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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.

Network191.7.0.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
191.7.0.0
Broadcast address
191.7.31.255
First usable
191.7.0.1
Last usable
191.7.31.254
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 BF070000 · Integer 3204907008 to 3204915199
Reverse DNS zones
0.7.191.in-addr.arpa
1.7.191.in-addr.arpa
2.7.191.in-addr.arpa
3.7.191.in-addr.arpa
4.7.191.in-addr.arpa
5.7.191.in-addr.arpa
6.7.191.in-addr.arpa
7.7.191.in-addr.arpa
8.7.191.in-addr.arpa
9.7.191.in-addr.arpa
10.7.191.in-addr.arpa
11.7.191.in-addr.arpa
12.7.191.in-addr.arpa
13.7.191.in-addr.arpa
14.7.191.in-addr.arpa
15.7.191.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
Address10111111.00000111.00000000.00000000191.7.0.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network10111111.00000111.00000000.00000000191.7.0.0
Broadcast10111111.00000111.00011111.11111111191.7.31.255
Split into smaller subnets/30
/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)

191.7.0.0/19 makes 2,048 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1191.7.0.0/30191.7.0.1 to 191.7.0.2191.7.0.32
2191.7.0.4/30191.7.0.5 to 191.7.0.6191.7.0.72
3191.7.0.8/30191.7.0.9 to 191.7.0.10191.7.0.112
4191.7.0.12/30191.7.0.13 to 191.7.0.14191.7.0.152
5191.7.0.16/30191.7.0.17 to 191.7.0.18191.7.0.192
6191.7.0.20/30191.7.0.21 to 191.7.0.22191.7.0.232
7191.7.0.24/30191.7.0.25 to 191.7.0.26191.7.0.272
8191.7.0.28/30191.7.0.29 to 191.7.0.30191.7.0.312
9191.7.0.32/30191.7.0.33 to 191.7.0.34191.7.0.352
10191.7.0.36/30191.7.0.37 to 191.7.0.38191.7.0.392
11191.7.0.40/30191.7.0.41 to 191.7.0.42191.7.0.432
12191.7.0.44/30191.7.0.45 to 191.7.0.46191.7.0.472
13191.7.0.48/30191.7.0.49 to 191.7.0.50191.7.0.512
14191.7.0.52/30191.7.0.53 to 191.7.0.54191.7.0.552
15191.7.0.56/30191.7.0.57 to 191.7.0.58191.7.0.592
16191.7.0.60/30191.7.0.61 to 191.7.0.62191.7.0.632
17191.7.0.64/30191.7.0.65 to 191.7.0.66191.7.0.672
18191.7.0.68/30191.7.0.69 to 191.7.0.70191.7.0.712
19191.7.0.72/30191.7.0.73 to 191.7.0.74191.7.0.752
20191.7.0.76/30191.7.0.77 to 191.7.0.78191.7.0.792
21191.7.0.80/30191.7.0.81 to 191.7.0.82191.7.0.832
22191.7.0.84/30191.7.0.85 to 191.7.0.86191.7.0.872
23191.7.0.88/30191.7.0.89 to 191.7.0.90191.7.0.912
24191.7.0.92/30191.7.0.93 to 191.7.0.94191.7.0.952
25191.7.0.96/30191.7.0.97 to 191.7.0.98191.7.0.992
26191.7.0.100/30191.7.0.101 to 191.7.0.102191.7.0.1032
27191.7.0.104/30191.7.0.105 to 191.7.0.106191.7.0.1072
28191.7.0.108/30191.7.0.109 to 191.7.0.110191.7.0.1112
29191.7.0.112/30191.7.0.113 to 191.7.0.114191.7.0.1152
30191.7.0.116/30191.7.0.117 to 191.7.0.118191.7.0.1192
31191.7.0.120/30191.7.0.121 to 191.7.0.122191.7.0.1232
32191.7.0.124/30191.7.0.125 to 191.7.0.126191.7.0.1272
33191.7.0.128/30191.7.0.129 to 191.7.0.130191.7.0.1312
34191.7.0.132/30191.7.0.133 to 191.7.0.134191.7.0.1352
35191.7.0.136/30191.7.0.137 to 191.7.0.138191.7.0.1392
36191.7.0.140/30191.7.0.141 to 191.7.0.142191.7.0.1432
37191.7.0.144/30191.7.0.145 to 191.7.0.146191.7.0.1472
38191.7.0.148/30191.7.0.149 to 191.7.0.150191.7.0.1512
39191.7.0.152/30191.7.0.153 to 191.7.0.154191.7.0.1552
40191.7.0.156/30191.7.0.157 to 191.7.0.158191.7.0.1592
41191.7.0.160/30191.7.0.161 to 191.7.0.162191.7.0.1632
42191.7.0.164/30191.7.0.165 to 191.7.0.166191.7.0.1672
43191.7.0.168/30191.7.0.169 to 191.7.0.170191.7.0.1712
44191.7.0.172/30191.7.0.173 to 191.7.0.174191.7.0.1752
45191.7.0.176/30191.7.0.177 to 191.7.0.178191.7.0.1792
46191.7.0.180/30191.7.0.181 to 191.7.0.182191.7.0.1832
47191.7.0.184/30191.7.0.185 to 191.7.0.186191.7.0.1872
48191.7.0.188/30191.7.0.189 to 191.7.0.190191.7.0.1912
49191.7.0.192/30191.7.0.193 to 191.7.0.194191.7.0.1952
50191.7.0.196/30191.7.0.197 to 191.7.0.198191.7.0.1992
51191.7.0.200/30191.7.0.201 to 191.7.0.202191.7.0.2032
52191.7.0.204/30191.7.0.205 to 191.7.0.206191.7.0.2072
53191.7.0.208/30191.7.0.209 to 191.7.0.210191.7.0.2112
54191.7.0.212/30191.7.0.213 to 191.7.0.214191.7.0.2152
55191.7.0.216/30191.7.0.217 to 191.7.0.218191.7.0.2192
56191.7.0.220/30191.7.0.221 to 191.7.0.222191.7.0.2232
57191.7.0.224/30191.7.0.225 to 191.7.0.226191.7.0.2272
58191.7.0.228/30191.7.0.229 to 191.7.0.230191.7.0.2312
59191.7.0.232/30191.7.0.233 to 191.7.0.234191.7.0.2352
60191.7.0.236/30191.7.0.237 to 191.7.0.238191.7.0.2392
61191.7.0.240/30191.7.0.241 to 191.7.0.242191.7.0.2432
62191.7.0.244/30191.7.0.245 to 191.7.0.246191.7.0.2472
63191.7.0.248/30191.7.0.249 to 191.7.0.250191.7.0.2512
64191.7.0.252/30191.7.0.253 to 191.7.0.254191.7.0.2552
65191.7.1.0/30191.7.1.1 to 191.7.1.2191.7.1.32
66191.7.1.4/30191.7.1.5 to 191.7.1.6191.7.1.72
67191.7.1.8/30191.7.1.9 to 191.7.1.10191.7.1.112
68191.7.1.12/30191.7.1.13 to 191.7.1.14191.7.1.152
69191.7.1.16/30191.7.1.17 to 191.7.1.18191.7.1.192
70191.7.1.20/30191.7.1.21 to 191.7.1.22191.7.1.232
71191.7.1.24/30191.7.1.25 to 191.7.1.26191.7.1.272
72191.7.1.28/30191.7.1.29 to 191.7.1.30191.7.1.312
73191.7.1.32/30191.7.1.33 to 191.7.1.34191.7.1.352
74191.7.1.36/30191.7.1.37 to 191.7.1.38191.7.1.392
75191.7.1.40/30191.7.1.41 to 191.7.1.42191.7.1.432
76191.7.1.44/30191.7.1.45 to 191.7.1.46191.7.1.472
77191.7.1.48/30191.7.1.49 to 191.7.1.50191.7.1.512
78191.7.1.52/30191.7.1.53 to 191.7.1.54191.7.1.552
79191.7.1.56/30191.7.1.57 to 191.7.1.58191.7.1.592
80191.7.1.60/30191.7.1.61 to 191.7.1.62191.7.1.632
81191.7.1.64/30191.7.1.65 to 191.7.1.66191.7.1.672
82191.7.1.68/30191.7.1.69 to 191.7.1.70191.7.1.712
83191.7.1.72/30191.7.1.73 to 191.7.1.74191.7.1.752
84191.7.1.76/30191.7.1.77 to 191.7.1.78191.7.1.792
85191.7.1.80/30191.7.1.81 to 191.7.1.82191.7.1.832
86191.7.1.84/30191.7.1.85 to 191.7.1.86191.7.1.872
87191.7.1.88/30191.7.1.89 to 191.7.1.90191.7.1.912
88191.7.1.92/30191.7.1.93 to 191.7.1.94191.7.1.952
89191.7.1.96/30191.7.1.97 to 191.7.1.98191.7.1.992
90191.7.1.100/30191.7.1.101 to 191.7.1.102191.7.1.1032
91191.7.1.104/30191.7.1.105 to 191.7.1.106191.7.1.1072
92191.7.1.108/30191.7.1.109 to 191.7.1.110191.7.1.1112
93191.7.1.112/30191.7.1.113 to 191.7.1.114191.7.1.1152
94191.7.1.116/30191.7.1.117 to 191.7.1.118191.7.1.1192
95191.7.1.120/30191.7.1.121 to 191.7.1.122191.7.1.1232
96191.7.1.124/30191.7.1.125 to 191.7.1.126191.7.1.1272
97191.7.1.128/30191.7.1.129 to 191.7.1.130191.7.1.1312
98191.7.1.132/30191.7.1.133 to 191.7.1.134191.7.1.1352
99191.7.1.136/30191.7.1.137 to 191.7.1.138191.7.1.1392
100191.7.1.140/30191.7.1.141 to 191.7.1.142191.7.1.1432
101191.7.1.144/30191.7.1.145 to 191.7.1.146191.7.1.1472
102191.7.1.148/30191.7.1.149 to 191.7.1.150191.7.1.1512
103191.7.1.152/30191.7.1.153 to 191.7.1.154191.7.1.1552
104191.7.1.156/30191.7.1.157 to 191.7.1.158191.7.1.1592
105191.7.1.160/30191.7.1.161 to 191.7.1.162191.7.1.1632
106191.7.1.164/30191.7.1.165 to 191.7.1.166191.7.1.1672
107191.7.1.168/30191.7.1.169 to 191.7.1.170191.7.1.1712
108191.7.1.172/30191.7.1.173 to 191.7.1.174191.7.1.1752
109191.7.1.176/30191.7.1.177 to 191.7.1.178191.7.1.1792
110191.7.1.180/30191.7.1.181 to 191.7.1.182191.7.1.1832
111191.7.1.184/30191.7.1.185 to 191.7.1.186191.7.1.1872
112191.7.1.188/30191.7.1.189 to 191.7.1.190191.7.1.1912
113191.7.1.192/30191.7.1.193 to 191.7.1.194191.7.1.1952
114191.7.1.196/30191.7.1.197 to 191.7.1.198191.7.1.1992
115191.7.1.200/30191.7.1.201 to 191.7.1.202191.7.1.2032
116191.7.1.204/30191.7.1.205 to 191.7.1.206191.7.1.2072
117191.7.1.208/30191.7.1.209 to 191.7.1.210191.7.1.2112
118191.7.1.212/30191.7.1.213 to 191.7.1.214191.7.1.2152
119191.7.1.216/30191.7.1.217 to 191.7.1.218191.7.1.2192
120191.7.1.220/30191.7.1.221 to 191.7.1.222191.7.1.2232
121191.7.1.224/30191.7.1.225 to 191.7.1.226191.7.1.2272
122191.7.1.228/30191.7.1.229 to 191.7.1.230191.7.1.2312
123191.7.1.232/30191.7.1.233 to 191.7.1.234191.7.1.2352
124191.7.1.236/30191.7.1.237 to 191.7.1.238191.7.1.2392
125191.7.1.240/30191.7.1.241 to 191.7.1.242191.7.1.2432
126191.7.1.244/30191.7.1.245 to 191.7.1.246191.7.1.2472
127191.7.1.248/30191.7.1.249 to 191.7.1.250191.7.1.2512
128191.7.1.252/30191.7.1.253 to 191.7.1.254191.7.1.2552
129191.7.2.0/30191.7.2.1 to 191.7.2.2191.7.2.32
130191.7.2.4/30191.7.2.5 to 191.7.2.6191.7.2.72
131191.7.2.8/30191.7.2.9 to 191.7.2.10191.7.2.112
132191.7.2.12/30191.7.2.13 to 191.7.2.14191.7.2.152
133191.7.2.16/30191.7.2.17 to 191.7.2.18191.7.2.192
134191.7.2.20/30191.7.2.21 to 191.7.2.22191.7.2.232
135191.7.2.24/30191.7.2.25 to 191.7.2.26191.7.2.272
136191.7.2.28/30191.7.2.29 to 191.7.2.30191.7.2.312
137191.7.2.32/30191.7.2.33 to 191.7.2.34191.7.2.352
138191.7.2.36/30191.7.2.37 to 191.7.2.38191.7.2.392
139191.7.2.40/30191.7.2.41 to 191.7.2.42191.7.2.432
140191.7.2.44/30191.7.2.45 to 191.7.2.46191.7.2.472
141191.7.2.48/30191.7.2.49 to 191.7.2.50191.7.2.512
142191.7.2.52/30191.7.2.53 to 191.7.2.54191.7.2.552
143191.7.2.56/30191.7.2.57 to 191.7.2.58191.7.2.592
144191.7.2.60/30191.7.2.61 to 191.7.2.62191.7.2.632
145191.7.2.64/30191.7.2.65 to 191.7.2.66191.7.2.672
146191.7.2.68/30191.7.2.69 to 191.7.2.70191.7.2.712
147191.7.2.72/30191.7.2.73 to 191.7.2.74191.7.2.752
148191.7.2.76/30191.7.2.77 to 191.7.2.78191.7.2.792
149191.7.2.80/30191.7.2.81 to 191.7.2.82191.7.2.832
150191.7.2.84/30191.7.2.85 to 191.7.2.86191.7.2.872
151191.7.2.88/30191.7.2.89 to 191.7.2.90191.7.2.912
152191.7.2.92/30191.7.2.93 to 191.7.2.94191.7.2.952
153191.7.2.96/30191.7.2.97 to 191.7.2.98191.7.2.992
154191.7.2.100/30191.7.2.101 to 191.7.2.102191.7.2.1032
155191.7.2.104/30191.7.2.105 to 191.7.2.106191.7.2.1072
156191.7.2.108/30191.7.2.109 to 191.7.2.110191.7.2.1112
157191.7.2.112/30191.7.2.113 to 191.7.2.114191.7.2.1152
158191.7.2.116/30191.7.2.117 to 191.7.2.118191.7.2.1192
159191.7.2.120/30191.7.2.121 to 191.7.2.122191.7.2.1232
160191.7.2.124/30191.7.2.125 to 191.7.2.126191.7.2.1272
161191.7.2.128/30191.7.2.129 to 191.7.2.130191.7.2.1312
162191.7.2.132/30191.7.2.133 to 191.7.2.134191.7.2.1352
163191.7.2.136/30191.7.2.137 to 191.7.2.138191.7.2.1392
164191.7.2.140/30191.7.2.141 to 191.7.2.142191.7.2.1432
165191.7.2.144/30191.7.2.145 to 191.7.2.146191.7.2.1472
166191.7.2.148/30191.7.2.149 to 191.7.2.150191.7.2.1512
167191.7.2.152/30191.7.2.153 to 191.7.2.154191.7.2.1552
168191.7.2.156/30191.7.2.157 to 191.7.2.158191.7.2.1592
169191.7.2.160/30191.7.2.161 to 191.7.2.162191.7.2.1632
170191.7.2.164/30191.7.2.165 to 191.7.2.166191.7.2.1672
171191.7.2.168/30191.7.2.169 to 191.7.2.170191.7.2.1712
172191.7.2.172/30191.7.2.173 to 191.7.2.174191.7.2.1752
173191.7.2.176/30191.7.2.177 to 191.7.2.178191.7.2.1792
174191.7.2.180/30191.7.2.181 to 191.7.2.182191.7.2.1832
175191.7.2.184/30191.7.2.185 to 191.7.2.186191.7.2.1872
176191.7.2.188/30191.7.2.189 to 191.7.2.190191.7.2.1912
177191.7.2.192/30191.7.2.193 to 191.7.2.194191.7.2.1952
178191.7.2.196/30191.7.2.197 to 191.7.2.198191.7.2.1992
179191.7.2.200/30191.7.2.201 to 191.7.2.202191.7.2.2032
180191.7.2.204/30191.7.2.205 to 191.7.2.206191.7.2.2072
181191.7.2.208/30191.7.2.209 to 191.7.2.210191.7.2.2112
182191.7.2.212/30191.7.2.213 to 191.7.2.214191.7.2.2152
183191.7.2.216/30191.7.2.217 to 191.7.2.218191.7.2.2192
184191.7.2.220/30191.7.2.221 to 191.7.2.222191.7.2.2232
185191.7.2.224/30191.7.2.225 to 191.7.2.226191.7.2.2272
186191.7.2.228/30191.7.2.229 to 191.7.2.230191.7.2.2312
187191.7.2.232/30191.7.2.233 to 191.7.2.234191.7.2.2352
188191.7.2.236/30191.7.2.237 to 191.7.2.238191.7.2.2392
189191.7.2.240/30191.7.2.241 to 191.7.2.242191.7.2.2432
190191.7.2.244/30191.7.2.245 to 191.7.2.246191.7.2.2472
191191.7.2.248/30191.7.2.249 to 191.7.2.250191.7.2.2512
192191.7.2.252/30191.7.2.253 to 191.7.2.254191.7.2.2552
193191.7.3.0/30191.7.3.1 to 191.7.3.2191.7.3.32
194191.7.3.4/30191.7.3.5 to 191.7.3.6191.7.3.72
195191.7.3.8/30191.7.3.9 to 191.7.3.10191.7.3.112
196191.7.3.12/30191.7.3.13 to 191.7.3.14191.7.3.152
197191.7.3.16/30191.7.3.17 to 191.7.3.18191.7.3.192
198191.7.3.20/30191.7.3.21 to 191.7.3.22191.7.3.232
199191.7.3.24/30191.7.3.25 to 191.7.3.26191.7.3.272
200191.7.3.28/30191.7.3.29 to 191.7.3.30191.7.3.312
201191.7.3.32/30191.7.3.33 to 191.7.3.34191.7.3.352
202191.7.3.36/30191.7.3.37 to 191.7.3.38191.7.3.392
203191.7.3.40/30191.7.3.41 to 191.7.3.42191.7.3.432
204191.7.3.44/30191.7.3.45 to 191.7.3.46191.7.3.472
205191.7.3.48/30191.7.3.49 to 191.7.3.50191.7.3.512
206191.7.3.52/30191.7.3.53 to 191.7.3.54191.7.3.552
207191.7.3.56/30191.7.3.57 to 191.7.3.58191.7.3.592
208191.7.3.60/30191.7.3.61 to 191.7.3.62191.7.3.632
209191.7.3.64/30191.7.3.65 to 191.7.3.66191.7.3.672
210191.7.3.68/30191.7.3.69 to 191.7.3.70191.7.3.712
211191.7.3.72/30191.7.3.73 to 191.7.3.74191.7.3.752
212191.7.3.76/30191.7.3.77 to 191.7.3.78191.7.3.792
213191.7.3.80/30191.7.3.81 to 191.7.3.82191.7.3.832
214191.7.3.84/30191.7.3.85 to 191.7.3.86191.7.3.872
215191.7.3.88/30191.7.3.89 to 191.7.3.90191.7.3.912
216191.7.3.92/30191.7.3.93 to 191.7.3.94191.7.3.952
217191.7.3.96/30191.7.3.97 to 191.7.3.98191.7.3.992
218191.7.3.100/30191.7.3.101 to 191.7.3.102191.7.3.1032
219191.7.3.104/30191.7.3.105 to 191.7.3.106191.7.3.1072
220191.7.3.108/30191.7.3.109 to 191.7.3.110191.7.3.1112
221191.7.3.112/30191.7.3.113 to 191.7.3.114191.7.3.1152
222191.7.3.116/30191.7.3.117 to 191.7.3.118191.7.3.1192
223191.7.3.120/30191.7.3.121 to 191.7.3.122191.7.3.1232
224191.7.3.124/30191.7.3.125 to 191.7.3.126191.7.3.1272
225191.7.3.128/30191.7.3.129 to 191.7.3.130191.7.3.1312
226191.7.3.132/30191.7.3.133 to 191.7.3.134191.7.3.1352
227191.7.3.136/30191.7.3.137 to 191.7.3.138191.7.3.1392
228191.7.3.140/30191.7.3.141 to 191.7.3.142191.7.3.1432
229191.7.3.144/30191.7.3.145 to 191.7.3.146191.7.3.1472
230191.7.3.148/30191.7.3.149 to 191.7.3.150191.7.3.1512
231191.7.3.152/30191.7.3.153 to 191.7.3.154191.7.3.1552
232191.7.3.156/30191.7.3.157 to 191.7.3.158191.7.3.1592
233191.7.3.160/30191.7.3.161 to 191.7.3.162191.7.3.1632
234191.7.3.164/30191.7.3.165 to 191.7.3.166191.7.3.1672
235191.7.3.168/30191.7.3.169 to 191.7.3.170191.7.3.1712
236191.7.3.172/30191.7.3.173 to 191.7.3.174191.7.3.1752
237191.7.3.176/30191.7.3.177 to 191.7.3.178191.7.3.1792
238191.7.3.180/30191.7.3.181 to 191.7.3.182191.7.3.1832
239191.7.3.184/30191.7.3.185 to 191.7.3.186191.7.3.1872
240191.7.3.188/30191.7.3.189 to 191.7.3.190191.7.3.1912
241191.7.3.192/30191.7.3.193 to 191.7.3.194191.7.3.1952
242191.7.3.196/30191.7.3.197 to 191.7.3.198191.7.3.1992
243191.7.3.200/30191.7.3.201 to 191.7.3.202191.7.3.2032
244191.7.3.204/30191.7.3.205 to 191.7.3.206191.7.3.2072
245191.7.3.208/30191.7.3.209 to 191.7.3.210191.7.3.2112
246191.7.3.212/30191.7.3.213 to 191.7.3.214191.7.3.2152
247191.7.3.216/30191.7.3.217 to 191.7.3.218191.7.3.2192
248191.7.3.220/30191.7.3.221 to 191.7.3.222191.7.3.2232
249191.7.3.224/30191.7.3.225 to 191.7.3.226191.7.3.2272
250191.7.3.228/30191.7.3.229 to 191.7.3.230191.7.3.2312
251191.7.3.232/30191.7.3.233 to 191.7.3.234191.7.3.2352
252191.7.3.236/30191.7.3.237 to 191.7.3.238191.7.3.2392
253191.7.3.240/30191.7.3.241 to 191.7.3.242191.7.3.2432
254191.7.3.244/30191.7.3.245 to 191.7.3.246191.7.3.2472
255191.7.3.248/30191.7.3.249 to 191.7.3.250191.7.3.2512
256191.7.3.252/30191.7.3.253 to 191.7.3.254191.7.3.2552

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.