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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.

Network254.2.16.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
254.2.16.0
Broadcast address
254.2.31.255
First usable
254.2.16.1
Last usable
254.2.31.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FE021000 · Integer 4261548032 to 4261552127
Reverse DNS zones
16.2.254.in-addr.arpa
17.2.254.in-addr.arpa
18.2.254.in-addr.arpa
19.2.254.in-addr.arpa
20.2.254.in-addr.arpa
21.2.254.in-addr.arpa
22.2.254.in-addr.arpa
23.2.254.in-addr.arpa
24.2.254.in-addr.arpa
25.2.254.in-addr.arpa
26.2.254.in-addr.arpa
27.2.254.in-addr.arpa
28.2.254.in-addr.arpa
29.2.254.in-addr.arpa
30.2.254.in-addr.arpa
31.2.254.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
Address11111110.00000010.00010000.00000000254.2.16.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network11111110.00000010.00010000.00000000254.2.16.0
Broadcast11111110.00000010.00011111.11111111254.2.31.255
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)

254.2.16.0/20 makes 1,024 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1254.2.16.0/30254.2.16.1 to 254.2.16.2254.2.16.32
2254.2.16.4/30254.2.16.5 to 254.2.16.6254.2.16.72
3254.2.16.8/30254.2.16.9 to 254.2.16.10254.2.16.112
4254.2.16.12/30254.2.16.13 to 254.2.16.14254.2.16.152
5254.2.16.16/30254.2.16.17 to 254.2.16.18254.2.16.192
6254.2.16.20/30254.2.16.21 to 254.2.16.22254.2.16.232
7254.2.16.24/30254.2.16.25 to 254.2.16.26254.2.16.272
8254.2.16.28/30254.2.16.29 to 254.2.16.30254.2.16.312
9254.2.16.32/30254.2.16.33 to 254.2.16.34254.2.16.352
10254.2.16.36/30254.2.16.37 to 254.2.16.38254.2.16.392
11254.2.16.40/30254.2.16.41 to 254.2.16.42254.2.16.432
12254.2.16.44/30254.2.16.45 to 254.2.16.46254.2.16.472
13254.2.16.48/30254.2.16.49 to 254.2.16.50254.2.16.512
14254.2.16.52/30254.2.16.53 to 254.2.16.54254.2.16.552
15254.2.16.56/30254.2.16.57 to 254.2.16.58254.2.16.592
16254.2.16.60/30254.2.16.61 to 254.2.16.62254.2.16.632
17254.2.16.64/30254.2.16.65 to 254.2.16.66254.2.16.672
18254.2.16.68/30254.2.16.69 to 254.2.16.70254.2.16.712
19254.2.16.72/30254.2.16.73 to 254.2.16.74254.2.16.752
20254.2.16.76/30254.2.16.77 to 254.2.16.78254.2.16.792
21254.2.16.80/30254.2.16.81 to 254.2.16.82254.2.16.832
22254.2.16.84/30254.2.16.85 to 254.2.16.86254.2.16.872
23254.2.16.88/30254.2.16.89 to 254.2.16.90254.2.16.912
24254.2.16.92/30254.2.16.93 to 254.2.16.94254.2.16.952
25254.2.16.96/30254.2.16.97 to 254.2.16.98254.2.16.992
26254.2.16.100/30254.2.16.101 to 254.2.16.102254.2.16.1032
27254.2.16.104/30254.2.16.105 to 254.2.16.106254.2.16.1072
28254.2.16.108/30254.2.16.109 to 254.2.16.110254.2.16.1112
29254.2.16.112/30254.2.16.113 to 254.2.16.114254.2.16.1152
30254.2.16.116/30254.2.16.117 to 254.2.16.118254.2.16.1192
31254.2.16.120/30254.2.16.121 to 254.2.16.122254.2.16.1232
32254.2.16.124/30254.2.16.125 to 254.2.16.126254.2.16.1272
33254.2.16.128/30254.2.16.129 to 254.2.16.130254.2.16.1312
34254.2.16.132/30254.2.16.133 to 254.2.16.134254.2.16.1352
35254.2.16.136/30254.2.16.137 to 254.2.16.138254.2.16.1392
36254.2.16.140/30254.2.16.141 to 254.2.16.142254.2.16.1432
37254.2.16.144/30254.2.16.145 to 254.2.16.146254.2.16.1472
38254.2.16.148/30254.2.16.149 to 254.2.16.150254.2.16.1512
39254.2.16.152/30254.2.16.153 to 254.2.16.154254.2.16.1552
40254.2.16.156/30254.2.16.157 to 254.2.16.158254.2.16.1592
41254.2.16.160/30254.2.16.161 to 254.2.16.162254.2.16.1632
42254.2.16.164/30254.2.16.165 to 254.2.16.166254.2.16.1672
43254.2.16.168/30254.2.16.169 to 254.2.16.170254.2.16.1712
44254.2.16.172/30254.2.16.173 to 254.2.16.174254.2.16.1752
45254.2.16.176/30254.2.16.177 to 254.2.16.178254.2.16.1792
46254.2.16.180/30254.2.16.181 to 254.2.16.182254.2.16.1832
47254.2.16.184/30254.2.16.185 to 254.2.16.186254.2.16.1872
48254.2.16.188/30254.2.16.189 to 254.2.16.190254.2.16.1912
49254.2.16.192/30254.2.16.193 to 254.2.16.194254.2.16.1952
50254.2.16.196/30254.2.16.197 to 254.2.16.198254.2.16.1992
51254.2.16.200/30254.2.16.201 to 254.2.16.202254.2.16.2032
52254.2.16.204/30254.2.16.205 to 254.2.16.206254.2.16.2072
53254.2.16.208/30254.2.16.209 to 254.2.16.210254.2.16.2112
54254.2.16.212/30254.2.16.213 to 254.2.16.214254.2.16.2152
55254.2.16.216/30254.2.16.217 to 254.2.16.218254.2.16.2192
56254.2.16.220/30254.2.16.221 to 254.2.16.222254.2.16.2232
57254.2.16.224/30254.2.16.225 to 254.2.16.226254.2.16.2272
58254.2.16.228/30254.2.16.229 to 254.2.16.230254.2.16.2312
59254.2.16.232/30254.2.16.233 to 254.2.16.234254.2.16.2352
60254.2.16.236/30254.2.16.237 to 254.2.16.238254.2.16.2392
61254.2.16.240/30254.2.16.241 to 254.2.16.242254.2.16.2432
62254.2.16.244/30254.2.16.245 to 254.2.16.246254.2.16.2472
63254.2.16.248/30254.2.16.249 to 254.2.16.250254.2.16.2512
64254.2.16.252/30254.2.16.253 to 254.2.16.254254.2.16.2552
65254.2.17.0/30254.2.17.1 to 254.2.17.2254.2.17.32
66254.2.17.4/30254.2.17.5 to 254.2.17.6254.2.17.72
67254.2.17.8/30254.2.17.9 to 254.2.17.10254.2.17.112
68254.2.17.12/30254.2.17.13 to 254.2.17.14254.2.17.152
69254.2.17.16/30254.2.17.17 to 254.2.17.18254.2.17.192
70254.2.17.20/30254.2.17.21 to 254.2.17.22254.2.17.232
71254.2.17.24/30254.2.17.25 to 254.2.17.26254.2.17.272
72254.2.17.28/30254.2.17.29 to 254.2.17.30254.2.17.312
73254.2.17.32/30254.2.17.33 to 254.2.17.34254.2.17.352
74254.2.17.36/30254.2.17.37 to 254.2.17.38254.2.17.392
75254.2.17.40/30254.2.17.41 to 254.2.17.42254.2.17.432
76254.2.17.44/30254.2.17.45 to 254.2.17.46254.2.17.472
77254.2.17.48/30254.2.17.49 to 254.2.17.50254.2.17.512
78254.2.17.52/30254.2.17.53 to 254.2.17.54254.2.17.552
79254.2.17.56/30254.2.17.57 to 254.2.17.58254.2.17.592
80254.2.17.60/30254.2.17.61 to 254.2.17.62254.2.17.632
81254.2.17.64/30254.2.17.65 to 254.2.17.66254.2.17.672
82254.2.17.68/30254.2.17.69 to 254.2.17.70254.2.17.712
83254.2.17.72/30254.2.17.73 to 254.2.17.74254.2.17.752
84254.2.17.76/30254.2.17.77 to 254.2.17.78254.2.17.792
85254.2.17.80/30254.2.17.81 to 254.2.17.82254.2.17.832
86254.2.17.84/30254.2.17.85 to 254.2.17.86254.2.17.872
87254.2.17.88/30254.2.17.89 to 254.2.17.90254.2.17.912
88254.2.17.92/30254.2.17.93 to 254.2.17.94254.2.17.952
89254.2.17.96/30254.2.17.97 to 254.2.17.98254.2.17.992
90254.2.17.100/30254.2.17.101 to 254.2.17.102254.2.17.1032
91254.2.17.104/30254.2.17.105 to 254.2.17.106254.2.17.1072
92254.2.17.108/30254.2.17.109 to 254.2.17.110254.2.17.1112
93254.2.17.112/30254.2.17.113 to 254.2.17.114254.2.17.1152
94254.2.17.116/30254.2.17.117 to 254.2.17.118254.2.17.1192
95254.2.17.120/30254.2.17.121 to 254.2.17.122254.2.17.1232
96254.2.17.124/30254.2.17.125 to 254.2.17.126254.2.17.1272
97254.2.17.128/30254.2.17.129 to 254.2.17.130254.2.17.1312
98254.2.17.132/30254.2.17.133 to 254.2.17.134254.2.17.1352
99254.2.17.136/30254.2.17.137 to 254.2.17.138254.2.17.1392
100254.2.17.140/30254.2.17.141 to 254.2.17.142254.2.17.1432
101254.2.17.144/30254.2.17.145 to 254.2.17.146254.2.17.1472
102254.2.17.148/30254.2.17.149 to 254.2.17.150254.2.17.1512
103254.2.17.152/30254.2.17.153 to 254.2.17.154254.2.17.1552
104254.2.17.156/30254.2.17.157 to 254.2.17.158254.2.17.1592
105254.2.17.160/30254.2.17.161 to 254.2.17.162254.2.17.1632
106254.2.17.164/30254.2.17.165 to 254.2.17.166254.2.17.1672
107254.2.17.168/30254.2.17.169 to 254.2.17.170254.2.17.1712
108254.2.17.172/30254.2.17.173 to 254.2.17.174254.2.17.1752
109254.2.17.176/30254.2.17.177 to 254.2.17.178254.2.17.1792
110254.2.17.180/30254.2.17.181 to 254.2.17.182254.2.17.1832
111254.2.17.184/30254.2.17.185 to 254.2.17.186254.2.17.1872
112254.2.17.188/30254.2.17.189 to 254.2.17.190254.2.17.1912
113254.2.17.192/30254.2.17.193 to 254.2.17.194254.2.17.1952
114254.2.17.196/30254.2.17.197 to 254.2.17.198254.2.17.1992
115254.2.17.200/30254.2.17.201 to 254.2.17.202254.2.17.2032
116254.2.17.204/30254.2.17.205 to 254.2.17.206254.2.17.2072
117254.2.17.208/30254.2.17.209 to 254.2.17.210254.2.17.2112
118254.2.17.212/30254.2.17.213 to 254.2.17.214254.2.17.2152
119254.2.17.216/30254.2.17.217 to 254.2.17.218254.2.17.2192
120254.2.17.220/30254.2.17.221 to 254.2.17.222254.2.17.2232
121254.2.17.224/30254.2.17.225 to 254.2.17.226254.2.17.2272
122254.2.17.228/30254.2.17.229 to 254.2.17.230254.2.17.2312
123254.2.17.232/30254.2.17.233 to 254.2.17.234254.2.17.2352
124254.2.17.236/30254.2.17.237 to 254.2.17.238254.2.17.2392
125254.2.17.240/30254.2.17.241 to 254.2.17.242254.2.17.2432
126254.2.17.244/30254.2.17.245 to 254.2.17.246254.2.17.2472
127254.2.17.248/30254.2.17.249 to 254.2.17.250254.2.17.2512
128254.2.17.252/30254.2.17.253 to 254.2.17.254254.2.17.2552
129254.2.18.0/30254.2.18.1 to 254.2.18.2254.2.18.32
130254.2.18.4/30254.2.18.5 to 254.2.18.6254.2.18.72
131254.2.18.8/30254.2.18.9 to 254.2.18.10254.2.18.112
132254.2.18.12/30254.2.18.13 to 254.2.18.14254.2.18.152
133254.2.18.16/30254.2.18.17 to 254.2.18.18254.2.18.192
134254.2.18.20/30254.2.18.21 to 254.2.18.22254.2.18.232
135254.2.18.24/30254.2.18.25 to 254.2.18.26254.2.18.272
136254.2.18.28/30254.2.18.29 to 254.2.18.30254.2.18.312
137254.2.18.32/30254.2.18.33 to 254.2.18.34254.2.18.352
138254.2.18.36/30254.2.18.37 to 254.2.18.38254.2.18.392
139254.2.18.40/30254.2.18.41 to 254.2.18.42254.2.18.432
140254.2.18.44/30254.2.18.45 to 254.2.18.46254.2.18.472
141254.2.18.48/30254.2.18.49 to 254.2.18.50254.2.18.512
142254.2.18.52/30254.2.18.53 to 254.2.18.54254.2.18.552
143254.2.18.56/30254.2.18.57 to 254.2.18.58254.2.18.592
144254.2.18.60/30254.2.18.61 to 254.2.18.62254.2.18.632
145254.2.18.64/30254.2.18.65 to 254.2.18.66254.2.18.672
146254.2.18.68/30254.2.18.69 to 254.2.18.70254.2.18.712
147254.2.18.72/30254.2.18.73 to 254.2.18.74254.2.18.752
148254.2.18.76/30254.2.18.77 to 254.2.18.78254.2.18.792
149254.2.18.80/30254.2.18.81 to 254.2.18.82254.2.18.832
150254.2.18.84/30254.2.18.85 to 254.2.18.86254.2.18.872
151254.2.18.88/30254.2.18.89 to 254.2.18.90254.2.18.912
152254.2.18.92/30254.2.18.93 to 254.2.18.94254.2.18.952
153254.2.18.96/30254.2.18.97 to 254.2.18.98254.2.18.992
154254.2.18.100/30254.2.18.101 to 254.2.18.102254.2.18.1032
155254.2.18.104/30254.2.18.105 to 254.2.18.106254.2.18.1072
156254.2.18.108/30254.2.18.109 to 254.2.18.110254.2.18.1112
157254.2.18.112/30254.2.18.113 to 254.2.18.114254.2.18.1152
158254.2.18.116/30254.2.18.117 to 254.2.18.118254.2.18.1192
159254.2.18.120/30254.2.18.121 to 254.2.18.122254.2.18.1232
160254.2.18.124/30254.2.18.125 to 254.2.18.126254.2.18.1272
161254.2.18.128/30254.2.18.129 to 254.2.18.130254.2.18.1312
162254.2.18.132/30254.2.18.133 to 254.2.18.134254.2.18.1352
163254.2.18.136/30254.2.18.137 to 254.2.18.138254.2.18.1392
164254.2.18.140/30254.2.18.141 to 254.2.18.142254.2.18.1432
165254.2.18.144/30254.2.18.145 to 254.2.18.146254.2.18.1472
166254.2.18.148/30254.2.18.149 to 254.2.18.150254.2.18.1512
167254.2.18.152/30254.2.18.153 to 254.2.18.154254.2.18.1552
168254.2.18.156/30254.2.18.157 to 254.2.18.158254.2.18.1592
169254.2.18.160/30254.2.18.161 to 254.2.18.162254.2.18.1632
170254.2.18.164/30254.2.18.165 to 254.2.18.166254.2.18.1672
171254.2.18.168/30254.2.18.169 to 254.2.18.170254.2.18.1712
172254.2.18.172/30254.2.18.173 to 254.2.18.174254.2.18.1752
173254.2.18.176/30254.2.18.177 to 254.2.18.178254.2.18.1792
174254.2.18.180/30254.2.18.181 to 254.2.18.182254.2.18.1832
175254.2.18.184/30254.2.18.185 to 254.2.18.186254.2.18.1872
176254.2.18.188/30254.2.18.189 to 254.2.18.190254.2.18.1912
177254.2.18.192/30254.2.18.193 to 254.2.18.194254.2.18.1952
178254.2.18.196/30254.2.18.197 to 254.2.18.198254.2.18.1992
179254.2.18.200/30254.2.18.201 to 254.2.18.202254.2.18.2032
180254.2.18.204/30254.2.18.205 to 254.2.18.206254.2.18.2072
181254.2.18.208/30254.2.18.209 to 254.2.18.210254.2.18.2112
182254.2.18.212/30254.2.18.213 to 254.2.18.214254.2.18.2152
183254.2.18.216/30254.2.18.217 to 254.2.18.218254.2.18.2192
184254.2.18.220/30254.2.18.221 to 254.2.18.222254.2.18.2232
185254.2.18.224/30254.2.18.225 to 254.2.18.226254.2.18.2272
186254.2.18.228/30254.2.18.229 to 254.2.18.230254.2.18.2312
187254.2.18.232/30254.2.18.233 to 254.2.18.234254.2.18.2352
188254.2.18.236/30254.2.18.237 to 254.2.18.238254.2.18.2392
189254.2.18.240/30254.2.18.241 to 254.2.18.242254.2.18.2432
190254.2.18.244/30254.2.18.245 to 254.2.18.246254.2.18.2472
191254.2.18.248/30254.2.18.249 to 254.2.18.250254.2.18.2512
192254.2.18.252/30254.2.18.253 to 254.2.18.254254.2.18.2552
193254.2.19.0/30254.2.19.1 to 254.2.19.2254.2.19.32
194254.2.19.4/30254.2.19.5 to 254.2.19.6254.2.19.72
195254.2.19.8/30254.2.19.9 to 254.2.19.10254.2.19.112
196254.2.19.12/30254.2.19.13 to 254.2.19.14254.2.19.152
197254.2.19.16/30254.2.19.17 to 254.2.19.18254.2.19.192
198254.2.19.20/30254.2.19.21 to 254.2.19.22254.2.19.232
199254.2.19.24/30254.2.19.25 to 254.2.19.26254.2.19.272
200254.2.19.28/30254.2.19.29 to 254.2.19.30254.2.19.312
201254.2.19.32/30254.2.19.33 to 254.2.19.34254.2.19.352
202254.2.19.36/30254.2.19.37 to 254.2.19.38254.2.19.392
203254.2.19.40/30254.2.19.41 to 254.2.19.42254.2.19.432
204254.2.19.44/30254.2.19.45 to 254.2.19.46254.2.19.472
205254.2.19.48/30254.2.19.49 to 254.2.19.50254.2.19.512
206254.2.19.52/30254.2.19.53 to 254.2.19.54254.2.19.552
207254.2.19.56/30254.2.19.57 to 254.2.19.58254.2.19.592
208254.2.19.60/30254.2.19.61 to 254.2.19.62254.2.19.632
209254.2.19.64/30254.2.19.65 to 254.2.19.66254.2.19.672
210254.2.19.68/30254.2.19.69 to 254.2.19.70254.2.19.712
211254.2.19.72/30254.2.19.73 to 254.2.19.74254.2.19.752
212254.2.19.76/30254.2.19.77 to 254.2.19.78254.2.19.792
213254.2.19.80/30254.2.19.81 to 254.2.19.82254.2.19.832
214254.2.19.84/30254.2.19.85 to 254.2.19.86254.2.19.872
215254.2.19.88/30254.2.19.89 to 254.2.19.90254.2.19.912
216254.2.19.92/30254.2.19.93 to 254.2.19.94254.2.19.952
217254.2.19.96/30254.2.19.97 to 254.2.19.98254.2.19.992
218254.2.19.100/30254.2.19.101 to 254.2.19.102254.2.19.1032
219254.2.19.104/30254.2.19.105 to 254.2.19.106254.2.19.1072
220254.2.19.108/30254.2.19.109 to 254.2.19.110254.2.19.1112
221254.2.19.112/30254.2.19.113 to 254.2.19.114254.2.19.1152
222254.2.19.116/30254.2.19.117 to 254.2.19.118254.2.19.1192
223254.2.19.120/30254.2.19.121 to 254.2.19.122254.2.19.1232
224254.2.19.124/30254.2.19.125 to 254.2.19.126254.2.19.1272
225254.2.19.128/30254.2.19.129 to 254.2.19.130254.2.19.1312
226254.2.19.132/30254.2.19.133 to 254.2.19.134254.2.19.1352
227254.2.19.136/30254.2.19.137 to 254.2.19.138254.2.19.1392
228254.2.19.140/30254.2.19.141 to 254.2.19.142254.2.19.1432
229254.2.19.144/30254.2.19.145 to 254.2.19.146254.2.19.1472
230254.2.19.148/30254.2.19.149 to 254.2.19.150254.2.19.1512
231254.2.19.152/30254.2.19.153 to 254.2.19.154254.2.19.1552
232254.2.19.156/30254.2.19.157 to 254.2.19.158254.2.19.1592
233254.2.19.160/30254.2.19.161 to 254.2.19.162254.2.19.1632
234254.2.19.164/30254.2.19.165 to 254.2.19.166254.2.19.1672
235254.2.19.168/30254.2.19.169 to 254.2.19.170254.2.19.1712
236254.2.19.172/30254.2.19.173 to 254.2.19.174254.2.19.1752
237254.2.19.176/30254.2.19.177 to 254.2.19.178254.2.19.1792
238254.2.19.180/30254.2.19.181 to 254.2.19.182254.2.19.1832
239254.2.19.184/30254.2.19.185 to 254.2.19.186254.2.19.1872
240254.2.19.188/30254.2.19.189 to 254.2.19.190254.2.19.1912
241254.2.19.192/30254.2.19.193 to 254.2.19.194254.2.19.1952
242254.2.19.196/30254.2.19.197 to 254.2.19.198254.2.19.1992
243254.2.19.200/30254.2.19.201 to 254.2.19.202254.2.19.2032
244254.2.19.204/30254.2.19.205 to 254.2.19.206254.2.19.2072
245254.2.19.208/30254.2.19.209 to 254.2.19.210254.2.19.2112
246254.2.19.212/30254.2.19.213 to 254.2.19.214254.2.19.2152
247254.2.19.216/30254.2.19.217 to 254.2.19.218254.2.19.2192
248254.2.19.220/30254.2.19.221 to 254.2.19.222254.2.19.2232
249254.2.19.224/30254.2.19.225 to 254.2.19.226254.2.19.2272
250254.2.19.228/30254.2.19.229 to 254.2.19.230254.2.19.2312
251254.2.19.232/30254.2.19.233 to 254.2.19.234254.2.19.2352
252254.2.19.236/30254.2.19.237 to 254.2.19.238254.2.19.2392
253254.2.19.240/30254.2.19.241 to 254.2.19.242254.2.19.2432
254254.2.19.244/30254.2.19.245 to 254.2.19.246254.2.19.2472
255254.2.19.248/30254.2.19.249 to 254.2.19.250254.2.19.2512
256254.2.19.252/30254.2.19.253 to 254.2.19.254254.2.19.2552

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.