 to 217.4.31.254217.4.31.2554,094
67217.4.32.0/20217.4.32.1 to 217.4.47.254217.4.47.2554,094
68217.4.48.0/20217.4.48.1 to 217.4.63.254217.4.63.2554,094
69217.4.64.0/20217.4.64.1 to 217.4.79.254217.4.79.2554,094
70217.4.80.0/20217.4.80.1 to 217.4.95.254217.4.95.2554,094
71217.4.96.0/20217.4.96.1 to 217.4.111.254217.4.111.2554,094
72217.4.112.0/20217.4.112.1 to 217.4.127.254217.4.127.2554,094
73217.4.128.0/20217.4.128.1 to 217.4.143.254217.4.143.2554,094
74217.4.144.0/20217.4.144.1 to 217.4.159.254217.4.159.2554,094
75217.4.160.0/20217.4.160.1 to 217.4.175.254217.4.175.2554,094
76217.4.176.0/20217.4.176.1 to 217.4.191.254217.4.191.2554,094
77217.4.192.0/20217.4.192.1 to 217.4.207.254217.4.207.2554,094
78217.4.208.0/20217.4.208.1 to 217.4.223.254217.4.223.2554,094
79217.4.224.0/20217.4.224.1 to 217.4.239.254217.4.239.2554,094
80217.4.240.0/20217.4.240.1 to 217.4.255.254217.4.255.2554,094
81217.5.0.0/20217.5.0.1 to 217.5.15.254217.5.15.2554,094
82217.5.16.0/20217.5.16.1 to 217.5.31.254217.5.31.2554,094
83217.5.32.0/20217.5.32.1 to 217.5.47.254217.5.47.2554,094
84217.5.48.0/20217.5.48.1 to 217.5.63.254217.5.63.2554,094
85217.5.64.0/20217.5.64.1 to 217.5.79.254217.5.79.2554,094
86217.5.80.0/20217.5.80.1 to 217.5.95.254217.5.95.2554,094
87217.5.96.0/20217.5.96.1 to 217.5.111.254217.5.111.2554,094
88217.5.112.0/20217.5.112.1 to 217.5.127.254217.5.127.2554,094
89217.5.128.0/20217.5.128.1 to 217.5.143.254217.5.143.2554,094
90217.5.144.0/20217.5.144.1 to 217.5.159.254217.5.159.2554,094
91217.5.160.0/20217.5.160.1 to 217.5.175.254217.5.175.2554,094
92217.5.176.0/20217.5.176.1 to 217.5.191.254217.5.191.2554,094
93217.5.192.0/20217.5.192.1 to 217.5.207.254217.5.207.2554,094
94217.5.208.0/20217.5.208.1 to 217.5.223.254217.5.223.2554,094
95217.5.224.0/20217.5.224.1 to 217.5.239.254217.5.239.2554,094
96217.5.240.0/20217.5.240.1 to 217.5.255.254217.5.255.2554,094
97217.6.0.0/20217.6.0.1 to 217.6.15.254217.6.15.2554,094
98217.6.16.0/20217.6.16.1 to 217.6.31.254217.6.31.2554,094
99217.6.32.0/20217.6.32.1 to 217.6.47.254217.6.47.2554,094
100217.6.48.0/20217.6.48.1 to 217.6.63.254217.6.63.2554,094
101217.6.64.0/20217.6.64.1 to 217.6.79.254217.6.79.2554,094
102217.6.80.0/20217.6.80.1 to 217.6.95.254217.6.95.2554,094
103217.6.96.0/20217.6.96.1 to 217.6.111.254217.6.111.2554,094
104217.6.112.0/20217.6.112.1 to 217.6.127.254217.6.127.2554,094
105217.6.128.0/20217.6.128.1 to 217.6.143.254217.6.143.2554,094
106217.6.144.0/20217.6.144.1 to 217.6.159.254217.6.159.2554,094
107217.6.160.0/20217.6.160.1 to 217.6.175.254217.6.175.2554,094
108217.6.176.0/20217.6.176.1 to 217.6.191.254217.6.191.2554,094
109217.6.192.0/20217.6.192.1 to 217.6.207.254217.6.207.2554,094
110217.6.208.0/20217.6.208.1 to 217.6.223.254217.6.223.2554,094
111217.6.224.0/20217.6.224.1 to 217.6.239.254217.6.239.2554,094
112217.6.240.0/20217.6.240.1 to 217.6.255.254217.6.255.2554,094
113217.7.0.0/20217.7.0.1 to 217.7.15.254217.7.15.2554,094
114217.7.16.0/20217.7.16.1 to 217.7.31.254217.7.31.2554,094
115217.7.32.0/20217.7.32.1 to 217.7.47.254217.7.47.2554,094
116217.7.48.0/20217.7.48.1 to 217.7.63.254217.7.63.2554,094
117217.7.64.0/20217.7.64.1 to 217.7.79.254217.7.79.2554,094
118217.7.80.0/20217.7.80.1 to 217.7.95.254217.7.95.2554,094
119217.7.96.0/20217.7.96.1 to 217.7.111.254217.7.111.2554,094
120217.7.112.0/20217.7.112.1 to 217.7.127.254217.7.127.2554,094
121217.7.128.0/20217.7.128.1 to 217.7.143.254217.7.143.2554,094
122217.7.144.0/20217.7.144.1 to 217.7.159.254217.7.159.2554,094
123217.7.160.0/20217.7.160.1 to 217.7.175.254217.7.175.2554,094
124217.7.176.0/20217.7.176.1 to 217.7.191.254217.7.191.2554,094
125217.7.192.0/20217.7.192.1 to 217.7.207.254217.7.207.2554,094
126217.7.208.0/20217.7.208.1 to 217.7.223.254217.7.223.2554,094
127217.7.224.0/20217.7.224.1 to 217.7.239.254217.7.239.2554,094
128217.7.240.0/20217.7.240.1 to 217.7.255.254217.7.255.2554,094
129217.8.0.0/20217.8.0.1 to 217.8.15.254217.8.15.2554,094
130217.8.16.0/20217.8.16.1 to 217.8.31.254217.8.31.2554,094
131217.8.32.0/20217.8.32.1 to 217.8.47.254217.8.47.2554,094
132217.8.48.0/20217.8.48.1 to 217.8.63.254217.8.63.2554,094
133217.8.64.0/20217.8.64.1 to 217.8.79.254217.8.79.2554,094
134217.8.80.0/20217.8.80.1 to 217.8.95.254217.8.95.2554,094
135217.8.96.0/20217.8.96.1 to 217.8.111.254217.8.111.2554,094
136217.8.112.0/20217.8.112.1 to 217.8.127.254217.8.127.2554,094
137217.8.128.0/20217.8.128.1 to 217.8.143.254217.8.143.2554,094
138217.8.144.0/20217.8.144.1 to 217.8.159.254217.8.159.2554,094
139217.8.160.0/20217.8.160.1 to 217.8.175.254217.8.175.2554,094
140217.8.176.0/20217.8.176.1 to 217.8.191.254217.8.191.2554,094
141217.8.192.0/20217.8.192.1 to 217.8.207.254217.8.207.2554,094
142217.8.208.0/20217.8.208.1 to 217.8.223.254217.8.223.2554,094
143217.8.224.0/20217.8.224.1 to 217.8.239.254217.8.239.2554,094
144217.8.240.0/20217.8.240.1 to 217.8.255.254217.8.255.2554,094
145217.9.0.0/20217.9.0.1 to 217.9.15.254217.9.15.2554,094
146217.9.16.0/20217.9.16.1 to 217.9.31.254217.9.31.2554,094
147217.9.32.0/20217.9.32.1 to 217.9.47.254217.9.47.2554,094
148217.9.48.0/20217.9.48.1 to 217.9.63.254217.9.63.2554,094
149217.9.64.0/20217.9.64.1 to 217.9.79.254217.9.79.2554,094
150217.9.80.0/20217.9.80.1 to 217.9.95.254217.9.95.2554,094
151217.9.96.0/20217.9.96.1 to 217.9.111.254217.9.111.2554,094
152217.9.112.0/20217.9.112.1 to 217.9.127.254217.9.127.2554,094
153217.9.128.0/20217.9.128.1 to 217.9.143.254217.9.143.2554,094
154217.9.144.0/20217.9.144.1 to 217.9.159.254217.9.159.2554,094
155217.9.160.0/20217.9.160.1 to 217.9.175.254217.9.175.2554,094
156217.9.176.0/20217.9.176.1 to 217.9.191.254217.9.191.2554,094
157217.9.192.0/20217.9.192.1 to 217.9.207.254217.9.207.2554,094
158217.9.208.0/20217.9.208.1 to 217.9.223.254217.9.223.2554,094
159217.9.224.0/20217.9.224.1 to 217.9.239.254217.9.239.2554,094
160217.9.240.0/20217.9.240.1 to 217.9.255.254217.9.255.2554,094
161217.10.0.0/20217.10.0.1 to 217.10.15.254217.10.15.2554,094
162217.10.16.0/20217.10.16.1 to 217.10.31.254217.10.31.2554,094
163217.10.32.0/20217.10.32.1 to 217.10.47.254217.10.47.2554,094
164217.10.48.0/20217.10.48.1 to 217.10.63.254217.10.63.2554,094
165217.10.64.0/20217.10.64.1 to 217.10.79.254217.10.79.2554,094
166217.10.80.0/20217.10.80.1 to 217.10.95.254217.10.95.2554,094
167217.10.96.0/20217.10.96.1 to 217.10.111.254217.10.111.2554,094
168217.10.112.0/20217.10.112.1 to 217.10.127.254217.10.127.2554,094
169217.10.128.0/20217.10.128.1 to 217.10.143.254217.10.143.2554,094
170217.10.144.0/20217.10.144.1 to 217.10.159.254217.10.159.2554,094
171217.10.160.0/20217.10.160.1 to 217.10.175.254217.10.175.2554,094
172217.10.176.0/20217.10.176.1 to 217.10.191.254217.10.191.2554,094
173217.10.192.0/20217.10.192.1 to 217.10.207.254217.10.207.2554,094
174217.10.208.0/20217.10.208.1 to 217.10.223.254217.10.223.2554,094
175217.10.224.0/20217.10.224.1 to 217.10.239.254217.10.239.2554,094
176217.10.240.0/20217.10.240.1 to 217.10.255.254217.10.255.2554,094
177217.11.0.0/20217.11.0.1 to 217.11.15.254217.11.15.2554,094
178217.11.16.0/20217.11.16.1 to 217.11.31.254217.11.31.2554,094
179217.11.32.0/20217.11.32.1 to 217.11.47.254217.11.47.2554,094
180217.11.48.0/20217.11.48.1 to 217.11.63.254217.11.63.2554,094
181217.11.64.0/20217.11.64.1 to 217.11.79.254217.11.79.2554,094
182217.11.80.0/20217.11.80.1 to 217.11.95.254217.11.95.2554,094
183217.11.96.0/20217.11.96.1 to 217.11.111.254217.11.111.2554,094
184217.11.112.0/20217.11.112.1 to 217.11.127.254217.11.127.2554,094
185217.11.128.0/20217.11.128.1 to 217.11.143.254217.11.143.2554,094
186217.11.144.0/20217.11.144.1 to 217.11.159.254217.11.159.2554,094
187217.11.160.0/20217.11.160.1 to 217.11.175.254217.11.175.2554,094
188217.11.176.0/20217.11.176.1 to 217.11.191.254217.11.191.2554,094
189217.11.192.0/20217.11.192.1 to 217.11.207.254217.11.207.2554,094
190217.11.208.0/20217.11.208.1 to 217.11.223.254217.11.223.2554,094
191217.11.224.0/20217.11.224.1 to 217.11.239.254217.11.239.2554,094
192217.11.240.0/20217.11.240.1 to 217.11.255.254217.11.255.2554,094
193217.12.0.0/20217.12.0.1 to 217.12.15.254217.12.15.2554,094
194217.12.16.0/20217.12.16.1 to 217.12.31.254217.12.31.2554,094
195217.12.32.0/20217.12.32.1 to 217.12.47.254217.12.47.2554,094
196217.12.48.0/20217.12.48.1 to 217.12.63.254217.12.63.2554,094
197217.12.64.0/20217.12.64.1 to 217.12.79.254217.12.79.2554,094
198217.12.80.0/20217.12.80.1 to 217.12.95.254217.12.95.2554,094
199217.12.96.0/20217.12.96.1 to 217.12.111.254217.12.111.2554,094
200217.12.112.0/20217.12.112.1 to 217.12.127.254217.12.127.2554,094
201217.12.128.0/20217.12.128.1 to 217.12.143.254217.12.143.2554,094
202217.12.144.0/20217.12.144.1 to 217.12.159.254217.12.159.2554,094
203217.12.160.0/20217.12.160.1 to 217.12.175.254217.12.175.2554,094
204217.12.176.0/20217.12.176.1 to 217.12.191.254217.12.191.2554,094
205217.12.192.0/20217.12.192.1 to 217.12.207.254217.12.207.2554,094
206217.12.208.0/20217.12.208.1 to 217.12.223.254217.12.223.2554,094
207217.12.224.0/20217.12.224.1 to 217.12.239.254217.12.239.2554,094
208217.12.240.0/20217.12.240.1 to 217.12.255.254217.12.255.2554,094
209217.13.0.0/20217.13.0.1 to 217.13.15.254217.13.15.2554,094
210217.13.16.0/20217.13.16.1 to 217.13.31.254217.13.31.2554,094
211217.13.32.0/20217.13.32.1 to 217.13.47.254217.13.47.2554,094
212217.13.48.0/20217.13.48.1 to 217.13.63.254217.13.63.2554,094
213217.13.64.0/20217.13.64.1 to 217.13.79.254217.13.79.2554,094
214217.13.80.0/20217.13.80.1 to 217.13.95.254217.13.95.2554,094
215217.13.96.0/20217.13.96.1 to 217.13.111.254217.13.111.2554,094
216217.13.112.0/20217.13.112.1 to 217.13.127.254217.13.127.2554,094
217217.13.128.0/20217.13.128.1 to 217.13.143.254217.13.143.2554,094
218217.13.144.0/20217.13.144.1 to 217.13.159.254217.13.159.2554,094
219217.13.160.0/20217.13.160.1 to 217.13.175.254217.13.175.2554,094
220217.13.176.0/20217.13.176.1 to 217.13.191.254217.13.191.2554,094
221217.13.192.0/20217.13.192.1 to 217.13.207.254217.13.207.2554,094
222217.13.208.0/20217.13.208.1 to 217.13.223.254217.13.223.2554,094
223217.13.224.0/20217.13.224.1 to 217.13.239.254217.13.239.2554,094
224217.13.240.0/20217.13.240.1 to 217.13.255.254217.13.255.2554,094
225217.14.0.0/20217.14.0.1 to 217.14.15.254217.14.15.2554,094
226217.14.16.0/20217.14.16.1 to 217.14.31.254217.14.31.2554,094
227217.14.32.0/20217.14.32.1 to 217.14.47.254217.14.47.2554,094
228217.14.48.0/20217.14.48.1 to 217.14.63.254217.14.63.2554,094
229217.14.64.0/20217.14.64.1 to 217.14.79.254217.14.79.2554,094
230217.14.80.0/20217.14.80.1 to 217.14.95.254217.14.95.2554,094
231217.14.96.0/20217.14.96.1 to 217.14.111.254217.14.111.2554,094
232217.14.112.0/20217.14.112.1 to 217.14.127.254217.14.127.2554,094
233217.14.128.0/20217.14.128.1 to 217.14.143.254217.14.143.2554,094
234217.14.144.0/20217.14.144.1 to 217.14.159.254217.14.159.2554,094
235217.14.160.0/20217.14.160.1 to 217.14.175.254217.14.175.2554,094
236217.14.176.0/20217.14.176.1 to 217.14.191.254217.14.191.2554,094
237217.14.192.0/20217.14.192.1 to 217.14.207.254217.14.207.2554,094
238217.14.208.0/20217.14.208.1 to 217.14.223.254217.14.223.2554,094
239217.14.224.0/20217.14.224.1 to 217.14.239.254217.14.239.2554,094
240217.14.240.0/20217.14.240.1 to 217.14.255.254217.14.255.2554,094
241217.15.0.0/20217.15.0.1 to 217.15.15.254217.15.15.2554,094
242217.15.16.0/20217.15.16.1 to 217.15.31.254217.15.31.2554,094
243217.15.32.0/20217.15.32.1 to 217.15.47.254217.15.47.2554,094
244217.15.48.0/20217.15.48.1 to 217.15.63.254217.15.63.2554,094
245217.15.64.0/20217.15.64.1 to 217.15.79.254217.15.79.2554,094
246217.15.80.0/20217.15.80.1 to 217.15.95.254217.15.95.2554,094
247217.15.96.0/20217.15.96.1 to 217.15.111.254217.15.111.2554,094
248217.15.112.0/20217.15.112.1 to 217.15.127.254217.15.127.2554,094
249217.15.128.0/20217.15.128.1 to 217.15.143.254217.15.143.2554,094
250217.15.144.0/20217.15.144.1 to 217.15.159.254217.15.159.2554,094
251217.15.160.0/20217.15.160.1 to 217.15.175.254217.15.175.2554,094
252217.15.176.0/20217.15.176.1 to 217.15.191.254217.15.191.2554,094
253217.15.192.0/20217.15.192.1 to 217.15.207.254217.15.207.2554,094
254217.15.208.0/20217.15.208.1 to 217.15.223.254217.15.223.2554,094
255217.15.224.0/20217.15.224.1 to 217.15.239.254217.15.239.2554,094
256217.15.240.0/20217.15.240.1 to 217.15.255.254217.15.255.2554,094

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.