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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.

Network242.3.0.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
242.3.0.0
Broadcast address
242.3.15.255
First usable
242.3.0.1
Last usable
242.3.15.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F2030000 · Integer 4060282880 to 4060286975
Reverse DNS zones
0.3.242.in-addr.arpa
1.3.242.in-addr.arpa
2.3.242.in-addr.arpa
3.3.242.in-addr.arpa
4.3.242.in-addr.arpa
5.3.242.in-addr.arpa
6.3.242.in-addr.arpa
7.3.242.in-addr.arpa
8.3.242.in-addr.arpa
9.3.242.in-addr.arpa
10.3.242.in-addr.arpa
11.3.242.in-addr.arpa
12.3.242.in-addr.arpa
13.3.242.in-addr.arpa
14.3.242.in-addr.arpa
15.3.242.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110010.00000011.00000000.00000000242.3.0.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network11110010.00000011.00000000.00000000242.3.0.0
Broadcast11110010.00000011.00001111.11111111242.3.15.255
Split into smaller subnets/30
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

242.3.0.0/20 makes 1,024 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1242.3.0.0/30242.3.0.1 to 242.3.0.2242.3.0.32
2242.3.0.4/30242.3.0.5 to 242.3.0.6242.3.0.72
3242.3.0.8/30242.3.0.9 to 242.3.0.10242.3.0.112
4242.3.0.12/30242.3.0.13 to 242.3.0.14242.3.0.152
5242.3.0.16/30242.3.0.17 to 242.3.0.18242.3.0.192
6242.3.0.20/30242.3.0.21 to 242.3.0.22242.3.0.232
7242.3.0.24/30242.3.0.25 to 242.3.0.26242.3.0.272
8242.3.0.28/30242.3.0.29 to 242.3.0.30242.3.0.312
9242.3.0.32/30242.3.0.33 to 242.3.0.34242.3.0.352
10242.3.0.36/30242.3.0.37 to 242.3.0.38242.3.0.392
11242.3.0.40/30242.3.0.41 to 242.3.0.42242.3.0.432
12242.3.0.44/30242.3.0.45 to 242.3.0.46242.3.0.472
13242.3.0.48/30242.3.0.49 to 242.3.0.50242.3.0.512
14242.3.0.52/30242.3.0.53 to 242.3.0.54242.3.0.552
15242.3.0.56/30242.3.0.57 to 242.3.0.58242.3.0.592
16242.3.0.60/30242.3.0.61 to 242.3.0.62242.3.0.632
17242.3.0.64/30242.3.0.65 to 242.3.0.66242.3.0.672
18242.3.0.68/30242.3.0.69 to 242.3.0.70242.3.0.712
19242.3.0.72/30242.3.0.73 to 242.3.0.74242.3.0.752
20242.3.0.76/30242.3.0.77 to 242.3.0.78242.3.0.792
21242.3.0.80/30242.3.0.81 to 242.3.0.82242.3.0.832
22242.3.0.84/30242.3.0.85 to 242.3.0.86242.3.0.872
23242.3.0.88/30242.3.0.89 to 242.3.0.90242.3.0.912
24242.3.0.92/30242.3.0.93 to 242.3.0.94242.3.0.952
25242.3.0.96/30242.3.0.97 to 242.3.0.98242.3.0.992
26242.3.0.100/30242.3.0.101 to 242.3.0.102242.3.0.1032
27242.3.0.104/30242.3.0.105 to 242.3.0.106242.3.0.1072
28242.3.0.108/30242.3.0.109 to 242.3.0.110242.3.0.1112
29242.3.0.112/30242.3.0.113 to 242.3.0.114242.3.0.1152
30242.3.0.116/30242.3.0.117 to 242.3.0.118242.3.0.1192
31242.3.0.120/30242.3.0.121 to 242.3.0.122242.3.0.1232
32242.3.0.124/30242.3.0.125 to 242.3.0.126242.3.0.1272
33242.3.0.128/30242.3.0.129 to 242.3.0.130242.3.0.1312
34242.3.0.132/30242.3.0.133 to 242.3.0.134242.3.0.1352
35242.3.0.136/30242.3.0.137 to 242.3.0.138242.3.0.1392
36242.3.0.140/30242.3.0.141 to 242.3.0.142242.3.0.1432
37242.3.0.144/30242.3.0.145 to 242.3.0.146242.3.0.1472
38242.3.0.148/30242.3.0.149 to 242.3.0.150242.3.0.1512
39242.3.0.152/30242.3.0.153 to 242.3.0.154242.3.0.1552
40242.3.0.156/30242.3.0.157 to 242.3.0.158242.3.0.1592
41242.3.0.160/30242.3.0.161 to 242.3.0.162242.3.0.1632
42242.3.0.164/30242.3.0.165 to 242.3.0.166242.3.0.1672
43242.3.0.168/30242.3.0.169 to 242.3.0.170242.3.0.1712
44242.3.0.172/30242.3.0.173 to 242.3.0.174242.3.0.1752
45242.3.0.176/30242.3.0.177 to 242.3.0.178242.3.0.1792
46242.3.0.180/30242.3.0.181 to 242.3.0.182242.3.0.1832
47242.3.0.184/30242.3.0.185 to 242.3.0.186242.3.0.1872
48242.3.0.188/30242.3.0.189 to 242.3.0.190242.3.0.1912
49242.3.0.192/30242.3.0.193 to 242.3.0.194242.3.0.1952
50242.3.0.196/30242.3.0.197 to 242.3.0.198242.3.0.1992
51242.3.0.200/30242.3.0.201 to 242.3.0.202242.3.0.2032
52242.3.0.204/30242.3.0.205 to 242.3.0.206242.3.0.2072
53242.3.0.208/30242.3.0.209 to 242.3.0.210242.3.0.2112
54242.3.0.212/30242.3.0.213 to 242.3.0.214242.3.0.2152
55242.3.0.216/30242.3.0.217 to 242.3.0.218242.3.0.2192
56242.3.0.220/30242.3.0.221 to 242.3.0.222242.3.0.2232
57242.3.0.224/30242.3.0.225 to 242.3.0.226242.3.0.2272
58242.3.0.228/30242.3.0.229 to 242.3.0.230242.3.0.2312
59242.3.0.232/30242.3.0.233 to 242.3.0.234242.3.0.2352
60242.3.0.236/30242.3.0.237 to 242.3.0.238242.3.0.2392
61242.3.0.240/30242.3.0.241 to 242.3.0.242242.3.0.2432
62242.3.0.244/30242.3.0.245 to 242.3.0.246242.3.0.2472
63242.3.0.248/30242.3.0.249 to 242.3.0.250242.3.0.2512
64242.3.0.252/30242.3.0.253 to 242.3.0.254242.3.0.2552
65242.3.1.0/30242.3.1.1 to 242.3.1.2242.3.1.32
66242.3.1.4/30242.3.1.5 to 242.3.1.6242.3.1.72
67242.3.1.8/30242.3.1.9 to 242.3.1.10242.3.1.112
68242.3.1.12/30242.3.1.13 to 242.3.1.14242.3.1.152
69242.3.1.16/30242.3.1.17 to 242.3.1.18242.3.1.192
70242.3.1.20/30242.3.1.21 to 242.3.1.22242.3.1.232
71242.3.1.24/30242.3.1.25 to 242.3.1.26242.3.1.272
72242.3.1.28/30242.3.1.29 to 242.3.1.30242.3.1.312
73242.3.1.32/30242.3.1.33 to 242.3.1.34242.3.1.352
74242.3.1.36/30242.3.1.37 to 242.3.1.38242.3.1.392
75242.3.1.40/30242.3.1.41 to 242.3.1.42242.3.1.432
76242.3.1.44/30242.3.1.45 to 242.3.1.46242.3.1.472
77242.3.1.48/30242.3.1.49 to 242.3.1.50242.3.1.512
78242.3.1.52/30242.3.1.53 to 242.3.1.54242.3.1.552
79242.3.1.56/30242.3.1.57 to 242.3.1.58242.3.1.592
80242.3.1.60/30242.3.1.61 to 242.3.1.62242.3.1.632
81242.3.1.64/30242.3.1.65 to 242.3.1.66242.3.1.672
82242.3.1.68/30242.3.1.69 to 242.3.1.70242.3.1.712
83242.3.1.72/30242.3.1.73 to 242.3.1.74242.3.1.752
84242.3.1.76/30242.3.1.77 to 242.3.1.78242.3.1.792
85242.3.1.80/30242.3.1.81 to 242.3.1.82242.3.1.832
86242.3.1.84/30242.3.1.85 to 242.3.1.86242.3.1.872
87242.3.1.88/30242.3.1.89 to 242.3.1.90242.3.1.912
88242.3.1.92/30242.3.1.93 to 242.3.1.94242.3.1.952
89242.3.1.96/30242.3.1.97 to 242.3.1.98242.3.1.992
90242.3.1.100/30242.3.1.101 to 242.3.1.102242.3.1.1032
91242.3.1.104/30242.3.1.105 to 242.3.1.106242.3.1.1072
92242.3.1.108/30242.3.1.109 to 242.3.1.110242.3.1.1112
93242.3.1.112/30242.3.1.113 to 242.3.1.114242.3.1.1152
94242.3.1.116/30242.3.1.117 to 242.3.1.118242.3.1.1192
95242.3.1.120/30242.3.1.121 to 242.3.1.122242.3.1.1232
96242.3.1.124/30242.3.1.125 to 242.3.1.126242.3.1.1272
97242.3.1.128/30242.3.1.129 to 242.3.1.130242.3.1.1312
98242.3.1.132/30242.3.1.133 to 242.3.1.134242.3.1.1352
99242.3.1.136/30242.3.1.137 to 242.3.1.138242.3.1.1392
100242.3.1.140/30242.3.1.141 to 242.3.1.142242.3.1.1432
101242.3.1.144/30242.3.1.145 to 242.3.1.146242.3.1.1472
102242.3.1.148/30242.3.1.149 to 242.3.1.150242.3.1.1512
103242.3.1.152/30242.3.1.153 to 242.3.1.154242.3.1.1552
104242.3.1.156/30242.3.1.157 to 242.3.1.158242.3.1.1592
105242.3.1.160/30242.3.1.161 to 242.3.1.162242.3.1.1632
106242.3.1.164/30242.3.1.165 to 242.3.1.166242.3.1.1672
107242.3.1.168/30242.3.1.169 to 242.3.1.170242.3.1.1712
108242.3.1.172/30242.3.1.173 to 242.3.1.174242.3.1.1752
109242.3.1.176/30242.3.1.177 to 242.3.1.178242.3.1.1792
110242.3.1.180/30242.3.1.181 to 242.3.1.182242.3.1.1832
111242.3.1.184/30242.3.1.185 to 242.3.1.186242.3.1.1872
112242.3.1.188/30242.3.1.189 to 242.3.1.190242.3.1.1912
113242.3.1.192/30242.3.1.193 to 242.3.1.194242.3.1.1952
114242.3.1.196/30242.3.1.197 to 242.3.1.198242.3.1.1992
115242.3.1.200/30242.3.1.201 to 242.3.1.202242.3.1.2032
116242.3.1.204/30242.3.1.205 to 242.3.1.206242.3.1.2072
117242.3.1.208/30242.3.1.209 to 242.3.1.210242.3.1.2112
118242.3.1.212/30242.3.1.213 to 242.3.1.214242.3.1.2152
119242.3.1.216/30242.3.1.217 to 242.3.1.218242.3.1.2192
120242.3.1.220/30242.3.1.221 to 242.3.1.222242.3.1.2232
121242.3.1.224/30242.3.1.225 to 242.3.1.226242.3.1.2272
122242.3.1.228/30242.3.1.229 to 242.3.1.230242.3.1.2312
123242.3.1.232/30242.3.1.233 to 242.3.1.234242.3.1.2352
124242.3.1.236/30242.3.1.237 to 242.3.1.238242.3.1.2392
125242.3.1.240/30242.3.1.241 to 242.3.1.242242.3.1.2432
126242.3.1.244/30242.3.1.245 to 242.3.1.246242.3.1.2472
127242.3.1.248/30242.3.1.249 to 242.3.1.250242.3.1.2512
128242.3.1.252/30242.3.1.253 to 242.3.1.254242.3.1.2552
129242.3.2.0/30242.3.2.1 to 242.3.2.2242.3.2.32
130242.3.2.4/30242.3.2.5 to 242.3.2.6242.3.2.72
131242.3.2.8/30242.3.2.9 to 242.3.2.10242.3.2.112
132242.3.2.12/30242.3.2.13 to 242.3.2.14242.3.2.152
133242.3.2.16/30242.3.2.17 to 242.3.2.18242.3.2.192
134242.3.2.20/30242.3.2.21 to 242.3.2.22242.3.2.232
135242.3.2.24/30242.3.2.25 to 242.3.2.26242.3.2.272
136242.3.2.28/30242.3.2.29 to 242.3.2.30242.3.2.312
137242.3.2.32/30242.3.2.33 to 242.3.2.34242.3.2.352
138242.3.2.36/30242.3.2.37 to 242.3.2.38242.3.2.392
139242.3.2.40/30242.3.2.41 to 242.3.2.42242.3.2.432
140242.3.2.44/30242.3.2.45 to 242.3.2.46242.3.2.472
141242.3.2.48/30242.3.2.49 to 242.3.2.50242.3.2.512
142242.3.2.52/30242.3.2.53 to 242.3.2.54242.3.2.552
143242.3.2.56/30242.3.2.57 to 242.3.2.58242.3.2.592
144242.3.2.60/30242.3.2.61 to 242.3.2.62242.3.2.632
145242.3.2.64/30242.3.2.65 to 242.3.2.66242.3.2.672
146242.3.2.68/30242.3.2.69 to 242.3.2.70242.3.2.712
147242.3.2.72/30242.3.2.73 to 242.3.2.74242.3.2.752
148242.3.2.76/30242.3.2.77 to 242.3.2.78242.3.2.792
149242.3.2.80/30242.3.2.81 to 242.3.2.82242.3.2.832
150242.3.2.84/30242.3.2.85 to 242.3.2.86242.3.2.872
151242.3.2.88/30242.3.2.89 to 242.3.2.90242.3.2.912
152242.3.2.92/30242.3.2.93 to 242.3.2.94242.3.2.952
153242.3.2.96/30242.3.2.97 to 242.3.2.98242.3.2.992
154242.3.2.100/30242.3.2.101 to 242.3.2.102242.3.2.1032
155242.3.2.104/30242.3.2.105 to 242.3.2.106242.3.2.1072
156242.3.2.108/30242.3.2.109 to 242.3.2.110242.3.2.1112
157242.3.2.112/30242.3.2.113 to 242.3.2.114242.3.2.1152
158242.3.2.116/30242.3.2.117 to 242.3.2.118242.3.2.1192
159242.3.2.120/30242.3.2.121 to 242.3.2.122242.3.2.1232
160242.3.2.124/30242.3.2.125 to 242.3.2.126242.3.2.1272
161242.3.2.128/30242.3.2.129 to 242.3.2.130242.3.2.1312
162242.3.2.132/30242.3.2.133 to 242.3.2.134242.3.2.1352
163242.3.2.136/30242.3.2.137 to 242.3.2.138242.3.2.1392
164242.3.2.140/30242.3.2.141 to 242.3.2.142242.3.2.1432
165242.3.2.144/30242.3.2.145 to 242.3.2.146242.3.2.1472
166242.3.2.148/30242.3.2.149 to 242.3.2.150242.3.2.1512
167242.3.2.152/30242.3.2.153 to 242.3.2.154242.3.2.1552
168242.3.2.156/30242.3.2.157 to 242.3.2.158242.3.2.1592
169242.3.2.160/30242.3.2.161 to 242.3.2.162242.3.2.1632
170242.3.2.164/30242.3.2.165 to 242.3.2.166242.3.2.1672
171242.3.2.168/30242.3.2.169 to 242.3.2.170242.3.2.1712
172242.3.2.172/30242.3.2.173 to 242.3.2.174242.3.2.1752
173242.3.2.176/30242.3.2.177 to 242.3.2.178242.3.2.1792
174242.3.2.180/30242.3.2.181 to 242.3.2.182242.3.2.1832
175242.3.2.184/30242.3.2.185 to 242.3.2.186242.3.2.1872
176242.3.2.188/30242.3.2.189 to 242.3.2.190242.3.2.1912
177242.3.2.192/30242.3.2.193 to 242.3.2.194242.3.2.1952
178242.3.2.196/30242.3.2.197 to 242.3.2.198242.3.2.1992
179242.3.2.200/30242.3.2.201 to 242.3.2.202242.3.2.2032
180242.3.2.204/30242.3.2.205 to 242.3.2.206242.3.2.2072
181242.3.2.208/30242.3.2.209 to 242.3.2.210242.3.2.2112
182242.3.2.212/30242.3.2.213 to 242.3.2.214242.3.2.2152
183242.3.2.216/30242.3.2.217 to 242.3.2.218242.3.2.2192
184242.3.2.220/30242.3.2.221 to 242.3.2.222242.3.2.2232
185242.3.2.224/30242.3.2.225 to 242.3.2.226242.3.2.2272
186242.3.2.228/30242.3.2.229 to 242.3.2.230242.3.2.2312
187242.3.2.232/30242.3.2.233 to 242.3.2.234242.3.2.2352
188242.3.2.236/30242.3.2.237 to 242.3.2.238242.3.2.2392
189242.3.2.240/30242.3.2.241 to 242.3.2.242242.3.2.2432
190242.3.2.244/30242.3.2.245 to 242.3.2.246242.3.2.2472
191242.3.2.248/30242.3.2.249 to 242.3.2.250242.3.2.2512
192242.3.2.252/30242.3.2.253 to 242.3.2.254242.3.2.2552
193242.3.3.0/30242.3.3.1 to 242.3.3.2242.3.3.32
194242.3.3.4/30242.3.3.5 to 242.3.3.6242.3.3.72
195242.3.3.8/30242.3.3.9 to 242.3.3.10242.3.3.112
196242.3.3.12/30242.3.3.13 to 242.3.3.14242.3.3.152
197242.3.3.16/30242.3.3.17 to 242.3.3.18242.3.3.192
198242.3.3.20/30242.3.3.21 to 242.3.3.22242.3.3.232
199242.3.3.24/30242.3.3.25 to 242.3.3.26242.3.3.272
200242.3.3.28/30242.3.3.29 to 242.3.3.30242.3.3.312
201242.3.3.32/30242.3.3.33 to 242.3.3.34242.3.3.352
202242.3.3.36/30242.3.3.37 to 242.3.3.38242.3.3.392
203242.3.3.40/30242.3.3.41 to 242.3.3.42242.3.3.432
204242.3.3.44/30242.3.3.45 to 242.3.3.46242.3.3.472
205242.3.3.48/30242.3.3.49 to 242.3.3.50242.3.3.512
206242.3.3.52/30242.3.3.53 to 242.3.3.54242.3.3.552
207242.3.3.56/30242.3.3.57 to 242.3.3.58242.3.3.592
208242.3.3.60/30242.3.3.61 to 242.3.3.62242.3.3.632
209242.3.3.64/30242.3.3.65 to 242.3.3.66242.3.3.672
210242.3.3.68/30242.3.3.69 to 242.3.3.70242.3.3.712
211242.3.3.72/30242.3.3.73 to 242.3.3.74242.3.3.752
212242.3.3.76/30242.3.3.77 to 242.3.3.78242.3.3.792
213242.3.3.80/30242.3.3.81 to 242.3.3.82242.3.3.832
214242.3.3.84/30242.3.3.85 to 242.3.3.86242.3.3.872
215242.3.3.88/30242.3.3.89 to 242.3.3.90242.3.3.912
216242.3.3.92/30242.3.3.93 to 242.3.3.94242.3.3.952
217242.3.3.96/30242.3.3.97 to 242.3.3.98242.3.3.992
218242.3.3.100/30242.3.3.101 to 242.3.3.102242.3.3.1032
219242.3.3.104/30242.3.3.105 to 242.3.3.106242.3.3.1072
220242.3.3.108/30242.3.3.109 to 242.3.3.110242.3.3.1112
221242.3.3.112/30242.3.3.113 to 242.3.3.114242.3.3.1152
222242.3.3.116/30242.3.3.117 to 242.3.3.118242.3.3.1192
223242.3.3.120/30242.3.3.121 to 242.3.3.122242.3.3.1232
224242.3.3.124/30242.3.3.125 to 242.3.3.126242.3.3.1272
225242.3.3.128/30242.3.3.129 to 242.3.3.130242.3.3.1312
226242.3.3.132/30242.3.3.133 to 242.3.3.134242.3.3.1352
227242.3.3.136/30242.3.3.137 to 242.3.3.138242.3.3.1392
228242.3.3.140/30242.3.3.141 to 242.3.3.142242.3.3.1432
229242.3.3.144/30242.3.3.145 to 242.3.3.146242.3.3.1472
230242.3.3.148/30242.3.3.149 to 242.3.3.150242.3.3.1512
231242.3.3.152/30242.3.3.153 to 242.3.3.154242.3.3.1552
232242.3.3.156/30242.3.3.157 to 242.3.3.158242.3.3.1592
233242.3.3.160/30242.3.3.161 to 242.3.3.162242.3.3.1632
234242.3.3.164/30242.3.3.165 to 242.3.3.166242.3.3.1672
235242.3.3.168/30242.3.3.169 to 242.3.3.170242.3.3.1712
236242.3.3.172/30242.3.3.173 to 242.3.3.174242.3.3.1752
237242.3.3.176/30242.3.3.177 to 242.3.3.178242.3.3.1792
238242.3.3.180/30242.3.3.181 to 242.3.3.182242.3.3.1832
239242.3.3.184/30242.3.3.185 to 242.3.3.186242.3.3.1872
240242.3.3.188/30242.3.3.189 to 242.3.3.190242.3.3.1912
241242.3.3.192/30242.3.3.193 to 242.3.3.194242.3.3.1952
242242.3.3.196/30242.3.3.197 to 242.3.3.198242.3.3.1992
243242.3.3.200/30242.3.3.201 to 242.3.3.202242.3.3.2032
244242.3.3.204/30242.3.3.205 to 242.3.3.206242.3.3.2072
245242.3.3.208/30242.3.3.209 to 242.3.3.210242.3.3.2112
246242.3.3.212/30242.3.3.213 to 242.3.3.214242.3.3.2152
247242.3.3.216/30242.3.3.217 to 242.3.3.218242.3.3.2192
248242.3.3.220/30242.3.3.221 to 242.3.3.222242.3.3.2232
249242.3.3.224/30242.3.3.225 to 242.3.3.226242.3.3.2272
250242.3.3.228/30242.3.3.229 to 242.3.3.230242.3.3.2312
251242.3.3.232/30242.3.3.233 to 242.3.3.234242.3.3.2352
252242.3.3.236/30242.3.3.237 to 242.3.3.238242.3.3.2392
253242.3.3.240/30242.3.3.241 to 242.3.3.242242.3.3.2432
254242.3.3.244/30242.3.3.245 to 242.3.3.246242.3.3.2472
255242.3.3.248/30242.3.3.249 to 242.3.3.250242.3.3.2512
256242.3.3.252/30242.3.3.253 to 242.3.3.254242.3.3.2552

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.