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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.

Network217.3.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
217.3.0.0
Broadcast address
217.3.63.255
First usable
217.3.0.1
Last usable
217.3.63.254
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 D9030000 · Integer 3640852480 to 3640868863
Reverse DNS zones
0.3.217.in-addr.arpa
1.3.217.in-addr.arpa
2.3.217.in-addr.arpa
3.3.217.in-addr.arpa
4.3.217.in-addr.arpa
5.3.217.in-addr.arpa
6.3.217.in-addr.arpa
7.3.217.in-addr.arpa
8.3.217.in-addr.arpa
9.3.217.in-addr.arpa
10.3.217.in-addr.arpa
11.3.217.in-addr.arpa
12.3.217.in-addr.arpa
13.3.217.in-addr.arpa
14.3.217.in-addr.arpa
15.3.217.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
Address11011001.00000011.00000000.00000000217.3.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network11011001.00000011.00000000.00000000217.3.0.0
Broadcast11011001.00000011.00111111.11111111217.3.63.255
Split into smaller subnets/29
/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)

217.3.0.0/18 makes 2,048 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1217.3.0.0/29217.3.0.1 to 217.3.0.6217.3.0.76
2217.3.0.8/29217.3.0.9 to 217.3.0.14217.3.0.156
3217.3.0.16/29217.3.0.17 to 217.3.0.22217.3.0.236
4217.3.0.24/29217.3.0.25 to 217.3.0.30217.3.0.316
5217.3.0.32/29217.3.0.33 to 217.3.0.38217.3.0.396
6217.3.0.40/29217.3.0.41 to 217.3.0.46217.3.0.476
7217.3.0.48/29217.3.0.49 to 217.3.0.54217.3.0.556
8217.3.0.56/29217.3.0.57 to 217.3.0.62217.3.0.636
9217.3.0.64/29217.3.0.65 to 217.3.0.70217.3.0.716
10217.3.0.72/29217.3.0.73 to 217.3.0.78217.3.0.796
11217.3.0.80/29217.3.0.81 to 217.3.0.86217.3.0.876
12217.3.0.88/29217.3.0.89 to 217.3.0.94217.3.0.956
13217.3.0.96/29217.3.0.97 to 217.3.0.102217.3.0.1036
14217.3.0.104/29217.3.0.105 to 217.3.0.110217.3.0.1116
15217.3.0.112/29217.3.0.113 to 217.3.0.118217.3.0.1196
16217.3.0.120/29217.3.0.121 to 217.3.0.126217.3.0.1276
17217.3.0.128/29217.3.0.129 to 217.3.0.134217.3.0.1356
18217.3.0.136/29217.3.0.137 to 217.3.0.142217.3.0.1436
19217.3.0.144/29217.3.0.145 to 217.3.0.150217.3.0.1516
20217.3.0.152/29217.3.0.153 to 217.3.0.158217.3.0.1596
21217.3.0.160/29217.3.0.161 to 217.3.0.166217.3.0.1676
22217.3.0.168/29217.3.0.169 to 217.3.0.174217.3.0.1756
23217.3.0.176/29217.3.0.177 to 217.3.0.182217.3.0.1836
24217.3.0.184/29217.3.0.185 to 217.3.0.190217.3.0.1916
25217.3.0.192/29217.3.0.193 to 217.3.0.198217.3.0.1996
26217.3.0.200/29217.3.0.201 to 217.3.0.206217.3.0.2076
27217.3.0.208/29217.3.0.209 to 217.3.0.214217.3.0.2156
28217.3.0.216/29217.3.0.217 to 217.3.0.222217.3.0.2236
29217.3.0.224/29217.3.0.225 to 217.3.0.230217.3.0.2316
30217.3.0.232/29217.3.0.233 to 217.3.0.238217.3.0.2396
31217.3.0.240/29217.3.0.241 to 217.3.0.246217.3.0.2476
32217.3.0.248/29217.3.0.249 to 217.3.0.254217.3.0.2556
33217.3.1.0/29217.3.1.1 to 217.3.1.6217.3.1.76
34217.3.1.8/29217.3.1.9 to 217.3.1.14217.3.1.156
35217.3.1.16/29217.3.1.17 to 217.3.1.22217.3.1.236
36217.3.1.24/29217.3.1.25 to 217.3.1.30217.3.1.316
37217.3.1.32/29217.3.1.33 to 217.3.1.38217.3.1.396
38217.3.1.40/29217.3.1.41 to 217.3.1.46217.3.1.476
39217.3.1.48/29217.3.1.49 to 217.3.1.54217.3.1.556
40217.3.1.56/29217.3.1.57 to 217.3.1.62217.3.1.636
41217.3.1.64/29217.3.1.65 to 217.3.1.70217.3.1.716
42217.3.1.72/29217.3.1.73 to 217.3.1.78217.3.1.796
43217.3.1.80/29217.3.1.81 to 217.3.1.86217.3.1.876
44217.3.1.88/29217.3.1.89 to 217.3.1.94217.3.1.956
45217.3.1.96/29217.3.1.97 to 217.3.1.102217.3.1.1036
46217.3.1.104/29217.3.1.105 to 217.3.1.110217.3.1.1116
47217.3.1.112/29217.3.1.113 to 217.3.1.118217.3.1.1196
48217.3.1.120/29217.3.1.121 to 217.3.1.126217.3.1.1276
49217.3.1.128/29217.3.1.129 to 217.3.1.134217.3.1.1356
50217.3.1.136/29217.3.1.137 to 217.3.1.142217.3.1.1436
51217.3.1.144/29217.3.1.145 to 217.3.1.150217.3.1.1516
52217.3.1.152/29217.3.1.153 to 217.3.1.158217.3.1.1596
53217.3.1.160/29217.3.1.161 to 217.3.1.166217.3.1.1676
54217.3.1.168/29217.3.1.169 to 217.3.1.174217.3.1.1756
55217.3.1.176/29217.3.1.177 to 217.3.1.182217.3.1.1836
56217.3.1.184/29217.3.1.185 to 217.3.1.190217.3.1.1916
57217.3.1.192/29217.3.1.193 to 217.3.1.198217.3.1.1996
58217.3.1.200/29217.3.1.201 to 217.3.1.206217.3.1.2076
59217.3.1.208/29217.3.1.209 to 217.3.1.214217.3.1.2156
60217.3.1.216/29217.3.1.217 to 217.3.1.222217.3.1.2236
61217.3.1.224/29217.3.1.225 to 217.3.1.230217.3.1.2316
62217.3.1.232/29217.3.1.233 to 217.3.1.238217.3.1.2396
63217.3.1.240/29217.3.1.241 to 217.3.1.246217.3.1.2476
64217.3.1.248/29217.3.1.249 to 217.3.1.254217.3.1.2556
65217.3.2.0/29217.3.2.1 to 217.3.2.6217.3.2.76
66217.3.2.8/29217.3.2.9 to 217.3.2.14217.3.2.156
67217.3.2.16/29217.3.2.17 to 217.3.2.22217.3.2.236
68217.3.2.24/29217.3.2.25 to 217.3.2.30217.3.2.316
69217.3.2.32/29217.3.2.33 to 217.3.2.38217.3.2.396
70217.3.2.40/29217.3.2.41 to 217.3.2.46217.3.2.476
71217.3.2.48/29217.3.2.49 to 217.3.2.54217.3.2.556
72217.3.2.56/29217.3.2.57 to 217.3.2.62217.3.2.636
73217.3.2.64/29217.3.2.65 to 217.3.2.70217.3.2.716
74217.3.2.72/29217.3.2.73 to 217.3.2.78217.3.2.796
75217.3.2.80/29217.3.2.81 to 217.3.2.86217.3.2.876
76217.3.2.88/29217.3.2.89 to 217.3.2.94217.3.2.956
77217.3.2.96/29217.3.2.97 to 217.3.2.102217.3.2.1036
78217.3.2.104/29217.3.2.105 to 217.3.2.110217.3.2.1116
79217.3.2.112/29217.3.2.113 to 217.3.2.118217.3.2.1196
80217.3.2.120/29217.3.2.121 to 217.3.2.126217.3.2.1276
81217.3.2.128/29217.3.2.129 to 217.3.2.134217.3.2.1356
82217.3.2.136/29217.3.2.137 to 217.3.2.142217.3.2.1436
83217.3.2.144/29217.3.2.145 to 217.3.2.150217.3.2.1516
84217.3.2.152/29217.3.2.153 to 217.3.2.158217.3.2.1596
85217.3.2.160/29217.3.2.161 to 217.3.2.166217.3.2.1676
86217.3.2.168/29217.3.2.169 to 217.3.2.174217.3.2.1756
87217.3.2.176/29217.3.2.177 to 217.3.2.182217.3.2.1836
88217.3.2.184/29217.3.2.185 to 217.3.2.190217.3.2.1916
89217.3.2.192/29217.3.2.193 to 217.3.2.198217.3.2.1996
90217.3.2.200/29217.3.2.201 to 217.3.2.206217.3.2.2076
91217.3.2.208/29217.3.2.209 to 217.3.2.214217.3.2.2156
92217.3.2.216/29217.3.2.217 to 217.3.2.222217.3.2.2236
93217.3.2.224/29217.3.2.225 to 217.3.2.230217.3.2.2316
94217.3.2.232/29217.3.2.233 to 217.3.2.238217.3.2.2396
95217.3.2.240/29217.3.2.241 to 217.3.2.246217.3.2.2476
96217.3.2.248/29217.3.2.249 to 217.3.2.254217.3.2.2556
97217.3.3.0/29217.3.3.1 to 217.3.3.6217.3.3.76
98217.3.3.8/29217.3.3.9 to 217.3.3.14217.3.3.156
99217.3.3.16/29217.3.3.17 to 217.3.3.22217.3.3.236
100217.3.3.24/29217.3.3.25 to 217.3.3.30217.3.3.316
101217.3.3.32/29217.3.3.33 to 217.3.3.38217.3.3.396
102217.3.3.40/29217.3.3.41 to 217.3.3.46217.3.3.476
103217.3.3.48/29217.3.3.49 to 217.3.3.54217.3.3.556
104217.3.3.56/29217.3.3.57 to 217.3.3.62217.3.3.636
105217.3.3.64/29217.3.3.65 to 217.3.3.70217.3.3.716
106217.3.3.72/29217.3.3.73 to 217.3.3.78217.3.3.796
107217.3.3.80/29217.3.3.81 to 217.3.3.86217.3.3.876
108217.3.3.88/29217.3.3.89 to 217.3.3.94217.3.3.956
109217.3.3.96/29217.3.3.97 to 217.3.3.102217.3.3.1036
110217.3.3.104/29217.3.3.105 to 217.3.3.110217.3.3.1116
111217.3.3.112/29217.3.3.113 to 217.3.3.118217.3.3.1196
112217.3.3.120/29217.3.3.121 to 217.3.3.126217.3.3.1276
113217.3.3.128/29217.3.3.129 to 217.3.3.134217.3.3.1356
114217.3.3.136/29217.3.3.137 to 217.3.3.142217.3.3.1436
115217.3.3.144/29217.3.3.145 to 217.3.3.150217.3.3.1516
116217.3.3.152/29217.3.3.153 to 217.3.3.158217.3.3.1596
117217.3.3.160/29217.3.3.161 to 217.3.3.166217.3.3.1676
118217.3.3.168/29217.3.3.169 to 217.3.3.174217.3.3.1756
119217.3.3.176/29217.3.3.177 to 217.3.3.182217.3.3.1836
120217.3.3.184/29217.3.3.185 to 217.3.3.190217.3.3.1916
121217.3.3.192/29217.3.3.193 to 217.3.3.198217.3.3.1996
122217.3.3.200/29217.3.3.201 to 217.3.3.206217.3.3.2076
123217.3.3.208/29217.3.3.209 to 217.3.3.214217.3.3.2156
124217.3.3.216/29217.3.3.217 to 217.3.3.222217.3.3.2236
125217.3.3.224/29217.3.3.225 to 217.3.3.230217.3.3.2316
126217.3.3.232/29217.3.3.233 to 217.3.3.238217.3.3.2396
127217.3.3.240/29217.3.3.241 to 217.3.3.246217.3.3.2476
128217.3.3.248/29217.3.3.249 to 217.3.3.254217.3.3.2556
129217.3.4.0/29217.3.4.1 to 217.3.4.6217.3.4.76
130217.3.4.8/29217.3.4.9 to 217.3.4.14217.3.4.156
131217.3.4.16/29217.3.4.17 to 217.3.4.22217.3.4.236
132217.3.4.24/29217.3.4.25 to 217.3.4.30217.3.4.316
133217.3.4.32/29217.3.4.33 to 217.3.4.38217.3.4.396
134217.3.4.40/29217.3.4.41 to 217.3.4.46217.3.4.476
135217.3.4.48/29217.3.4.49 to 217.3.4.54217.3.4.556
136217.3.4.56/29217.3.4.57 to 217.3.4.62217.3.4.636
137217.3.4.64/29217.3.4.65 to 217.3.4.70217.3.4.716
138217.3.4.72/29217.3.4.73 to 217.3.4.78217.3.4.796
139217.3.4.80/29217.3.4.81 to 217.3.4.86217.3.4.876
140217.3.4.88/29217.3.4.89 to 217.3.4.94217.3.4.956
141217.3.4.96/29217.3.4.97 to 217.3.4.102217.3.4.1036
142217.3.4.104/29217.3.4.105 to 217.3.4.110217.3.4.1116
143217.3.4.112/29217.3.4.113 to 217.3.4.118217.3.4.1196
144217.3.4.120/29217.3.4.121 to 217.3.4.126217.3.4.1276
145217.3.4.128/29217.3.4.129 to 217.3.4.134217.3.4.1356
146217.3.4.136/29217.3.4.137 to 217.3.4.142217.3.4.1436
147217.3.4.144/29217.3.4.145 to 217.3.4.150217.3.4.1516
148217.3.4.152/29217.3.4.153 to 217.3.4.158217.3.4.1596
149217.3.4.160/29217.3.4.161 to 217.3.4.166217.3.4.1676
150217.3.4.168/29217.3.4.169 to 217.3.4.174217.3.4.1756
151217.3.4.176/29217.3.4.177 to 217.3.4.182217.3.4.1836
152217.3.4.184/29217.3.4.185 to 217.3.4.190217.3.4.1916
153217.3.4.192/29217.3.4.193 to 217.3.4.198217.3.4.1996
154217.3.4.200/29217.3.4.201 to 217.3.4.206217.3.4.2076
155217.3.4.208/29217.3.4.209 to 217.3.4.214217.3.4.2156
156217.3.4.216/29217.3.4.217 to 217.3.4.222217.3.4.2236
157217.3.4.224/29217.3.4.225 to 217.3.4.230217.3.4.2316
158217.3.4.232/29217.3.4.233 to 217.3.4.238217.3.4.2396
159217.3.4.240/29217.3.4.241 to 217.3.4.246217.3.4.2476
160217.3.4.248/29217.3.4.249 to 217.3.4.254217.3.4.2556
161217.3.5.0/29217.3.5.1 to 217.3.5.6217.3.5.76
162217.3.5.8/29217.3.5.9 to 217.3.5.14217.3.5.156
163217.3.5.16/29217.3.5.17 to 217.3.5.22217.3.5.236
164217.3.5.24/29217.3.5.25 to 217.3.5.30217.3.5.316
165217.3.5.32/29217.3.5.33 to 217.3.5.38217.3.5.396
166217.3.5.40/29217.3.5.41 to 217.3.5.46217.3.5.476
167217.3.5.48/29217.3.5.49 to 217.3.5.54217.3.5.556
168217.3.5.56/29217.3.5.57 to 217.3.5.62217.3.5.636
169217.3.5.64/29217.3.5.65 to 217.3.5.70217.3.5.716
170217.3.5.72/29217.3.5.73 to 217.3.5.78217.3.5.796
171217.3.5.80/29217.3.5.81 to 217.3.5.86217.3.5.876
172217.3.5.88/29217.3.5.89 to 217.3.5.94217.3.5.956
173217.3.5.96/29217.3.5.97 to 217.3.5.102217.3.5.1036
174217.3.5.104/29217.3.5.105 to 217.3.5.110217.3.5.1116
175217.3.5.112/29217.3.5.113 to 217.3.5.118217.3.5.1196
176217.3.5.120/29217.3.5.121 to 217.3.5.126217.3.5.1276
177217.3.5.128/29217.3.5.129 to 217.3.5.134217.3.5.1356
178217.3.5.136/29217.3.5.137 to 217.3.5.142217.3.5.1436
179217.3.5.144/29217.3.5.145 to 217.3.5.150217.3.5.1516
180217.3.5.152/29217.3.5.153 to 217.3.5.158217.3.5.1596
181217.3.5.160/29217.3.5.161 to 217.3.5.166217.3.5.1676
182217.3.5.168/29217.3.5.169 to 217.3.5.174217.3.5.1756
183217.3.5.176/29217.3.5.177 to 217.3.5.182217.3.5.1836
184217.3.5.184/29217.3.5.185 to 217.3.5.190217.3.5.1916
185217.3.5.192/29217.3.5.193 to 217.3.5.198217.3.5.1996
186217.3.5.200/29217.3.5.201 to 217.3.5.206217.3.5.2076
187217.3.5.208/29217.3.5.209 to 217.3.5.214217.3.5.2156
188217.3.5.216/29217.3.5.217 to 217.3.5.222217.3.5.2236
189217.3.5.224/29217.3.5.225 to 217.3.5.230217.3.5.2316
190217.3.5.232/29217.3.5.233 to 217.3.5.238217.3.5.2396
191217.3.5.240/29217.3.5.241 to 217.3.5.246217.3.5.2476
192217.3.5.248/29217.3.5.249 to 217.3.5.254217.3.5.2556
193217.3.6.0/29217.3.6.1 to 217.3.6.6217.3.6.76
194217.3.6.8/29217.3.6.9 to 217.3.6.14217.3.6.156
195217.3.6.16/29217.3.6.17 to 217.3.6.22217.3.6.236
196217.3.6.24/29217.3.6.25 to 217.3.6.30217.3.6.316
197217.3.6.32/29217.3.6.33 to 217.3.6.38217.3.6.396
198217.3.6.40/29217.3.6.41 to 217.3.6.46217.3.6.476
199217.3.6.48/29217.3.6.49 to 217.3.6.54217.3.6.556
200217.3.6.56/29217.3.6.57 to 217.3.6.62217.3.6.636
201217.3.6.64/29217.3.6.65 to 217.3.6.70217.3.6.716
202217.3.6.72/29217.3.6.73 to 217.3.6.78217.3.6.796
203217.3.6.80/29217.3.6.81 to 217.3.6.86217.3.6.876
204217.3.6.88/29217.3.6.89 to 217.3.6.94217.3.6.956
205217.3.6.96/29217.3.6.97 to 217.3.6.102217.3.6.1036
206217.3.6.104/29217.3.6.105 to 217.3.6.110217.3.6.1116
207217.3.6.112/29217.3.6.113 to 217.3.6.118217.3.6.1196
208217.3.6.120/29217.3.6.121 to 217.3.6.126217.3.6.1276
209217.3.6.128/29217.3.6.129 to 217.3.6.134217.3.6.1356
210217.3.6.136/29217.3.6.137 to 217.3.6.142217.3.6.1436
211217.3.6.144/29217.3.6.145 to 217.3.6.150217.3.6.1516
212217.3.6.152/29217.3.6.153 to 217.3.6.158217.3.6.1596
213217.3.6.160/29217.3.6.161 to 217.3.6.166217.3.6.1676
214217.3.6.168/29217.3.6.169 to 217.3.6.174217.3.6.1756
215217.3.6.176/29217.3.6.177 to 217.3.6.182217.3.6.1836
216217.3.6.184/29217.3.6.185 to 217.3.6.190217.3.6.1916
217217.3.6.192/29217.3.6.193 to 217.3.6.198217.3.6.1996
218217.3.6.200/29217.3.6.201 to 217.3.6.206217.3.6.2076
219217.3.6.208/29217.3.6.209 to 217.3.6.214217.3.6.2156
220217.3.6.216/29217.3.6.217 to 217.3.6.222217.3.6.2236
221217.3.6.224/29217.3.6.225 to 217.3.6.230217.3.6.2316
222217.3.6.232/29217.3.6.233 to 217.3.6.238217.3.6.2396
223217.3.6.240/29217.3.6.241 to 217.3.6.246217.3.6.2476
224217.3.6.248/29217.3.6.249 to 217.3.6.254217.3.6.2556
225217.3.7.0/29217.3.7.1 to 217.3.7.6217.3.7.76
226217.3.7.8/29217.3.7.9 to 217.3.7.14217.3.7.156
227217.3.7.16/29217.3.7.17 to 217.3.7.22217.3.7.236
228217.3.7.24/29217.3.7.25 to 217.3.7.30217.3.7.316
229217.3.7.32/29217.3.7.33 to 217.3.7.38217.3.7.396
230217.3.7.40/29217.3.7.41 to 217.3.7.46217.3.7.476
231217.3.7.48/29217.3.7.49 to 217.3.7.54217.3.7.556
232217.3.7.56/29217.3.7.57 to 217.3.7.62217.3.7.636
233217.3.7.64/29217.3.7.65 to 217.3.7.70217.3.7.716
234217.3.7.72/29217.3.7.73 to 217.3.7.78217.3.7.796
235217.3.7.80/29217.3.7.81 to 217.3.7.86217.3.7.876
236217.3.7.88/29217.3.7.89 to 217.3.7.94217.3.7.956
237217.3.7.96/29217.3.7.97 to 217.3.7.102217.3.7.1036
238217.3.7.104/29217.3.7.105 to 217.3.7.110217.3.7.1116
239217.3.7.112/29217.3.7.113 to 217.3.7.118217.3.7.1196
240217.3.7.120/29217.3.7.121 to 217.3.7.126217.3.7.1276
241217.3.7.128/29217.3.7.129 to 217.3.7.134217.3.7.1356
242217.3.7.136/29217.3.7.137 to 217.3.7.142217.3.7.1436
243217.3.7.144/29217.3.7.145 to 217.3.7.150217.3.7.1516
244217.3.7.152/29217.3.7.153 to 217.3.7.158217.3.7.1596
245217.3.7.160/29217.3.7.161 to 217.3.7.166217.3.7.1676
246217.3.7.168/29217.3.7.169 to 217.3.7.174217.3.7.1756
247217.3.7.176/29217.3.7.177 to 217.3.7.182217.3.7.1836
248217.3.7.184/29217.3.7.185 to 217.3.7.190217.3.7.1916
249217.3.7.192/29217.3.7.193 to 217.3.7.198217.3.7.1996
250217.3.7.200/29217.3.7.201 to 217.3.7.206217.3.7.2076
251217.3.7.208/29217.3.7.209 to 217.3.7.214217.3.7.2156
252217.3.7.216/29217.3.7.217 to 217.3.7.222217.3.7.2236
253217.3.7.224/29217.3.7.225 to 217.3.7.230217.3.7.2316
254217.3.7.232/29217.3.7.233 to 217.3.7.238217.3.7.2396
255217.3.7.240/29217.3.7.241 to 217.3.7.246217.3.7.2476
256217.3.7.248/29217.3.7.249 to 217.3.7.254217.3.7.2556

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.