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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.

Network242.3.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
242.3.0.0
Broadcast address
242.3.63.255
First usable
242.3.0.1
Last usable
242.3.63.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F2030000 · Integer 4060282880 to 4060299263
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
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
Address11110010.00000011.00000000.00000000242.3.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network11110010.00000011.00000000.00000000242.3.0.0
Broadcast11110010.00000011.00111111.11111111242.3.63.255
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)

242.3.0.0/18 makes 2,048 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1242.3.0.0/29242.3.0.1 to 242.3.0.6242.3.0.76
2242.3.0.8/29242.3.0.9 to 242.3.0.14242.3.0.156
3242.3.0.16/29242.3.0.17 to 242.3.0.22242.3.0.236
4242.3.0.24/29242.3.0.25 to 242.3.0.30242.3.0.316
5242.3.0.32/29242.3.0.33 to 242.3.0.38242.3.0.396
6242.3.0.40/29242.3.0.41 to 242.3.0.46242.3.0.476
7242.3.0.48/29242.3.0.49 to 242.3.0.54242.3.0.556
8242.3.0.56/29242.3.0.57 to 242.3.0.62242.3.0.636
9242.3.0.64/29242.3.0.65 to 242.3.0.70242.3.0.716
10242.3.0.72/29242.3.0.73 to 242.3.0.78242.3.0.796
11242.3.0.80/29242.3.0.81 to 242.3.0.86242.3.0.876
12242.3.0.88/29242.3.0.89 to 242.3.0.94242.3.0.956
13242.3.0.96/29242.3.0.97 to 242.3.0.102242.3.0.1036
14242.3.0.104/29242.3.0.105 to 242.3.0.110242.3.0.1116
15242.3.0.112/29242.3.0.113 to 242.3.0.118242.3.0.1196
16242.3.0.120/29242.3.0.121 to 242.3.0.126242.3.0.1276
17242.3.0.128/29242.3.0.129 to 242.3.0.134242.3.0.1356
18242.3.0.136/29242.3.0.137 to 242.3.0.142242.3.0.1436
19242.3.0.144/29242.3.0.145 to 242.3.0.150242.3.0.1516
20242.3.0.152/29242.3.0.153 to 242.3.0.158242.3.0.1596
21242.3.0.160/29242.3.0.161 to 242.3.0.166242.3.0.1676
22242.3.0.168/29242.3.0.169 to 242.3.0.174242.3.0.1756
23242.3.0.176/29242.3.0.177 to 242.3.0.182242.3.0.1836
24242.3.0.184/29242.3.0.185 to 242.3.0.190242.3.0.1916
25242.3.0.192/29242.3.0.193 to 242.3.0.198242.3.0.1996
26242.3.0.200/29242.3.0.201 to 242.3.0.206242.3.0.2076
27242.3.0.208/29242.3.0.209 to 242.3.0.214242.3.0.2156
28242.3.0.216/29242.3.0.217 to 242.3.0.222242.3.0.2236
29242.3.0.224/29242.3.0.225 to 242.3.0.230242.3.0.2316
30242.3.0.232/29242.3.0.233 to 242.3.0.238242.3.0.2396
31242.3.0.240/29242.3.0.241 to 242.3.0.246242.3.0.2476
32242.3.0.248/29242.3.0.249 to 242.3.0.254242.3.0.2556
33242.3.1.0/29242.3.1.1 to 242.3.1.6242.3.1.76
34242.3.1.8/29242.3.1.9 to 242.3.1.14242.3.1.156
35242.3.1.16/29242.3.1.17 to 242.3.1.22242.3.1.236
36242.3.1.24/29242.3.1.25 to 242.3.1.30242.3.1.316
37242.3.1.32/29242.3.1.33 to 242.3.1.38242.3.1.396
38242.3.1.40/29242.3.1.41 to 242.3.1.46242.3.1.476
39242.3.1.48/29242.3.1.49 to 242.3.1.54242.3.1.556
40242.3.1.56/29242.3.1.57 to 242.3.1.62242.3.1.636
41242.3.1.64/29242.3.1.65 to 242.3.1.70242.3.1.716
42242.3.1.72/29242.3.1.73 to 242.3.1.78242.3.1.796
43242.3.1.80/29242.3.1.81 to 242.3.1.86242.3.1.876
44242.3.1.88/29242.3.1.89 to 242.3.1.94242.3.1.956
45242.3.1.96/29242.3.1.97 to 242.3.1.102242.3.1.1036
46242.3.1.104/29242.3.1.105 to 242.3.1.110242.3.1.1116
47242.3.1.112/29242.3.1.113 to 242.3.1.118242.3.1.1196
48242.3.1.120/29242.3.1.121 to 242.3.1.126242.3.1.1276
49242.3.1.128/29242.3.1.129 to 242.3.1.134242.3.1.1356
50242.3.1.136/29242.3.1.137 to 242.3.1.142242.3.1.1436
51242.3.1.144/29242.3.1.145 to 242.3.1.150242.3.1.1516
52242.3.1.152/29242.3.1.153 to 242.3.1.158242.3.1.1596
53242.3.1.160/29242.3.1.161 to 242.3.1.166242.3.1.1676
54242.3.1.168/29242.3.1.169 to 242.3.1.174242.3.1.1756
55242.3.1.176/29242.3.1.177 to 242.3.1.182242.3.1.1836
56242.3.1.184/29242.3.1.185 to 242.3.1.190242.3.1.1916
57242.3.1.192/29242.3.1.193 to 242.3.1.198242.3.1.1996
58242.3.1.200/29242.3.1.201 to 242.3.1.206242.3.1.2076
59242.3.1.208/29242.3.1.209 to 242.3.1.214242.3.1.2156
60242.3.1.216/29242.3.1.217 to 242.3.1.222242.3.1.2236
61242.3.1.224/29242.3.1.225 to 242.3.1.230242.3.1.2316
62242.3.1.232/29242.3.1.233 to 242.3.1.238242.3.1.2396
63242.3.1.240/29242.3.1.241 to 242.3.1.246242.3.1.2476
64242.3.1.248/29242.3.1.249 to 242.3.1.254242.3.1.2556
65242.3.2.0/29242.3.2.1 to 242.3.2.6242.3.2.76
66242.3.2.8/29242.3.2.9 to 242.3.2.14242.3.2.156
67242.3.2.16/29242.3.2.17 to 242.3.2.22242.3.2.236
68242.3.2.24/29242.3.2.25 to 242.3.2.30242.3.2.316
69242.3.2.32/29242.3.2.33 to 242.3.2.38242.3.2.396
70242.3.2.40/29242.3.2.41 to 242.3.2.46242.3.2.476
71242.3.2.48/29242.3.2.49 to 242.3.2.54242.3.2.556
72242.3.2.56/29242.3.2.57 to 242.3.2.62242.3.2.636
73242.3.2.64/29242.3.2.65 to 242.3.2.70242.3.2.716
74242.3.2.72/29242.3.2.73 to 242.3.2.78242.3.2.796
75242.3.2.80/29242.3.2.81 to 242.3.2.86242.3.2.876
76242.3.2.88/29242.3.2.89 to 242.3.2.94242.3.2.956
77242.3.2.96/29242.3.2.97 to 242.3.2.102242.3.2.1036
78242.3.2.104/29242.3.2.105 to 242.3.2.110242.3.2.1116
79242.3.2.112/29242.3.2.113 to 242.3.2.118242.3.2.1196
80242.3.2.120/29242.3.2.121 to 242.3.2.126242.3.2.1276
81242.3.2.128/29242.3.2.129 to 242.3.2.134242.3.2.1356
82242.3.2.136/29242.3.2.137 to 242.3.2.142242.3.2.1436
83242.3.2.144/29242.3.2.145 to 242.3.2.150242.3.2.1516
84242.3.2.152/29242.3.2.153 to 242.3.2.158242.3.2.1596
85242.3.2.160/29242.3.2.161 to 242.3.2.166242.3.2.1676
86242.3.2.168/29242.3.2.169 to 242.3.2.174242.3.2.1756
87242.3.2.176/29242.3.2.177 to 242.3.2.182242.3.2.1836
88242.3.2.184/29242.3.2.185 to 242.3.2.190242.3.2.1916
89242.3.2.192/29242.3.2.193 to 242.3.2.198242.3.2.1996
90242.3.2.200/29242.3.2.201 to 242.3.2.206242.3.2.2076
91242.3.2.208/29242.3.2.209 to 242.3.2.214242.3.2.2156
92242.3.2.216/29242.3.2.217 to 242.3.2.222242.3.2.2236
93242.3.2.224/29242.3.2.225 to 242.3.2.230242.3.2.2316
94242.3.2.232/29242.3.2.233 to 242.3.2.238242.3.2.2396
95242.3.2.240/29242.3.2.241 to 242.3.2.246242.3.2.2476
96242.3.2.248/29242.3.2.249 to 242.3.2.254242.3.2.2556
97242.3.3.0/29242.3.3.1 to 242.3.3.6242.3.3.76
98242.3.3.8/29242.3.3.9 to 242.3.3.14242.3.3.156
99242.3.3.16/29242.3.3.17 to 242.3.3.22242.3.3.236
100242.3.3.24/29242.3.3.25 to 242.3.3.30242.3.3.316
101242.3.3.32/29242.3.3.33 to 242.3.3.38242.3.3.396
102242.3.3.40/29242.3.3.41 to 242.3.3.46242.3.3.476
103242.3.3.48/29242.3.3.49 to 242.3.3.54242.3.3.556
104242.3.3.56/29242.3.3.57 to 242.3.3.62242.3.3.636
105242.3.3.64/29242.3.3.65 to 242.3.3.70242.3.3.716
106242.3.3.72/29242.3.3.73 to 242.3.3.78242.3.3.796
107242.3.3.80/29242.3.3.81 to 242.3.3.86242.3.3.876
108242.3.3.88/29242.3.3.89 to 242.3.3.94242.3.3.956
109242.3.3.96/29242.3.3.97 to 242.3.3.102242.3.3.1036
110242.3.3.104/29242.3.3.105 to 242.3.3.110242.3.3.1116
111242.3.3.112/29242.3.3.113 to 242.3.3.118242.3.3.1196
112242.3.3.120/29242.3.3.121 to 242.3.3.126242.3.3.1276
113242.3.3.128/29242.3.3.129 to 242.3.3.134242.3.3.1356
114242.3.3.136/29242.3.3.137 to 242.3.3.142242.3.3.1436
115242.3.3.144/29242.3.3.145 to 242.3.3.150242.3.3.1516
116242.3.3.152/29242.3.3.153 to 242.3.3.158242.3.3.1596
117242.3.3.160/29242.3.3.161 to 242.3.3.166242.3.3.1676
118242.3.3.168/29242.3.3.169 to 242.3.3.174242.3.3.1756
119242.3.3.176/29242.3.3.177 to 242.3.3.182242.3.3.1836
120242.3.3.184/29242.3.3.185 to 242.3.3.190242.3.3.1916
121242.3.3.192/29242.3.3.193 to 242.3.3.198242.3.3.1996
122242.3.3.200/29242.3.3.201 to 242.3.3.206242.3.3.2076
123242.3.3.208/29242.3.3.209 to 242.3.3.214242.3.3.2156
124242.3.3.216/29242.3.3.217 to 242.3.3.222242.3.3.2236
125242.3.3.224/29242.3.3.225 to 242.3.3.230242.3.3.2316
126242.3.3.232/29242.3.3.233 to 242.3.3.238242.3.3.2396
127242.3.3.240/29242.3.3.241 to 242.3.3.246242.3.3.2476
128242.3.3.248/29242.3.3.249 to 242.3.3.254242.3.3.2556
129242.3.4.0/29242.3.4.1 to 242.3.4.6242.3.4.76
130242.3.4.8/29242.3.4.9 to 242.3.4.14242.3.4.156
131242.3.4.16/29242.3.4.17 to 242.3.4.22242.3.4.236
132242.3.4.24/29242.3.4.25 to 242.3.4.30242.3.4.316
133242.3.4.32/29242.3.4.33 to 242.3.4.38242.3.4.396
134242.3.4.40/29242.3.4.41 to 242.3.4.46242.3.4.476
135242.3.4.48/29242.3.4.49 to 242.3.4.54242.3.4.556
136242.3.4.56/29242.3.4.57 to 242.3.4.62242.3.4.636
137242.3.4.64/29242.3.4.65 to 242.3.4.70242.3.4.716
138242.3.4.72/29242.3.4.73 to 242.3.4.78242.3.4.796
139242.3.4.80/29242.3.4.81 to 242.3.4.86242.3.4.876
140242.3.4.88/29242.3.4.89 to 242.3.4.94242.3.4.956
141242.3.4.96/29242.3.4.97 to 242.3.4.102242.3.4.1036
142242.3.4.104/29242.3.4.105 to 242.3.4.110242.3.4.1116
143242.3.4.112/29242.3.4.113 to 242.3.4.118242.3.4.1196
144242.3.4.120/29242.3.4.121 to 242.3.4.126242.3.4.1276
145242.3.4.128/29242.3.4.129 to 242.3.4.134242.3.4.1356
146242.3.4.136/29242.3.4.137 to 242.3.4.142242.3.4.1436
147242.3.4.144/29242.3.4.145 to 242.3.4.150242.3.4.1516
148242.3.4.152/29242.3.4.153 to 242.3.4.158242.3.4.1596
149242.3.4.160/29242.3.4.161 to 242.3.4.166242.3.4.1676
150242.3.4.168/29242.3.4.169 to 242.3.4.174242.3.4.1756
151242.3.4.176/29242.3.4.177 to 242.3.4.182242.3.4.1836
152242.3.4.184/29242.3.4.185 to 242.3.4.190242.3.4.1916
153242.3.4.192/29242.3.4.193 to 242.3.4.198242.3.4.1996
154242.3.4.200/29242.3.4.201 to 242.3.4.206242.3.4.2076
155242.3.4.208/29242.3.4.209 to 242.3.4.214242.3.4.2156
156242.3.4.216/29242.3.4.217 to 242.3.4.222242.3.4.2236
157242.3.4.224/29242.3.4.225 to 242.3.4.230242.3.4.2316
158242.3.4.232/29242.3.4.233 to 242.3.4.238242.3.4.2396
159242.3.4.240/29242.3.4.241 to 242.3.4.246242.3.4.2476
160242.3.4.248/29242.3.4.249 to 242.3.4.254242.3.4.2556
161242.3.5.0/29242.3.5.1 to 242.3.5.6242.3.5.76
162242.3.5.8/29242.3.5.9 to 242.3.5.14242.3.5.156
163242.3.5.16/29242.3.5.17 to 242.3.5.22242.3.5.236
164242.3.5.24/29242.3.5.25 to 242.3.5.30242.3.5.316
165242.3.5.32/29242.3.5.33 to 242.3.5.38242.3.5.396
166242.3.5.40/29242.3.5.41 to 242.3.5.46242.3.5.476
167242.3.5.48/29242.3.5.49 to 242.3.5.54242.3.5.556
168242.3.5.56/29242.3.5.57 to 242.3.5.62242.3.5.636
169242.3.5.64/29242.3.5.65 to 242.3.5.70242.3.5.716
170242.3.5.72/29242.3.5.73 to 242.3.5.78242.3.5.796
171242.3.5.80/29242.3.5.81 to 242.3.5.86242.3.5.876
172242.3.5.88/29242.3.5.89 to 242.3.5.94242.3.5.956
173242.3.5.96/29242.3.5.97 to 242.3.5.102242.3.5.1036
174242.3.5.104/29242.3.5.105 to 242.3.5.110242.3.5.1116
175242.3.5.112/29242.3.5.113 to 242.3.5.118242.3.5.1196
176242.3.5.120/29242.3.5.121 to 242.3.5.126242.3.5.1276
177242.3.5.128/29242.3.5.129 to 242.3.5.134242.3.5.1356
178242.3.5.136/29242.3.5.137 to 242.3.5.142242.3.5.1436
179242.3.5.144/29242.3.5.145 to 242.3.5.150242.3.5.1516
180242.3.5.152/29242.3.5.153 to 242.3.5.158242.3.5.1596
181242.3.5.160/29242.3.5.161 to 242.3.5.166242.3.5.1676
182242.3.5.168/29242.3.5.169 to 242.3.5.174242.3.5.1756
183242.3.5.176/29242.3.5.177 to 242.3.5.182242.3.5.1836
184242.3.5.184/29242.3.5.185 to 242.3.5.190242.3.5.1916
185242.3.5.192/29242.3.5.193 to 242.3.5.198242.3.5.1996
186242.3.5.200/29242.3.5.201 to 242.3.5.206242.3.5.2076
187242.3.5.208/29242.3.5.209 to 242.3.5.214242.3.5.2156
188242.3.5.216/29242.3.5.217 to 242.3.5.222242.3.5.2236
189242.3.5.224/29242.3.5.225 to 242.3.5.230242.3.5.2316
190242.3.5.232/29242.3.5.233 to 242.3.5.238242.3.5.2396
191242.3.5.240/29242.3.5.241 to 242.3.5.246242.3.5.2476
192242.3.5.248/29242.3.5.249 to 242.3.5.254242.3.5.2556
193242.3.6.0/29242.3.6.1 to 242.3.6.6242.3.6.76
194242.3.6.8/29242.3.6.9 to 242.3.6.14242.3.6.156
195242.3.6.16/29242.3.6.17 to 242.3.6.22242.3.6.236
196242.3.6.24/29242.3.6.25 to 242.3.6.30242.3.6.316
197242.3.6.32/29242.3.6.33 to 242.3.6.38242.3.6.396
198242.3.6.40/29242.3.6.41 to 242.3.6.46242.3.6.476
199242.3.6.48/29242.3.6.49 to 242.3.6.54242.3.6.556
200242.3.6.56/29242.3.6.57 to 242.3.6.62242.3.6.636
201242.3.6.64/29242.3.6.65 to 242.3.6.70242.3.6.716
202242.3.6.72/29242.3.6.73 to 242.3.6.78242.3.6.796
203242.3.6.80/29242.3.6.81 to 242.3.6.86242.3.6.876
204242.3.6.88/29242.3.6.89 to 242.3.6.94242.3.6.956
205242.3.6.96/29242.3.6.97 to 242.3.6.102242.3.6.1036
206242.3.6.104/29242.3.6.105 to 242.3.6.110242.3.6.1116
207242.3.6.112/29242.3.6.113 to 242.3.6.118242.3.6.1196
208242.3.6.120/29242.3.6.121 to 242.3.6.126242.3.6.1276
209242.3.6.128/29242.3.6.129 to 242.3.6.134242.3.6.1356
210242.3.6.136/29242.3.6.137 to 242.3.6.142242.3.6.1436
211242.3.6.144/29242.3.6.145 to 242.3.6.150242.3.6.1516
212242.3.6.152/29242.3.6.153 to 242.3.6.158242.3.6.1596
213242.3.6.160/29242.3.6.161 to 242.3.6.166242.3.6.1676
214242.3.6.168/29242.3.6.169 to 242.3.6.174242.3.6.1756
215242.3.6.176/29242.3.6.177 to 242.3.6.182242.3.6.1836
216242.3.6.184/29242.3.6.185 to 242.3.6.190242.3.6.1916
217242.3.6.192/29242.3.6.193 to 242.3.6.198242.3.6.1996
218242.3.6.200/29242.3.6.201 to 242.3.6.206242.3.6.2076
219242.3.6.208/29242.3.6.209 to 242.3.6.214242.3.6.2156
220242.3.6.216/29242.3.6.217 to 242.3.6.222242.3.6.2236
221242.3.6.224/29242.3.6.225 to 242.3.6.230242.3.6.2316
222242.3.6.232/29242.3.6.233 to 242.3.6.238242.3.6.2396
223242.3.6.240/29242.3.6.241 to 242.3.6.246242.3.6.2476
224242.3.6.248/29242.3.6.249 to 242.3.6.254242.3.6.2556
225242.3.7.0/29242.3.7.1 to 242.3.7.6242.3.7.76
226242.3.7.8/29242.3.7.9 to 242.3.7.14242.3.7.156
227242.3.7.16/29242.3.7.17 to 242.3.7.22242.3.7.236
228242.3.7.24/29242.3.7.25 to 242.3.7.30242.3.7.316
229242.3.7.32/29242.3.7.33 to 242.3.7.38242.3.7.396
230242.3.7.40/29242.3.7.41 to 242.3.7.46242.3.7.476
231242.3.7.48/29242.3.7.49 to 242.3.7.54242.3.7.556
232242.3.7.56/29242.3.7.57 to 242.3.7.62242.3.7.636
233242.3.7.64/29242.3.7.65 to 242.3.7.70242.3.7.716
234242.3.7.72/29242.3.7.73 to 242.3.7.78242.3.7.796
235242.3.7.80/29242.3.7.81 to 242.3.7.86242.3.7.876
236242.3.7.88/29242.3.7.89 to 242.3.7.94242.3.7.956
237242.3.7.96/29242.3.7.97 to 242.3.7.102242.3.7.1036
238242.3.7.104/29242.3.7.105 to 242.3.7.110242.3.7.1116
239242.3.7.112/29242.3.7.113 to 242.3.7.118242.3.7.1196
240242.3.7.120/29242.3.7.121 to 242.3.7.126242.3.7.1276
241242.3.7.128/29242.3.7.129 to 242.3.7.134242.3.7.1356
242242.3.7.136/29242.3.7.137 to 242.3.7.142242.3.7.1436
243242.3.7.144/29242.3.7.145 to 242.3.7.150242.3.7.1516
244242.3.7.152/29242.3.7.153 to 242.3.7.158242.3.7.1596
245242.3.7.160/29242.3.7.161 to 242.3.7.166242.3.7.1676
246242.3.7.168/29242.3.7.169 to 242.3.7.174242.3.7.1756
247242.3.7.176/29242.3.7.177 to 242.3.7.182242.3.7.1836
248242.3.7.184/29242.3.7.185 to 242.3.7.190242.3.7.1916
249242.3.7.192/29242.3.7.193 to 242.3.7.198242.3.7.1996
250242.3.7.200/29242.3.7.201 to 242.3.7.206242.3.7.2076
251242.3.7.208/29242.3.7.209 to 242.3.7.214242.3.7.2156
252242.3.7.216/29242.3.7.217 to 242.3.7.222242.3.7.2236
253242.3.7.224/29242.3.7.225 to 242.3.7.230242.3.7.2316
254242.3.7.232/29242.3.7.233 to 242.3.7.238242.3.7.2396
255242.3.7.240/29242.3.7.241 to 242.3.7.246242.3.7.2476
256242.3.7.248/29242.3.7.249 to 242.3.7.254242.3.7.2556

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.