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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/31
/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 2,048 subnets of /31; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1213.2.64.0/31213.2.64.0 to 213.2.64.1—2
2213.2.64.2/31213.2.64.2 to 213.2.64.3—2
3213.2.64.4/31213.2.64.4 to 213.2.64.5—2
4213.2.64.6/31213.2.64.6 to 213.2.64.7—2
5213.2.64.8/31213.2.64.8 to 213.2.64.9—2
6213.2.64.10/31213.2.64.10 to 213.2.64.11—2
7213.2.64.12/31213.2.64.12 to 213.2.64.13—2
8213.2.64.14/31213.2.64.14 to 213.2.64.15—2
9213.2.64.16/31213.2.64.16 to 213.2.64.17—2
10213.2.64.18/31213.2.64.18 to 213.2.64.19—2
11213.2.64.20/31213.2.64.20 to 213.2.64.21—2
12213.2.64.22/31213.2.64.22 to 213.2.64.23—2
13213.2.64.24/31213.2.64.24 to 213.2.64.25—2
14213.2.64.26/31213.2.64.26 to 213.2.64.27—2
15213.2.64.28/31213.2.64.28 to 213.2.64.29—2
16213.2.64.30/31213.2.64.30 to 213.2.64.31—2
17213.2.64.32/31213.2.64.32 to 213.2.64.33—2
18213.2.64.34/31213.2.64.34 to 213.2.64.35—2
19213.2.64.36/31213.2.64.36 to 213.2.64.37—2
20213.2.64.38/31213.2.64.38 to 213.2.64.39—2
21213.2.64.40/31213.2.64.40 to 213.2.64.41—2
22213.2.64.42/31213.2.64.42 to 213.2.64.43—2
23213.2.64.44/31213.2.64.44 to 213.2.64.45—2
24213.2.64.46/31213.2.64.46 to 213.2.64.47—2
25213.2.64.48/31213.2.64.48 to 213.2.64.49—2
26213.2.64.50/31213.2.64.50 to 213.2.64.51—2
27213.2.64.52/31213.2.64.52 to 213.2.64.53—2
28213.2.64.54/31213.2.64.54 to 213.2.64.55—2
29213.2.64.56/31213.2.64.56 to 213.2.64.57—2
30213.2.64.58/31213.2.64.58 to 213.2.64.59—2
31213.2.64.60/31213.2.64.60 to 213.2.64.61—2
32213.2.64.62/31213.2.64.62 to 213.2.64.63—2
33213.2.64.64/31213.2.64.64 to 213.2.64.65—2
34213.2.64.66/31213.2.64.66 to 213.2.64.67—2
35213.2.64.68/31213.2.64.68 to 213.2.64.69—2
36213.2.64.70/31213.2.64.70 to 213.2.64.71—2
37213.2.64.72/31213.2.64.72 to 213.2.64.73—2
38213.2.64.74/31213.2.64.74 to 213.2.64.75—2
39213.2.64.76/31213.2.64.76 to 213.2.64.77—2
40213.2.64.78/31213.2.64.78 to 213.2.64.79—2
41213.2.64.80/31213.2.64.80 to 213.2.64.81—2
42213.2.64.82/31213.2.64.82 to 213.2.64.83—2
43213.2.64.84/31213.2.64.84 to 213.2.64.85—2
44213.2.64.86/31213.2.64.86 to 213.2.64.87—2
45213.2.64.88/31213.2.64.88 to 213.2.64.89—2
46213.2.64.90/31213.2.64.90 to 213.2.64.91—2
47213.2.64.92/31213.2.64.92 to 213.2.64.93—2
48213.2.64.94/31213.2.64.94 to 213.2.64.95—2
49213.2.64.96/31213.2.64.96 to 213.2.64.97—2
50213.2.64.98/31213.2.64.98 to 213.2.64.99—2
51213.2.64.100/31213.2.64.100 to 213.2.64.101—2
52213.2.64.102/31213.2.64.102 to 213.2.64.103—2
53213.2.64.104/31213.2.64.104 to 213.2.64.105—2
54213.2.64.106/31213.2.64.106 to 213.2.64.107—2
55213.2.64.108/31213.2.64.108 to 213.2.64.109—2
56213.2.64.110/31213.2.64.110 to 213.2.64.111—2
57213.2.64.112/31213.2.64.112 to 213.2.64.113—2
58213.2.64.114/31213.2.64.114 to 213.2.64.115—2
59213.2.64.116/31213.2.64.116 to 213.2.64.117—2
60213.2.64.118/31213.2.64.118 to 213.2.64.119—2
61213.2.64.120/31213.2.64.120 to 213.2.64.121—2
62213.2.64.122/31213.2.64.122 to 213.2.64.123—2
63213.2.64.124/31213.2.64.124 to 213.2.64.125—2
64213.2.64.126/31213.2.64.126 to 213.2.64.127—2
65213.2.64.128/31213.2.64.128 to 213.2.64.129—2
66213.2.64.130/31213.2.64.130 to 213.2.64.131—2
67213.2.64.132/31213.2.64.132 to 213.2.64.133—2
68213.2.64.134/31213.2.64.134 to 213.2.64.135—2
69213.2.64.136/31213.2.64.136 to 213.2.64.137—2
70213.2.64.138/31213.2.64.138 to 213.2.64.139—2
71213.2.64.140/31213.2.64.140 to 213.2.64.141—2
72213.2.64.142/31213.2.64.142 to 213.2.64.143—2
73213.2.64.144/31213.2.64.144 to 213.2.64.145—2
74213.2.64.146/31213.2.64.146 to 213.2.64.147—2
75213.2.64.148/31213.2.64.148 to 213.2.64.149—2
76213.2.64.150/31213.2.64.150 to 213.2.64.151—2
77213.2.64.152/31213.2.64.152 to 213.2.64.153—2
78213.2.64.154/31213.2.64.154 to 213.2.64.155—2
79213.2.64.156/31213.2.64.156 to 213.2.64.157—2
80213.2.64.158/31213.2.64.158 to 213.2.64.159—2
81213.2.64.160/31213.2.64.160 to 213.2.64.161—2
82213.2.64.162/31213.2.64.162 to 213.2.64.163—2
83213.2.64.164/31213.2.64.164 to 213.2.64.165—2
84213.2.64.166/31213.2.64.166 to 213.2.64.167—2
85213.2.64.168/31213.2.64.168 to 213.2.64.169—2
86213.2.64.170/31213.2.64.170 to 213.2.64.171—2
87213.2.64.172/31213.2.64.172 to 213.2.64.173—2
88213.2.64.174/31213.2.64.174 to 213.2.64.175—2
89213.2.64.176/31213.2.64.176 to 213.2.64.177—2
90213.2.64.178/31213.2.64.178 to 213.2.64.179—2
91213.2.64.180/31213.2.64.180 to 213.2.64.181—2
92213.2.64.182/31213.2.64.182 to 213.2.64.183—2
93213.2.64.184/31213.2.64.184 to 213.2.64.185—2
94213.2.64.186/31213.2.64.186 to 213.2.64.187—2
95213.2.64.188/31213.2.64.188 to 213.2.64.189—2
96213.2.64.190/31213.2.64.190 to 213.2.64.191—2
97213.2.64.192/31213.2.64.192 to 213.2.64.193—2
98213.2.64.194/31213.2.64.194 to 213.2.64.195—2
99213.2.64.196/31213.2.64.196 to 213.2.64.197—2
100213.2.64.198/31213.2.64.198 to 213.2.64.199—2
101213.2.64.200/31213.2.64.200 to 213.2.64.201—2
102213.2.64.202/31213.2.64.202 to 213.2.64.203—2
103213.2.64.204/31213.2.64.204 to 213.2.64.205—2
104213.2.64.206/31213.2.64.206 to 213.2.64.207—2
105213.2.64.208/31213.2.64.208 to 213.2.64.209—2
106213.2.64.210/31213.2.64.210 to 213.2.64.211—2
107213.2.64.212/31213.2.64.212 to 213.2.64.213—2
108213.2.64.214/31213.2.64.214 to 213.2.64.215—2
109213.2.64.216/31213.2.64.216 to 213.2.64.217—2
110213.2.64.218/31213.2.64.218 to 213.2.64.219—2
111213.2.64.220/31213.2.64.220 to 213.2.64.221—2
112213.2.64.222/31213.2.64.222 to 213.2.64.223—2
113213.2.64.224/31213.2.64.224 to 213.2.64.225—2
114213.2.64.226/31213.2.64.226 to 213.2.64.227—2
115213.2.64.228/31213.2.64.228 to 213.2.64.229—2
116213.2.64.230/31213.2.64.230 to 213.2.64.231—2
117213.2.64.232/31213.2.64.232 to 213.2.64.233—2
118213.2.64.234/31213.2.64.234 to 213.2.64.235—2
119213.2.64.236/31213.2.64.236 to 213.2.64.237—2
120213.2.64.238/31213.2.64.238 to 213.2.64.239—2
121213.2.64.240/31213.2.64.240 to 213.2.64.241—2
122213.2.64.242/31213.2.64.242 to 213.2.64.243—2
123213.2.64.244/31213.2.64.244 to 213.2.64.245—2
124213.2.64.246/31213.2.64.246 to 213.2.64.247—2
125213.2.64.248/31213.2.64.248 to 213.2.64.249—2
126213.2.64.250/31213.2.64.250 to 213.2.64.251—2
127213.2.64.252/31213.2.64.252 to 213.2.64.253—2
128213.2.64.254/31213.2.64.254 to 213.2.64.255—2
129213.2.65.0/31213.2.65.0 to 213.2.65.1—2
130213.2.65.2/31213.2.65.2 to 213.2.65.3—2
131213.2.65.4/31213.2.65.4 to 213.2.65.5—2
132213.2.65.6/31213.2.65.6 to 213.2.65.7—2
133213.2.65.8/31213.2.65.8 to 213.2.65.9—2
134213.2.65.10/31213.2.65.10 to 213.2.65.11—2
135213.2.65.12/31213.2.65.12 to 213.2.65.13—2
136213.2.65.14/31213.2.65.14 to 213.2.65.15—2
137213.2.65.16/31213.2.65.16 to 213.2.65.17—2
138213.2.65.18/31213.2.65.18 to 213.2.65.19—2
139213.2.65.20/31213.2.65.20 to 213.2.65.21—2
140213.2.65.22/31213.2.65.22 to 213.2.65.23—2
141213.2.65.24/31213.2.65.24 to 213.2.65.25—2
142213.2.65.26/31213.2.65.26 to 213.2.65.27—2
143213.2.65.28/31213.2.65.28 to 213.2.65.29—2
144213.2.65.30/31213.2.65.30 to 213.2.65.31—2
145213.2.65.32/31213.2.65.32 to 213.2.65.33—2
146213.2.65.34/31213.2.65.34 to 213.2.65.35—2
147213.2.65.36/31213.2.65.36 to 213.2.65.37—2
148213.2.65.38/31213.2.65.38 to 213.2.65.39—2
149213.2.65.40/31213.2.65.40 to 213.2.65.41—2
150213.2.65.42/31213.2.65.42 to 213.2.65.43—2
151213.2.65.44/31213.2.65.44 to 213.2.65.45—2
152213.2.65.46/31213.2.65.46 to 213.2.65.47—2
153213.2.65.48/31213.2.65.48 to 213.2.65.49—2
154213.2.65.50/31213.2.65.50 to 213.2.65.51—2
155213.2.65.52/31213.2.65.52 to 213.2.65.53—2
156213.2.65.54/31213.2.65.54 to 213.2.65.55—2
157213.2.65.56/31213.2.65.56 to 213.2.65.57—2
158213.2.65.58/31213.2.65.58 to 213.2.65.59—2
159213.2.65.60/31213.2.65.60 to 213.2.65.61—2
160213.2.65.62/31213.2.65.62 to 213.2.65.63—2
161213.2.65.64/31213.2.65.64 to 213.2.65.65—2
162213.2.65.66/31213.2.65.66 to 213.2.65.67—2
163213.2.65.68/31213.2.65.68 to 213.2.65.69—2
164213.2.65.70/31213.2.65.70 to 213.2.65.71—2
165213.2.65.72/31213.2.65.72 to 213.2.65.73—2
166213.2.65.74/31213.2.65.74 to 213.2.65.75—2
167213.2.65.76/31213.2.65.76 to 213.2.65.77—2
168213.2.65.78/31213.2.65.78 to 213.2.65.79—2
169213.2.65.80/31213.2.65.80 to 213.2.65.81—2
170213.2.65.82/31213.2.65.82 to 213.2.65.83—2
171213.2.65.84/31213.2.65.84 to 213.2.65.85—2
172213.2.65.86/31213.2.65.86 to 213.2.65.87—2
173213.2.65.88/31213.2.65.88 to 213.2.65.89—2
174213.2.65.90/31213.2.65.90 to 213.2.65.91—2
175213.2.65.92/31213.2.65.92 to 213.2.65.93—2
176213.2.65.94/31213.2.65.94 to 213.2.65.95—2
177213.2.65.96/31213.2.65.96 to 213.2.65.97—2
178213.2.65.98/31213.2.65.98 to 213.2.65.99—2
179213.2.65.100/31213.2.65.100 to 213.2.65.101—2
180213.2.65.102/31213.2.65.102 to 213.2.65.103—2
181213.2.65.104/31213.2.65.104 to 213.2.65.105—2
182213.2.65.106/31213.2.65.106 to 213.2.65.107—2
183213.2.65.108/31213.2.65.108 to 213.2.65.109—2
184213.2.65.110/31213.2.65.110 to 213.2.65.111—2
185213.2.65.112/31213.2.65.112 to 213.2.65.113—2
186213.2.65.114/31213.2.65.114 to 213.2.65.115—2
187213.2.65.116/31213.2.65.116 to 213.2.65.117—2
188213.2.65.118/31213.2.65.118 to 213.2.65.119—2
189213.2.65.120/31213.2.65.120 to 213.2.65.121—2
190213.2.65.122/31213.2.65.122 to 213.2.65.123—2
191213.2.65.124/31213.2.65.124 to 213.2.65.125—2
192213.2.65.126/31213.2.65.126 to 213.2.65.127—2
193213.2.65.128/31213.2.65.128 to 213.2.65.129—2
194213.2.65.130/31213.2.65.130 to 213.2.65.131—2
195213.2.65.132/31213.2.65.132 to 213.2.65.133—2
196213.2.65.134/31213.2.65.134 to 213.2.65.135—2
197213.2.65.136/31213.2.65.136 to 213.2.65.137—2
198213.2.65.138/31213.2.65.138 to 213.2.65.139—2
199213.2.65.140/31213.2.65.140 to 213.2.65.141—2
200213.2.65.142/31213.2.65.142 to 213.2.65.143—2
201213.2.65.144/31213.2.65.144 to 213.2.65.145—2
202213.2.65.146/31213.2.65.146 to 213.2.65.147—2
203213.2.65.148/31213.2.65.148 to 213.2.65.149—2
204213.2.65.150/31213.2.65.150 to 213.2.65.151—2
205213.2.65.152/31213.2.65.152 to 213.2.65.153—2
206213.2.65.154/31213.2.65.154 to 213.2.65.155—2
207213.2.65.156/31213.2.65.156 to 213.2.65.157—2
208213.2.65.158/31213.2.65.158 to 213.2.65.159—2
209213.2.65.160/31213.2.65.160 to 213.2.65.161—2
210213.2.65.162/31213.2.65.162 to 213.2.65.163—2
211213.2.65.164/31213.2.65.164 to 213.2.65.165—2
212213.2.65.166/31213.2.65.166 to 213.2.65.167—2
213213.2.65.168/31213.2.65.168 to 213.2.65.169—2
214213.2.65.170/31213.2.65.170 to 213.2.65.171—2
215213.2.65.172/31213.2.65.172 to 213.2.65.173—2
216213.2.65.174/31213.2.65.174 to 213.2.65.175—2
217213.2.65.176/31213.2.65.176 to 213.2.65.177—2
218213.2.65.178/31213.2.65.178 to 213.2.65.179—2
219213.2.65.180/31213.2.65.180 to 213.2.65.181—2
220213.2.65.182/31213.2.65.182 to 213.2.65.183—2
221213.2.65.184/31213.2.65.184 to 213.2.65.185—2
222213.2.65.186/31213.2.65.186 to 213.2.65.187—2
223213.2.65.188/31213.2.65.188 to 213.2.65.189—2
224213.2.65.190/31213.2.65.190 to 213.2.65.191—2
225213.2.65.192/31213.2.65.192 to 213.2.65.193—2
226213.2.65.194/31213.2.65.194 to 213.2.65.195—2
227213.2.65.196/31213.2.65.196 to 213.2.65.197—2
228213.2.65.198/31213.2.65.198 to 213.2.65.199—2
229213.2.65.200/31213.2.65.200 to 213.2.65.201—2
230213.2.65.202/31213.2.65.202 to 213.2.65.203—2
231213.2.65.204/31213.2.65.204 to 213.2.65.205—2
232213.2.65.206/31213.2.65.206 to 213.2.65.207—2
233213.2.65.208/31213.2.65.208 to 213.2.65.209—2
234213.2.65.210/31213.2.65.210 to 213.2.65.211—2
235213.2.65.212/31213.2.65.212 to 213.2.65.213—2
236213.2.65.214/31213.2.65.214 to 213.2.65.215—2
237213.2.65.216/31213.2.65.216 to 213.2.65.217—2
238213.2.65.218/31213.2.65.218 to 213.2.65.219—2
239213.2.65.220/31213.2.65.220 to 213.2.65.221—2
240213.2.65.222/31213.2.65.222 to 213.2.65.223—2
241213.2.65.224/31213.2.65.224 to 213.2.65.225—2
242213.2.65.226/31213.2.65.226 to 213.2.65.227—2
243213.2.65.228/31213.2.65.228 to 213.2.65.229—2
244213.2.65.230/31213.2.65.230 to 213.2.65.231—2
245213.2.65.232/31213.2.65.232 to 213.2.65.233—2
246213.2.65.234/31213.2.65.234 to 213.2.65.235—2
247213.2.65.236/31213.2.65.236 to 213.2.65.237—2
248213.2.65.238/31213.2.65.238 to 213.2.65.239—2
249213.2.65.240/31213.2.65.240 to 213.2.65.241—2
250213.2.65.242/31213.2.65.242 to 213.2.65.243—2
251213.2.65.244/31213.2.65.244 to 213.2.65.245—2
252213.2.65.246/31213.2.65.246 to 213.2.65.247—2
253213.2.65.248/31213.2.65.248 to 213.2.65.249—2
254213.2.65.250/31213.2.65.250 to 213.2.65.251—2
255213.2.65.252/31213.2.65.252 to 213.2.65.253—2
256213.2.65.254/31213.2.65.254 to 213.2.65.255—2

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.