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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.

Network155.65.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
155.65.0.0
Broadcast address
155.65.127.255
First usable
155.65.0.1
Last usable
155.65.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
B (default /16)
As numbers
Hex 9B410000 · Integer 2604728320 to 2604761087
Reverse DNS zones
0.65.155.in-addr.arpa
1.65.155.in-addr.arpa
2.65.155.in-addr.arpa
3.65.155.in-addr.arpa
4.65.155.in-addr.arpa
5.65.155.in-addr.arpa
6.65.155.in-addr.arpa
7.65.155.in-addr.arpa
8.65.155.in-addr.arpa
9.65.155.in-addr.arpa
10.65.155.in-addr.arpa
11.65.155.in-addr.arpa
12.65.155.in-addr.arpa
13.65.155.in-addr.arpa
14.65.155.in-addr.arpa
15.65.155.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10011011.01000001.00000000.00000000155.65.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10011011.01000001.00000000.00000000155.65.0.0
Broadcast10011011.01000001.01111111.11111111155.65.127.255
Split into smaller subnets/29
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

155.65.0.0/17 makes 4,096 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1155.65.0.0/29155.65.0.1 to 155.65.0.6155.65.0.76
2155.65.0.8/29155.65.0.9 to 155.65.0.14155.65.0.156
3155.65.0.16/29155.65.0.17 to 155.65.0.22155.65.0.236
4155.65.0.24/29155.65.0.25 to 155.65.0.30155.65.0.316
5155.65.0.32/29155.65.0.33 to 155.65.0.38155.65.0.396
6155.65.0.40/29155.65.0.41 to 155.65.0.46155.65.0.476
7155.65.0.48/29155.65.0.49 to 155.65.0.54155.65.0.556
8155.65.0.56/29155.65.0.57 to 155.65.0.62155.65.0.636
9155.65.0.64/29155.65.0.65 to 155.65.0.70155.65.0.716
10155.65.0.72/29155.65.0.73 to 155.65.0.78155.65.0.796
11155.65.0.80/29155.65.0.81 to 155.65.0.86155.65.0.876
12155.65.0.88/29155.65.0.89 to 155.65.0.94155.65.0.956
13155.65.0.96/29155.65.0.97 to 155.65.0.102155.65.0.1036
14155.65.0.104/29155.65.0.105 to 155.65.0.110155.65.0.1116
15155.65.0.112/29155.65.0.113 to 155.65.0.118155.65.0.1196
16155.65.0.120/29155.65.0.121 to 155.65.0.126155.65.0.1276
17155.65.0.128/29155.65.0.129 to 155.65.0.134155.65.0.1356
18155.65.0.136/29155.65.0.137 to 155.65.0.142155.65.0.1436
19155.65.0.144/29155.65.0.145 to 155.65.0.150155.65.0.1516
20155.65.0.152/29155.65.0.153 to 155.65.0.158155.65.0.1596
21155.65.0.160/29155.65.0.161 to 155.65.0.166155.65.0.1676
22155.65.0.168/29155.65.0.169 to 155.65.0.174155.65.0.1756
23155.65.0.176/29155.65.0.177 to 155.65.0.182155.65.0.1836
24155.65.0.184/29155.65.0.185 to 155.65.0.190155.65.0.1916
25155.65.0.192/29155.65.0.193 to 155.65.0.198155.65.0.1996
26155.65.0.200/29155.65.0.201 to 155.65.0.206155.65.0.2076
27155.65.0.208/29155.65.0.209 to 155.65.0.214155.65.0.2156
28155.65.0.216/29155.65.0.217 to 155.65.0.222155.65.0.2236
29155.65.0.224/29155.65.0.225 to 155.65.0.230155.65.0.2316
30155.65.0.232/29155.65.0.233 to 155.65.0.238155.65.0.2396
31155.65.0.240/29155.65.0.241 to 155.65.0.246155.65.0.2476
32155.65.0.248/29155.65.0.249 to 155.65.0.254155.65.0.2556
33155.65.1.0/29155.65.1.1 to 155.65.1.6155.65.1.76
34155.65.1.8/29155.65.1.9 to 155.65.1.14155.65.1.156
35155.65.1.16/29155.65.1.17 to 155.65.1.22155.65.1.236
36155.65.1.24/29155.65.1.25 to 155.65.1.30155.65.1.316
37155.65.1.32/29155.65.1.33 to 155.65.1.38155.65.1.396
38155.65.1.40/29155.65.1.41 to 155.65.1.46155.65.1.476
39155.65.1.48/29155.65.1.49 to 155.65.1.54155.65.1.556
40155.65.1.56/29155.65.1.57 to 155.65.1.62155.65.1.636
41155.65.1.64/29155.65.1.65 to 155.65.1.70155.65.1.716
42155.65.1.72/29155.65.1.73 to 155.65.1.78155.65.1.796
43155.65.1.80/29155.65.1.81 to 155.65.1.86155.65.1.876
44155.65.1.88/29155.65.1.89 to 155.65.1.94155.65.1.956
45155.65.1.96/29155.65.1.97 to 155.65.1.102155.65.1.1036
46155.65.1.104/29155.65.1.105 to 155.65.1.110155.65.1.1116
47155.65.1.112/29155.65.1.113 to 155.65.1.118155.65.1.1196
48155.65.1.120/29155.65.1.121 to 155.65.1.126155.65.1.1276
49155.65.1.128/29155.65.1.129 to 155.65.1.134155.65.1.1356
50155.65.1.136/29155.65.1.137 to 155.65.1.142155.65.1.1436
51155.65.1.144/29155.65.1.145 to 155.65.1.150155.65.1.1516
52155.65.1.152/29155.65.1.153 to 155.65.1.158155.65.1.1596
53155.65.1.160/29155.65.1.161 to 155.65.1.166155.65.1.1676
54155.65.1.168/29155.65.1.169 to 155.65.1.174155.65.1.1756
55155.65.1.176/29155.65.1.177 to 155.65.1.182155.65.1.1836
56155.65.1.184/29155.65.1.185 to 155.65.1.190155.65.1.1916
57155.65.1.192/29155.65.1.193 to 155.65.1.198155.65.1.1996
58155.65.1.200/29155.65.1.201 to 155.65.1.206155.65.1.2076
59155.65.1.208/29155.65.1.209 to 155.65.1.214155.65.1.2156
60155.65.1.216/29155.65.1.217 to 155.65.1.222155.65.1.2236
61155.65.1.224/29155.65.1.225 to 155.65.1.230155.65.1.2316
62155.65.1.232/29155.65.1.233 to 155.65.1.238155.65.1.2396
63155.65.1.240/29155.65.1.241 to 155.65.1.246155.65.1.2476
64155.65.1.248/29155.65.1.249 to 155.65.1.254155.65.1.2556
65155.65.2.0/29155.65.2.1 to 155.65.2.6155.65.2.76
66155.65.2.8/29155.65.2.9 to 155.65.2.14155.65.2.156
67155.65.2.16/29155.65.2.17 to 155.65.2.22155.65.2.236
68155.65.2.24/29155.65.2.25 to 155.65.2.30155.65.2.316
69155.65.2.32/29155.65.2.33 to 155.65.2.38155.65.2.396
70155.65.2.40/29155.65.2.41 to 155.65.2.46155.65.2.476
71155.65.2.48/29155.65.2.49 to 155.65.2.54155.65.2.556
72155.65.2.56/29155.65.2.57 to 155.65.2.62155.65.2.636
73155.65.2.64/29155.65.2.65 to 155.65.2.70155.65.2.716
74155.65.2.72/29155.65.2.73 to 155.65.2.78155.65.2.796
75155.65.2.80/29155.65.2.81 to 155.65.2.86155.65.2.876
76155.65.2.88/29155.65.2.89 to 155.65.2.94155.65.2.956
77155.65.2.96/29155.65.2.97 to 155.65.2.102155.65.2.1036
78155.65.2.104/29155.65.2.105 to 155.65.2.110155.65.2.1116
79155.65.2.112/29155.65.2.113 to 155.65.2.118155.65.2.1196
80155.65.2.120/29155.65.2.121 to 155.65.2.126155.65.2.1276
81155.65.2.128/29155.65.2.129 to 155.65.2.134155.65.2.1356
82155.65.2.136/29155.65.2.137 to 155.65.2.142155.65.2.1436
83155.65.2.144/29155.65.2.145 to 155.65.2.150155.65.2.1516
84155.65.2.152/29155.65.2.153 to 155.65.2.158155.65.2.1596
85155.65.2.160/29155.65.2.161 to 155.65.2.166155.65.2.1676
86155.65.2.168/29155.65.2.169 to 155.65.2.174155.65.2.1756
87155.65.2.176/29155.65.2.177 to 155.65.2.182155.65.2.1836
88155.65.2.184/29155.65.2.185 to 155.65.2.190155.65.2.1916
89155.65.2.192/29155.65.2.193 to 155.65.2.198155.65.2.1996
90155.65.2.200/29155.65.2.201 to 155.65.2.206155.65.2.2076
91155.65.2.208/29155.65.2.209 to 155.65.2.214155.65.2.2156
92155.65.2.216/29155.65.2.217 to 155.65.2.222155.65.2.2236
93155.65.2.224/29155.65.2.225 to 155.65.2.230155.65.2.2316
94155.65.2.232/29155.65.2.233 to 155.65.2.238155.65.2.2396
95155.65.2.240/29155.65.2.241 to 155.65.2.246155.65.2.2476
96155.65.2.248/29155.65.2.249 to 155.65.2.254155.65.2.2556
97155.65.3.0/29155.65.3.1 to 155.65.3.6155.65.3.76
98155.65.3.8/29155.65.3.9 to 155.65.3.14155.65.3.156
99155.65.3.16/29155.65.3.17 to 155.65.3.22155.65.3.236
100155.65.3.24/29155.65.3.25 to 155.65.3.30155.65.3.316
101155.65.3.32/29155.65.3.33 to 155.65.3.38155.65.3.396
102155.65.3.40/29155.65.3.41 to 155.65.3.46155.65.3.476
103155.65.3.48/29155.65.3.49 to 155.65.3.54155.65.3.556
104155.65.3.56/29155.65.3.57 to 155.65.3.62155.65.3.636
105155.65.3.64/29155.65.3.65 to 155.65.3.70155.65.3.716
106155.65.3.72/29155.65.3.73 to 155.65.3.78155.65.3.796
107155.65.3.80/29155.65.3.81 to 155.65.3.86155.65.3.876
108155.65.3.88/29155.65.3.89 to 155.65.3.94155.65.3.956
109155.65.3.96/29155.65.3.97 to 155.65.3.102155.65.3.1036
110155.65.3.104/29155.65.3.105 to 155.65.3.110155.65.3.1116
111155.65.3.112/29155.65.3.113 to 155.65.3.118155.65.3.1196
112155.65.3.120/29155.65.3.121 to 155.65.3.126155.65.3.1276
113155.65.3.128/29155.65.3.129 to 155.65.3.134155.65.3.1356
114155.65.3.136/29155.65.3.137 to 155.65.3.142155.65.3.1436
115155.65.3.144/29155.65.3.145 to 155.65.3.150155.65.3.1516
116155.65.3.152/29155.65.3.153 to 155.65.3.158155.65.3.1596
117155.65.3.160/29155.65.3.161 to 155.65.3.166155.65.3.1676
118155.65.3.168/29155.65.3.169 to 155.65.3.174155.65.3.1756
119155.65.3.176/29155.65.3.177 to 155.65.3.182155.65.3.1836
120155.65.3.184/29155.65.3.185 to 155.65.3.190155.65.3.1916
121155.65.3.192/29155.65.3.193 to 155.65.3.198155.65.3.1996
122155.65.3.200/29155.65.3.201 to 155.65.3.206155.65.3.2076
123155.65.3.208/29155.65.3.209 to 155.65.3.214155.65.3.2156
124155.65.3.216/29155.65.3.217 to 155.65.3.222155.65.3.2236
125155.65.3.224/29155.65.3.225 to 155.65.3.230155.65.3.2316
126155.65.3.232/29155.65.3.233 to 155.65.3.238155.65.3.2396
127155.65.3.240/29155.65.3.241 to 155.65.3.246155.65.3.2476
128155.65.3.248/29155.65.3.249 to 155.65.3.254155.65.3.2556
129155.65.4.0/29155.65.4.1 to 155.65.4.6155.65.4.76
130155.65.4.8/29155.65.4.9 to 155.65.4.14155.65.4.156
131155.65.4.16/29155.65.4.17 to 155.65.4.22155.65.4.236
132155.65.4.24/29155.65.4.25 to 155.65.4.30155.65.4.316
133155.65.4.32/29155.65.4.33 to 155.65.4.38155.65.4.396
134155.65.4.40/29155.65.4.41 to 155.65.4.46155.65.4.476
135155.65.4.48/29155.65.4.49 to 155.65.4.54155.65.4.556
136155.65.4.56/29155.65.4.57 to 155.65.4.62155.65.4.636
137155.65.4.64/29155.65.4.65 to 155.65.4.70155.65.4.716
138155.65.4.72/29155.65.4.73 to 155.65.4.78155.65.4.796
139155.65.4.80/29155.65.4.81 to 155.65.4.86155.65.4.876
140155.65.4.88/29155.65.4.89 to 155.65.4.94155.65.4.956
141155.65.4.96/29155.65.4.97 to 155.65.4.102155.65.4.1036
142155.65.4.104/29155.65.4.105 to 155.65.4.110155.65.4.1116
143155.65.4.112/29155.65.4.113 to 155.65.4.118155.65.4.1196
144155.65.4.120/29155.65.4.121 to 155.65.4.126155.65.4.1276
145155.65.4.128/29155.65.4.129 to 155.65.4.134155.65.4.1356
146155.65.4.136/29155.65.4.137 to 155.65.4.142155.65.4.1436
147155.65.4.144/29155.65.4.145 to 155.65.4.150155.65.4.1516
148155.65.4.152/29155.65.4.153 to 155.65.4.158155.65.4.1596
149155.65.4.160/29155.65.4.161 to 155.65.4.166155.65.4.1676
150155.65.4.168/29155.65.4.169 to 155.65.4.174155.65.4.1756
151155.65.4.176/29155.65.4.177 to 155.65.4.182155.65.4.1836
152155.65.4.184/29155.65.4.185 to 155.65.4.190155.65.4.1916
153155.65.4.192/29155.65.4.193 to 155.65.4.198155.65.4.1996
154155.65.4.200/29155.65.4.201 to 155.65.4.206155.65.4.2076
155155.65.4.208/29155.65.4.209 to 155.65.4.214155.65.4.2156
156155.65.4.216/29155.65.4.217 to 155.65.4.222155.65.4.2236
157155.65.4.224/29155.65.4.225 to 155.65.4.230155.65.4.2316
158155.65.4.232/29155.65.4.233 to 155.65.4.238155.65.4.2396
159155.65.4.240/29155.65.4.241 to 155.65.4.246155.65.4.2476
160155.65.4.248/29155.65.4.249 to 155.65.4.254155.65.4.2556
161155.65.5.0/29155.65.5.1 to 155.65.5.6155.65.5.76
162155.65.5.8/29155.65.5.9 to 155.65.5.14155.65.5.156
163155.65.5.16/29155.65.5.17 to 155.65.5.22155.65.5.236
164155.65.5.24/29155.65.5.25 to 155.65.5.30155.65.5.316
165155.65.5.32/29155.65.5.33 to 155.65.5.38155.65.5.396
166155.65.5.40/29155.65.5.41 to 155.65.5.46155.65.5.476
167155.65.5.48/29155.65.5.49 to 155.65.5.54155.65.5.556
168155.65.5.56/29155.65.5.57 to 155.65.5.62155.65.5.636
169155.65.5.64/29155.65.5.65 to 155.65.5.70155.65.5.716
170155.65.5.72/29155.65.5.73 to 155.65.5.78155.65.5.796
171155.65.5.80/29155.65.5.81 to 155.65.5.86155.65.5.876
172155.65.5.88/29155.65.5.89 to 155.65.5.94155.65.5.956
173155.65.5.96/29155.65.5.97 to 155.65.5.102155.65.5.1036
174155.65.5.104/29155.65.5.105 to 155.65.5.110155.65.5.1116
175155.65.5.112/29155.65.5.113 to 155.65.5.118155.65.5.1196
176155.65.5.120/29155.65.5.121 to 155.65.5.126155.65.5.1276
177155.65.5.128/29155.65.5.129 to 155.65.5.134155.65.5.1356
178155.65.5.136/29155.65.5.137 to 155.65.5.142155.65.5.1436
179155.65.5.144/29155.65.5.145 to 155.65.5.150155.65.5.1516
180155.65.5.152/29155.65.5.153 to 155.65.5.158155.65.5.1596
181155.65.5.160/29155.65.5.161 to 155.65.5.166155.65.5.1676
182155.65.5.168/29155.65.5.169 to 155.65.5.174155.65.5.1756
183155.65.5.176/29155.65.5.177 to 155.65.5.182155.65.5.1836
184155.65.5.184/29155.65.5.185 to 155.65.5.190155.65.5.1916
185155.65.5.192/29155.65.5.193 to 155.65.5.198155.65.5.1996
186155.65.5.200/29155.65.5.201 to 155.65.5.206155.65.5.2076
187155.65.5.208/29155.65.5.209 to 155.65.5.214155.65.5.2156
188155.65.5.216/29155.65.5.217 to 155.65.5.222155.65.5.2236
189155.65.5.224/29155.65.5.225 to 155.65.5.230155.65.5.2316
190155.65.5.232/29155.65.5.233 to 155.65.5.238155.65.5.2396
191155.65.5.240/29155.65.5.241 to 155.65.5.246155.65.5.2476
192155.65.5.248/29155.65.5.249 to 155.65.5.254155.65.5.2556
193155.65.6.0/29155.65.6.1 to 155.65.6.6155.65.6.76
194155.65.6.8/29155.65.6.9 to 155.65.6.14155.65.6.156
195155.65.6.16/29155.65.6.17 to 155.65.6.22155.65.6.236
196155.65.6.24/29155.65.6.25 to 155.65.6.30155.65.6.316
197155.65.6.32/29155.65.6.33 to 155.65.6.38155.65.6.396
198155.65.6.40/29155.65.6.41 to 155.65.6.46155.65.6.476
199155.65.6.48/29155.65.6.49 to 155.65.6.54155.65.6.556
200155.65.6.56/29155.65.6.57 to 155.65.6.62155.65.6.636
201155.65.6.64/29155.65.6.65 to 155.65.6.70155.65.6.716
202155.65.6.72/29155.65.6.73 to 155.65.6.78155.65.6.796
203155.65.6.80/29155.65.6.81 to 155.65.6.86155.65.6.876
204155.65.6.88/29155.65.6.89 to 155.65.6.94155.65.6.956
205155.65.6.96/29155.65.6.97 to 155.65.6.102155.65.6.1036
206155.65.6.104/29155.65.6.105 to 155.65.6.110155.65.6.1116
207155.65.6.112/29155.65.6.113 to 155.65.6.118155.65.6.1196
208155.65.6.120/29155.65.6.121 to 155.65.6.126155.65.6.1276
209155.65.6.128/29155.65.6.129 to 155.65.6.134155.65.6.1356
210155.65.6.136/29155.65.6.137 to 155.65.6.142155.65.6.1436
211155.65.6.144/29155.65.6.145 to 155.65.6.150155.65.6.1516
212155.65.6.152/29155.65.6.153 to 155.65.6.158155.65.6.1596
213155.65.6.160/29155.65.6.161 to 155.65.6.166155.65.6.1676
214155.65.6.168/29155.65.6.169 to 155.65.6.174155.65.6.1756
215155.65.6.176/29155.65.6.177 to 155.65.6.182155.65.6.1836
216155.65.6.184/29155.65.6.185 to 155.65.6.190155.65.6.1916
217155.65.6.192/29155.65.6.193 to 155.65.6.198155.65.6.1996
218155.65.6.200/29155.65.6.201 to 155.65.6.206155.65.6.2076
219155.65.6.208/29155.65.6.209 to 155.65.6.214155.65.6.2156
220155.65.6.216/29155.65.6.217 to 155.65.6.222155.65.6.2236
221155.65.6.224/29155.65.6.225 to 155.65.6.230155.65.6.2316
222155.65.6.232/29155.65.6.233 to 155.65.6.238155.65.6.2396
223155.65.6.240/29155.65.6.241 to 155.65.6.246155.65.6.2476
224155.65.6.248/29155.65.6.249 to 155.65.6.254155.65.6.2556
225155.65.7.0/29155.65.7.1 to 155.65.7.6155.65.7.76
226155.65.7.8/29155.65.7.9 to 155.65.7.14155.65.7.156
227155.65.7.16/29155.65.7.17 to 155.65.7.22155.65.7.236
228155.65.7.24/29155.65.7.25 to 155.65.7.30155.65.7.316
229155.65.7.32/29155.65.7.33 to 155.65.7.38155.65.7.396
230155.65.7.40/29155.65.7.41 to 155.65.7.46155.65.7.476
231155.65.7.48/29155.65.7.49 to 155.65.7.54155.65.7.556
232155.65.7.56/29155.65.7.57 to 155.65.7.62155.65.7.636
233155.65.7.64/29155.65.7.65 to 155.65.7.70155.65.7.716
234155.65.7.72/29155.65.7.73 to 155.65.7.78155.65.7.796
235155.65.7.80/29155.65.7.81 to 155.65.7.86155.65.7.876
236155.65.7.88/29155.65.7.89 to 155.65.7.94155.65.7.956
237155.65.7.96/29155.65.7.97 to 155.65.7.102155.65.7.1036
238155.65.7.104/29155.65.7.105 to 155.65.7.110155.65.7.1116
239155.65.7.112/29155.65.7.113 to 155.65.7.118155.65.7.1196
240155.65.7.120/29155.65.7.121 to 155.65.7.126155.65.7.1276
241155.65.7.128/29155.65.7.129 to 155.65.7.134155.65.7.1356
242155.65.7.136/29155.65.7.137 to 155.65.7.142155.65.7.1436
243155.65.7.144/29155.65.7.145 to 155.65.7.150155.65.7.1516
244155.65.7.152/29155.65.7.153 to 155.65.7.158155.65.7.1596
245155.65.7.160/29155.65.7.161 to 155.65.7.166155.65.7.1676
246155.65.7.168/29155.65.7.169 to 155.65.7.174155.65.7.1756
247155.65.7.176/29155.65.7.177 to 155.65.7.182155.65.7.1836
248155.65.7.184/29155.65.7.185 to 155.65.7.190155.65.7.1916
249155.65.7.192/29155.65.7.193 to 155.65.7.198155.65.7.1996
250155.65.7.200/29155.65.7.201 to 155.65.7.206155.65.7.2076
251155.65.7.208/29155.65.7.209 to 155.65.7.214155.65.7.2156
252155.65.7.216/29155.65.7.217 to 155.65.7.222155.65.7.2236
253155.65.7.224/29155.65.7.225 to 155.65.7.230155.65.7.2316
254155.65.7.232/29155.65.7.233 to 155.65.7.238155.65.7.2396
255155.65.7.240/29155.65.7.241 to 155.65.7.246155.65.7.2476
256155.65.7.248/29155.65.7.249 to 155.65.7.254155.65.7.2556

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.