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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.

Network161.0.0.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
161.0.0.0
Broadcast address
161.0.15.255
First usable
161.0.0.1
Last usable
161.0.15.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
B (default /16)
As numbers
Hex A1000000 · Integer 2701131776 to 2701135871
Reverse DNS zones
0.0.161.in-addr.arpa
1.0.161.in-addr.arpa
2.0.161.in-addr.arpa
3.0.161.in-addr.arpa
4.0.161.in-addr.arpa
5.0.161.in-addr.arpa
6.0.161.in-addr.arpa
7.0.161.in-addr.arpa
8.0.161.in-addr.arpa
9.0.161.in-addr.arpa
10.0.161.in-addr.arpa
11.0.161.in-addr.arpa
12.0.161.in-addr.arpa
13.0.161.in-addr.arpa
14.0.161.in-addr.arpa
15.0.161.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100001.00000000.00000000.00000000161.0.0.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network10100001.00000000.00000000.00000000161.0.0.0
Broadcast10100001.00000000.00001111.11111111161.0.15.255
Split into smaller subnets/28
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

161.0.0.0/20 makes 256 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1161.0.0.0/28161.0.0.1 to 161.0.0.14161.0.0.1514
2161.0.0.16/28161.0.0.17 to 161.0.0.30161.0.0.3114
3161.0.0.32/28161.0.0.33 to 161.0.0.46161.0.0.4714
4161.0.0.48/28161.0.0.49 to 161.0.0.62161.0.0.6314
5161.0.0.64/28161.0.0.65 to 161.0.0.78161.0.0.7914
6161.0.0.80/28161.0.0.81 to 161.0.0.94161.0.0.9514
7161.0.0.96/28161.0.0.97 to 161.0.0.110161.0.0.11114
8161.0.0.112/28161.0.0.113 to 161.0.0.126161.0.0.12714
9161.0.0.128/28161.0.0.129 to 161.0.0.142161.0.0.14314
10161.0.0.144/28161.0.0.145 to 161.0.0.158161.0.0.15914
11161.0.0.160/28161.0.0.161 to 161.0.0.174161.0.0.17514
12161.0.0.176/28161.0.0.177 to 161.0.0.190161.0.0.19114
13161.0.0.192/28161.0.0.193 to 161.0.0.206161.0.0.20714
14161.0.0.208/28161.0.0.209 to 161.0.0.222161.0.0.22314
15161.0.0.224/28161.0.0.225 to 161.0.0.238161.0.0.23914
16161.0.0.240/28161.0.0.241 to 161.0.0.254161.0.0.25514
17161.0.1.0/28161.0.1.1 to 161.0.1.14161.0.1.1514
18161.0.1.16/28161.0.1.17 to 161.0.1.30161.0.1.3114
19161.0.1.32/28161.0.1.33 to 161.0.1.46161.0.1.4714
20161.0.1.48/28161.0.1.49 to 161.0.1.62161.0.1.6314
21161.0.1.64/28161.0.1.65 to 161.0.1.78161.0.1.7914
22161.0.1.80/28161.0.1.81 to 161.0.1.94161.0.1.9514
23161.0.1.96/28161.0.1.97 to 161.0.1.110161.0.1.11114
24161.0.1.112/28161.0.1.113 to 161.0.1.126161.0.1.12714
25161.0.1.128/28161.0.1.129 to 161.0.1.142161.0.1.14314
26161.0.1.144/28161.0.1.145 to 161.0.1.158161.0.1.15914
27161.0.1.160/28161.0.1.161 to 161.0.1.174161.0.1.17514
28161.0.1.176/28161.0.1.177 to 161.0.1.190161.0.1.19114
29161.0.1.192/28161.0.1.193 to 161.0.1.206161.0.1.20714
30161.0.1.208/28161.0.1.209 to 161.0.1.222161.0.1.22314
31161.0.1.224/28161.0.1.225 to 161.0.1.238161.0.1.23914
32161.0.1.240/28161.0.1.241 to 161.0.1.254161.0.1.25514
33161.0.2.0/28161.0.2.1 to 161.0.2.14161.0.2.1514
34161.0.2.16/28161.0.2.17 to 161.0.2.30161.0.2.3114
35161.0.2.32/28161.0.2.33 to 161.0.2.46161.0.2.4714
36161.0.2.48/28161.0.2.49 to 161.0.2.62161.0.2.6314
37161.0.2.64/28161.0.2.65 to 161.0.2.78161.0.2.7914
38161.0.2.80/28161.0.2.81 to 161.0.2.94161.0.2.9514
39161.0.2.96/28161.0.2.97 to 161.0.2.110161.0.2.11114
40161.0.2.112/28161.0.2.113 to 161.0.2.126161.0.2.12714
41161.0.2.128/28161.0.2.129 to 161.0.2.142161.0.2.14314
42161.0.2.144/28161.0.2.145 to 161.0.2.158161.0.2.15914
43161.0.2.160/28161.0.2.161 to 161.0.2.174161.0.2.17514
44161.0.2.176/28161.0.2.177 to 161.0.2.190161.0.2.19114
45161.0.2.192/28161.0.2.193 to 161.0.2.206161.0.2.20714
46161.0.2.208/28161.0.2.209 to 161.0.2.222161.0.2.22314
47161.0.2.224/28161.0.2.225 to 161.0.2.238161.0.2.23914
48161.0.2.240/28161.0.2.241 to 161.0.2.254161.0.2.25514
49161.0.3.0/28161.0.3.1 to 161.0.3.14161.0.3.1514
50161.0.3.16/28161.0.3.17 to 161.0.3.30161.0.3.3114
51161.0.3.32/28161.0.3.33 to 161.0.3.46161.0.3.4714
52161.0.3.48/28161.0.3.49 to 161.0.3.62161.0.3.6314
53161.0.3.64/28161.0.3.65 to 161.0.3.78161.0.3.7914
54161.0.3.80/28161.0.3.81 to 161.0.3.94161.0.3.9514
55161.0.3.96/28161.0.3.97 to 161.0.3.110161.0.3.11114
56161.0.3.112/28161.0.3.113 to 161.0.3.126161.0.3.12714
57161.0.3.128/28161.0.3.129 to 161.0.3.142161.0.3.14314
58161.0.3.144/28161.0.3.145 to 161.0.3.158161.0.3.15914
59161.0.3.160/28161.0.3.161 to 161.0.3.174161.0.3.17514
60161.0.3.176/28161.0.3.177 to 161.0.3.190161.0.3.19114
61161.0.3.192/28161.0.3.193 to 161.0.3.206161.0.3.20714
62161.0.3.208/28161.0.3.209 to 161.0.3.222161.0.3.22314
63161.0.3.224/28161.0.3.225 to 161.0.3.238161.0.3.23914
64161.0.3.240/28161.0.3.241 to 161.0.3.254161.0.3.25514
65161.0.4.0/28161.0.4.1 to 161.0.4.14161.0.4.1514
66161.0.4.16/28161.0.4.17 to 161.0.4.30161.0.4.3114
67161.0.4.32/28161.0.4.33 to 161.0.4.46161.0.4.4714
68161.0.4.48/28161.0.4.49 to 161.0.4.62161.0.4.6314
69161.0.4.64/28161.0.4.65 to 161.0.4.78161.0.4.7914
70161.0.4.80/28161.0.4.81 to 161.0.4.94161.0.4.9514
71161.0.4.96/28161.0.4.97 to 161.0.4.110161.0.4.11114
72161.0.4.112/28161.0.4.113 to 161.0.4.126161.0.4.12714
73161.0.4.128/28161.0.4.129 to 161.0.4.142161.0.4.14314
74161.0.4.144/28161.0.4.145 to 161.0.4.158161.0.4.15914
75161.0.4.160/28161.0.4.161 to 161.0.4.174161.0.4.17514
76161.0.4.176/28161.0.4.177 to 161.0.4.190161.0.4.19114
77161.0.4.192/28161.0.4.193 to 161.0.4.206161.0.4.20714
78161.0.4.208/28161.0.4.209 to 161.0.4.222161.0.4.22314
79161.0.4.224/28161.0.4.225 to 161.0.4.238161.0.4.23914
80161.0.4.240/28161.0.4.241 to 161.0.4.254161.0.4.25514
81161.0.5.0/28161.0.5.1 to 161.0.5.14161.0.5.1514
82161.0.5.16/28161.0.5.17 to 161.0.5.30161.0.5.3114
83161.0.5.32/28161.0.5.33 to 161.0.5.46161.0.5.4714
84161.0.5.48/28161.0.5.49 to 161.0.5.62161.0.5.6314
85161.0.5.64/28161.0.5.65 to 161.0.5.78161.0.5.7914
86161.0.5.80/28161.0.5.81 to 161.0.5.94161.0.5.9514
87161.0.5.96/28161.0.5.97 to 161.0.5.110161.0.5.11114
88161.0.5.112/28161.0.5.113 to 161.0.5.126161.0.5.12714
89161.0.5.128/28161.0.5.129 to 161.0.5.142161.0.5.14314
90161.0.5.144/28161.0.5.145 to 161.0.5.158161.0.5.15914
91161.0.5.160/28161.0.5.161 to 161.0.5.174161.0.5.17514
92161.0.5.176/28161.0.5.177 to 161.0.5.190161.0.5.19114
93161.0.5.192/28161.0.5.193 to 161.0.5.206161.0.5.20714
94161.0.5.208/28161.0.5.209 to 161.0.5.222161.0.5.22314
95161.0.5.224/28161.0.5.225 to 161.0.5.238161.0.5.23914
96161.0.5.240/28161.0.5.241 to 161.0.5.254161.0.5.25514
97161.0.6.0/28161.0.6.1 to 161.0.6.14161.0.6.1514
98161.0.6.16/28161.0.6.17 to 161.0.6.30161.0.6.3114
99161.0.6.32/28161.0.6.33 to 161.0.6.46161.0.6.4714
100161.0.6.48/28161.0.6.49 to 161.0.6.62161.0.6.6314
101161.0.6.64/28161.0.6.65 to 161.0.6.78161.0.6.7914
102161.0.6.80/28161.0.6.81 to 161.0.6.94161.0.6.9514
103161.0.6.96/28161.0.6.97 to 161.0.6.110161.0.6.11114
104161.0.6.112/28161.0.6.113 to 161.0.6.126161.0.6.12714
105161.0.6.128/28161.0.6.129 to 161.0.6.142161.0.6.14314
106161.0.6.144/28161.0.6.145 to 161.0.6.158161.0.6.15914
107161.0.6.160/28161.0.6.161 to 161.0.6.174161.0.6.17514
108161.0.6.176/28161.0.6.177 to 161.0.6.190161.0.6.19114
109161.0.6.192/28161.0.6.193 to 161.0.6.206161.0.6.20714
110161.0.6.208/28161.0.6.209 to 161.0.6.222161.0.6.22314
111161.0.6.224/28161.0.6.225 to 161.0.6.238161.0.6.23914
112161.0.6.240/28161.0.6.241 to 161.0.6.254161.0.6.25514
113161.0.7.0/28161.0.7.1 to 161.0.7.14161.0.7.1514
114161.0.7.16/28161.0.7.17 to 161.0.7.30161.0.7.3114
115161.0.7.32/28161.0.7.33 to 161.0.7.46161.0.7.4714
116161.0.7.48/28161.0.7.49 to 161.0.7.62161.0.7.6314
117161.0.7.64/28161.0.7.65 to 161.0.7.78161.0.7.7914
118161.0.7.80/28161.0.7.81 to 161.0.7.94161.0.7.9514
119161.0.7.96/28161.0.7.97 to 161.0.7.110161.0.7.11114
120161.0.7.112/28161.0.7.113 to 161.0.7.126161.0.7.12714
121161.0.7.128/28161.0.7.129 to 161.0.7.142161.0.7.14314
122161.0.7.144/28161.0.7.145 to 161.0.7.158161.0.7.15914
123161.0.7.160/28161.0.7.161 to 161.0.7.174161.0.7.17514
124161.0.7.176/28161.0.7.177 to 161.0.7.190161.0.7.19114
125161.0.7.192/28161.0.7.193 to 161.0.7.206161.0.7.20714
126161.0.7.208/28161.0.7.209 to 161.0.7.222161.0.7.22314
127161.0.7.224/28161.0.7.225 to 161.0.7.238161.0.7.23914
128161.0.7.240/28161.0.7.241 to 161.0.7.254161.0.7.25514
129161.0.8.0/28161.0.8.1 to 161.0.8.14161.0.8.1514
130161.0.8.16/28161.0.8.17 to 161.0.8.30161.0.8.3114
131161.0.8.32/28161.0.8.33 to 161.0.8.46161.0.8.4714
132161.0.8.48/28161.0.8.49 to 161.0.8.62161.0.8.6314
133161.0.8.64/28161.0.8.65 to 161.0.8.78161.0.8.7914
134161.0.8.80/28161.0.8.81 to 161.0.8.94161.0.8.9514
135161.0.8.96/28161.0.8.97 to 161.0.8.110161.0.8.11114
136161.0.8.112/28161.0.8.113 to 161.0.8.126161.0.8.12714
137161.0.8.128/28161.0.8.129 to 161.0.8.142161.0.8.14314
138161.0.8.144/28161.0.8.145 to 161.0.8.158161.0.8.15914
139161.0.8.160/28161.0.8.161 to 161.0.8.174161.0.8.17514
140161.0.8.176/28161.0.8.177 to 161.0.8.190161.0.8.19114
141161.0.8.192/28161.0.8.193 to 161.0.8.206161.0.8.20714
142161.0.8.208/28161.0.8.209 to 161.0.8.222161.0.8.22314
143161.0.8.224/28161.0.8.225 to 161.0.8.238161.0.8.23914
144161.0.8.240/28161.0.8.241 to 161.0.8.254161.0.8.25514
145161.0.9.0/28161.0.9.1 to 161.0.9.14161.0.9.1514
146161.0.9.16/28161.0.9.17 to 161.0.9.30161.0.9.3114
147161.0.9.32/28161.0.9.33 to 161.0.9.46161.0.9.4714
148161.0.9.48/28161.0.9.49 to 161.0.9.62161.0.9.6314
149161.0.9.64/28161.0.9.65 to 161.0.9.78161.0.9.7914
150161.0.9.80/28161.0.9.81 to 161.0.9.94161.0.9.9514
151161.0.9.96/28161.0.9.97 to 161.0.9.110161.0.9.11114
152161.0.9.112/28161.0.9.113 to 161.0.9.126161.0.9.12714
153161.0.9.128/28161.0.9.129 to 161.0.9.142161.0.9.14314
154161.0.9.144/28161.0.9.145 to 161.0.9.158161.0.9.15914
155161.0.9.160/28161.0.9.161 to 161.0.9.174161.0.9.17514
156161.0.9.176/28161.0.9.177 to 161.0.9.190161.0.9.19114
157161.0.9.192/28161.0.9.193 to 161.0.9.206161.0.9.20714
158161.0.9.208/28161.0.9.209 to 161.0.9.222161.0.9.22314
159161.0.9.224/28161.0.9.225 to 161.0.9.238161.0.9.23914
160161.0.9.240/28161.0.9.241 to 161.0.9.254161.0.9.25514
161161.0.10.0/28161.0.10.1 to 161.0.10.14161.0.10.1514
162161.0.10.16/28161.0.10.17 to 161.0.10.30161.0.10.3114
163161.0.10.32/28161.0.10.33 to 161.0.10.46161.0.10.4714
164161.0.10.48/28161.0.10.49 to 161.0.10.62161.0.10.6314
165161.0.10.64/28161.0.10.65 to 161.0.10.78161.0.10.7914
166161.0.10.80/28161.0.10.81 to 161.0.10.94161.0.10.9514
167161.0.10.96/28161.0.10.97 to 161.0.10.110161.0.10.11114
168161.0.10.112/28161.0.10.113 to 161.0.10.126161.0.10.12714
169161.0.10.128/28161.0.10.129 to 161.0.10.142161.0.10.14314
170161.0.10.144/28161.0.10.145 to 161.0.10.158161.0.10.15914
171161.0.10.160/28161.0.10.161 to 161.0.10.174161.0.10.17514
172161.0.10.176/28161.0.10.177 to 161.0.10.190161.0.10.19114
173161.0.10.192/28161.0.10.193 to 161.0.10.206161.0.10.20714
174161.0.10.208/28161.0.10.209 to 161.0.10.222161.0.10.22314
175161.0.10.224/28161.0.10.225 to 161.0.10.238161.0.10.23914
176161.0.10.240/28161.0.10.241 to 161.0.10.254161.0.10.25514
177161.0.11.0/28161.0.11.1 to 161.0.11.14161.0.11.1514
178161.0.11.16/28161.0.11.17 to 161.0.11.30161.0.11.3114
179161.0.11.32/28161.0.11.33 to 161.0.11.46161.0.11.4714
180161.0.11.48/28161.0.11.49 to 161.0.11.62161.0.11.6314
181161.0.11.64/28161.0.11.65 to 161.0.11.78161.0.11.7914
182161.0.11.80/28161.0.11.81 to 161.0.11.94161.0.11.9514
183161.0.11.96/28161.0.11.97 to 161.0.11.110161.0.11.11114
184161.0.11.112/28161.0.11.113 to 161.0.11.126161.0.11.12714
185161.0.11.128/28161.0.11.129 to 161.0.11.142161.0.11.14314
186161.0.11.144/28161.0.11.145 to 161.0.11.158161.0.11.15914
187161.0.11.160/28161.0.11.161 to 161.0.11.174161.0.11.17514
188161.0.11.176/28161.0.11.177 to 161.0.11.190161.0.11.19114
189161.0.11.192/28161.0.11.193 to 161.0.11.206161.0.11.20714
190161.0.11.208/28161.0.11.209 to 161.0.11.222161.0.11.22314
191161.0.11.224/28161.0.11.225 to 161.0.11.238161.0.11.23914
192161.0.11.240/28161.0.11.241 to 161.0.11.254161.0.11.25514
193161.0.12.0/28161.0.12.1 to 161.0.12.14161.0.12.1514
194161.0.12.16/28161.0.12.17 to 161.0.12.30161.0.12.3114
195161.0.12.32/28161.0.12.33 to 161.0.12.46161.0.12.4714
196161.0.12.48/28161.0.12.49 to 161.0.12.62161.0.12.6314
197161.0.12.64/28161.0.12.65 to 161.0.12.78161.0.12.7914
198161.0.12.80/28161.0.12.81 to 161.0.12.94161.0.12.9514
199161.0.12.96/28161.0.12.97 to 161.0.12.110161.0.12.11114
200161.0.12.112/28161.0.12.113 to 161.0.12.126161.0.12.12714
201161.0.12.128/28161.0.12.129 to 161.0.12.142161.0.12.14314
202161.0.12.144/28161.0.12.145 to 161.0.12.158161.0.12.15914
203161.0.12.160/28161.0.12.161 to 161.0.12.174161.0.12.17514
204161.0.12.176/28161.0.12.177 to 161.0.12.190161.0.12.19114
205161.0.12.192/28161.0.12.193 to 161.0.12.206161.0.12.20714
206161.0.12.208/28161.0.12.209 to 161.0.12.222161.0.12.22314
207161.0.12.224/28161.0.12.225 to 161.0.12.238161.0.12.23914
208161.0.12.240/28161.0.12.241 to 161.0.12.254161.0.12.25514
209161.0.13.0/28161.0.13.1 to 161.0.13.14161.0.13.1514
210161.0.13.16/28161.0.13.17 to 161.0.13.30161.0.13.3114
211161.0.13.32/28161.0.13.33 to 161.0.13.46161.0.13.4714
212161.0.13.48/28161.0.13.49 to 161.0.13.62161.0.13.6314
213161.0.13.64/28161.0.13.65 to 161.0.13.78161.0.13.7914
214161.0.13.80/28161.0.13.81 to 161.0.13.94161.0.13.9514
215161.0.13.96/28161.0.13.97 to 161.0.13.110161.0.13.11114
216161.0.13.112/28161.0.13.113 to 161.0.13.126161.0.13.12714
217161.0.13.128/28161.0.13.129 to 161.0.13.142161.0.13.14314
218161.0.13.144/28161.0.13.145 to 161.0.13.158161.0.13.15914
219161.0.13.160/28161.0.13.161 to 161.0.13.174161.0.13.17514
220161.0.13.176/28161.0.13.177 to 161.0.13.190161.0.13.19114
221161.0.13.192/28161.0.13.193 to 161.0.13.206161.0.13.20714
222161.0.13.208/28161.0.13.209 to 161.0.13.222161.0.13.22314
223161.0.13.224/28161.0.13.225 to 161.0.13.238161.0.13.23914
224161.0.13.240/28161.0.13.241 to 161.0.13.254161.0.13.25514
225161.0.14.0/28161.0.14.1 to 161.0.14.14161.0.14.1514
226161.0.14.16/28161.0.14.17 to 161.0.14.30161.0.14.3114
227161.0.14.32/28161.0.14.33 to 161.0.14.46161.0.14.4714
228161.0.14.48/28161.0.14.49 to 161.0.14.62161.0.14.6314
229161.0.14.64/28161.0.14.65 to 161.0.14.78161.0.14.7914
230161.0.14.80/28161.0.14.81 to 161.0.14.94161.0.14.9514
231161.0.14.96/28161.0.14.97 to 161.0.14.110161.0.14.11114
232161.0.14.112/28161.0.14.113 to 161.0.14.126161.0.14.12714
233161.0.14.128/28161.0.14.129 to 161.0.14.142161.0.14.14314
234161.0.14.144/28161.0.14.145 to 161.0.14.158161.0.14.15914
235161.0.14.160/28161.0.14.161 to 161.0.14.174161.0.14.17514
236161.0.14.176/28161.0.14.177 to 161.0.14.190161.0.14.19114
237161.0.14.192/28161.0.14.193 to 161.0.14.206161.0.14.20714
238161.0.14.208/28161.0.14.209 to 161.0.14.222161.0.14.22314
239161.0.14.224/28161.0.14.225 to 161.0.14.238161.0.14.23914
240161.0.14.240/28161.0.14.241 to 161.0.14.254161.0.14.25514
241161.0.15.0/28161.0.15.1 to 161.0.15.14161.0.15.1514
242161.0.15.16/28161.0.15.17 to 161.0.15.30161.0.15.3114
243161.0.15.32/28161.0.15.33 to 161.0.15.46161.0.15.4714
244161.0.15.48/28161.0.15.49 to 161.0.15.62161.0.15.6314
245161.0.15.64/28161.0.15.65 to 161.0.15.78161.0.15.7914
246161.0.15.80/28161.0.15.81 to 161.0.15.94161.0.15.9514
247161.0.15.96/28161.0.15.97 to 161.0.15.110161.0.15.11114
248161.0.15.112/28161.0.15.113 to 161.0.15.126161.0.15.12714
249161.0.15.128/28161.0.15.129 to 161.0.15.142161.0.15.14314
250161.0.15.144/28161.0.15.145 to 161.0.15.158161.0.15.15914
251161.0.15.160/28161.0.15.161 to 161.0.15.174161.0.15.17514
252161.0.15.176/28161.0.15.177 to 161.0.15.190161.0.15.19114
253161.0.15.192/28161.0.15.193 to 161.0.15.206161.0.15.20714
254161.0.15.208/28161.0.15.209 to 161.0.15.222161.0.15.22314
255161.0.15.224/28161.0.15.225 to 161.0.15.238161.0.15.23914
256161.0.15.240/28161.0.15.241 to 161.0.15.254161.0.15.25514

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.