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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.

Network237.192.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
237.192.0.0
Broadcast address
237.192.127.255
First usable
237.192.0.1
Last usable
237.192.127.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EDC00000 · Integer 3988783104 to 3988815871
Reverse DNS zones
0.192.237.in-addr.arpa
1.192.237.in-addr.arpa
2.192.237.in-addr.arpa
3.192.237.in-addr.arpa
4.192.237.in-addr.arpa
5.192.237.in-addr.arpa
6.192.237.in-addr.arpa
7.192.237.in-addr.arpa
8.192.237.in-addr.arpa
9.192.237.in-addr.arpa
10.192.237.in-addr.arpa
11.192.237.in-addr.arpa
12.192.237.in-addr.arpa
13.192.237.in-addr.arpa
14.192.237.in-addr.arpa
15.192.237.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
Address11101101.11000000.00000000.00000000237.192.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11101101.11000000.00000000.00000000237.192.0.0
Broadcast11101101.11000000.01111111.11111111237.192.127.255
Split into smaller subnets/27
/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)

237.192.0.0/17 makes 1,024 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1237.192.0.0/27237.192.0.1 to 237.192.0.30237.192.0.3130
2237.192.0.32/27237.192.0.33 to 237.192.0.62237.192.0.6330
3237.192.0.64/27237.192.0.65 to 237.192.0.94237.192.0.9530
4237.192.0.96/27237.192.0.97 to 237.192.0.126237.192.0.12730
5237.192.0.128/27237.192.0.129 to 237.192.0.158237.192.0.15930
6237.192.0.160/27237.192.0.161 to 237.192.0.190237.192.0.19130
7237.192.0.192/27237.192.0.193 to 237.192.0.222237.192.0.22330
8237.192.0.224/27237.192.0.225 to 237.192.0.254237.192.0.25530
9237.192.1.0/27237.192.1.1 to 237.192.1.30237.192.1.3130
10237.192.1.32/27237.192.1.33 to 237.192.1.62237.192.1.6330
11237.192.1.64/27237.192.1.65 to 237.192.1.94237.192.1.9530
12237.192.1.96/27237.192.1.97 to 237.192.1.126237.192.1.12730
13237.192.1.128/27237.192.1.129 to 237.192.1.158237.192.1.15930
14237.192.1.160/27237.192.1.161 to 237.192.1.190237.192.1.19130
15237.192.1.192/27237.192.1.193 to 237.192.1.222237.192.1.22330
16237.192.1.224/27237.192.1.225 to 237.192.1.254237.192.1.25530
17237.192.2.0/27237.192.2.1 to 237.192.2.30237.192.2.3130
18237.192.2.32/27237.192.2.33 to 237.192.2.62237.192.2.6330
19237.192.2.64/27237.192.2.65 to 237.192.2.94237.192.2.9530
20237.192.2.96/27237.192.2.97 to 237.192.2.126237.192.2.12730
21237.192.2.128/27237.192.2.129 to 237.192.2.158237.192.2.15930
22237.192.2.160/27237.192.2.161 to 237.192.2.190237.192.2.19130
23237.192.2.192/27237.192.2.193 to 237.192.2.222237.192.2.22330
24237.192.2.224/27237.192.2.225 to 237.192.2.254237.192.2.25530
25237.192.3.0/27237.192.3.1 to 237.192.3.30237.192.3.3130
26237.192.3.32/27237.192.3.33 to 237.192.3.62237.192.3.6330
27237.192.3.64/27237.192.3.65 to 237.192.3.94237.192.3.9530
28237.192.3.96/27237.192.3.97 to 237.192.3.126237.192.3.12730
29237.192.3.128/27237.192.3.129 to 237.192.3.158237.192.3.15930
30237.192.3.160/27237.192.3.161 to 237.192.3.190237.192.3.19130
31237.192.3.192/27237.192.3.193 to 237.192.3.222237.192.3.22330
32237.192.3.224/27237.192.3.225 to 237.192.3.254237.192.3.25530
33237.192.4.0/27237.192.4.1 to 237.192.4.30237.192.4.3130
34237.192.4.32/27237.192.4.33 to 237.192.4.62237.192.4.6330
35237.192.4.64/27237.192.4.65 to 237.192.4.94237.192.4.9530
36237.192.4.96/27237.192.4.97 to 237.192.4.126237.192.4.12730
37237.192.4.128/27237.192.4.129 to 237.192.4.158237.192.4.15930
38237.192.4.160/27237.192.4.161 to 237.192.4.190237.192.4.19130
39237.192.4.192/27237.192.4.193 to 237.192.4.222237.192.4.22330
40237.192.4.224/27237.192.4.225 to 237.192.4.254237.192.4.25530
41237.192.5.0/27237.192.5.1 to 237.192.5.30237.192.5.3130
42237.192.5.32/27237.192.5.33 to 237.192.5.62237.192.5.6330
43237.192.5.64/27237.192.5.65 to 237.192.5.94237.192.5.9530
44237.192.5.96/27237.192.5.97 to 237.192.5.126237.192.5.12730
45237.192.5.128/27237.192.5.129 to 237.192.5.158237.192.5.15930
46237.192.5.160/27237.192.5.161 to 237.192.5.190237.192.5.19130
47237.192.5.192/27237.192.5.193 to 237.192.5.222237.192.5.22330
48237.192.5.224/27237.192.5.225 to 237.192.5.254237.192.5.25530
49237.192.6.0/27237.192.6.1 to 237.192.6.30237.192.6.3130
50237.192.6.32/27237.192.6.33 to 237.192.6.62237.192.6.6330
51237.192.6.64/27237.192.6.65 to 237.192.6.94237.192.6.9530
52237.192.6.96/27237.192.6.97 to 237.192.6.126237.192.6.12730
53237.192.6.128/27237.192.6.129 to 237.192.6.158237.192.6.15930
54237.192.6.160/27237.192.6.161 to 237.192.6.190237.192.6.19130
55237.192.6.192/27237.192.6.193 to 237.192.6.222237.192.6.22330
56237.192.6.224/27237.192.6.225 to 237.192.6.254237.192.6.25530
57237.192.7.0/27237.192.7.1 to 237.192.7.30237.192.7.3130
58237.192.7.32/27237.192.7.33 to 237.192.7.62237.192.7.6330
59237.192.7.64/27237.192.7.65 to 237.192.7.94237.192.7.9530
60237.192.7.96/27237.192.7.97 to 237.192.7.126237.192.7.12730
61237.192.7.128/27237.192.7.129 to 237.192.7.158237.192.7.15930
62237.192.7.160/27237.192.7.161 to 237.192.7.190237.192.7.19130
63237.192.7.192/27237.192.7.193 to 237.192.7.222237.192.7.22330
64237.192.7.224/27237.192.7.225 to 237.192.7.254237.192.7.25530
65237.192.8.0/27237.192.8.1 to 237.192.8.30237.192.8.3130
66237.192.8.32/27237.192.8.33 to 237.192.8.62237.192.8.6330
67237.192.8.64/27237.192.8.65 to 237.192.8.94237.192.8.9530
68237.192.8.96/27237.192.8.97 to 237.192.8.126237.192.8.12730
69237.192.8.128/27237.192.8.129 to 237.192.8.158237.192.8.15930
70237.192.8.160/27237.192.8.161 to 237.192.8.190237.192.8.19130
71237.192.8.192/27237.192.8.193 to 237.192.8.222237.192.8.22330
72237.192.8.224/27237.192.8.225 to 237.192.8.254237.192.8.25530
73237.192.9.0/27237.192.9.1 to 237.192.9.30237.192.9.3130
74237.192.9.32/27237.192.9.33 to 237.192.9.62237.192.9.6330
75237.192.9.64/27237.192.9.65 to 237.192.9.94237.192.9.9530
76237.192.9.96/27237.192.9.97 to 237.192.9.126237.192.9.12730
77237.192.9.128/27237.192.9.129 to 237.192.9.158237.192.9.15930
78237.192.9.160/27237.192.9.161 to 237.192.9.190237.192.9.19130
79237.192.9.192/27237.192.9.193 to 237.192.9.222237.192.9.22330
80237.192.9.224/27237.192.9.225 to 237.192.9.254237.192.9.25530
81237.192.10.0/27237.192.10.1 to 237.192.10.30237.192.10.3130
82237.192.10.32/27237.192.10.33 to 237.192.10.62237.192.10.6330
83237.192.10.64/27237.192.10.65 to 237.192.10.94237.192.10.9530
84237.192.10.96/27237.192.10.97 to 237.192.10.126237.192.10.12730
85237.192.10.128/27237.192.10.129 to 237.192.10.158237.192.10.15930
86237.192.10.160/27237.192.10.161 to 237.192.10.190237.192.10.19130
87237.192.10.192/27237.192.10.193 to 237.192.10.222237.192.10.22330
88237.192.10.224/27237.192.10.225 to 237.192.10.254237.192.10.25530
89237.192.11.0/27237.192.11.1 to 237.192.11.30237.192.11.3130
90237.192.11.32/27237.192.11.33 to 237.192.11.62237.192.11.6330
91237.192.11.64/27237.192.11.65 to 237.192.11.94237.192.11.9530
92237.192.11.96/27237.192.11.97 to 237.192.11.126237.192.11.12730
93237.192.11.128/27237.192.11.129 to 237.192.11.158237.192.11.15930
94237.192.11.160/27237.192.11.161 to 237.192.11.190237.192.11.19130
95237.192.11.192/27237.192.11.193 to 237.192.11.222237.192.11.22330
96237.192.11.224/27237.192.11.225 to 237.192.11.254237.192.11.25530
97237.192.12.0/27237.192.12.1 to 237.192.12.30237.192.12.3130
98237.192.12.32/27237.192.12.33 to 237.192.12.62237.192.12.6330
99237.192.12.64/27237.192.12.65 to 237.192.12.94237.192.12.9530
100237.192.12.96/27237.192.12.97 to 237.192.12.126237.192.12.12730
101237.192.12.128/27237.192.12.129 to 237.192.12.158237.192.12.15930
102237.192.12.160/27237.192.12.161 to 237.192.12.190237.192.12.19130
103237.192.12.192/27237.192.12.193 to 237.192.12.222237.192.12.22330
104237.192.12.224/27237.192.12.225 to 237.192.12.254237.192.12.25530
105237.192.13.0/27237.192.13.1 to 237.192.13.30237.192.13.3130
106237.192.13.32/27237.192.13.33 to 237.192.13.62237.192.13.6330
107237.192.13.64/27237.192.13.65 to 237.192.13.94237.192.13.9530
108237.192.13.96/27237.192.13.97 to 237.192.13.126237.192.13.12730
109237.192.13.128/27237.192.13.129 to 237.192.13.158237.192.13.15930
110237.192.13.160/27237.192.13.161 to 237.192.13.190237.192.13.19130
111237.192.13.192/27237.192.13.193 to 237.192.13.222237.192.13.22330
112237.192.13.224/27237.192.13.225 to 237.192.13.254237.192.13.25530
113237.192.14.0/27237.192.14.1 to 237.192.14.30237.192.14.3130
114237.192.14.32/27237.192.14.33 to 237.192.14.62237.192.14.6330
115237.192.14.64/27237.192.14.65 to 237.192.14.94237.192.14.9530
116237.192.14.96/27237.192.14.97 to 237.192.14.126237.192.14.12730
117237.192.14.128/27237.192.14.129 to 237.192.14.158237.192.14.15930
118237.192.14.160/27237.192.14.161 to 237.192.14.190237.192.14.19130
119237.192.14.192/27237.192.14.193 to 237.192.14.222237.192.14.22330
120237.192.14.224/27237.192.14.225 to 237.192.14.254237.192.14.25530
121237.192.15.0/27237.192.15.1 to 237.192.15.30237.192.15.3130
122237.192.15.32/27237.192.15.33 to 237.192.15.62237.192.15.6330
123237.192.15.64/27237.192.15.65 to 237.192.15.94237.192.15.9530
124237.192.15.96/27237.192.15.97 to 237.192.15.126237.192.15.12730
125237.192.15.128/27237.192.15.129 to 237.192.15.158237.192.15.15930
126237.192.15.160/27237.192.15.161 to 237.192.15.190237.192.15.19130
127237.192.15.192/27237.192.15.193 to 237.192.15.222237.192.15.22330
128237.192.15.224/27237.192.15.225 to 237.192.15.254237.192.15.25530
129237.192.16.0/27237.192.16.1 to 237.192.16.30237.192.16.3130
130237.192.16.32/27237.192.16.33 to 237.192.16.62237.192.16.6330
131237.192.16.64/27237.192.16.65 to 237.192.16.94237.192.16.9530
132237.192.16.96/27237.192.16.97 to 237.192.16.126237.192.16.12730
133237.192.16.128/27237.192.16.129 to 237.192.16.158237.192.16.15930
134237.192.16.160/27237.192.16.161 to 237.192.16.190237.192.16.19130
135237.192.16.192/27237.192.16.193 to 237.192.16.222237.192.16.22330
136237.192.16.224/27237.192.16.225 to 237.192.16.254237.192.16.25530
137237.192.17.0/27237.192.17.1 to 237.192.17.30237.192.17.3130
138237.192.17.32/27237.192.17.33 to 237.192.17.62237.192.17.6330
139237.192.17.64/27237.192.17.65 to 237.192.17.94237.192.17.9530
140237.192.17.96/27237.192.17.97 to 237.192.17.126237.192.17.12730
141237.192.17.128/27237.192.17.129 to 237.192.17.158237.192.17.15930
142237.192.17.160/27237.192.17.161 to 237.192.17.190237.192.17.19130
143237.192.17.192/27237.192.17.193 to 237.192.17.222237.192.17.22330
144237.192.17.224/27237.192.17.225 to 237.192.17.254237.192.17.25530
145237.192.18.0/27237.192.18.1 to 237.192.18.30237.192.18.3130
146237.192.18.32/27237.192.18.33 to 237.192.18.62237.192.18.6330
147237.192.18.64/27237.192.18.65 to 237.192.18.94237.192.18.9530
148237.192.18.96/27237.192.18.97 to 237.192.18.126237.192.18.12730
149237.192.18.128/27237.192.18.129 to 237.192.18.158237.192.18.15930
150237.192.18.160/27237.192.18.161 to 237.192.18.190237.192.18.19130
151237.192.18.192/27237.192.18.193 to 237.192.18.222237.192.18.22330
152237.192.18.224/27237.192.18.225 to 237.192.18.254237.192.18.25530
153237.192.19.0/27237.192.19.1 to 237.192.19.30237.192.19.3130
154237.192.19.32/27237.192.19.33 to 237.192.19.62237.192.19.6330
155237.192.19.64/27237.192.19.65 to 237.192.19.94237.192.19.9530
156237.192.19.96/27237.192.19.97 to 237.192.19.126237.192.19.12730
157237.192.19.128/27237.192.19.129 to 237.192.19.158237.192.19.15930
158237.192.19.160/27237.192.19.161 to 237.192.19.190237.192.19.19130
159237.192.19.192/27237.192.19.193 to 237.192.19.222237.192.19.22330
160237.192.19.224/27237.192.19.225 to 237.192.19.254237.192.19.25530
161237.192.20.0/27237.192.20.1 to 237.192.20.30237.192.20.3130
162237.192.20.32/27237.192.20.33 to 237.192.20.62237.192.20.6330
163237.192.20.64/27237.192.20.65 to 237.192.20.94237.192.20.9530
164237.192.20.96/27237.192.20.97 to 237.192.20.126237.192.20.12730
165237.192.20.128/27237.192.20.129 to 237.192.20.158237.192.20.15930
166237.192.20.160/27237.192.20.161 to 237.192.20.190237.192.20.19130
167237.192.20.192/27237.192.20.193 to 237.192.20.222237.192.20.22330
168237.192.20.224/27237.192.20.225 to 237.192.20.254237.192.20.25530
169237.192.21.0/27237.192.21.1 to 237.192.21.30237.192.21.3130
170237.192.21.32/27237.192.21.33 to 237.192.21.62237.192.21.6330
171237.192.21.64/27237.192.21.65 to 237.192.21.94237.192.21.9530
172237.192.21.96/27237.192.21.97 to 237.192.21.126237.192.21.12730
173237.192.21.128/27237.192.21.129 to 237.192.21.158237.192.21.15930
174237.192.21.160/27237.192.21.161 to 237.192.21.190237.192.21.19130
175237.192.21.192/27237.192.21.193 to 237.192.21.222237.192.21.22330
176237.192.21.224/27237.192.21.225 to 237.192.21.254237.192.21.25530
177237.192.22.0/27237.192.22.1 to 237.192.22.30237.192.22.3130
178237.192.22.32/27237.192.22.33 to 237.192.22.62237.192.22.6330
179237.192.22.64/27237.192.22.65 to 237.192.22.94237.192.22.9530
180237.192.22.96/27237.192.22.97 to 237.192.22.126237.192.22.12730
181237.192.22.128/27237.192.22.129 to 237.192.22.158237.192.22.15930
182237.192.22.160/27237.192.22.161 to 237.192.22.190237.192.22.19130
183237.192.22.192/27237.192.22.193 to 237.192.22.222237.192.22.22330
184237.192.22.224/27237.192.22.225 to 237.192.22.254237.192.22.25530
185237.192.23.0/27237.192.23.1 to 237.192.23.30237.192.23.3130
186237.192.23.32/27237.192.23.33 to 237.192.23.62237.192.23.6330
187237.192.23.64/27237.192.23.65 to 237.192.23.94237.192.23.9530
188237.192.23.96/27237.192.23.97 to 237.192.23.126237.192.23.12730
189237.192.23.128/27237.192.23.129 to 237.192.23.158237.192.23.15930
190237.192.23.160/27237.192.23.161 to 237.192.23.190237.192.23.19130
191237.192.23.192/27237.192.23.193 to 237.192.23.222237.192.23.22330
192237.192.23.224/27237.192.23.225 to 237.192.23.254237.192.23.25530
193237.192.24.0/27237.192.24.1 to 237.192.24.30237.192.24.3130
194237.192.24.32/27237.192.24.33 to 237.192.24.62237.192.24.6330
195237.192.24.64/27237.192.24.65 to 237.192.24.94237.192.24.9530
196237.192.24.96/27237.192.24.97 to 237.192.24.126237.192.24.12730
197237.192.24.128/27237.192.24.129 to 237.192.24.158237.192.24.15930
198237.192.24.160/27237.192.24.161 to 237.192.24.190237.192.24.19130
199237.192.24.192/27237.192.24.193 to 237.192.24.222237.192.24.22330
200237.192.24.224/27237.192.24.225 to 237.192.24.254237.192.24.25530
201237.192.25.0/27237.192.25.1 to 237.192.25.30237.192.25.3130
202237.192.25.32/27237.192.25.33 to 237.192.25.62237.192.25.6330
203237.192.25.64/27237.192.25.65 to 237.192.25.94237.192.25.9530
204237.192.25.96/27237.192.25.97 to 237.192.25.126237.192.25.12730
205237.192.25.128/27237.192.25.129 to 237.192.25.158237.192.25.15930
206237.192.25.160/27237.192.25.161 to 237.192.25.190237.192.25.19130
207237.192.25.192/27237.192.25.193 to 237.192.25.222237.192.25.22330
208237.192.25.224/27237.192.25.225 to 237.192.25.254237.192.25.25530
209237.192.26.0/27237.192.26.1 to 237.192.26.30237.192.26.3130
210237.192.26.32/27237.192.26.33 to 237.192.26.62237.192.26.6330
211237.192.26.64/27237.192.26.65 to 237.192.26.94237.192.26.9530
212237.192.26.96/27237.192.26.97 to 237.192.26.126237.192.26.12730
213237.192.26.128/27237.192.26.129 to 237.192.26.158237.192.26.15930
214237.192.26.160/27237.192.26.161 to 237.192.26.190237.192.26.19130
215237.192.26.192/27237.192.26.193 to 237.192.26.222237.192.26.22330
216237.192.26.224/27237.192.26.225 to 237.192.26.254237.192.26.25530
217237.192.27.0/27237.192.27.1 to 237.192.27.30237.192.27.3130
218237.192.27.32/27237.192.27.33 to 237.192.27.62237.192.27.6330
219237.192.27.64/27237.192.27.65 to 237.192.27.94237.192.27.9530
220237.192.27.96/27237.192.27.97 to 237.192.27.126237.192.27.12730
221237.192.27.128/27237.192.27.129 to 237.192.27.158237.192.27.15930
222237.192.27.160/27237.192.27.161 to 237.192.27.190237.192.27.19130
223237.192.27.192/27237.192.27.193 to 237.192.27.222237.192.27.22330
224237.192.27.224/27237.192.27.225 to 237.192.27.254237.192.27.25530
225237.192.28.0/27237.192.28.1 to 237.192.28.30237.192.28.3130
226237.192.28.32/27237.192.28.33 to 237.192.28.62237.192.28.6330
227237.192.28.64/27237.192.28.65 to 237.192.28.94237.192.28.9530
228237.192.28.96/27237.192.28.97 to 237.192.28.126237.192.28.12730
229237.192.28.128/27237.192.28.129 to 237.192.28.158237.192.28.15930
230237.192.28.160/27237.192.28.161 to 237.192.28.190237.192.28.19130
231237.192.28.192/27237.192.28.193 to 237.192.28.222237.192.28.22330
232237.192.28.224/27237.192.28.225 to 237.192.28.254237.192.28.25530
233237.192.29.0/27237.192.29.1 to 237.192.29.30237.192.29.3130
234237.192.29.32/27237.192.29.33 to 237.192.29.62237.192.29.6330
235237.192.29.64/27237.192.29.65 to 237.192.29.94237.192.29.9530
236237.192.29.96/27237.192.29.97 to 237.192.29.126237.192.29.12730
237237.192.29.128/27237.192.29.129 to 237.192.29.158237.192.29.15930
238237.192.29.160/27237.192.29.161 to 237.192.29.190237.192.29.19130
239237.192.29.192/27237.192.29.193 to 237.192.29.222237.192.29.22330
240237.192.29.224/27237.192.29.225 to 237.192.29.254237.192.29.25530
241237.192.30.0/27237.192.30.1 to 237.192.30.30237.192.30.3130
242237.192.30.32/27237.192.30.33 to 237.192.30.62237.192.30.6330
243237.192.30.64/27237.192.30.65 to 237.192.30.94237.192.30.9530
244237.192.30.96/27237.192.30.97 to 237.192.30.126237.192.30.12730
245237.192.30.128/27237.192.30.129 to 237.192.30.158237.192.30.15930
246237.192.30.160/27237.192.30.161 to 237.192.30.190237.192.30.19130
247237.192.30.192/27237.192.30.193 to 237.192.30.222237.192.30.22330
248237.192.30.224/27237.192.30.225 to 237.192.30.254237.192.30.25530
249237.192.31.0/27237.192.31.1 to 237.192.31.30237.192.31.3130
250237.192.31.32/27237.192.31.33 to 237.192.31.62237.192.31.6330
251237.192.31.64/27237.192.31.65 to 237.192.31.94237.192.31.9530
252237.192.31.96/27237.192.31.97 to 237.192.31.126237.192.31.12730
253237.192.31.128/27237.192.31.129 to 237.192.31.158237.192.31.15930
254237.192.31.160/27237.192.31.161 to 237.192.31.190237.192.31.19130
255237.192.31.192/27237.192.31.193 to 237.192.31.222237.192.31.22330
256237.192.31.224/27237.192.31.225 to 237.192.31.254237.192.31.25530

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.