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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.

Network161.2.112.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
161.2.112.0
Broadcast address
161.2.127.255
First usable
161.2.112.1
Last usable
161.2.127.254
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 A1027000 · Integer 2701291520 to 2701295615
Reverse DNS zones
112.2.161.in-addr.arpa
113.2.161.in-addr.arpa
114.2.161.in-addr.arpa
115.2.161.in-addr.arpa
116.2.161.in-addr.arpa
117.2.161.in-addr.arpa
118.2.161.in-addr.arpa
119.2.161.in-addr.arpa
120.2.161.in-addr.arpa
121.2.161.in-addr.arpa
122.2.161.in-addr.arpa
123.2.161.in-addr.arpa
124.2.161.in-addr.arpa
125.2.161.in-addr.arpa
126.2.161.in-addr.arpa
127.2.161.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
Address10100001.00000010.01110000.00000000161.2.112.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network10100001.00000010.01110000.00000000161.2.112.0
Broadcast10100001.00000010.01111111.11111111161.2.127.255
Split into smaller subnets/30
/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)

161.2.112.0/20 makes 1,024 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1161.2.112.0/30161.2.112.1 to 161.2.112.2161.2.112.32
2161.2.112.4/30161.2.112.5 to 161.2.112.6161.2.112.72
3161.2.112.8/30161.2.112.9 to 161.2.112.10161.2.112.112
4161.2.112.12/30161.2.112.13 to 161.2.112.14161.2.112.152
5161.2.112.16/30161.2.112.17 to 161.2.112.18161.2.112.192
6161.2.112.20/30161.2.112.21 to 161.2.112.22161.2.112.232
7161.2.112.24/30161.2.112.25 to 161.2.112.26161.2.112.272
8161.2.112.28/30161.2.112.29 to 161.2.112.30161.2.112.312
9161.2.112.32/30161.2.112.33 to 161.2.112.34161.2.112.352
10161.2.112.36/30161.2.112.37 to 161.2.112.38161.2.112.392
11161.2.112.40/30161.2.112.41 to 161.2.112.42161.2.112.432
12161.2.112.44/30161.2.112.45 to 161.2.112.46161.2.112.472
13161.2.112.48/30161.2.112.49 to 161.2.112.50161.2.112.512
14161.2.112.52/30161.2.112.53 to 161.2.112.54161.2.112.552
15161.2.112.56/30161.2.112.57 to 161.2.112.58161.2.112.592
16161.2.112.60/30161.2.112.61 to 161.2.112.62161.2.112.632
17161.2.112.64/30161.2.112.65 to 161.2.112.66161.2.112.672
18161.2.112.68/30161.2.112.69 to 161.2.112.70161.2.112.712
19161.2.112.72/30161.2.112.73 to 161.2.112.74161.2.112.752
20161.2.112.76/30161.2.112.77 to 161.2.112.78161.2.112.792
21161.2.112.80/30161.2.112.81 to 161.2.112.82161.2.112.832
22161.2.112.84/30161.2.112.85 to 161.2.112.86161.2.112.872
23161.2.112.88/30161.2.112.89 to 161.2.112.90161.2.112.912
24161.2.112.92/30161.2.112.93 to 161.2.112.94161.2.112.952
25161.2.112.96/30161.2.112.97 to 161.2.112.98161.2.112.992
26161.2.112.100/30161.2.112.101 to 161.2.112.102161.2.112.1032
27161.2.112.104/30161.2.112.105 to 161.2.112.106161.2.112.1072
28161.2.112.108/30161.2.112.109 to 161.2.112.110161.2.112.1112
29161.2.112.112/30161.2.112.113 to 161.2.112.114161.2.112.1152
30161.2.112.116/30161.2.112.117 to 161.2.112.118161.2.112.1192
31161.2.112.120/30161.2.112.121 to 161.2.112.122161.2.112.1232
32161.2.112.124/30161.2.112.125 to 161.2.112.126161.2.112.1272
33161.2.112.128/30161.2.112.129 to 161.2.112.130161.2.112.1312
34161.2.112.132/30161.2.112.133 to 161.2.112.134161.2.112.1352
35161.2.112.136/30161.2.112.137 to 161.2.112.138161.2.112.1392
36161.2.112.140/30161.2.112.141 to 161.2.112.142161.2.112.1432
37161.2.112.144/30161.2.112.145 to 161.2.112.146161.2.112.1472
38161.2.112.148/30161.2.112.149 to 161.2.112.150161.2.112.1512
39161.2.112.152/30161.2.112.153 to 161.2.112.154161.2.112.1552
40161.2.112.156/30161.2.112.157 to 161.2.112.158161.2.112.1592
41161.2.112.160/30161.2.112.161 to 161.2.112.162161.2.112.1632
42161.2.112.164/30161.2.112.165 to 161.2.112.166161.2.112.1672
43161.2.112.168/30161.2.112.169 to 161.2.112.170161.2.112.1712
44161.2.112.172/30161.2.112.173 to 161.2.112.174161.2.112.1752
45161.2.112.176/30161.2.112.177 to 161.2.112.178161.2.112.1792
46161.2.112.180/30161.2.112.181 to 161.2.112.182161.2.112.1832
47161.2.112.184/30161.2.112.185 to 161.2.112.186161.2.112.1872
48161.2.112.188/30161.2.112.189 to 161.2.112.190161.2.112.1912
49161.2.112.192/30161.2.112.193 to 161.2.112.194161.2.112.1952
50161.2.112.196/30161.2.112.197 to 161.2.112.198161.2.112.1992
51161.2.112.200/30161.2.112.201 to 161.2.112.202161.2.112.2032
52161.2.112.204/30161.2.112.205 to 161.2.112.206161.2.112.2072
53161.2.112.208/30161.2.112.209 to 161.2.112.210161.2.112.2112
54161.2.112.212/30161.2.112.213 to 161.2.112.214161.2.112.2152
55161.2.112.216/30161.2.112.217 to 161.2.112.218161.2.112.2192
56161.2.112.220/30161.2.112.221 to 161.2.112.222161.2.112.2232
57161.2.112.224/30161.2.112.225 to 161.2.112.226161.2.112.2272
58161.2.112.228/30161.2.112.229 to 161.2.112.230161.2.112.2312
59161.2.112.232/30161.2.112.233 to 161.2.112.234161.2.112.2352
60161.2.112.236/30161.2.112.237 to 161.2.112.238161.2.112.2392
61161.2.112.240/30161.2.112.241 to 161.2.112.242161.2.112.2432
62161.2.112.244/30161.2.112.245 to 161.2.112.246161.2.112.2472
63161.2.112.248/30161.2.112.249 to 161.2.112.250161.2.112.2512
64161.2.112.252/30161.2.112.253 to 161.2.112.254161.2.112.2552
65161.2.113.0/30161.2.113.1 to 161.2.113.2161.2.113.32
66161.2.113.4/30161.2.113.5 to 161.2.113.6161.2.113.72
67161.2.113.8/30161.2.113.9 to 161.2.113.10161.2.113.112
68161.2.113.12/30161.2.113.13 to 161.2.113.14161.2.113.152
69161.2.113.16/30161.2.113.17 to 161.2.113.18161.2.113.192
70161.2.113.20/30161.2.113.21 to 161.2.113.22161.2.113.232
71161.2.113.24/30161.2.113.25 to 161.2.113.26161.2.113.272
72161.2.113.28/30161.2.113.29 to 161.2.113.30161.2.113.312
73161.2.113.32/30161.2.113.33 to 161.2.113.34161.2.113.352
74161.2.113.36/30161.2.113.37 to 161.2.113.38161.2.113.392
75161.2.113.40/30161.2.113.41 to 161.2.113.42161.2.113.432
76161.2.113.44/30161.2.113.45 to 161.2.113.46161.2.113.472
77161.2.113.48/30161.2.113.49 to 161.2.113.50161.2.113.512
78161.2.113.52/30161.2.113.53 to 161.2.113.54161.2.113.552
79161.2.113.56/30161.2.113.57 to 161.2.113.58161.2.113.592
80161.2.113.60/30161.2.113.61 to 161.2.113.62161.2.113.632
81161.2.113.64/30161.2.113.65 to 161.2.113.66161.2.113.672
82161.2.113.68/30161.2.113.69 to 161.2.113.70161.2.113.712
83161.2.113.72/30161.2.113.73 to 161.2.113.74161.2.113.752
84161.2.113.76/30161.2.113.77 to 161.2.113.78161.2.113.792
85161.2.113.80/30161.2.113.81 to 161.2.113.82161.2.113.832
86161.2.113.84/30161.2.113.85 to 161.2.113.86161.2.113.872
87161.2.113.88/30161.2.113.89 to 161.2.113.90161.2.113.912
88161.2.113.92/30161.2.113.93 to 161.2.113.94161.2.113.952
89161.2.113.96/30161.2.113.97 to 161.2.113.98161.2.113.992
90161.2.113.100/30161.2.113.101 to 161.2.113.102161.2.113.1032
91161.2.113.104/30161.2.113.105 to 161.2.113.106161.2.113.1072
92161.2.113.108/30161.2.113.109 to 161.2.113.110161.2.113.1112
93161.2.113.112/30161.2.113.113 to 161.2.113.114161.2.113.1152
94161.2.113.116/30161.2.113.117 to 161.2.113.118161.2.113.1192
95161.2.113.120/30161.2.113.121 to 161.2.113.122161.2.113.1232
96161.2.113.124/30161.2.113.125 to 161.2.113.126161.2.113.1272
97161.2.113.128/30161.2.113.129 to 161.2.113.130161.2.113.1312
98161.2.113.132/30161.2.113.133 to 161.2.113.134161.2.113.1352
99161.2.113.136/30161.2.113.137 to 161.2.113.138161.2.113.1392
100161.2.113.140/30161.2.113.141 to 161.2.113.142161.2.113.1432
101161.2.113.144/30161.2.113.145 to 161.2.113.146161.2.113.1472
102161.2.113.148/30161.2.113.149 to 161.2.113.150161.2.113.1512
103161.2.113.152/30161.2.113.153 to 161.2.113.154161.2.113.1552
104161.2.113.156/30161.2.113.157 to 161.2.113.158161.2.113.1592
105161.2.113.160/30161.2.113.161 to 161.2.113.162161.2.113.1632
106161.2.113.164/30161.2.113.165 to 161.2.113.166161.2.113.1672
107161.2.113.168/30161.2.113.169 to 161.2.113.170161.2.113.1712
108161.2.113.172/30161.2.113.173 to 161.2.113.174161.2.113.1752
109161.2.113.176/30161.2.113.177 to 161.2.113.178161.2.113.1792
110161.2.113.180/30161.2.113.181 to 161.2.113.182161.2.113.1832
111161.2.113.184/30161.2.113.185 to 161.2.113.186161.2.113.1872
112161.2.113.188/30161.2.113.189 to 161.2.113.190161.2.113.1912
113161.2.113.192/30161.2.113.193 to 161.2.113.194161.2.113.1952
114161.2.113.196/30161.2.113.197 to 161.2.113.198161.2.113.1992
115161.2.113.200/30161.2.113.201 to 161.2.113.202161.2.113.2032
116161.2.113.204/30161.2.113.205 to 161.2.113.206161.2.113.2072
117161.2.113.208/30161.2.113.209 to 161.2.113.210161.2.113.2112
118161.2.113.212/30161.2.113.213 to 161.2.113.214161.2.113.2152
119161.2.113.216/30161.2.113.217 to 161.2.113.218161.2.113.2192
120161.2.113.220/30161.2.113.221 to 161.2.113.222161.2.113.2232
121161.2.113.224/30161.2.113.225 to 161.2.113.226161.2.113.2272
122161.2.113.228/30161.2.113.229 to 161.2.113.230161.2.113.2312
123161.2.113.232/30161.2.113.233 to 161.2.113.234161.2.113.2352
124161.2.113.236/30161.2.113.237 to 161.2.113.238161.2.113.2392
125161.2.113.240/30161.2.113.241 to 161.2.113.242161.2.113.2432
126161.2.113.244/30161.2.113.245 to 161.2.113.246161.2.113.2472
127161.2.113.248/30161.2.113.249 to 161.2.113.250161.2.113.2512
128161.2.113.252/30161.2.113.253 to 161.2.113.254161.2.113.2552
129161.2.114.0/30161.2.114.1 to 161.2.114.2161.2.114.32
130161.2.114.4/30161.2.114.5 to 161.2.114.6161.2.114.72
131161.2.114.8/30161.2.114.9 to 161.2.114.10161.2.114.112
132161.2.114.12/30161.2.114.13 to 161.2.114.14161.2.114.152
133161.2.114.16/30161.2.114.17 to 161.2.114.18161.2.114.192
134161.2.114.20/30161.2.114.21 to 161.2.114.22161.2.114.232
135161.2.114.24/30161.2.114.25 to 161.2.114.26161.2.114.272
136161.2.114.28/30161.2.114.29 to 161.2.114.30161.2.114.312
137161.2.114.32/30161.2.114.33 to 161.2.114.34161.2.114.352
138161.2.114.36/30161.2.114.37 to 161.2.114.38161.2.114.392
139161.2.114.40/30161.2.114.41 to 161.2.114.42161.2.114.432
140161.2.114.44/30161.2.114.45 to 161.2.114.46161.2.114.472
141161.2.114.48/30161.2.114.49 to 161.2.114.50161.2.114.512
142161.2.114.52/30161.2.114.53 to 161.2.114.54161.2.114.552
143161.2.114.56/30161.2.114.57 to 161.2.114.58161.2.114.592
144161.2.114.60/30161.2.114.61 to 161.2.114.62161.2.114.632
145161.2.114.64/30161.2.114.65 to 161.2.114.66161.2.114.672
146161.2.114.68/30161.2.114.69 to 161.2.114.70161.2.114.712
147161.2.114.72/30161.2.114.73 to 161.2.114.74161.2.114.752
148161.2.114.76/30161.2.114.77 to 161.2.114.78161.2.114.792
149161.2.114.80/30161.2.114.81 to 161.2.114.82161.2.114.832
150161.2.114.84/30161.2.114.85 to 161.2.114.86161.2.114.872
151161.2.114.88/30161.2.114.89 to 161.2.114.90161.2.114.912
152161.2.114.92/30161.2.114.93 to 161.2.114.94161.2.114.952
153161.2.114.96/30161.2.114.97 to 161.2.114.98161.2.114.992
154161.2.114.100/30161.2.114.101 to 161.2.114.102161.2.114.1032
155161.2.114.104/30161.2.114.105 to 161.2.114.106161.2.114.1072
156161.2.114.108/30161.2.114.109 to 161.2.114.110161.2.114.1112
157161.2.114.112/30161.2.114.113 to 161.2.114.114161.2.114.1152
158161.2.114.116/30161.2.114.117 to 161.2.114.118161.2.114.1192
159161.2.114.120/30161.2.114.121 to 161.2.114.122161.2.114.1232
160161.2.114.124/30161.2.114.125 to 161.2.114.126161.2.114.1272
161161.2.114.128/30161.2.114.129 to 161.2.114.130161.2.114.1312
162161.2.114.132/30161.2.114.133 to 161.2.114.134161.2.114.1352
163161.2.114.136/30161.2.114.137 to 161.2.114.138161.2.114.1392
164161.2.114.140/30161.2.114.141 to 161.2.114.142161.2.114.1432
165161.2.114.144/30161.2.114.145 to 161.2.114.146161.2.114.1472
166161.2.114.148/30161.2.114.149 to 161.2.114.150161.2.114.1512
167161.2.114.152/30161.2.114.153 to 161.2.114.154161.2.114.1552
168161.2.114.156/30161.2.114.157 to 161.2.114.158161.2.114.1592
169161.2.114.160/30161.2.114.161 to 161.2.114.162161.2.114.1632
170161.2.114.164/30161.2.114.165 to 161.2.114.166161.2.114.1672
171161.2.114.168/30161.2.114.169 to 161.2.114.170161.2.114.1712
172161.2.114.172/30161.2.114.173 to 161.2.114.174161.2.114.1752
173161.2.114.176/30161.2.114.177 to 161.2.114.178161.2.114.1792
174161.2.114.180/30161.2.114.181 to 161.2.114.182161.2.114.1832
175161.2.114.184/30161.2.114.185 to 161.2.114.186161.2.114.1872
176161.2.114.188/30161.2.114.189 to 161.2.114.190161.2.114.1912
177161.2.114.192/30161.2.114.193 to 161.2.114.194161.2.114.1952
178161.2.114.196/30161.2.114.197 to 161.2.114.198161.2.114.1992
179161.2.114.200/30161.2.114.201 to 161.2.114.202161.2.114.2032
180161.2.114.204/30161.2.114.205 to 161.2.114.206161.2.114.2072
181161.2.114.208/30161.2.114.209 to 161.2.114.210161.2.114.2112
182161.2.114.212/30161.2.114.213 to 161.2.114.214161.2.114.2152
183161.2.114.216/30161.2.114.217 to 161.2.114.218161.2.114.2192
184161.2.114.220/30161.2.114.221 to 161.2.114.222161.2.114.2232
185161.2.114.224/30161.2.114.225 to 161.2.114.226161.2.114.2272
186161.2.114.228/30161.2.114.229 to 161.2.114.230161.2.114.2312
187161.2.114.232/30161.2.114.233 to 161.2.114.234161.2.114.2352
188161.2.114.236/30161.2.114.237 to 161.2.114.238161.2.114.2392
189161.2.114.240/30161.2.114.241 to 161.2.114.242161.2.114.2432
190161.2.114.244/30161.2.114.245 to 161.2.114.246161.2.114.2472
191161.2.114.248/30161.2.114.249 to 161.2.114.250161.2.114.2512
192161.2.114.252/30161.2.114.253 to 161.2.114.254161.2.114.2552
193161.2.115.0/30161.2.115.1 to 161.2.115.2161.2.115.32
194161.2.115.4/30161.2.115.5 to 161.2.115.6161.2.115.72
195161.2.115.8/30161.2.115.9 to 161.2.115.10161.2.115.112
196161.2.115.12/30161.2.115.13 to 161.2.115.14161.2.115.152
197161.2.115.16/30161.2.115.17 to 161.2.115.18161.2.115.192
198161.2.115.20/30161.2.115.21 to 161.2.115.22161.2.115.232
199161.2.115.24/30161.2.115.25 to 161.2.115.26161.2.115.272
200161.2.115.28/30161.2.115.29 to 161.2.115.30161.2.115.312
201161.2.115.32/30161.2.115.33 to 161.2.115.34161.2.115.352
202161.2.115.36/30161.2.115.37 to 161.2.115.38161.2.115.392
203161.2.115.40/30161.2.115.41 to 161.2.115.42161.2.115.432
204161.2.115.44/30161.2.115.45 to 161.2.115.46161.2.115.472
205161.2.115.48/30161.2.115.49 to 161.2.115.50161.2.115.512
206161.2.115.52/30161.2.115.53 to 161.2.115.54161.2.115.552
207161.2.115.56/30161.2.115.57 to 161.2.115.58161.2.115.592
208161.2.115.60/30161.2.115.61 to 161.2.115.62161.2.115.632
209161.2.115.64/30161.2.115.65 to 161.2.115.66161.2.115.672
210161.2.115.68/30161.2.115.69 to 161.2.115.70161.2.115.712
211161.2.115.72/30161.2.115.73 to 161.2.115.74161.2.115.752
212161.2.115.76/30161.2.115.77 to 161.2.115.78161.2.115.792
213161.2.115.80/30161.2.115.81 to 161.2.115.82161.2.115.832
214161.2.115.84/30161.2.115.85 to 161.2.115.86161.2.115.872
215161.2.115.88/30161.2.115.89 to 161.2.115.90161.2.115.912
216161.2.115.92/30161.2.115.93 to 161.2.115.94161.2.115.952
217161.2.115.96/30161.2.115.97 to 161.2.115.98161.2.115.992
218161.2.115.100/30161.2.115.101 to 161.2.115.102161.2.115.1032
219161.2.115.104/30161.2.115.105 to 161.2.115.106161.2.115.1072
220161.2.115.108/30161.2.115.109 to 161.2.115.110161.2.115.1112
221161.2.115.112/30161.2.115.113 to 161.2.115.114161.2.115.1152
222161.2.115.116/30161.2.115.117 to 161.2.115.118161.2.115.1192
223161.2.115.120/30161.2.115.121 to 161.2.115.122161.2.115.1232
224161.2.115.124/30161.2.115.125 to 161.2.115.126161.2.115.1272
225161.2.115.128/30161.2.115.129 to 161.2.115.130161.2.115.1312
226161.2.115.132/30161.2.115.133 to 161.2.115.134161.2.115.1352
227161.2.115.136/30161.2.115.137 to 161.2.115.138161.2.115.1392
228161.2.115.140/30161.2.115.141 to 161.2.115.142161.2.115.1432
229161.2.115.144/30161.2.115.145 to 161.2.115.146161.2.115.1472
230161.2.115.148/30161.2.115.149 to 161.2.115.150161.2.115.1512
231161.2.115.152/30161.2.115.153 to 161.2.115.154161.2.115.1552
232161.2.115.156/30161.2.115.157 to 161.2.115.158161.2.115.1592
233161.2.115.160/30161.2.115.161 to 161.2.115.162161.2.115.1632
234161.2.115.164/30161.2.115.165 to 161.2.115.166161.2.115.1672
235161.2.115.168/30161.2.115.169 to 161.2.115.170161.2.115.1712
236161.2.115.172/30161.2.115.173 to 161.2.115.174161.2.115.1752
237161.2.115.176/30161.2.115.177 to 161.2.115.178161.2.115.1792
238161.2.115.180/30161.2.115.181 to 161.2.115.182161.2.115.1832
239161.2.115.184/30161.2.115.185 to 161.2.115.186161.2.115.1872
240161.2.115.188/30161.2.115.189 to 161.2.115.190161.2.115.1912
241161.2.115.192/30161.2.115.193 to 161.2.115.194161.2.115.1952
242161.2.115.196/30161.2.115.197 to 161.2.115.198161.2.115.1992
243161.2.115.200/30161.2.115.201 to 161.2.115.202161.2.115.2032
244161.2.115.204/30161.2.115.205 to 161.2.115.206161.2.115.2072
245161.2.115.208/30161.2.115.209 to 161.2.115.210161.2.115.2112
246161.2.115.212/30161.2.115.213 to 161.2.115.214161.2.115.2152
247161.2.115.216/30161.2.115.217 to 161.2.115.218161.2.115.2192
248161.2.115.220/30161.2.115.221 to 161.2.115.222161.2.115.2232
249161.2.115.224/30161.2.115.225 to 161.2.115.226161.2.115.2272
250161.2.115.228/30161.2.115.229 to 161.2.115.230161.2.115.2312
251161.2.115.232/30161.2.115.233 to 161.2.115.234161.2.115.2352
252161.2.115.236/30161.2.115.237 to 161.2.115.238161.2.115.2392
253161.2.115.240/30161.2.115.241 to 161.2.115.242161.2.115.2432
254161.2.115.244/30161.2.115.245 to 161.2.115.246161.2.115.2472
255161.2.115.248/30161.2.115.249 to 161.2.115.250161.2.115.2512
256161.2.115.252/30161.2.115.253 to 161.2.115.254161.2.115.2552

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.