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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.

Network161.1.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
161.1.0.0
Broadcast address
161.1.127.255
First usable
161.1.0.1
Last usable
161.1.127.254
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 A1010000 · Integer 2701197312 to 2701230079
Reverse DNS zones
0.1.161.in-addr.arpa
1.1.161.in-addr.arpa
2.1.161.in-addr.arpa
3.1.161.in-addr.arpa
4.1.161.in-addr.arpa
5.1.161.in-addr.arpa
6.1.161.in-addr.arpa
7.1.161.in-addr.arpa
8.1.161.in-addr.arpa
9.1.161.in-addr.arpa
10.1.161.in-addr.arpa
11.1.161.in-addr.arpa
12.1.161.in-addr.arpa
13.1.161.in-addr.arpa
14.1.161.in-addr.arpa
15.1.161.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
Address10100001.00000001.00000000.00000000161.1.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10100001.00000001.00000000.00000000161.1.0.0
Broadcast10100001.00000001.01111111.11111111161.1.127.255
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)

161.1.0.0/17 makes 1,024 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1161.1.0.0/27161.1.0.1 to 161.1.0.30161.1.0.3130
2161.1.0.32/27161.1.0.33 to 161.1.0.62161.1.0.6330
3161.1.0.64/27161.1.0.65 to 161.1.0.94161.1.0.9530
4161.1.0.96/27161.1.0.97 to 161.1.0.126161.1.0.12730
5161.1.0.128/27161.1.0.129 to 161.1.0.158161.1.0.15930
6161.1.0.160/27161.1.0.161 to 161.1.0.190161.1.0.19130
7161.1.0.192/27161.1.0.193 to 161.1.0.222161.1.0.22330
8161.1.0.224/27161.1.0.225 to 161.1.0.254161.1.0.25530
9161.1.1.0/27161.1.1.1 to 161.1.1.30161.1.1.3130
10161.1.1.32/27161.1.1.33 to 161.1.1.62161.1.1.6330
11161.1.1.64/27161.1.1.65 to 161.1.1.94161.1.1.9530
12161.1.1.96/27161.1.1.97 to 161.1.1.126161.1.1.12730
13161.1.1.128/27161.1.1.129 to 161.1.1.158161.1.1.15930
14161.1.1.160/27161.1.1.161 to 161.1.1.190161.1.1.19130
15161.1.1.192/27161.1.1.193 to 161.1.1.222161.1.1.22330
16161.1.1.224/27161.1.1.225 to 161.1.1.254161.1.1.25530
17161.1.2.0/27161.1.2.1 to 161.1.2.30161.1.2.3130
18161.1.2.32/27161.1.2.33 to 161.1.2.62161.1.2.6330
19161.1.2.64/27161.1.2.65 to 161.1.2.94161.1.2.9530
20161.1.2.96/27161.1.2.97 to 161.1.2.126161.1.2.12730
21161.1.2.128/27161.1.2.129 to 161.1.2.158161.1.2.15930
22161.1.2.160/27161.1.2.161 to 161.1.2.190161.1.2.19130
23161.1.2.192/27161.1.2.193 to 161.1.2.222161.1.2.22330
24161.1.2.224/27161.1.2.225 to 161.1.2.254161.1.2.25530
25161.1.3.0/27161.1.3.1 to 161.1.3.30161.1.3.3130
26161.1.3.32/27161.1.3.33 to 161.1.3.62161.1.3.6330
27161.1.3.64/27161.1.3.65 to 161.1.3.94161.1.3.9530
28161.1.3.96/27161.1.3.97 to 161.1.3.126161.1.3.12730
29161.1.3.128/27161.1.3.129 to 161.1.3.158161.1.3.15930
30161.1.3.160/27161.1.3.161 to 161.1.3.190161.1.3.19130
31161.1.3.192/27161.1.3.193 to 161.1.3.222161.1.3.22330
32161.1.3.224/27161.1.3.225 to 161.1.3.254161.1.3.25530
33161.1.4.0/27161.1.4.1 to 161.1.4.30161.1.4.3130
34161.1.4.32/27161.1.4.33 to 161.1.4.62161.1.4.6330
35161.1.4.64/27161.1.4.65 to 161.1.4.94161.1.4.9530
36161.1.4.96/27161.1.4.97 to 161.1.4.126161.1.4.12730
37161.1.4.128/27161.1.4.129 to 161.1.4.158161.1.4.15930
38161.1.4.160/27161.1.4.161 to 161.1.4.190161.1.4.19130
39161.1.4.192/27161.1.4.193 to 161.1.4.222161.1.4.22330
40161.1.4.224/27161.1.4.225 to 161.1.4.254161.1.4.25530
41161.1.5.0/27161.1.5.1 to 161.1.5.30161.1.5.3130
42161.1.5.32/27161.1.5.33 to 161.1.5.62161.1.5.6330
43161.1.5.64/27161.1.5.65 to 161.1.5.94161.1.5.9530
44161.1.5.96/27161.1.5.97 to 161.1.5.126161.1.5.12730
45161.1.5.128/27161.1.5.129 to 161.1.5.158161.1.5.15930
46161.1.5.160/27161.1.5.161 to 161.1.5.190161.1.5.19130
47161.1.5.192/27161.1.5.193 to 161.1.5.222161.1.5.22330
48161.1.5.224/27161.1.5.225 to 161.1.5.254161.1.5.25530
49161.1.6.0/27161.1.6.1 to 161.1.6.30161.1.6.3130
50161.1.6.32/27161.1.6.33 to 161.1.6.62161.1.6.6330
51161.1.6.64/27161.1.6.65 to 161.1.6.94161.1.6.9530
52161.1.6.96/27161.1.6.97 to 161.1.6.126161.1.6.12730
53161.1.6.128/27161.1.6.129 to 161.1.6.158161.1.6.15930
54161.1.6.160/27161.1.6.161 to 161.1.6.190161.1.6.19130
55161.1.6.192/27161.1.6.193 to 161.1.6.222161.1.6.22330
56161.1.6.224/27161.1.6.225 to 161.1.6.254161.1.6.25530
57161.1.7.0/27161.1.7.1 to 161.1.7.30161.1.7.3130
58161.1.7.32/27161.1.7.33 to 161.1.7.62161.1.7.6330
59161.1.7.64/27161.1.7.65 to 161.1.7.94161.1.7.9530
60161.1.7.96/27161.1.7.97 to 161.1.7.126161.1.7.12730
61161.1.7.128/27161.1.7.129 to 161.1.7.158161.1.7.15930
62161.1.7.160/27161.1.7.161 to 161.1.7.190161.1.7.19130
63161.1.7.192/27161.1.7.193 to 161.1.7.222161.1.7.22330
64161.1.7.224/27161.1.7.225 to 161.1.7.254161.1.7.25530
65161.1.8.0/27161.1.8.1 to 161.1.8.30161.1.8.3130
66161.1.8.32/27161.1.8.33 to 161.1.8.62161.1.8.6330
67161.1.8.64/27161.1.8.65 to 161.1.8.94161.1.8.9530
68161.1.8.96/27161.1.8.97 to 161.1.8.126161.1.8.12730
69161.1.8.128/27161.1.8.129 to 161.1.8.158161.1.8.15930
70161.1.8.160/27161.1.8.161 to 161.1.8.190161.1.8.19130
71161.1.8.192/27161.1.8.193 to 161.1.8.222161.1.8.22330
72161.1.8.224/27161.1.8.225 to 161.1.8.254161.1.8.25530
73161.1.9.0/27161.1.9.1 to 161.1.9.30161.1.9.3130
74161.1.9.32/27161.1.9.33 to 161.1.9.62161.1.9.6330
75161.1.9.64/27161.1.9.65 to 161.1.9.94161.1.9.9530
76161.1.9.96/27161.1.9.97 to 161.1.9.126161.1.9.12730
77161.1.9.128/27161.1.9.129 to 161.1.9.158161.1.9.15930
78161.1.9.160/27161.1.9.161 to 161.1.9.190161.1.9.19130
79161.1.9.192/27161.1.9.193 to 161.1.9.222161.1.9.22330
80161.1.9.224/27161.1.9.225 to 161.1.9.254161.1.9.25530
81161.1.10.0/27161.1.10.1 to 161.1.10.30161.1.10.3130
82161.1.10.32/27161.1.10.33 to 161.1.10.62161.1.10.6330
83161.1.10.64/27161.1.10.65 to 161.1.10.94161.1.10.9530
84161.1.10.96/27161.1.10.97 to 161.1.10.126161.1.10.12730
85161.1.10.128/27161.1.10.129 to 161.1.10.158161.1.10.15930
86161.1.10.160/27161.1.10.161 to 161.1.10.190161.1.10.19130
87161.1.10.192/27161.1.10.193 to 161.1.10.222161.1.10.22330
88161.1.10.224/27161.1.10.225 to 161.1.10.254161.1.10.25530
89161.1.11.0/27161.1.11.1 to 161.1.11.30161.1.11.3130
90161.1.11.32/27161.1.11.33 to 161.1.11.62161.1.11.6330
91161.1.11.64/27161.1.11.65 to 161.1.11.94161.1.11.9530
92161.1.11.96/27161.1.11.97 to 161.1.11.126161.1.11.12730
93161.1.11.128/27161.1.11.129 to 161.1.11.158161.1.11.15930
94161.1.11.160/27161.1.11.161 to 161.1.11.190161.1.11.19130
95161.1.11.192/27161.1.11.193 to 161.1.11.222161.1.11.22330
96161.1.11.224/27161.1.11.225 to 161.1.11.254161.1.11.25530
97161.1.12.0/27161.1.12.1 to 161.1.12.30161.1.12.3130
98161.1.12.32/27161.1.12.33 to 161.1.12.62161.1.12.6330
99161.1.12.64/27161.1.12.65 to 161.1.12.94161.1.12.9530
100161.1.12.96/27161.1.12.97 to 161.1.12.126161.1.12.12730
101161.1.12.128/27161.1.12.129 to 161.1.12.158161.1.12.15930
102161.1.12.160/27161.1.12.161 to 161.1.12.190161.1.12.19130
103161.1.12.192/27161.1.12.193 to 161.1.12.222161.1.12.22330
104161.1.12.224/27161.1.12.225 to 161.1.12.254161.1.12.25530
105161.1.13.0/27161.1.13.1 to 161.1.13.30161.1.13.3130
106161.1.13.32/27161.1.13.33 to 161.1.13.62161.1.13.6330
107161.1.13.64/27161.1.13.65 to 161.1.13.94161.1.13.9530
108161.1.13.96/27161.1.13.97 to 161.1.13.126161.1.13.12730
109161.1.13.128/27161.1.13.129 to 161.1.13.158161.1.13.15930
110161.1.13.160/27161.1.13.161 to 161.1.13.190161.1.13.19130
111161.1.13.192/27161.1.13.193 to 161.1.13.222161.1.13.22330
112161.1.13.224/27161.1.13.225 to 161.1.13.254161.1.13.25530
113161.1.14.0/27161.1.14.1 to 161.1.14.30161.1.14.3130
114161.1.14.32/27161.1.14.33 to 161.1.14.62161.1.14.6330
115161.1.14.64/27161.1.14.65 to 161.1.14.94161.1.14.9530
116161.1.14.96/27161.1.14.97 to 161.1.14.126161.1.14.12730
117161.1.14.128/27161.1.14.129 to 161.1.14.158161.1.14.15930
118161.1.14.160/27161.1.14.161 to 161.1.14.190161.1.14.19130
119161.1.14.192/27161.1.14.193 to 161.1.14.222161.1.14.22330
120161.1.14.224/27161.1.14.225 to 161.1.14.254161.1.14.25530
121161.1.15.0/27161.1.15.1 to 161.1.15.30161.1.15.3130
122161.1.15.32/27161.1.15.33 to 161.1.15.62161.1.15.6330
123161.1.15.64/27161.1.15.65 to 161.1.15.94161.1.15.9530
124161.1.15.96/27161.1.15.97 to 161.1.15.126161.1.15.12730
125161.1.15.128/27161.1.15.129 to 161.1.15.158161.1.15.15930
126161.1.15.160/27161.1.15.161 to 161.1.15.190161.1.15.19130
127161.1.15.192/27161.1.15.193 to 161.1.15.222161.1.15.22330
128161.1.15.224/27161.1.15.225 to 161.1.15.254161.1.15.25530
129161.1.16.0/27161.1.16.1 to 161.1.16.30161.1.16.3130
130161.1.16.32/27161.1.16.33 to 161.1.16.62161.1.16.6330
131161.1.16.64/27161.1.16.65 to 161.1.16.94161.1.16.9530
132161.1.16.96/27161.1.16.97 to 161.1.16.126161.1.16.12730
133161.1.16.128/27161.1.16.129 to 161.1.16.158161.1.16.15930
134161.1.16.160/27161.1.16.161 to 161.1.16.190161.1.16.19130
135161.1.16.192/27161.1.16.193 to 161.1.16.222161.1.16.22330
136161.1.16.224/27161.1.16.225 to 161.1.16.254161.1.16.25530
137161.1.17.0/27161.1.17.1 to 161.1.17.30161.1.17.3130
138161.1.17.32/27161.1.17.33 to 161.1.17.62161.1.17.6330
139161.1.17.64/27161.1.17.65 to 161.1.17.94161.1.17.9530
140161.1.17.96/27161.1.17.97 to 161.1.17.126161.1.17.12730
141161.1.17.128/27161.1.17.129 to 161.1.17.158161.1.17.15930
142161.1.17.160/27161.1.17.161 to 161.1.17.190161.1.17.19130
143161.1.17.192/27161.1.17.193 to 161.1.17.222161.1.17.22330
144161.1.17.224/27161.1.17.225 to 161.1.17.254161.1.17.25530
145161.1.18.0/27161.1.18.1 to 161.1.18.30161.1.18.3130
146161.1.18.32/27161.1.18.33 to 161.1.18.62161.1.18.6330
147161.1.18.64/27161.1.18.65 to 161.1.18.94161.1.18.9530
148161.1.18.96/27161.1.18.97 to 161.1.18.126161.1.18.12730
149161.1.18.128/27161.1.18.129 to 161.1.18.158161.1.18.15930
150161.1.18.160/27161.1.18.161 to 161.1.18.190161.1.18.19130
151161.1.18.192/27161.1.18.193 to 161.1.18.222161.1.18.22330
152161.1.18.224/27161.1.18.225 to 161.1.18.254161.1.18.25530
153161.1.19.0/27161.1.19.1 to 161.1.19.30161.1.19.3130
154161.1.19.32/27161.1.19.33 to 161.1.19.62161.1.19.6330
155161.1.19.64/27161.1.19.65 to 161.1.19.94161.1.19.9530
156161.1.19.96/27161.1.19.97 to 161.1.19.126161.1.19.12730
157161.1.19.128/27161.1.19.129 to 161.1.19.158161.1.19.15930
158161.1.19.160/27161.1.19.161 to 161.1.19.190161.1.19.19130
159161.1.19.192/27161.1.19.193 to 161.1.19.222161.1.19.22330
160161.1.19.224/27161.1.19.225 to 161.1.19.254161.1.19.25530
161161.1.20.0/27161.1.20.1 to 161.1.20.30161.1.20.3130
162161.1.20.32/27161.1.20.33 to 161.1.20.62161.1.20.6330
163161.1.20.64/27161.1.20.65 to 161.1.20.94161.1.20.9530
164161.1.20.96/27161.1.20.97 to 161.1.20.126161.1.20.12730
165161.1.20.128/27161.1.20.129 to 161.1.20.158161.1.20.15930
166161.1.20.160/27161.1.20.161 to 161.1.20.190161.1.20.19130
167161.1.20.192/27161.1.20.193 to 161.1.20.222161.1.20.22330
168161.1.20.224/27161.1.20.225 to 161.1.20.254161.1.20.25530
169161.1.21.0/27161.1.21.1 to 161.1.21.30161.1.21.3130
170161.1.21.32/27161.1.21.33 to 161.1.21.62161.1.21.6330
171161.1.21.64/27161.1.21.65 to 161.1.21.94161.1.21.9530
172161.1.21.96/27161.1.21.97 to 161.1.21.126161.1.21.12730
173161.1.21.128/27161.1.21.129 to 161.1.21.158161.1.21.15930
174161.1.21.160/27161.1.21.161 to 161.1.21.190161.1.21.19130
175161.1.21.192/27161.1.21.193 to 161.1.21.222161.1.21.22330
176161.1.21.224/27161.1.21.225 to 161.1.21.254161.1.21.25530
177161.1.22.0/27161.1.22.1 to 161.1.22.30161.1.22.3130
178161.1.22.32/27161.1.22.33 to 161.1.22.62161.1.22.6330
179161.1.22.64/27161.1.22.65 to 161.1.22.94161.1.22.9530
180161.1.22.96/27161.1.22.97 to 161.1.22.126161.1.22.12730
181161.1.22.128/27161.1.22.129 to 161.1.22.158161.1.22.15930
182161.1.22.160/27161.1.22.161 to 161.1.22.190161.1.22.19130
183161.1.22.192/27161.1.22.193 to 161.1.22.222161.1.22.22330
184161.1.22.224/27161.1.22.225 to 161.1.22.254161.1.22.25530
185161.1.23.0/27161.1.23.1 to 161.1.23.30161.1.23.3130
186161.1.23.32/27161.1.23.33 to 161.1.23.62161.1.23.6330
187161.1.23.64/27161.1.23.65 to 161.1.23.94161.1.23.9530
188161.1.23.96/27161.1.23.97 to 161.1.23.126161.1.23.12730
189161.1.23.128/27161.1.23.129 to 161.1.23.158161.1.23.15930
190161.1.23.160/27161.1.23.161 to 161.1.23.190161.1.23.19130
191161.1.23.192/27161.1.23.193 to 161.1.23.222161.1.23.22330
192161.1.23.224/27161.1.23.225 to 161.1.23.254161.1.23.25530
193161.1.24.0/27161.1.24.1 to 161.1.24.30161.1.24.3130
194161.1.24.32/27161.1.24.33 to 161.1.24.62161.1.24.6330
195161.1.24.64/27161.1.24.65 to 161.1.24.94161.1.24.9530
196161.1.24.96/27161.1.24.97 to 161.1.24.126161.1.24.12730
197161.1.24.128/27161.1.24.129 to 161.1.24.158161.1.24.15930
198161.1.24.160/27161.1.24.161 to 161.1.24.190161.1.24.19130
199161.1.24.192/27161.1.24.193 to 161.1.24.222161.1.24.22330
200161.1.24.224/27161.1.24.225 to 161.1.24.254161.1.24.25530
201161.1.25.0/27161.1.25.1 to 161.1.25.30161.1.25.3130
202161.1.25.32/27161.1.25.33 to 161.1.25.62161.1.25.6330
203161.1.25.64/27161.1.25.65 to 161.1.25.94161.1.25.9530
204161.1.25.96/27161.1.25.97 to 161.1.25.126161.1.25.12730
205161.1.25.128/27161.1.25.129 to 161.1.25.158161.1.25.15930
206161.1.25.160/27161.1.25.161 to 161.1.25.190161.1.25.19130
207161.1.25.192/27161.1.25.193 to 161.1.25.222161.1.25.22330
208161.1.25.224/27161.1.25.225 to 161.1.25.254161.1.25.25530
209161.1.26.0/27161.1.26.1 to 161.1.26.30161.1.26.3130
210161.1.26.32/27161.1.26.33 to 161.1.26.62161.1.26.6330
211161.1.26.64/27161.1.26.65 to 161.1.26.94161.1.26.9530
212161.1.26.96/27161.1.26.97 to 161.1.26.126161.1.26.12730
213161.1.26.128/27161.1.26.129 to 161.1.26.158161.1.26.15930
214161.1.26.160/27161.1.26.161 to 161.1.26.190161.1.26.19130
215161.1.26.192/27161.1.26.193 to 161.1.26.222161.1.26.22330
216161.1.26.224/27161.1.26.225 to 161.1.26.254161.1.26.25530
217161.1.27.0/27161.1.27.1 to 161.1.27.30161.1.27.3130
218161.1.27.32/27161.1.27.33 to 161.1.27.62161.1.27.6330
219161.1.27.64/27161.1.27.65 to 161.1.27.94161.1.27.9530
220161.1.27.96/27161.1.27.97 to 161.1.27.126161.1.27.12730
221161.1.27.128/27161.1.27.129 to 161.1.27.158161.1.27.15930
222161.1.27.160/27161.1.27.161 to 161.1.27.190161.1.27.19130
223161.1.27.192/27161.1.27.193 to 161.1.27.222161.1.27.22330
224161.1.27.224/27161.1.27.225 to 161.1.27.254161.1.27.25530
225161.1.28.0/27161.1.28.1 to 161.1.28.30161.1.28.3130
226161.1.28.32/27161.1.28.33 to 161.1.28.62161.1.28.6330
227161.1.28.64/27161.1.28.65 to 161.1.28.94161.1.28.9530
228161.1.28.96/27161.1.28.97 to 161.1.28.126161.1.28.12730
229161.1.28.128/27161.1.28.129 to 161.1.28.158161.1.28.15930
230161.1.28.160/27161.1.28.161 to 161.1.28.190161.1.28.19130
231161.1.28.192/27161.1.28.193 to 161.1.28.222161.1.28.22330
232161.1.28.224/27161.1.28.225 to 161.1.28.254161.1.28.25530
233161.1.29.0/27161.1.29.1 to 161.1.29.30161.1.29.3130
234161.1.29.32/27161.1.29.33 to 161.1.29.62161.1.29.6330
235161.1.29.64/27161.1.29.65 to 161.1.29.94161.1.29.9530
236161.1.29.96/27161.1.29.97 to 161.1.29.126161.1.29.12730
237161.1.29.128/27161.1.29.129 to 161.1.29.158161.1.29.15930
238161.1.29.160/27161.1.29.161 to 161.1.29.190161.1.29.19130
239161.1.29.192/27161.1.29.193 to 161.1.29.222161.1.29.22330
240161.1.29.224/27161.1.29.225 to 161.1.29.254161.1.29.25530
241161.1.30.0/27161.1.30.1 to 161.1.30.30161.1.30.3130
242161.1.30.32/27161.1.30.33 to 161.1.30.62161.1.30.6330
243161.1.30.64/27161.1.30.65 to 161.1.30.94161.1.30.9530
244161.1.30.96/27161.1.30.97 to 161.1.30.126161.1.30.12730
245161.1.30.128/27161.1.30.129 to 161.1.30.158161.1.30.15930
246161.1.30.160/27161.1.30.161 to 161.1.30.190161.1.30.19130
247161.1.30.192/27161.1.30.193 to 161.1.30.222161.1.30.22330
248161.1.30.224/27161.1.30.225 to 161.1.30.254161.1.30.25530
249161.1.31.0/27161.1.31.1 to 161.1.31.30161.1.31.3130
250161.1.31.32/27161.1.31.33 to 161.1.31.62161.1.31.6330
251161.1.31.64/27161.1.31.65 to 161.1.31.94161.1.31.9530
252161.1.31.96/27161.1.31.97 to 161.1.31.126161.1.31.12730
253161.1.31.128/27161.1.31.129 to 161.1.31.158161.1.31.15930
254161.1.31.160/27161.1.31.161 to 161.1.31.190161.1.31.19130
255161.1.31.192/27161.1.31.193 to 161.1.31.222161.1.31.22330
256161.1.31.224/27161.1.31.225 to 161.1.31.254161.1.31.25530

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.