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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.

Network191.2.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
191.2.64.0
Broadcast address
191.2.95.255
First usable
191.2.64.1
Last usable
191.2.95.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
B (default /16)
As numbers
Hex BF024000 · Integer 3204595712 to 3204603903
Reverse DNS zones
64.2.191.in-addr.arpa
65.2.191.in-addr.arpa
66.2.191.in-addr.arpa
67.2.191.in-addr.arpa
68.2.191.in-addr.arpa
69.2.191.in-addr.arpa
70.2.191.in-addr.arpa
71.2.191.in-addr.arpa
72.2.191.in-addr.arpa
73.2.191.in-addr.arpa
74.2.191.in-addr.arpa
75.2.191.in-addr.arpa
76.2.191.in-addr.arpa
77.2.191.in-addr.arpa
78.2.191.in-addr.arpa
79.2.191.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111111.00000010.01000000.00000000191.2.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network10111111.00000010.01000000.00000000191.2.64.0
Broadcast10111111.00000010.01011111.11111111191.2.95.255
Split into smaller subnets/29
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

191.2.64.0/19 makes 1,024 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1191.2.64.0/29191.2.64.1 to 191.2.64.6191.2.64.76
2191.2.64.8/29191.2.64.9 to 191.2.64.14191.2.64.156
3191.2.64.16/29191.2.64.17 to 191.2.64.22191.2.64.236
4191.2.64.24/29191.2.64.25 to 191.2.64.30191.2.64.316
5191.2.64.32/29191.2.64.33 to 191.2.64.38191.2.64.396
6191.2.64.40/29191.2.64.41 to 191.2.64.46191.2.64.476
7191.2.64.48/29191.2.64.49 to 191.2.64.54191.2.64.556
8191.2.64.56/29191.2.64.57 to 191.2.64.62191.2.64.636
9191.2.64.64/29191.2.64.65 to 191.2.64.70191.2.64.716
10191.2.64.72/29191.2.64.73 to 191.2.64.78191.2.64.796
11191.2.64.80/29191.2.64.81 to 191.2.64.86191.2.64.876
12191.2.64.88/29191.2.64.89 to 191.2.64.94191.2.64.956
13191.2.64.96/29191.2.64.97 to 191.2.64.102191.2.64.1036
14191.2.64.104/29191.2.64.105 to 191.2.64.110191.2.64.1116
15191.2.64.112/29191.2.64.113 to 191.2.64.118191.2.64.1196
16191.2.64.120/29191.2.64.121 to 191.2.64.126191.2.64.1276
17191.2.64.128/29191.2.64.129 to 191.2.64.134191.2.64.1356
18191.2.64.136/29191.2.64.137 to 191.2.64.142191.2.64.1436
19191.2.64.144/29191.2.64.145 to 191.2.64.150191.2.64.1516
20191.2.64.152/29191.2.64.153 to 191.2.64.158191.2.64.1596
21191.2.64.160/29191.2.64.161 to 191.2.64.166191.2.64.1676
22191.2.64.168/29191.2.64.169 to 191.2.64.174191.2.64.1756
23191.2.64.176/29191.2.64.177 to 191.2.64.182191.2.64.1836
24191.2.64.184/29191.2.64.185 to 191.2.64.190191.2.64.1916
25191.2.64.192/29191.2.64.193 to 191.2.64.198191.2.64.1996
26191.2.64.200/29191.2.64.201 to 191.2.64.206191.2.64.2076
27191.2.64.208/29191.2.64.209 to 191.2.64.214191.2.64.2156
28191.2.64.216/29191.2.64.217 to 191.2.64.222191.2.64.2236
29191.2.64.224/29191.2.64.225 to 191.2.64.230191.2.64.2316
30191.2.64.232/29191.2.64.233 to 191.2.64.238191.2.64.2396
31191.2.64.240/29191.2.64.241 to 191.2.64.246191.2.64.2476
32191.2.64.248/29191.2.64.249 to 191.2.64.254191.2.64.2556
33191.2.65.0/29191.2.65.1 to 191.2.65.6191.2.65.76
34191.2.65.8/29191.2.65.9 to 191.2.65.14191.2.65.156
35191.2.65.16/29191.2.65.17 to 191.2.65.22191.2.65.236
36191.2.65.24/29191.2.65.25 to 191.2.65.30191.2.65.316
37191.2.65.32/29191.2.65.33 to 191.2.65.38191.2.65.396
38191.2.65.40/29191.2.65.41 to 191.2.65.46191.2.65.476
39191.2.65.48/29191.2.65.49 to 191.2.65.54191.2.65.556
40191.2.65.56/29191.2.65.57 to 191.2.65.62191.2.65.636
41191.2.65.64/29191.2.65.65 to 191.2.65.70191.2.65.716
42191.2.65.72/29191.2.65.73 to 191.2.65.78191.2.65.796
43191.2.65.80/29191.2.65.81 to 191.2.65.86191.2.65.876
44191.2.65.88/29191.2.65.89 to 191.2.65.94191.2.65.956
45191.2.65.96/29191.2.65.97 to 191.2.65.102191.2.65.1036
46191.2.65.104/29191.2.65.105 to 191.2.65.110191.2.65.1116
47191.2.65.112/29191.2.65.113 to 191.2.65.118191.2.65.1196
48191.2.65.120/29191.2.65.121 to 191.2.65.126191.2.65.1276
49191.2.65.128/29191.2.65.129 to 191.2.65.134191.2.65.1356
50191.2.65.136/29191.2.65.137 to 191.2.65.142191.2.65.1436
51191.2.65.144/29191.2.65.145 to 191.2.65.150191.2.65.1516
52191.2.65.152/29191.2.65.153 to 191.2.65.158191.2.65.1596
53191.2.65.160/29191.2.65.161 to 191.2.65.166191.2.65.1676
54191.2.65.168/29191.2.65.169 to 191.2.65.174191.2.65.1756
55191.2.65.176/29191.2.65.177 to 191.2.65.182191.2.65.1836
56191.2.65.184/29191.2.65.185 to 191.2.65.190191.2.65.1916
57191.2.65.192/29191.2.65.193 to 191.2.65.198191.2.65.1996
58191.2.65.200/29191.2.65.201 to 191.2.65.206191.2.65.2076
59191.2.65.208/29191.2.65.209 to 191.2.65.214191.2.65.2156
60191.2.65.216/29191.2.65.217 to 191.2.65.222191.2.65.2236
61191.2.65.224/29191.2.65.225 to 191.2.65.230191.2.65.2316
62191.2.65.232/29191.2.65.233 to 191.2.65.238191.2.65.2396
63191.2.65.240/29191.2.65.241 to 191.2.65.246191.2.65.2476
64191.2.65.248/29191.2.65.249 to 191.2.65.254191.2.65.2556
65191.2.66.0/29191.2.66.1 to 191.2.66.6191.2.66.76
66191.2.66.8/29191.2.66.9 to 191.2.66.14191.2.66.156
67191.2.66.16/29191.2.66.17 to 191.2.66.22191.2.66.236
68191.2.66.24/29191.2.66.25 to 191.2.66.30191.2.66.316
69191.2.66.32/29191.2.66.33 to 191.2.66.38191.2.66.396
70191.2.66.40/29191.2.66.41 to 191.2.66.46191.2.66.476
71191.2.66.48/29191.2.66.49 to 191.2.66.54191.2.66.556
72191.2.66.56/29191.2.66.57 to 191.2.66.62191.2.66.636
73191.2.66.64/29191.2.66.65 to 191.2.66.70191.2.66.716
74191.2.66.72/29191.2.66.73 to 191.2.66.78191.2.66.796
75191.2.66.80/29191.2.66.81 to 191.2.66.86191.2.66.876
76191.2.66.88/29191.2.66.89 to 191.2.66.94191.2.66.956
77191.2.66.96/29191.2.66.97 to 191.2.66.102191.2.66.1036
78191.2.66.104/29191.2.66.105 to 191.2.66.110191.2.66.1116
79191.2.66.112/29191.2.66.113 to 191.2.66.118191.2.66.1196
80191.2.66.120/29191.2.66.121 to 191.2.66.126191.2.66.1276
81191.2.66.128/29191.2.66.129 to 191.2.66.134191.2.66.1356
82191.2.66.136/29191.2.66.137 to 191.2.66.142191.2.66.1436
83191.2.66.144/29191.2.66.145 to 191.2.66.150191.2.66.1516
84191.2.66.152/29191.2.66.153 to 191.2.66.158191.2.66.1596
85191.2.66.160/29191.2.66.161 to 191.2.66.166191.2.66.1676
86191.2.66.168/29191.2.66.169 to 191.2.66.174191.2.66.1756
87191.2.66.176/29191.2.66.177 to 191.2.66.182191.2.66.1836
88191.2.66.184/29191.2.66.185 to 191.2.66.190191.2.66.1916
89191.2.66.192/29191.2.66.193 to 191.2.66.198191.2.66.1996
90191.2.66.200/29191.2.66.201 to 191.2.66.206191.2.66.2076
91191.2.66.208/29191.2.66.209 to 191.2.66.214191.2.66.2156
92191.2.66.216/29191.2.66.217 to 191.2.66.222191.2.66.2236
93191.2.66.224/29191.2.66.225 to 191.2.66.230191.2.66.2316
94191.2.66.232/29191.2.66.233 to 191.2.66.238191.2.66.2396
95191.2.66.240/29191.2.66.241 to 191.2.66.246191.2.66.2476
96191.2.66.248/29191.2.66.249 to 191.2.66.254191.2.66.2556
97191.2.67.0/29191.2.67.1 to 191.2.67.6191.2.67.76
98191.2.67.8/29191.2.67.9 to 191.2.67.14191.2.67.156
99191.2.67.16/29191.2.67.17 to 191.2.67.22191.2.67.236
100191.2.67.24/29191.2.67.25 to 191.2.67.30191.2.67.316
101191.2.67.32/29191.2.67.33 to 191.2.67.38191.2.67.396
102191.2.67.40/29191.2.67.41 to 191.2.67.46191.2.67.476
103191.2.67.48/29191.2.67.49 to 191.2.67.54191.2.67.556
104191.2.67.56/29191.2.67.57 to 191.2.67.62191.2.67.636
105191.2.67.64/29191.2.67.65 to 191.2.67.70191.2.67.716
106191.2.67.72/29191.2.67.73 to 191.2.67.78191.2.67.796
107191.2.67.80/29191.2.67.81 to 191.2.67.86191.2.67.876
108191.2.67.88/29191.2.67.89 to 191.2.67.94191.2.67.956
109191.2.67.96/29191.2.67.97 to 191.2.67.102191.2.67.1036
110191.2.67.104/29191.2.67.105 to 191.2.67.110191.2.67.1116
111191.2.67.112/29191.2.67.113 to 191.2.67.118191.2.67.1196
112191.2.67.120/29191.2.67.121 to 191.2.67.126191.2.67.1276
113191.2.67.128/29191.2.67.129 to 191.2.67.134191.2.67.1356
114191.2.67.136/29191.2.67.137 to 191.2.67.142191.2.67.1436
115191.2.67.144/29191.2.67.145 to 191.2.67.150191.2.67.1516
116191.2.67.152/29191.2.67.153 to 191.2.67.158191.2.67.1596
117191.2.67.160/29191.2.67.161 to 191.2.67.166191.2.67.1676
118191.2.67.168/29191.2.67.169 to 191.2.67.174191.2.67.1756
119191.2.67.176/29191.2.67.177 to 191.2.67.182191.2.67.1836
120191.2.67.184/29191.2.67.185 to 191.2.67.190191.2.67.1916
121191.2.67.192/29191.2.67.193 to 191.2.67.198191.2.67.1996
122191.2.67.200/29191.2.67.201 to 191.2.67.206191.2.67.2076
123191.2.67.208/29191.2.67.209 to 191.2.67.214191.2.67.2156
124191.2.67.216/29191.2.67.217 to 191.2.67.222191.2.67.2236
125191.2.67.224/29191.2.67.225 to 191.2.67.230191.2.67.2316
126191.2.67.232/29191.2.67.233 to 191.2.67.238191.2.67.2396
127191.2.67.240/29191.2.67.241 to 191.2.67.246191.2.67.2476
128191.2.67.248/29191.2.67.249 to 191.2.67.254191.2.67.2556
129191.2.68.0/29191.2.68.1 to 191.2.68.6191.2.68.76
130191.2.68.8/29191.2.68.9 to 191.2.68.14191.2.68.156
131191.2.68.16/29191.2.68.17 to 191.2.68.22191.2.68.236
132191.2.68.24/29191.2.68.25 to 191.2.68.30191.2.68.316
133191.2.68.32/29191.2.68.33 to 191.2.68.38191.2.68.396
134191.2.68.40/29191.2.68.41 to 191.2.68.46191.2.68.476
135191.2.68.48/29191.2.68.49 to 191.2.68.54191.2.68.556
136191.2.68.56/29191.2.68.57 to 191.2.68.62191.2.68.636
137191.2.68.64/29191.2.68.65 to 191.2.68.70191.2.68.716
138191.2.68.72/29191.2.68.73 to 191.2.68.78191.2.68.796
139191.2.68.80/29191.2.68.81 to 191.2.68.86191.2.68.876
140191.2.68.88/29191.2.68.89 to 191.2.68.94191.2.68.956
141191.2.68.96/29191.2.68.97 to 191.2.68.102191.2.68.1036
142191.2.68.104/29191.2.68.105 to 191.2.68.110191.2.68.1116
143191.2.68.112/29191.2.68.113 to 191.2.68.118191.2.68.1196
144191.2.68.120/29191.2.68.121 to 191.2.68.126191.2.68.1276
145191.2.68.128/29191.2.68.129 to 191.2.68.134191.2.68.1356
146191.2.68.136/29191.2.68.137 to 191.2.68.142191.2.68.1436
147191.2.68.144/29191.2.68.145 to 191.2.68.150191.2.68.1516
148191.2.68.152/29191.2.68.153 to 191.2.68.158191.2.68.1596
149191.2.68.160/29191.2.68.161 to 191.2.68.166191.2.68.1676
150191.2.68.168/29191.2.68.169 to 191.2.68.174191.2.68.1756
151191.2.68.176/29191.2.68.177 to 191.2.68.182191.2.68.1836
152191.2.68.184/29191.2.68.185 to 191.2.68.190191.2.68.1916
153191.2.68.192/29191.2.68.193 to 191.2.68.198191.2.68.1996
154191.2.68.200/29191.2.68.201 to 191.2.68.206191.2.68.2076
155191.2.68.208/29191.2.68.209 to 191.2.68.214191.2.68.2156
156191.2.68.216/29191.2.68.217 to 191.2.68.222191.2.68.2236
157191.2.68.224/29191.2.68.225 to 191.2.68.230191.2.68.2316
158191.2.68.232/29191.2.68.233 to 191.2.68.238191.2.68.2396
159191.2.68.240/29191.2.68.241 to 191.2.68.246191.2.68.2476
160191.2.68.248/29191.2.68.249 to 191.2.68.254191.2.68.2556
161191.2.69.0/29191.2.69.1 to 191.2.69.6191.2.69.76
162191.2.69.8/29191.2.69.9 to 191.2.69.14191.2.69.156
163191.2.69.16/29191.2.69.17 to 191.2.69.22191.2.69.236
164191.2.69.24/29191.2.69.25 to 191.2.69.30191.2.69.316
165191.2.69.32/29191.2.69.33 to 191.2.69.38191.2.69.396
166191.2.69.40/29191.2.69.41 to 191.2.69.46191.2.69.476
167191.2.69.48/29191.2.69.49 to 191.2.69.54191.2.69.556
168191.2.69.56/29191.2.69.57 to 191.2.69.62191.2.69.636
169191.2.69.64/29191.2.69.65 to 191.2.69.70191.2.69.716
170191.2.69.72/29191.2.69.73 to 191.2.69.78191.2.69.796
171191.2.69.80/29191.2.69.81 to 191.2.69.86191.2.69.876
172191.2.69.88/29191.2.69.89 to 191.2.69.94191.2.69.956
173191.2.69.96/29191.2.69.97 to 191.2.69.102191.2.69.1036
174191.2.69.104/29191.2.69.105 to 191.2.69.110191.2.69.1116
175191.2.69.112/29191.2.69.113 to 191.2.69.118191.2.69.1196
176191.2.69.120/29191.2.69.121 to 191.2.69.126191.2.69.1276
177191.2.69.128/29191.2.69.129 to 191.2.69.134191.2.69.1356
178191.2.69.136/29191.2.69.137 to 191.2.69.142191.2.69.1436
179191.2.69.144/29191.2.69.145 to 191.2.69.150191.2.69.1516
180191.2.69.152/29191.2.69.153 to 191.2.69.158191.2.69.1596
181191.2.69.160/29191.2.69.161 to 191.2.69.166191.2.69.1676
182191.2.69.168/29191.2.69.169 to 191.2.69.174191.2.69.1756
183191.2.69.176/29191.2.69.177 to 191.2.69.182191.2.69.1836
184191.2.69.184/29191.2.69.185 to 191.2.69.190191.2.69.1916
185191.2.69.192/29191.2.69.193 to 191.2.69.198191.2.69.1996
186191.2.69.200/29191.2.69.201 to 191.2.69.206191.2.69.2076
187191.2.69.208/29191.2.69.209 to 191.2.69.214191.2.69.2156
188191.2.69.216/29191.2.69.217 to 191.2.69.222191.2.69.2236
189191.2.69.224/29191.2.69.225 to 191.2.69.230191.2.69.2316
190191.2.69.232/29191.2.69.233 to 191.2.69.238191.2.69.2396
191191.2.69.240/29191.2.69.241 to 191.2.69.246191.2.69.2476
192191.2.69.248/29191.2.69.249 to 191.2.69.254191.2.69.2556
193191.2.70.0/29191.2.70.1 to 191.2.70.6191.2.70.76
194191.2.70.8/29191.2.70.9 to 191.2.70.14191.2.70.156
195191.2.70.16/29191.2.70.17 to 191.2.70.22191.2.70.236
196191.2.70.24/29191.2.70.25 to 191.2.70.30191.2.70.316
197191.2.70.32/29191.2.70.33 to 191.2.70.38191.2.70.396
198191.2.70.40/29191.2.70.41 to 191.2.70.46191.2.70.476
199191.2.70.48/29191.2.70.49 to 191.2.70.54191.2.70.556
200191.2.70.56/29191.2.70.57 to 191.2.70.62191.2.70.636
201191.2.70.64/29191.2.70.65 to 191.2.70.70191.2.70.716
202191.2.70.72/29191.2.70.73 to 191.2.70.78191.2.70.796
203191.2.70.80/29191.2.70.81 to 191.2.70.86191.2.70.876
204191.2.70.88/29191.2.70.89 to 191.2.70.94191.2.70.956
205191.2.70.96/29191.2.70.97 to 191.2.70.102191.2.70.1036
206191.2.70.104/29191.2.70.105 to 191.2.70.110191.2.70.1116
207191.2.70.112/29191.2.70.113 to 191.2.70.118191.2.70.1196
208191.2.70.120/29191.2.70.121 to 191.2.70.126191.2.70.1276
209191.2.70.128/29191.2.70.129 to 191.2.70.134191.2.70.1356
210191.2.70.136/29191.2.70.137 to 191.2.70.142191.2.70.1436
211191.2.70.144/29191.2.70.145 to 191.2.70.150191.2.70.1516
212191.2.70.152/29191.2.70.153 to 191.2.70.158191.2.70.1596
213191.2.70.160/29191.2.70.161 to 191.2.70.166191.2.70.1676
214191.2.70.168/29191.2.70.169 to 191.2.70.174191.2.70.1756
215191.2.70.176/29191.2.70.177 to 191.2.70.182191.2.70.1836
216191.2.70.184/29191.2.70.185 to 191.2.70.190191.2.70.1916
217191.2.70.192/29191.2.70.193 to 191.2.70.198191.2.70.1996
218191.2.70.200/29191.2.70.201 to 191.2.70.206191.2.70.2076
219191.2.70.208/29191.2.70.209 to 191.2.70.214191.2.70.2156
220191.2.70.216/29191.2.70.217 to 191.2.70.222191.2.70.2236
221191.2.70.224/29191.2.70.225 to 191.2.70.230191.2.70.2316
222191.2.70.232/29191.2.70.233 to 191.2.70.238191.2.70.2396
223191.2.70.240/29191.2.70.241 to 191.2.70.246191.2.70.2476
224191.2.70.248/29191.2.70.249 to 191.2.70.254191.2.70.2556
225191.2.71.0/29191.2.71.1 to 191.2.71.6191.2.71.76
226191.2.71.8/29191.2.71.9 to 191.2.71.14191.2.71.156
227191.2.71.16/29191.2.71.17 to 191.2.71.22191.2.71.236
228191.2.71.24/29191.2.71.25 to 191.2.71.30191.2.71.316
229191.2.71.32/29191.2.71.33 to 191.2.71.38191.2.71.396
230191.2.71.40/29191.2.71.41 to 191.2.71.46191.2.71.476
231191.2.71.48/29191.2.71.49 to 191.2.71.54191.2.71.556
232191.2.71.56/29191.2.71.57 to 191.2.71.62191.2.71.636
233191.2.71.64/29191.2.71.65 to 191.2.71.70191.2.71.716
234191.2.71.72/29191.2.71.73 to 191.2.71.78191.2.71.796
235191.2.71.80/29191.2.71.81 to 191.2.71.86191.2.71.876
236191.2.71.88/29191.2.71.89 to 191.2.71.94191.2.71.956
237191.2.71.96/29191.2.71.97 to 191.2.71.102191.2.71.1036
238191.2.71.104/29191.2.71.105 to 191.2.71.110191.2.71.1116
239191.2.71.112/29191.2.71.113 to 191.2.71.118191.2.71.1196
240191.2.71.120/29191.2.71.121 to 191.2.71.126191.2.71.1276
241191.2.71.128/29191.2.71.129 to 191.2.71.134191.2.71.1356
242191.2.71.136/29191.2.71.137 to 191.2.71.142191.2.71.1436
243191.2.71.144/29191.2.71.145 to 191.2.71.150191.2.71.1516
244191.2.71.152/29191.2.71.153 to 191.2.71.158191.2.71.1596
245191.2.71.160/29191.2.71.161 to 191.2.71.166191.2.71.1676
246191.2.71.168/29191.2.71.169 to 191.2.71.174191.2.71.1756
247191.2.71.176/29191.2.71.177 to 191.2.71.182191.2.71.1836
248191.2.71.184/29191.2.71.185 to 191.2.71.190191.2.71.1916
249191.2.71.192/29191.2.71.193 to 191.2.71.198191.2.71.1996
250191.2.71.200/29191.2.71.201 to 191.2.71.206191.2.71.2076
251191.2.71.208/29191.2.71.209 to 191.2.71.214191.2.71.2156
252191.2.71.216/29191.2.71.217 to 191.2.71.222191.2.71.2236
253191.2.71.224/29191.2.71.225 to 191.2.71.230191.2.71.2316
254191.2.71.232/29191.2.71.233 to 191.2.71.238191.2.71.2396
255191.2.71.240/29191.2.71.241 to 191.2.71.246191.2.71.2476
256191.2.71.248/29191.2.71.249 to 191.2.71.254191.2.71.2556

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.