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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.

Network188.3.64.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
188.3.64.0
Broadcast address
188.3.79.255
First usable
188.3.64.1
Last usable
188.3.79.254
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
B (default /16)
As numbers
Hex BC034000 · Integer 3154329600 to 3154333695
Reverse DNS zones
64.3.188.in-addr.arpa
65.3.188.in-addr.arpa
66.3.188.in-addr.arpa
67.3.188.in-addr.arpa
68.3.188.in-addr.arpa
69.3.188.in-addr.arpa
70.3.188.in-addr.arpa
71.3.188.in-addr.arpa
72.3.188.in-addr.arpa
73.3.188.in-addr.arpa
74.3.188.in-addr.arpa
75.3.188.in-addr.arpa
76.3.188.in-addr.arpa
77.3.188.in-addr.arpa
78.3.188.in-addr.arpa
79.3.188.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
Address10111100.00000011.01000000.00000000188.3.64.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network10111100.00000011.01000000.00000000188.3.64.0
Broadcast10111100.00000011.01001111.11111111188.3.79.255
Split into smaller subnets/32
/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)

188.3.64.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1188.3.64.0/32188.3.64.0 to 188.3.64.0—1
2188.3.64.1/32188.3.64.1 to 188.3.64.1—1
3188.3.64.2/32188.3.64.2 to 188.3.64.2—1
4188.3.64.3/32188.3.64.3 to 188.3.64.3—1
5188.3.64.4/32188.3.64.4 to 188.3.64.4—1
6188.3.64.5/32188.3.64.5 to 188.3.64.5—1
7188.3.64.6/32188.3.64.6 to 188.3.64.6—1
8188.3.64.7/32188.3.64.7 to 188.3.64.7—1
9188.3.64.8/32188.3.64.8 to 188.3.64.8—1
10188.3.64.9/32188.3.64.9 to 188.3.64.9—1
11188.3.64.10/32188.3.64.10 to 188.3.64.10—1
12188.3.64.11/32188.3.64.11 to 188.3.64.11—1
13188.3.64.12/32188.3.64.12 to 188.3.64.12—1
14188.3.64.13/32188.3.64.13 to 188.3.64.13—1
15188.3.64.14/32188.3.64.14 to 188.3.64.14—1
16188.3.64.15/32188.3.64.15 to 188.3.64.15—1
17188.3.64.16/32188.3.64.16 to 188.3.64.16—1
18188.3.64.17/32188.3.64.17 to 188.3.64.17—1
19188.3.64.18/32188.3.64.18 to 188.3.64.18—1
20188.3.64.19/32188.3.64.19 to 188.3.64.19—1
21188.3.64.20/32188.3.64.20 to 188.3.64.20—1
22188.3.64.21/32188.3.64.21 to 188.3.64.21—1
23188.3.64.22/32188.3.64.22 to 188.3.64.22—1
24188.3.64.23/32188.3.64.23 to 188.3.64.23—1
25188.3.64.24/32188.3.64.24 to 188.3.64.24—1
26188.3.64.25/32188.3.64.25 to 188.3.64.25—1
27188.3.64.26/32188.3.64.26 to 188.3.64.26—1
28188.3.64.27/32188.3.64.27 to 188.3.64.27—1
29188.3.64.28/32188.3.64.28 to 188.3.64.28—1
30188.3.64.29/32188.3.64.29 to 188.3.64.29—1
31188.3.64.30/32188.3.64.30 to 188.3.64.30—1
32188.3.64.31/32188.3.64.31 to 188.3.64.31—1
33188.3.64.32/32188.3.64.32 to 188.3.64.32—1
34188.3.64.33/32188.3.64.33 to 188.3.64.33—1
35188.3.64.34/32188.3.64.34 to 188.3.64.34—1
36188.3.64.35/32188.3.64.35 to 188.3.64.35—1
37188.3.64.36/32188.3.64.36 to 188.3.64.36—1
38188.3.64.37/32188.3.64.37 to 188.3.64.37—1
39188.3.64.38/32188.3.64.38 to 188.3.64.38—1
40188.3.64.39/32188.3.64.39 to 188.3.64.39—1
41188.3.64.40/32188.3.64.40 to 188.3.64.40—1
42188.3.64.41/32188.3.64.41 to 188.3.64.41—1
43188.3.64.42/32188.3.64.42 to 188.3.64.42—1
44188.3.64.43/32188.3.64.43 to 188.3.64.43—1
45188.3.64.44/32188.3.64.44 to 188.3.64.44—1
46188.3.64.45/32188.3.64.45 to 188.3.64.45—1
47188.3.64.46/32188.3.64.46 to 188.3.64.46—1
48188.3.64.47/32188.3.64.47 to 188.3.64.47—1
49188.3.64.48/32188.3.64.48 to 188.3.64.48—1
50188.3.64.49/32188.3.64.49 to 188.3.64.49—1
51188.3.64.50/32188.3.64.50 to 188.3.64.50—1
52188.3.64.51/32188.3.64.51 to 188.3.64.51—1
53188.3.64.52/32188.3.64.52 to 188.3.64.52—1
54188.3.64.53/32188.3.64.53 to 188.3.64.53—1
55188.3.64.54/32188.3.64.54 to 188.3.64.54—1
56188.3.64.55/32188.3.64.55 to 188.3.64.55—1
57188.3.64.56/32188.3.64.56 to 188.3.64.56—1
58188.3.64.57/32188.3.64.57 to 188.3.64.57—1
59188.3.64.58/32188.3.64.58 to 188.3.64.58—1
60188.3.64.59/32188.3.64.59 to 188.3.64.59—1
61188.3.64.60/32188.3.64.60 to 188.3.64.60—1
62188.3.64.61/32188.3.64.61 to 188.3.64.61—1
63188.3.64.62/32188.3.64.62 to 188.3.64.62—1
64188.3.64.63/32188.3.64.63 to 188.3.64.63—1
65188.3.64.64/32188.3.64.64 to 188.3.64.64—1
66188.3.64.65/32188.3.64.65 to 188.3.64.65—1
67188.3.64.66/32188.3.64.66 to 188.3.64.66—1
68188.3.64.67/32188.3.64.67 to 188.3.64.67—1
69188.3.64.68/32188.3.64.68 to 188.3.64.68—1
70188.3.64.69/32188.3.64.69 to 188.3.64.69—1
71188.3.64.70/32188.3.64.70 to 188.3.64.70—1
72188.3.64.71/32188.3.64.71 to 188.3.64.71—1
73188.3.64.72/32188.3.64.72 to 188.3.64.72—1
74188.3.64.73/32188.3.64.73 to 188.3.64.73—1
75188.3.64.74/32188.3.64.74 to 188.3.64.74—1
76188.3.64.75/32188.3.64.75 to 188.3.64.75—1
77188.3.64.76/32188.3.64.76 to 188.3.64.76—1
78188.3.64.77/32188.3.64.77 to 188.3.64.77—1
79188.3.64.78/32188.3.64.78 to 188.3.64.78—1
80188.3.64.79/32188.3.64.79 to 188.3.64.79—1
81188.3.64.80/32188.3.64.80 to 188.3.64.80—1
82188.3.64.81/32188.3.64.81 to 188.3.64.81—1
83188.3.64.82/32188.3.64.82 to 188.3.64.82—1
84188.3.64.83/32188.3.64.83 to 188.3.64.83—1
85188.3.64.84/32188.3.64.84 to 188.3.64.84—1
86188.3.64.85/32188.3.64.85 to 188.3.64.85—1
87188.3.64.86/32188.3.64.86 to 188.3.64.86—1
88188.3.64.87/32188.3.64.87 to 188.3.64.87—1
89188.3.64.88/32188.3.64.88 to 188.3.64.88—1
90188.3.64.89/32188.3.64.89 to 188.3.64.89—1
91188.3.64.90/32188.3.64.90 to 188.3.64.90—1
92188.3.64.91/32188.3.64.91 to 188.3.64.91—1
93188.3.64.92/32188.3.64.92 to 188.3.64.92—1
94188.3.64.93/32188.3.64.93 to 188.3.64.93—1
95188.3.64.94/32188.3.64.94 to 188.3.64.94—1
96188.3.64.95/32188.3.64.95 to 188.3.64.95—1
97188.3.64.96/32188.3.64.96 to 188.3.64.96—1
98188.3.64.97/32188.3.64.97 to 188.3.64.97—1
99188.3.64.98/32188.3.64.98 to 188.3.64.98—1
100188.3.64.99/32188.3.64.99 to 188.3.64.99—1
101188.3.64.100/32188.3.64.100 to 188.3.64.100—1
102188.3.64.101/32188.3.64.101 to 188.3.64.101—1
103188.3.64.102/32188.3.64.102 to 188.3.64.102—1
104188.3.64.103/32188.3.64.103 to 188.3.64.103—1
105188.3.64.104/32188.3.64.104 to 188.3.64.104—1
106188.3.64.105/32188.3.64.105 to 188.3.64.105—1
107188.3.64.106/32188.3.64.106 to 188.3.64.106—1
108188.3.64.107/32188.3.64.107 to 188.3.64.107—1
109188.3.64.108/32188.3.64.108 to 188.3.64.108—1
110188.3.64.109/32188.3.64.109 to 188.3.64.109—1
111188.3.64.110/32188.3.64.110 to 188.3.64.110—1
112188.3.64.111/32188.3.64.111 to 188.3.64.111—1
113188.3.64.112/32188.3.64.112 to 188.3.64.112—1
114188.3.64.113/32188.3.64.113 to 188.3.64.113—1
115188.3.64.114/32188.3.64.114 to 188.3.64.114—1
116188.3.64.115/32188.3.64.115 to 188.3.64.115—1
117188.3.64.116/32188.3.64.116 to 188.3.64.116—1
118188.3.64.117/32188.3.64.117 to 188.3.64.117—1
119188.3.64.118/32188.3.64.118 to 188.3.64.118—1
120188.3.64.119/32188.3.64.119 to 188.3.64.119—1
121188.3.64.120/32188.3.64.120 to 188.3.64.120—1
122188.3.64.121/32188.3.64.121 to 188.3.64.121—1
123188.3.64.122/32188.3.64.122 to 188.3.64.122—1
124188.3.64.123/32188.3.64.123 to 188.3.64.123—1
125188.3.64.124/32188.3.64.124 to 188.3.64.124—1
126188.3.64.125/32188.3.64.125 to 188.3.64.125—1
127188.3.64.126/32188.3.64.126 to 188.3.64.126—1
128188.3.64.127/32188.3.64.127 to 188.3.64.127—1
129188.3.64.128/32188.3.64.128 to 188.3.64.128—1
130188.3.64.129/32188.3.64.129 to 188.3.64.129—1
131188.3.64.130/32188.3.64.130 to 188.3.64.130—1
132188.3.64.131/32188.3.64.131 to 188.3.64.131—1
133188.3.64.132/32188.3.64.132 to 188.3.64.132—1
134188.3.64.133/32188.3.64.133 to 188.3.64.133—1
135188.3.64.134/32188.3.64.134 to 188.3.64.134—1
136188.3.64.135/32188.3.64.135 to 188.3.64.135—1
137188.3.64.136/32188.3.64.136 to 188.3.64.136—1
138188.3.64.137/32188.3.64.137 to 188.3.64.137—1
139188.3.64.138/32188.3.64.138 to 188.3.64.138—1
140188.3.64.139/32188.3.64.139 to 188.3.64.139—1
141188.3.64.140/32188.3.64.140 to 188.3.64.140—1
142188.3.64.141/32188.3.64.141 to 188.3.64.141—1
143188.3.64.142/32188.3.64.142 to 188.3.64.142—1
144188.3.64.143/32188.3.64.143 to 188.3.64.143—1
145188.3.64.144/32188.3.64.144 to 188.3.64.144—1
146188.3.64.145/32188.3.64.145 to 188.3.64.145—1
147188.3.64.146/32188.3.64.146 to 188.3.64.146—1
148188.3.64.147/32188.3.64.147 to 188.3.64.147—1
149188.3.64.148/32188.3.64.148 to 188.3.64.148—1
150188.3.64.149/32188.3.64.149 to 188.3.64.149—1
151188.3.64.150/32188.3.64.150 to 188.3.64.150—1
152188.3.64.151/32188.3.64.151 to 188.3.64.151—1
153188.3.64.152/32188.3.64.152 to 188.3.64.152—1
154188.3.64.153/32188.3.64.153 to 188.3.64.153—1
155188.3.64.154/32188.3.64.154 to 188.3.64.154—1
156188.3.64.155/32188.3.64.155 to 188.3.64.155—1
157188.3.64.156/32188.3.64.156 to 188.3.64.156—1
158188.3.64.157/32188.3.64.157 to 188.3.64.157—1
159188.3.64.158/32188.3.64.158 to 188.3.64.158—1
160188.3.64.159/32188.3.64.159 to 188.3.64.159—1
161188.3.64.160/32188.3.64.160 to 188.3.64.160—1
162188.3.64.161/32188.3.64.161 to 188.3.64.161—1
163188.3.64.162/32188.3.64.162 to 188.3.64.162—1
164188.3.64.163/32188.3.64.163 to 188.3.64.163—1
165188.3.64.164/32188.3.64.164 to 188.3.64.164—1
166188.3.64.165/32188.3.64.165 to 188.3.64.165—1
167188.3.64.166/32188.3.64.166 to 188.3.64.166—1
168188.3.64.167/32188.3.64.167 to 188.3.64.167—1
169188.3.64.168/32188.3.64.168 to 188.3.64.168—1
170188.3.64.169/32188.3.64.169 to 188.3.64.169—1
171188.3.64.170/32188.3.64.170 to 188.3.64.170—1
172188.3.64.171/32188.3.64.171 to 188.3.64.171—1
173188.3.64.172/32188.3.64.172 to 188.3.64.172—1
174188.3.64.173/32188.3.64.173 to 188.3.64.173—1
175188.3.64.174/32188.3.64.174 to 188.3.64.174—1
176188.3.64.175/32188.3.64.175 to 188.3.64.175—1
177188.3.64.176/32188.3.64.176 to 188.3.64.176—1
178188.3.64.177/32188.3.64.177 to 188.3.64.177—1
179188.3.64.178/32188.3.64.178 to 188.3.64.178—1
180188.3.64.179/32188.3.64.179 to 188.3.64.179—1
181188.3.64.180/32188.3.64.180 to 188.3.64.180—1
182188.3.64.181/32188.3.64.181 to 188.3.64.181—1
183188.3.64.182/32188.3.64.182 to 188.3.64.182—1
184188.3.64.183/32188.3.64.183 to 188.3.64.183—1
185188.3.64.184/32188.3.64.184 to 188.3.64.184—1
186188.3.64.185/32188.3.64.185 to 188.3.64.185—1
187188.3.64.186/32188.3.64.186 to 188.3.64.186—1
188188.3.64.187/32188.3.64.187 to 188.3.64.187—1
189188.3.64.188/32188.3.64.188 to 188.3.64.188—1
190188.3.64.189/32188.3.64.189 to 188.3.64.189—1
191188.3.64.190/32188.3.64.190 to 188.3.64.190—1
192188.3.64.191/32188.3.64.191 to 188.3.64.191—1
193188.3.64.192/32188.3.64.192 to 188.3.64.192—1
194188.3.64.193/32188.3.64.193 to 188.3.64.193—1
195188.3.64.194/32188.3.64.194 to 188.3.64.194—1
196188.3.64.195/32188.3.64.195 to 188.3.64.195—1
197188.3.64.196/32188.3.64.196 to 188.3.64.196—1
198188.3.64.197/32188.3.64.197 to 188.3.64.197—1
199188.3.64.198/32188.3.64.198 to 188.3.64.198—1
200188.3.64.199/32188.3.64.199 to 188.3.64.199—1
201188.3.64.200/32188.3.64.200 to 188.3.64.200—1
202188.3.64.201/32188.3.64.201 to 188.3.64.201—1
203188.3.64.202/32188.3.64.202 to 188.3.64.202—1
204188.3.64.203/32188.3.64.203 to 188.3.64.203—1
205188.3.64.204/32188.3.64.204 to 188.3.64.204—1
206188.3.64.205/32188.3.64.205 to 188.3.64.205—1
207188.3.64.206/32188.3.64.206 to 188.3.64.206—1
208188.3.64.207/32188.3.64.207 to 188.3.64.207—1
209188.3.64.208/32188.3.64.208 to 188.3.64.208—1
210188.3.64.209/32188.3.64.209 to 188.3.64.209—1
211188.3.64.210/32188.3.64.210 to 188.3.64.210—1
212188.3.64.211/32188.3.64.211 to 188.3.64.211—1
213188.3.64.212/32188.3.64.212 to 188.3.64.212—1
214188.3.64.213/32188.3.64.213 to 188.3.64.213—1
215188.3.64.214/32188.3.64.214 to 188.3.64.214—1
216188.3.64.215/32188.3.64.215 to 188.3.64.215—1
217188.3.64.216/32188.3.64.216 to 188.3.64.216—1
218188.3.64.217/32188.3.64.217 to 188.3.64.217—1
219188.3.64.218/32188.3.64.218 to 188.3.64.218—1
220188.3.64.219/32188.3.64.219 to 188.3.64.219—1
221188.3.64.220/32188.3.64.220 to 188.3.64.220—1
222188.3.64.221/32188.3.64.221 to 188.3.64.221—1
223188.3.64.222/32188.3.64.222 to 188.3.64.222—1
224188.3.64.223/32188.3.64.223 to 188.3.64.223—1
225188.3.64.224/32188.3.64.224 to 188.3.64.224—1
226188.3.64.225/32188.3.64.225 to 188.3.64.225—1
227188.3.64.226/32188.3.64.226 to 188.3.64.226—1
228188.3.64.227/32188.3.64.227 to 188.3.64.227—1
229188.3.64.228/32188.3.64.228 to 188.3.64.228—1
230188.3.64.229/32188.3.64.229 to 188.3.64.229—1
231188.3.64.230/32188.3.64.230 to 188.3.64.230—1
232188.3.64.231/32188.3.64.231 to 188.3.64.231—1
233188.3.64.232/32188.3.64.232 to 188.3.64.232—1
234188.3.64.233/32188.3.64.233 to 188.3.64.233—1
235188.3.64.234/32188.3.64.234 to 188.3.64.234—1
236188.3.64.235/32188.3.64.235 to 188.3.64.235—1
237188.3.64.236/32188.3.64.236 to 188.3.64.236—1
238188.3.64.237/32188.3.64.237 to 188.3.64.237—1
239188.3.64.238/32188.3.64.238 to 188.3.64.238—1
240188.3.64.239/32188.3.64.239 to 188.3.64.239—1
241188.3.64.240/32188.3.64.240 to 188.3.64.240—1
242188.3.64.241/32188.3.64.241 to 188.3.64.241—1
243188.3.64.242/32188.3.64.242 to 188.3.64.242—1
244188.3.64.243/32188.3.64.243 to 188.3.64.243—1
245188.3.64.244/32188.3.64.244 to 188.3.64.244—1
246188.3.64.245/32188.3.64.245 to 188.3.64.245—1
247188.3.64.246/32188.3.64.246 to 188.3.64.246—1
248188.3.64.247/32188.3.64.247 to 188.3.64.247—1
249188.3.64.248/32188.3.64.248 to 188.3.64.248—1
250188.3.64.249/32188.3.64.249 to 188.3.64.249—1
251188.3.64.250/32188.3.64.250 to 188.3.64.250—1
252188.3.64.251/32188.3.64.251 to 188.3.64.251—1
253188.3.64.252/32188.3.64.252 to 188.3.64.252—1
254188.3.64.253/32188.3.64.253 to 188.3.64.253—1
255188.3.64.254/32188.3.64.254 to 188.3.64.254—1
256188.3.64.255/32188.3.64.255 to 188.3.64.255—1

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.