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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.

Network213.2.64.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
213.2.64.0
Broadcast address
213.2.79.255
First usable
213.2.64.1
Last usable
213.2.79.254
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
C (default /24)
As numbers
Hex D5024000 · Integer 3573694464 to 3573698559
Reverse DNS zones
64.2.213.in-addr.arpa
65.2.213.in-addr.arpa
66.2.213.in-addr.arpa
67.2.213.in-addr.arpa
68.2.213.in-addr.arpa
69.2.213.in-addr.arpa
70.2.213.in-addr.arpa
71.2.213.in-addr.arpa
72.2.213.in-addr.arpa
73.2.213.in-addr.arpa
74.2.213.in-addr.arpa
75.2.213.in-addr.arpa
76.2.213.in-addr.arpa
77.2.213.in-addr.arpa
78.2.213.in-addr.arpa
79.2.213.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
Address11010101.00000010.01000000.00000000213.2.64.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network11010101.00000010.01000000.00000000213.2.64.0
Broadcast11010101.00000010.01001111.11111111213.2.79.255
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)

213.2.64.0/20 makes 1,024 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1213.2.64.0/30213.2.64.1 to 213.2.64.2213.2.64.32
2213.2.64.4/30213.2.64.5 to 213.2.64.6213.2.64.72
3213.2.64.8/30213.2.64.9 to 213.2.64.10213.2.64.112
4213.2.64.12/30213.2.64.13 to 213.2.64.14213.2.64.152
5213.2.64.16/30213.2.64.17 to 213.2.64.18213.2.64.192
6213.2.64.20/30213.2.64.21 to 213.2.64.22213.2.64.232
7213.2.64.24/30213.2.64.25 to 213.2.64.26213.2.64.272
8213.2.64.28/30213.2.64.29 to 213.2.64.30213.2.64.312
9213.2.64.32/30213.2.64.33 to 213.2.64.34213.2.64.352
10213.2.64.36/30213.2.64.37 to 213.2.64.38213.2.64.392
11213.2.64.40/30213.2.64.41 to 213.2.64.42213.2.64.432
12213.2.64.44/30213.2.64.45 to 213.2.64.46213.2.64.472
13213.2.64.48/30213.2.64.49 to 213.2.64.50213.2.64.512
14213.2.64.52/30213.2.64.53 to 213.2.64.54213.2.64.552
15213.2.64.56/30213.2.64.57 to 213.2.64.58213.2.64.592
16213.2.64.60/30213.2.64.61 to 213.2.64.62213.2.64.632
17213.2.64.64/30213.2.64.65 to 213.2.64.66213.2.64.672
18213.2.64.68/30213.2.64.69 to 213.2.64.70213.2.64.712
19213.2.64.72/30213.2.64.73 to 213.2.64.74213.2.64.752
20213.2.64.76/30213.2.64.77 to 213.2.64.78213.2.64.792
21213.2.64.80/30213.2.64.81 to 213.2.64.82213.2.64.832
22213.2.64.84/30213.2.64.85 to 213.2.64.86213.2.64.872
23213.2.64.88/30213.2.64.89 to 213.2.64.90213.2.64.912
24213.2.64.92/30213.2.64.93 to 213.2.64.94213.2.64.952
25213.2.64.96/30213.2.64.97 to 213.2.64.98213.2.64.992
26213.2.64.100/30213.2.64.101 to 213.2.64.102213.2.64.1032
27213.2.64.104/30213.2.64.105 to 213.2.64.106213.2.64.1072
28213.2.64.108/30213.2.64.109 to 213.2.64.110213.2.64.1112
29213.2.64.112/30213.2.64.113 to 213.2.64.114213.2.64.1152
30213.2.64.116/30213.2.64.117 to 213.2.64.118213.2.64.1192
31213.2.64.120/30213.2.64.121 to 213.2.64.122213.2.64.1232
32213.2.64.124/30213.2.64.125 to 213.2.64.126213.2.64.1272
33213.2.64.128/30213.2.64.129 to 213.2.64.130213.2.64.1312
34213.2.64.132/30213.2.64.133 to 213.2.64.134213.2.64.1352
35213.2.64.136/30213.2.64.137 to 213.2.64.138213.2.64.1392
36213.2.64.140/30213.2.64.141 to 213.2.64.142213.2.64.1432
37213.2.64.144/30213.2.64.145 to 213.2.64.146213.2.64.1472
38213.2.64.148/30213.2.64.149 to 213.2.64.150213.2.64.1512
39213.2.64.152/30213.2.64.153 to 213.2.64.154213.2.64.1552
40213.2.64.156/30213.2.64.157 to 213.2.64.158213.2.64.1592
41213.2.64.160/30213.2.64.161 to 213.2.64.162213.2.64.1632
42213.2.64.164/30213.2.64.165 to 213.2.64.166213.2.64.1672
43213.2.64.168/30213.2.64.169 to 213.2.64.170213.2.64.1712
44213.2.64.172/30213.2.64.173 to 213.2.64.174213.2.64.1752
45213.2.64.176/30213.2.64.177 to 213.2.64.178213.2.64.1792
46213.2.64.180/30213.2.64.181 to 213.2.64.182213.2.64.1832
47213.2.64.184/30213.2.64.185 to 213.2.64.186213.2.64.1872
48213.2.64.188/30213.2.64.189 to 213.2.64.190213.2.64.1912
49213.2.64.192/30213.2.64.193 to 213.2.64.194213.2.64.1952
50213.2.64.196/30213.2.64.197 to 213.2.64.198213.2.64.1992
51213.2.64.200/30213.2.64.201 to 213.2.64.202213.2.64.2032
52213.2.64.204/30213.2.64.205 to 213.2.64.206213.2.64.2072
53213.2.64.208/30213.2.64.209 to 213.2.64.210213.2.64.2112
54213.2.64.212/30213.2.64.213 to 213.2.64.214213.2.64.2152
55213.2.64.216/30213.2.64.217 to 213.2.64.218213.2.64.2192
56213.2.64.220/30213.2.64.221 to 213.2.64.222213.2.64.2232
57213.2.64.224/30213.2.64.225 to 213.2.64.226213.2.64.2272
58213.2.64.228/30213.2.64.229 to 213.2.64.230213.2.64.2312
59213.2.64.232/30213.2.64.233 to 213.2.64.234213.2.64.2352
60213.2.64.236/30213.2.64.237 to 213.2.64.238213.2.64.2392
61213.2.64.240/30213.2.64.241 to 213.2.64.242213.2.64.2432
62213.2.64.244/30213.2.64.245 to 213.2.64.246213.2.64.2472
63213.2.64.248/30213.2.64.249 to 213.2.64.250213.2.64.2512
64213.2.64.252/30213.2.64.253 to 213.2.64.254213.2.64.2552
65213.2.65.0/30213.2.65.1 to 213.2.65.2213.2.65.32
66213.2.65.4/30213.2.65.5 to 213.2.65.6213.2.65.72
67213.2.65.8/30213.2.65.9 to 213.2.65.10213.2.65.112
68213.2.65.12/30213.2.65.13 to 213.2.65.14213.2.65.152
69213.2.65.16/30213.2.65.17 to 213.2.65.18213.2.65.192
70213.2.65.20/30213.2.65.21 to 213.2.65.22213.2.65.232
71213.2.65.24/30213.2.65.25 to 213.2.65.26213.2.65.272
72213.2.65.28/30213.2.65.29 to 213.2.65.30213.2.65.312
73213.2.65.32/30213.2.65.33 to 213.2.65.34213.2.65.352
74213.2.65.36/30213.2.65.37 to 213.2.65.38213.2.65.392
75213.2.65.40/30213.2.65.41 to 213.2.65.42213.2.65.432
76213.2.65.44/30213.2.65.45 to 213.2.65.46213.2.65.472
77213.2.65.48/30213.2.65.49 to 213.2.65.50213.2.65.512
78213.2.65.52/30213.2.65.53 to 213.2.65.54213.2.65.552
79213.2.65.56/30213.2.65.57 to 213.2.65.58213.2.65.592
80213.2.65.60/30213.2.65.61 to 213.2.65.62213.2.65.632
81213.2.65.64/30213.2.65.65 to 213.2.65.66213.2.65.672
82213.2.65.68/30213.2.65.69 to 213.2.65.70213.2.65.712
83213.2.65.72/30213.2.65.73 to 213.2.65.74213.2.65.752
84213.2.65.76/30213.2.65.77 to 213.2.65.78213.2.65.792
85213.2.65.80/30213.2.65.81 to 213.2.65.82213.2.65.832
86213.2.65.84/30213.2.65.85 to 213.2.65.86213.2.65.872
87213.2.65.88/30213.2.65.89 to 213.2.65.90213.2.65.912
88213.2.65.92/30213.2.65.93 to 213.2.65.94213.2.65.952
89213.2.65.96/30213.2.65.97 to 213.2.65.98213.2.65.992
90213.2.65.100/30213.2.65.101 to 213.2.65.102213.2.65.1032
91213.2.65.104/30213.2.65.105 to 213.2.65.106213.2.65.1072
92213.2.65.108/30213.2.65.109 to 213.2.65.110213.2.65.1112
93213.2.65.112/30213.2.65.113 to 213.2.65.114213.2.65.1152
94213.2.65.116/30213.2.65.117 to 213.2.65.118213.2.65.1192
95213.2.65.120/30213.2.65.121 to 213.2.65.122213.2.65.1232
96213.2.65.124/30213.2.65.125 to 213.2.65.126213.2.65.1272
97213.2.65.128/30213.2.65.129 to 213.2.65.130213.2.65.1312
98213.2.65.132/30213.2.65.133 to 213.2.65.134213.2.65.1352
99213.2.65.136/30213.2.65.137 to 213.2.65.138213.2.65.1392
100213.2.65.140/30213.2.65.141 to 213.2.65.142213.2.65.1432
101213.2.65.144/30213.2.65.145 to 213.2.65.146213.2.65.1472
102213.2.65.148/30213.2.65.149 to 213.2.65.150213.2.65.1512
103213.2.65.152/30213.2.65.153 to 213.2.65.154213.2.65.1552
104213.2.65.156/30213.2.65.157 to 213.2.65.158213.2.65.1592
105213.2.65.160/30213.2.65.161 to 213.2.65.162213.2.65.1632
106213.2.65.164/30213.2.65.165 to 213.2.65.166213.2.65.1672
107213.2.65.168/30213.2.65.169 to 213.2.65.170213.2.65.1712
108213.2.65.172/30213.2.65.173 to 213.2.65.174213.2.65.1752
109213.2.65.176/30213.2.65.177 to 213.2.65.178213.2.65.1792
110213.2.65.180/30213.2.65.181 to 213.2.65.182213.2.65.1832
111213.2.65.184/30213.2.65.185 to 213.2.65.186213.2.65.1872
112213.2.65.188/30213.2.65.189 to 213.2.65.190213.2.65.1912
113213.2.65.192/30213.2.65.193 to 213.2.65.194213.2.65.1952
114213.2.65.196/30213.2.65.197 to 213.2.65.198213.2.65.1992
115213.2.65.200/30213.2.65.201 to 213.2.65.202213.2.65.2032
116213.2.65.204/30213.2.65.205 to 213.2.65.206213.2.65.2072
117213.2.65.208/30213.2.65.209 to 213.2.65.210213.2.65.2112
118213.2.65.212/30213.2.65.213 to 213.2.65.214213.2.65.2152
119213.2.65.216/30213.2.65.217 to 213.2.65.218213.2.65.2192
120213.2.65.220/30213.2.65.221 to 213.2.65.222213.2.65.2232
121213.2.65.224/30213.2.65.225 to 213.2.65.226213.2.65.2272
122213.2.65.228/30213.2.65.229 to 213.2.65.230213.2.65.2312
123213.2.65.232/30213.2.65.233 to 213.2.65.234213.2.65.2352
124213.2.65.236/30213.2.65.237 to 213.2.65.238213.2.65.2392
125213.2.65.240/30213.2.65.241 to 213.2.65.242213.2.65.2432
126213.2.65.244/30213.2.65.245 to 213.2.65.246213.2.65.2472
127213.2.65.248/30213.2.65.249 to 213.2.65.250213.2.65.2512
128213.2.65.252/30213.2.65.253 to 213.2.65.254213.2.65.2552
129213.2.66.0/30213.2.66.1 to 213.2.66.2213.2.66.32
130213.2.66.4/30213.2.66.5 to 213.2.66.6213.2.66.72
131213.2.66.8/30213.2.66.9 to 213.2.66.10213.2.66.112
132213.2.66.12/30213.2.66.13 to 213.2.66.14213.2.66.152
133213.2.66.16/30213.2.66.17 to 213.2.66.18213.2.66.192
134213.2.66.20/30213.2.66.21 to 213.2.66.22213.2.66.232
135213.2.66.24/30213.2.66.25 to 213.2.66.26213.2.66.272
136213.2.66.28/30213.2.66.29 to 213.2.66.30213.2.66.312
137213.2.66.32/30213.2.66.33 to 213.2.66.34213.2.66.352
138213.2.66.36/30213.2.66.37 to 213.2.66.38213.2.66.392
139213.2.66.40/30213.2.66.41 to 213.2.66.42213.2.66.432
140213.2.66.44/30213.2.66.45 to 213.2.66.46213.2.66.472
141213.2.66.48/30213.2.66.49 to 213.2.66.50213.2.66.512
142213.2.66.52/30213.2.66.53 to 213.2.66.54213.2.66.552
143213.2.66.56/30213.2.66.57 to 213.2.66.58213.2.66.592
144213.2.66.60/30213.2.66.61 to 213.2.66.62213.2.66.632
145213.2.66.64/30213.2.66.65 to 213.2.66.66213.2.66.672
146213.2.66.68/30213.2.66.69 to 213.2.66.70213.2.66.712
147213.2.66.72/30213.2.66.73 to 213.2.66.74213.2.66.752
148213.2.66.76/30213.2.66.77 to 213.2.66.78213.2.66.792
149213.2.66.80/30213.2.66.81 to 213.2.66.82213.2.66.832
150213.2.66.84/30213.2.66.85 to 213.2.66.86213.2.66.872
151213.2.66.88/30213.2.66.89 to 213.2.66.90213.2.66.912
152213.2.66.92/30213.2.66.93 to 213.2.66.94213.2.66.952
153213.2.66.96/30213.2.66.97 to 213.2.66.98213.2.66.992
154213.2.66.100/30213.2.66.101 to 213.2.66.102213.2.66.1032
155213.2.66.104/30213.2.66.105 to 213.2.66.106213.2.66.1072
156213.2.66.108/30213.2.66.109 to 213.2.66.110213.2.66.1112
157213.2.66.112/30213.2.66.113 to 213.2.66.114213.2.66.1152
158213.2.66.116/30213.2.66.117 to 213.2.66.118213.2.66.1192
159213.2.66.120/30213.2.66.121 to 213.2.66.122213.2.66.1232
160213.2.66.124/30213.2.66.125 to 213.2.66.126213.2.66.1272
161213.2.66.128/30213.2.66.129 to 213.2.66.130213.2.66.1312
162213.2.66.132/30213.2.66.133 to 213.2.66.134213.2.66.1352
163213.2.66.136/30213.2.66.137 to 213.2.66.138213.2.66.1392
164213.2.66.140/30213.2.66.141 to 213.2.66.142213.2.66.1432
165213.2.66.144/30213.2.66.145 to 213.2.66.146213.2.66.1472
166213.2.66.148/30213.2.66.149 to 213.2.66.150213.2.66.1512
167213.2.66.152/30213.2.66.153 to 213.2.66.154213.2.66.1552
168213.2.66.156/30213.2.66.157 to 213.2.66.158213.2.66.1592
169213.2.66.160/30213.2.66.161 to 213.2.66.162213.2.66.1632
170213.2.66.164/30213.2.66.165 to 213.2.66.166213.2.66.1672
171213.2.66.168/30213.2.66.169 to 213.2.66.170213.2.66.1712
172213.2.66.172/30213.2.66.173 to 213.2.66.174213.2.66.1752
173213.2.66.176/30213.2.66.177 to 213.2.66.178213.2.66.1792
174213.2.66.180/30213.2.66.181 to 213.2.66.182213.2.66.1832
175213.2.66.184/30213.2.66.185 to 213.2.66.186213.2.66.1872
176213.2.66.188/30213.2.66.189 to 213.2.66.190213.2.66.1912
177213.2.66.192/30213.2.66.193 to 213.2.66.194213.2.66.1952
178213.2.66.196/30213.2.66.197 to 213.2.66.198213.2.66.1992
179213.2.66.200/30213.2.66.201 to 213.2.66.202213.2.66.2032
180213.2.66.204/30213.2.66.205 to 213.2.66.206213.2.66.2072
181213.2.66.208/30213.2.66.209 to 213.2.66.210213.2.66.2112
182213.2.66.212/30213.2.66.213 to 213.2.66.214213.2.66.2152
183213.2.66.216/30213.2.66.217 to 213.2.66.218213.2.66.2192
184213.2.66.220/30213.2.66.221 to 213.2.66.222213.2.66.2232
185213.2.66.224/30213.2.66.225 to 213.2.66.226213.2.66.2272
186213.2.66.228/30213.2.66.229 to 213.2.66.230213.2.66.2312
187213.2.66.232/30213.2.66.233 to 213.2.66.234213.2.66.2352
188213.2.66.236/30213.2.66.237 to 213.2.66.238213.2.66.2392
189213.2.66.240/30213.2.66.241 to 213.2.66.242213.2.66.2432
190213.2.66.244/30213.2.66.245 to 213.2.66.246213.2.66.2472
191213.2.66.248/30213.2.66.249 to 213.2.66.250213.2.66.2512
192213.2.66.252/30213.2.66.253 to 213.2.66.254213.2.66.2552
193213.2.67.0/30213.2.67.1 to 213.2.67.2213.2.67.32
194213.2.67.4/30213.2.67.5 to 213.2.67.6213.2.67.72
195213.2.67.8/30213.2.67.9 to 213.2.67.10213.2.67.112
196213.2.67.12/30213.2.67.13 to 213.2.67.14213.2.67.152
197213.2.67.16/30213.2.67.17 to 213.2.67.18213.2.67.192
198213.2.67.20/30213.2.67.21 to 213.2.67.22213.2.67.232
199213.2.67.24/30213.2.67.25 to 213.2.67.26213.2.67.272
200213.2.67.28/30213.2.67.29 to 213.2.67.30213.2.67.312
201213.2.67.32/30213.2.67.33 to 213.2.67.34213.2.67.352
202213.2.67.36/30213.2.67.37 to 213.2.67.38213.2.67.392
203213.2.67.40/30213.2.67.41 to 213.2.67.42213.2.67.432
204213.2.67.44/30213.2.67.45 to 213.2.67.46213.2.67.472
205213.2.67.48/30213.2.67.49 to 213.2.67.50213.2.67.512
206213.2.67.52/30213.2.67.53 to 213.2.67.54213.2.67.552
207213.2.67.56/30213.2.67.57 to 213.2.67.58213.2.67.592
208213.2.67.60/30213.2.67.61 to 213.2.67.62213.2.67.632
209213.2.67.64/30213.2.67.65 to 213.2.67.66213.2.67.672
210213.2.67.68/30213.2.67.69 to 213.2.67.70213.2.67.712
211213.2.67.72/30213.2.67.73 to 213.2.67.74213.2.67.752
212213.2.67.76/30213.2.67.77 to 213.2.67.78213.2.67.792
213213.2.67.80/30213.2.67.81 to 213.2.67.82213.2.67.832
214213.2.67.84/30213.2.67.85 to 213.2.67.86213.2.67.872
215213.2.67.88/30213.2.67.89 to 213.2.67.90213.2.67.912
216213.2.67.92/30213.2.67.93 to 213.2.67.94213.2.67.952
217213.2.67.96/30213.2.67.97 to 213.2.67.98213.2.67.992
218213.2.67.100/30213.2.67.101 to 213.2.67.102213.2.67.1032
219213.2.67.104/30213.2.67.105 to 213.2.67.106213.2.67.1072
220213.2.67.108/30213.2.67.109 to 213.2.67.110213.2.67.1112
221213.2.67.112/30213.2.67.113 to 213.2.67.114213.2.67.1152
222213.2.67.116/30213.2.67.117 to 213.2.67.118213.2.67.1192
223213.2.67.120/30213.2.67.121 to 213.2.67.122213.2.67.1232
224213.2.67.124/30213.2.67.125 to 213.2.67.126213.2.67.1272
225213.2.67.128/30213.2.67.129 to 213.2.67.130213.2.67.1312
226213.2.67.132/30213.2.67.133 to 213.2.67.134213.2.67.1352
227213.2.67.136/30213.2.67.137 to 213.2.67.138213.2.67.1392
228213.2.67.140/30213.2.67.141 to 213.2.67.142213.2.67.1432
229213.2.67.144/30213.2.67.145 to 213.2.67.146213.2.67.1472
230213.2.67.148/30213.2.67.149 to 213.2.67.150213.2.67.1512
231213.2.67.152/30213.2.67.153 to 213.2.67.154213.2.67.1552
232213.2.67.156/30213.2.67.157 to 213.2.67.158213.2.67.1592
233213.2.67.160/30213.2.67.161 to 213.2.67.162213.2.67.1632
234213.2.67.164/30213.2.67.165 to 213.2.67.166213.2.67.1672
235213.2.67.168/30213.2.67.169 to 213.2.67.170213.2.67.1712
236213.2.67.172/30213.2.67.173 to 213.2.67.174213.2.67.1752
237213.2.67.176/30213.2.67.177 to 213.2.67.178213.2.67.1792
238213.2.67.180/30213.2.67.181 to 213.2.67.182213.2.67.1832
239213.2.67.184/30213.2.67.185 to 213.2.67.186213.2.67.1872
240213.2.67.188/30213.2.67.189 to 213.2.67.190213.2.67.1912
241213.2.67.192/30213.2.67.193 to 213.2.67.194213.2.67.1952
242213.2.67.196/30213.2.67.197 to 213.2.67.198213.2.67.1992
243213.2.67.200/30213.2.67.201 to 213.2.67.202213.2.67.2032
244213.2.67.204/30213.2.67.205 to 213.2.67.206213.2.67.2072
245213.2.67.208/30213.2.67.209 to 213.2.67.210213.2.67.2112
246213.2.67.212/30213.2.67.213 to 213.2.67.214213.2.67.2152
247213.2.67.216/30213.2.67.217 to 213.2.67.218213.2.67.2192
248213.2.67.220/30213.2.67.221 to 213.2.67.222213.2.67.2232
249213.2.67.224/30213.2.67.225 to 213.2.67.226213.2.67.2272
250213.2.67.228/30213.2.67.229 to 213.2.67.230213.2.67.2312
251213.2.67.232/30213.2.67.233 to 213.2.67.234213.2.67.2352
252213.2.67.236/30213.2.67.237 to 213.2.67.238213.2.67.2392
253213.2.67.240/30213.2.67.241 to 213.2.67.242213.2.67.2432
254213.2.67.244/30213.2.67.245 to 213.2.67.246213.2.67.2472
255213.2.67.248/30213.2.67.249 to 213.2.67.250213.2.67.2512
256213.2.67.252/30213.2.67.253 to 213.2.67.254213.2.67.2552

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.