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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.

Network217.2.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
217.2.64.0
Broadcast address
217.2.127.255
First usable
217.2.64.1
Last usable
217.2.127.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
C (default /24)
As numbers
Hex D9024000 · Integer 3640803328 to 3640819711
Reverse DNS zones
64.2.217.in-addr.arpa
65.2.217.in-addr.arpa
66.2.217.in-addr.arpa
67.2.217.in-addr.arpa
68.2.217.in-addr.arpa
69.2.217.in-addr.arpa
70.2.217.in-addr.arpa
71.2.217.in-addr.arpa
72.2.217.in-addr.arpa
73.2.217.in-addr.arpa
74.2.217.in-addr.arpa
75.2.217.in-addr.arpa
76.2.217.in-addr.arpa
77.2.217.in-addr.arpa
78.2.217.in-addr.arpa
79.2.217.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011001.00000010.01000000.00000000217.2.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network11011001.00000010.01000000.00000000217.2.64.0
Broadcast11011001.00000010.01111111.11111111217.2.127.255
Split into smaller subnets/30
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

217.2.64.0/18 makes 4,096 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1217.2.64.0/30217.2.64.1 to 217.2.64.2217.2.64.32
2217.2.64.4/30217.2.64.5 to 217.2.64.6217.2.64.72
3217.2.64.8/30217.2.64.9 to 217.2.64.10217.2.64.112
4217.2.64.12/30217.2.64.13 to 217.2.64.14217.2.64.152
5217.2.64.16/30217.2.64.17 to 217.2.64.18217.2.64.192
6217.2.64.20/30217.2.64.21 to 217.2.64.22217.2.64.232
7217.2.64.24/30217.2.64.25 to 217.2.64.26217.2.64.272
8217.2.64.28/30217.2.64.29 to 217.2.64.30217.2.64.312
9217.2.64.32/30217.2.64.33 to 217.2.64.34217.2.64.352
10217.2.64.36/30217.2.64.37 to 217.2.64.38217.2.64.392
11217.2.64.40/30217.2.64.41 to 217.2.64.42217.2.64.432
12217.2.64.44/30217.2.64.45 to 217.2.64.46217.2.64.472
13217.2.64.48/30217.2.64.49 to 217.2.64.50217.2.64.512
14217.2.64.52/30217.2.64.53 to 217.2.64.54217.2.64.552
15217.2.64.56/30217.2.64.57 to 217.2.64.58217.2.64.592
16217.2.64.60/30217.2.64.61 to 217.2.64.62217.2.64.632
17217.2.64.64/30217.2.64.65 to 217.2.64.66217.2.64.672
18217.2.64.68/30217.2.64.69 to 217.2.64.70217.2.64.712
19217.2.64.72/30217.2.64.73 to 217.2.64.74217.2.64.752
20217.2.64.76/30217.2.64.77 to 217.2.64.78217.2.64.792
21217.2.64.80/30217.2.64.81 to 217.2.64.82217.2.64.832
22217.2.64.84/30217.2.64.85 to 217.2.64.86217.2.64.872
23217.2.64.88/30217.2.64.89 to 217.2.64.90217.2.64.912
24217.2.64.92/30217.2.64.93 to 217.2.64.94217.2.64.952
25217.2.64.96/30217.2.64.97 to 217.2.64.98217.2.64.992
26217.2.64.100/30217.2.64.101 to 217.2.64.102217.2.64.1032
27217.2.64.104/30217.2.64.105 to 217.2.64.106217.2.64.1072
28217.2.64.108/30217.2.64.109 to 217.2.64.110217.2.64.1112
29217.2.64.112/30217.2.64.113 to 217.2.64.114217.2.64.1152
30217.2.64.116/30217.2.64.117 to 217.2.64.118217.2.64.1192
31217.2.64.120/30217.2.64.121 to 217.2.64.122217.2.64.1232
32217.2.64.124/30217.2.64.125 to 217.2.64.126217.2.64.1272
33217.2.64.128/30217.2.64.129 to 217.2.64.130217.2.64.1312
34217.2.64.132/30217.2.64.133 to 217.2.64.134217.2.64.1352
35217.2.64.136/30217.2.64.137 to 217.2.64.138217.2.64.1392
36217.2.64.140/30217.2.64.141 to 217.2.64.142217.2.64.1432
37217.2.64.144/30217.2.64.145 to 217.2.64.146217.2.64.1472
38217.2.64.148/30217.2.64.149 to 217.2.64.150217.2.64.1512
39217.2.64.152/30217.2.64.153 to 217.2.64.154217.2.64.1552
40217.2.64.156/30217.2.64.157 to 217.2.64.158217.2.64.1592
41217.2.64.160/30217.2.64.161 to 217.2.64.162217.2.64.1632
42217.2.64.164/30217.2.64.165 to 217.2.64.166217.2.64.1672
43217.2.64.168/30217.2.64.169 to 217.2.64.170217.2.64.1712
44217.2.64.172/30217.2.64.173 to 217.2.64.174217.2.64.1752
45217.2.64.176/30217.2.64.177 to 217.2.64.178217.2.64.1792
46217.2.64.180/30217.2.64.181 to 217.2.64.182217.2.64.1832
47217.2.64.184/30217.2.64.185 to 217.2.64.186217.2.64.1872
48217.2.64.188/30217.2.64.189 to 217.2.64.190217.2.64.1912
49217.2.64.192/30217.2.64.193 to 217.2.64.194217.2.64.1952
50217.2.64.196/30217.2.64.197 to 217.2.64.198217.2.64.1992
51217.2.64.200/30217.2.64.201 to 217.2.64.202217.2.64.2032
52217.2.64.204/30217.2.64.205 to 217.2.64.206217.2.64.2072
53217.2.64.208/30217.2.64.209 to 217.2.64.210217.2.64.2112
54217.2.64.212/30217.2.64.213 to 217.2.64.214217.2.64.2152
55217.2.64.216/30217.2.64.217 to 217.2.64.218217.2.64.2192
56217.2.64.220/30217.2.64.221 to 217.2.64.222217.2.64.2232
57217.2.64.224/30217.2.64.225 to 217.2.64.226217.2.64.2272
58217.2.64.228/30217.2.64.229 to 217.2.64.230217.2.64.2312
59217.2.64.232/30217.2.64.233 to 217.2.64.234217.2.64.2352
60217.2.64.236/30217.2.64.237 to 217.2.64.238217.2.64.2392
61217.2.64.240/30217.2.64.241 to 217.2.64.242217.2.64.2432
62217.2.64.244/30217.2.64.245 to 217.2.64.246217.2.64.2472
63217.2.64.248/30217.2.64.249 to 217.2.64.250217.2.64.2512
64217.2.64.252/30217.2.64.253 to 217.2.64.254217.2.64.2552
65217.2.65.0/30217.2.65.1 to 217.2.65.2217.2.65.32
66217.2.65.4/30217.2.65.5 to 217.2.65.6217.2.65.72
67217.2.65.8/30217.2.65.9 to 217.2.65.10217.2.65.112
68217.2.65.12/30217.2.65.13 to 217.2.65.14217.2.65.152
69217.2.65.16/30217.2.65.17 to 217.2.65.18217.2.65.192
70217.2.65.20/30217.2.65.21 to 217.2.65.22217.2.65.232
71217.2.65.24/30217.2.65.25 to 217.2.65.26217.2.65.272
72217.2.65.28/30217.2.65.29 to 217.2.65.30217.2.65.312
73217.2.65.32/30217.2.65.33 to 217.2.65.34217.2.65.352
74217.2.65.36/30217.2.65.37 to 217.2.65.38217.2.65.392
75217.2.65.40/30217.2.65.41 to 217.2.65.42217.2.65.432
76217.2.65.44/30217.2.65.45 to 217.2.65.46217.2.65.472
77217.2.65.48/30217.2.65.49 to 217.2.65.50217.2.65.512
78217.2.65.52/30217.2.65.53 to 217.2.65.54217.2.65.552
79217.2.65.56/30217.2.65.57 to 217.2.65.58217.2.65.592
80217.2.65.60/30217.2.65.61 to 217.2.65.62217.2.65.632
81217.2.65.64/30217.2.65.65 to 217.2.65.66217.2.65.672
82217.2.65.68/30217.2.65.69 to 217.2.65.70217.2.65.712
83217.2.65.72/30217.2.65.73 to 217.2.65.74217.2.65.752
84217.2.65.76/30217.2.65.77 to 217.2.65.78217.2.65.792
85217.2.65.80/30217.2.65.81 to 217.2.65.82217.2.65.832
86217.2.65.84/30217.2.65.85 to 217.2.65.86217.2.65.872
87217.2.65.88/30217.2.65.89 to 217.2.65.90217.2.65.912
88217.2.65.92/30217.2.65.93 to 217.2.65.94217.2.65.952
89217.2.65.96/30217.2.65.97 to 217.2.65.98217.2.65.992
90217.2.65.100/30217.2.65.101 to 217.2.65.102217.2.65.1032
91217.2.65.104/30217.2.65.105 to 217.2.65.106217.2.65.1072
92217.2.65.108/30217.2.65.109 to 217.2.65.110217.2.65.1112
93217.2.65.112/30217.2.65.113 to 217.2.65.114217.2.65.1152
94217.2.65.116/30217.2.65.117 to 217.2.65.118217.2.65.1192
95217.2.65.120/30217.2.65.121 to 217.2.65.122217.2.65.1232
96217.2.65.124/30217.2.65.125 to 217.2.65.126217.2.65.1272
97217.2.65.128/30217.2.65.129 to 217.2.65.130217.2.65.1312
98217.2.65.132/30217.2.65.133 to 217.2.65.134217.2.65.1352
99217.2.65.136/30217.2.65.137 to 217.2.65.138217.2.65.1392
100217.2.65.140/30217.2.65.141 to 217.2.65.142217.2.65.1432
101217.2.65.144/30217.2.65.145 to 217.2.65.146217.2.65.1472
102217.2.65.148/30217.2.65.149 to 217.2.65.150217.2.65.1512
103217.2.65.152/30217.2.65.153 to 217.2.65.154217.2.65.1552
104217.2.65.156/30217.2.65.157 to 217.2.65.158217.2.65.1592
105217.2.65.160/30217.2.65.161 to 217.2.65.162217.2.65.1632
106217.2.65.164/30217.2.65.165 to 217.2.65.166217.2.65.1672
107217.2.65.168/30217.2.65.169 to 217.2.65.170217.2.65.1712
108217.2.65.172/30217.2.65.173 to 217.2.65.174217.2.65.1752
109217.2.65.176/30217.2.65.177 to 217.2.65.178217.2.65.1792
110217.2.65.180/30217.2.65.181 to 217.2.65.182217.2.65.1832
111217.2.65.184/30217.2.65.185 to 217.2.65.186217.2.65.1872
112217.2.65.188/30217.2.65.189 to 217.2.65.190217.2.65.1912
113217.2.65.192/30217.2.65.193 to 217.2.65.194217.2.65.1952
114217.2.65.196/30217.2.65.197 to 217.2.65.198217.2.65.1992
115217.2.65.200/30217.2.65.201 to 217.2.65.202217.2.65.2032
116217.2.65.204/30217.2.65.205 to 217.2.65.206217.2.65.2072
117217.2.65.208/30217.2.65.209 to 217.2.65.210217.2.65.2112
118217.2.65.212/30217.2.65.213 to 217.2.65.214217.2.65.2152
119217.2.65.216/30217.2.65.217 to 217.2.65.218217.2.65.2192
120217.2.65.220/30217.2.65.221 to 217.2.65.222217.2.65.2232
121217.2.65.224/30217.2.65.225 to 217.2.65.226217.2.65.2272
122217.2.65.228/30217.2.65.229 to 217.2.65.230217.2.65.2312
123217.2.65.232/30217.2.65.233 to 217.2.65.234217.2.65.2352
124217.2.65.236/30217.2.65.237 to 217.2.65.238217.2.65.2392
125217.2.65.240/30217.2.65.241 to 217.2.65.242217.2.65.2432
126217.2.65.244/30217.2.65.245 to 217.2.65.246217.2.65.2472
127217.2.65.248/30217.2.65.249 to 217.2.65.250217.2.65.2512
128217.2.65.252/30217.2.65.253 to 217.2.65.254217.2.65.2552
129217.2.66.0/30217.2.66.1 to 217.2.66.2217.2.66.32
130217.2.66.4/30217.2.66.5 to 217.2.66.6217.2.66.72
131217.2.66.8/30217.2.66.9 to 217.2.66.10217.2.66.112
132217.2.66.12/30217.2.66.13 to 217.2.66.14217.2.66.152
133217.2.66.16/30217.2.66.17 to 217.2.66.18217.2.66.192
134217.2.66.20/30217.2.66.21 to 217.2.66.22217.2.66.232
135217.2.66.24/30217.2.66.25 to 217.2.66.26217.2.66.272
136217.2.66.28/30217.2.66.29 to 217.2.66.30217.2.66.312
137217.2.66.32/30217.2.66.33 to 217.2.66.34217.2.66.352
138217.2.66.36/30217.2.66.37 to 217.2.66.38217.2.66.392
139217.2.66.40/30217.2.66.41 to 217.2.66.42217.2.66.432
140217.2.66.44/30217.2.66.45 to 217.2.66.46217.2.66.472
141217.2.66.48/30217.2.66.49 to 217.2.66.50217.2.66.512
142217.2.66.52/30217.2.66.53 to 217.2.66.54217.2.66.552
143217.2.66.56/30217.2.66.57 to 217.2.66.58217.2.66.592
144217.2.66.60/30217.2.66.61 to 217.2.66.62217.2.66.632
145217.2.66.64/30217.2.66.65 to 217.2.66.66217.2.66.672
146217.2.66.68/30217.2.66.69 to 217.2.66.70217.2.66.712
147217.2.66.72/30217.2.66.73 to 217.2.66.74217.2.66.752
148217.2.66.76/30217.2.66.77 to 217.2.66.78217.2.66.792
149217.2.66.80/30217.2.66.81 to 217.2.66.82217.2.66.832
150217.2.66.84/30217.2.66.85 to 217.2.66.86217.2.66.872
151217.2.66.88/30217.2.66.89 to 217.2.66.90217.2.66.912
152217.2.66.92/30217.2.66.93 to 217.2.66.94217.2.66.952
153217.2.66.96/30217.2.66.97 to 217.2.66.98217.2.66.992
154217.2.66.100/30217.2.66.101 to 217.2.66.102217.2.66.1032
155217.2.66.104/30217.2.66.105 to 217.2.66.106217.2.66.1072
156217.2.66.108/30217.2.66.109 to 217.2.66.110217.2.66.1112
157217.2.66.112/30217.2.66.113 to 217.2.66.114217.2.66.1152
158217.2.66.116/30217.2.66.117 to 217.2.66.118217.2.66.1192
159217.2.66.120/30217.2.66.121 to 217.2.66.122217.2.66.1232
160217.2.66.124/30217.2.66.125 to 217.2.66.126217.2.66.1272
161217.2.66.128/30217.2.66.129 to 217.2.66.130217.2.66.1312
162217.2.66.132/30217.2.66.133 to 217.2.66.134217.2.66.1352
163217.2.66.136/30217.2.66.137 to 217.2.66.138217.2.66.1392
164217.2.66.140/30217.2.66.141 to 217.2.66.142217.2.66.1432
165217.2.66.144/30217.2.66.145 to 217.2.66.146217.2.66.1472
166217.2.66.148/30217.2.66.149 to 217.2.66.150217.2.66.1512
167217.2.66.152/30217.2.66.153 to 217.2.66.154217.2.66.1552
168217.2.66.156/30217.2.66.157 to 217.2.66.158217.2.66.1592
169217.2.66.160/30217.2.66.161 to 217.2.66.162217.2.66.1632
170217.2.66.164/30217.2.66.165 to 217.2.66.166217.2.66.1672
171217.2.66.168/30217.2.66.169 to 217.2.66.170217.2.66.1712
172217.2.66.172/30217.2.66.173 to 217.2.66.174217.2.66.1752
173217.2.66.176/30217.2.66.177 to 217.2.66.178217.2.66.1792
174217.2.66.180/30217.2.66.181 to 217.2.66.182217.2.66.1832
175217.2.66.184/30217.2.66.185 to 217.2.66.186217.2.66.1872
176217.2.66.188/30217.2.66.189 to 217.2.66.190217.2.66.1912
177217.2.66.192/30217.2.66.193 to 217.2.66.194217.2.66.1952
178217.2.66.196/30217.2.66.197 to 217.2.66.198217.2.66.1992
179217.2.66.200/30217.2.66.201 to 217.2.66.202217.2.66.2032
180217.2.66.204/30217.2.66.205 to 217.2.66.206217.2.66.2072
181217.2.66.208/30217.2.66.209 to 217.2.66.210217.2.66.2112
182217.2.66.212/30217.2.66.213 to 217.2.66.214217.2.66.2152
183217.2.66.216/30217.2.66.217 to 217.2.66.218217.2.66.2192
184217.2.66.220/30217.2.66.221 to 217.2.66.222217.2.66.2232
185217.2.66.224/30217.2.66.225 to 217.2.66.226217.2.66.2272
186217.2.66.228/30217.2.66.229 to 217.2.66.230217.2.66.2312
187217.2.66.232/30217.2.66.233 to 217.2.66.234217.2.66.2352
188217.2.66.236/30217.2.66.237 to 217.2.66.238217.2.66.2392
189217.2.66.240/30217.2.66.241 to 217.2.66.242217.2.66.2432
190217.2.66.244/30217.2.66.245 to 217.2.66.246217.2.66.2472
191217.2.66.248/30217.2.66.249 to 217.2.66.250217.2.66.2512
192217.2.66.252/30217.2.66.253 to 217.2.66.254217.2.66.2552
193217.2.67.0/30217.2.67.1 to 217.2.67.2217.2.67.32
194217.2.67.4/30217.2.67.5 to 217.2.67.6217.2.67.72
195217.2.67.8/30217.2.67.9 to 217.2.67.10217.2.67.112
196217.2.67.12/30217.2.67.13 to 217.2.67.14217.2.67.152
197217.2.67.16/30217.2.67.17 to 217.2.67.18217.2.67.192
198217.2.67.20/30217.2.67.21 to 217.2.67.22217.2.67.232
199217.2.67.24/30217.2.67.25 to 217.2.67.26217.2.67.272
200217.2.67.28/30217.2.67.29 to 217.2.67.30217.2.67.312
201217.2.67.32/30217.2.67.33 to 217.2.67.34217.2.67.352
202217.2.67.36/30217.2.67.37 to 217.2.67.38217.2.67.392
203217.2.67.40/30217.2.67.41 to 217.2.67.42217.2.67.432
204217.2.67.44/30217.2.67.45 to 217.2.67.46217.2.67.472
205217.2.67.48/30217.2.67.49 to 217.2.67.50217.2.67.512
206217.2.67.52/30217.2.67.53 to 217.2.67.54217.2.67.552
207217.2.67.56/30217.2.67.57 to 217.2.67.58217.2.67.592
208217.2.67.60/30217.2.67.61 to 217.2.67.62217.2.67.632
209217.2.67.64/30217.2.67.65 to 217.2.67.66217.2.67.672
210217.2.67.68/30217.2.67.69 to 217.2.67.70217.2.67.712
211217.2.67.72/30217.2.67.73 to 217.2.67.74217.2.67.752
212217.2.67.76/30217.2.67.77 to 217.2.67.78217.2.67.792
213217.2.67.80/30217.2.67.81 to 217.2.67.82217.2.67.832
214217.2.67.84/30217.2.67.85 to 217.2.67.86217.2.67.872
215217.2.67.88/30217.2.67.89 to 217.2.67.90217.2.67.912
216217.2.67.92/30217.2.67.93 to 217.2.67.94217.2.67.952
217217.2.67.96/30217.2.67.97 to 217.2.67.98217.2.67.992
218217.2.67.100/30217.2.67.101 to 217.2.67.102217.2.67.1032
219217.2.67.104/30217.2.67.105 to 217.2.67.106217.2.67.1072
220217.2.67.108/30217.2.67.109 to 217.2.67.110217.2.67.1112
221217.2.67.112/30217.2.67.113 to 217.2.67.114217.2.67.1152
222217.2.67.116/30217.2.67.117 to 217.2.67.118217.2.67.1192
223217.2.67.120/30217.2.67.121 to 217.2.67.122217.2.67.1232
224217.2.67.124/30217.2.67.125 to 217.2.67.126217.2.67.1272
225217.2.67.128/30217.2.67.129 to 217.2.67.130217.2.67.1312
226217.2.67.132/30217.2.67.133 to 217.2.67.134217.2.67.1352
227217.2.67.136/30217.2.67.137 to 217.2.67.138217.2.67.1392
228217.2.67.140/30217.2.67.141 to 217.2.67.142217.2.67.1432
229217.2.67.144/30217.2.67.145 to 217.2.67.146217.2.67.1472
230217.2.67.148/30217.2.67.149 to 217.2.67.150217.2.67.1512
231217.2.67.152/30217.2.67.153 to 217.2.67.154217.2.67.1552
232217.2.67.156/30217.2.67.157 to 217.2.67.158217.2.67.1592
233217.2.67.160/30217.2.67.161 to 217.2.67.162217.2.67.1632
234217.2.67.164/30217.2.67.165 to 217.2.67.166217.2.67.1672
235217.2.67.168/30217.2.67.169 to 217.2.67.170217.2.67.1712
236217.2.67.172/30217.2.67.173 to 217.2.67.174217.2.67.1752
237217.2.67.176/30217.2.67.177 to 217.2.67.178217.2.67.1792
238217.2.67.180/30217.2.67.181 to 217.2.67.182217.2.67.1832
239217.2.67.184/30217.2.67.185 to 217.2.67.186217.2.67.1872
240217.2.67.188/30217.2.67.189 to 217.2.67.190217.2.67.1912
241217.2.67.192/30217.2.67.193 to 217.2.67.194217.2.67.1952
242217.2.67.196/30217.2.67.197 to 217.2.67.198217.2.67.1992
243217.2.67.200/30217.2.67.201 to 217.2.67.202217.2.67.2032
244217.2.67.204/30217.2.67.205 to 217.2.67.206217.2.67.2072
245217.2.67.208/30217.2.67.209 to 217.2.67.210217.2.67.2112
246217.2.67.212/30217.2.67.213 to 217.2.67.214217.2.67.2152
247217.2.67.216/30217.2.67.217 to 217.2.67.218217.2.67.2192
248217.2.67.220/30217.2.67.221 to 217.2.67.222217.2.67.2232
249217.2.67.224/30217.2.67.225 to 217.2.67.226217.2.67.2272
250217.2.67.228/30217.2.67.229 to 217.2.67.230217.2.67.2312
251217.2.67.232/30217.2.67.233 to 217.2.67.234217.2.67.2352
252217.2.67.236/30217.2.67.237 to 217.2.67.238217.2.67.2392
253217.2.67.240/30217.2.67.241 to 217.2.67.242217.2.67.2432
254217.2.67.244/30217.2.67.245 to 217.2.67.246217.2.67.2472
255217.2.67.248/30217.2.67.249 to 217.2.67.250217.2.67.2512
256217.2.67.252/30217.2.67.253 to 217.2.67.254217.2.67.2552

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.