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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.

Network254.2.80.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
254.2.80.0
Broadcast address
254.2.95.255
First usable
254.2.80.1
Last usable
254.2.95.254
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 FE025000 · Integer 4261564416 to 4261568511
Reverse DNS zones
80.2.254.in-addr.arpa
81.2.254.in-addr.arpa
82.2.254.in-addr.arpa
83.2.254.in-addr.arpa
84.2.254.in-addr.arpa
85.2.254.in-addr.arpa
86.2.254.in-addr.arpa
87.2.254.in-addr.arpa
88.2.254.in-addr.arpa
89.2.254.in-addr.arpa
90.2.254.in-addr.arpa
91.2.254.in-addr.arpa
92.2.254.in-addr.arpa
93.2.254.in-addr.arpa
94.2.254.in-addr.arpa
95.2.254.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
Address11111110.00000010.01010000.00000000254.2.80.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network11111110.00000010.01010000.00000000254.2.80.0
Broadcast11111110.00000010.01011111.11111111254.2.95.255
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)

254.2.80.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1254.2.80.0/32254.2.80.0 to 254.2.80.0—1
2254.2.80.1/32254.2.80.1 to 254.2.80.1—1
3254.2.80.2/32254.2.80.2 to 254.2.80.2—1
4254.2.80.3/32254.2.80.3 to 254.2.80.3—1
5254.2.80.4/32254.2.80.4 to 254.2.80.4—1
6254.2.80.5/32254.2.80.5 to 254.2.80.5—1
7254.2.80.6/32254.2.80.6 to 254.2.80.6—1
8254.2.80.7/32254.2.80.7 to 254.2.80.7—1
9254.2.80.8/32254.2.80.8 to 254.2.80.8—1
10254.2.80.9/32254.2.80.9 to 254.2.80.9—1
11254.2.80.10/32254.2.80.10 to 254.2.80.10—1
12254.2.80.11/32254.2.80.11 to 254.2.80.11—1
13254.2.80.12/32254.2.80.12 to 254.2.80.12—1
14254.2.80.13/32254.2.80.13 to 254.2.80.13—1
15254.2.80.14/32254.2.80.14 to 254.2.80.14—1
16254.2.80.15/32254.2.80.15 to 254.2.80.15—1
17254.2.80.16/32254.2.80.16 to 254.2.80.16—1
18254.2.80.17/32254.2.80.17 to 254.2.80.17—1
19254.2.80.18/32254.2.80.18 to 254.2.80.18—1
20254.2.80.19/32254.2.80.19 to 254.2.80.19—1
21254.2.80.20/32254.2.80.20 to 254.2.80.20—1
22254.2.80.21/32254.2.80.21 to 254.2.80.21—1
23254.2.80.22/32254.2.80.22 to 254.2.80.22—1
24254.2.80.23/32254.2.80.23 to 254.2.80.23—1
25254.2.80.24/32254.2.80.24 to 254.2.80.24—1
26254.2.80.25/32254.2.80.25 to 254.2.80.25—1
27254.2.80.26/32254.2.80.26 to 254.2.80.26—1
28254.2.80.27/32254.2.80.27 to 254.2.80.27—1
29254.2.80.28/32254.2.80.28 to 254.2.80.28—1
30254.2.80.29/32254.2.80.29 to 254.2.80.29—1
31254.2.80.30/32254.2.80.30 to 254.2.80.30—1
32254.2.80.31/32254.2.80.31 to 254.2.80.31—1
33254.2.80.32/32254.2.80.32 to 254.2.80.32—1
34254.2.80.33/32254.2.80.33 to 254.2.80.33—1
35254.2.80.34/32254.2.80.34 to 254.2.80.34—1
36254.2.80.35/32254.2.80.35 to 254.2.80.35—1
37254.2.80.36/32254.2.80.36 to 254.2.80.36—1
38254.2.80.37/32254.2.80.37 to 254.2.80.37—1
39254.2.80.38/32254.2.80.38 to 254.2.80.38—1
40254.2.80.39/32254.2.80.39 to 254.2.80.39—1
41254.2.80.40/32254.2.80.40 to 254.2.80.40—1
42254.2.80.41/32254.2.80.41 to 254.2.80.41—1
43254.2.80.42/32254.2.80.42 to 254.2.80.42—1
44254.2.80.43/32254.2.80.43 to 254.2.80.43—1
45254.2.80.44/32254.2.80.44 to 254.2.80.44—1
46254.2.80.45/32254.2.80.45 to 254.2.80.45—1
47254.2.80.46/32254.2.80.46 to 254.2.80.46—1
48254.2.80.47/32254.2.80.47 to 254.2.80.47—1
49254.2.80.48/32254.2.80.48 to 254.2.80.48—1
50254.2.80.49/32254.2.80.49 to 254.2.80.49—1
51254.2.80.50/32254.2.80.50 to 254.2.80.50—1
52254.2.80.51/32254.2.80.51 to 254.2.80.51—1
53254.2.80.52/32254.2.80.52 to 254.2.80.52—1
54254.2.80.53/32254.2.80.53 to 254.2.80.53—1
55254.2.80.54/32254.2.80.54 to 254.2.80.54—1
56254.2.80.55/32254.2.80.55 to 254.2.80.55—1
57254.2.80.56/32254.2.80.56 to 254.2.80.56—1
58254.2.80.57/32254.2.80.57 to 254.2.80.57—1
59254.2.80.58/32254.2.80.58 to 254.2.80.58—1
60254.2.80.59/32254.2.80.59 to 254.2.80.59—1
61254.2.80.60/32254.2.80.60 to 254.2.80.60—1
62254.2.80.61/32254.2.80.61 to 254.2.80.61—1
63254.2.80.62/32254.2.80.62 to 254.2.80.62—1
64254.2.80.63/32254.2.80.63 to 254.2.80.63—1
65254.2.80.64/32254.2.80.64 to 254.2.80.64—1
66254.2.80.65/32254.2.80.65 to 254.2.80.65—1
67254.2.80.66/32254.2.80.66 to 254.2.80.66—1
68254.2.80.67/32254.2.80.67 to 254.2.80.67—1
69254.2.80.68/32254.2.80.68 to 254.2.80.68—1
70254.2.80.69/32254.2.80.69 to 254.2.80.69—1
71254.2.80.70/32254.2.80.70 to 254.2.80.70—1
72254.2.80.71/32254.2.80.71 to 254.2.80.71—1
73254.2.80.72/32254.2.80.72 to 254.2.80.72—1
74254.2.80.73/32254.2.80.73 to 254.2.80.73—1
75254.2.80.74/32254.2.80.74 to 254.2.80.74—1
76254.2.80.75/32254.2.80.75 to 254.2.80.75—1
77254.2.80.76/32254.2.80.76 to 254.2.80.76—1
78254.2.80.77/32254.2.80.77 to 254.2.80.77—1
79254.2.80.78/32254.2.80.78 to 254.2.80.78—1
80254.2.80.79/32254.2.80.79 to 254.2.80.79—1
81254.2.80.80/32254.2.80.80 to 254.2.80.80—1
82254.2.80.81/32254.2.80.81 to 254.2.80.81—1
83254.2.80.82/32254.2.80.82 to 254.2.80.82—1
84254.2.80.83/32254.2.80.83 to 254.2.80.83—1
85254.2.80.84/32254.2.80.84 to 254.2.80.84—1
86254.2.80.85/32254.2.80.85 to 254.2.80.85—1
87254.2.80.86/32254.2.80.86 to 254.2.80.86—1
88254.2.80.87/32254.2.80.87 to 254.2.80.87—1
89254.2.80.88/32254.2.80.88 to 254.2.80.88—1
90254.2.80.89/32254.2.80.89 to 254.2.80.89—1
91254.2.80.90/32254.2.80.90 to 254.2.80.90—1
92254.2.80.91/32254.2.80.91 to 254.2.80.91—1
93254.2.80.92/32254.2.80.92 to 254.2.80.92—1
94254.2.80.93/32254.2.80.93 to 254.2.80.93—1
95254.2.80.94/32254.2.80.94 to 254.2.80.94—1
96254.2.80.95/32254.2.80.95 to 254.2.80.95—1
97254.2.80.96/32254.2.80.96 to 254.2.80.96—1
98254.2.80.97/32254.2.80.97 to 254.2.80.97—1
99254.2.80.98/32254.2.80.98 to 254.2.80.98—1
100254.2.80.99/32254.2.80.99 to 254.2.80.99—1
101254.2.80.100/32254.2.80.100 to 254.2.80.100—1
102254.2.80.101/32254.2.80.101 to 254.2.80.101—1
103254.2.80.102/32254.2.80.102 to 254.2.80.102—1
104254.2.80.103/32254.2.80.103 to 254.2.80.103—1
105254.2.80.104/32254.2.80.104 to 254.2.80.104—1
106254.2.80.105/32254.2.80.105 to 254.2.80.105—1
107254.2.80.106/32254.2.80.106 to 254.2.80.106—1
108254.2.80.107/32254.2.80.107 to 254.2.80.107—1
109254.2.80.108/32254.2.80.108 to 254.2.80.108—1
110254.2.80.109/32254.2.80.109 to 254.2.80.109—1
111254.2.80.110/32254.2.80.110 to 254.2.80.110—1
112254.2.80.111/32254.2.80.111 to 254.2.80.111—1
113254.2.80.112/32254.2.80.112 to 254.2.80.112—1
114254.2.80.113/32254.2.80.113 to 254.2.80.113—1
115254.2.80.114/32254.2.80.114 to 254.2.80.114—1
116254.2.80.115/32254.2.80.115 to 254.2.80.115—1
117254.2.80.116/32254.2.80.116 to 254.2.80.116—1
118254.2.80.117/32254.2.80.117 to 254.2.80.117—1
119254.2.80.118/32254.2.80.118 to 254.2.80.118—1
120254.2.80.119/32254.2.80.119 to 254.2.80.119—1
121254.2.80.120/32254.2.80.120 to 254.2.80.120—1
122254.2.80.121/32254.2.80.121 to 254.2.80.121—1
123254.2.80.122/32254.2.80.122 to 254.2.80.122—1
124254.2.80.123/32254.2.80.123 to 254.2.80.123—1
125254.2.80.124/32254.2.80.124 to 254.2.80.124—1
126254.2.80.125/32254.2.80.125 to 254.2.80.125—1
127254.2.80.126/32254.2.80.126 to 254.2.80.126—1
128254.2.80.127/32254.2.80.127 to 254.2.80.127—1
129254.2.80.128/32254.2.80.128 to 254.2.80.128—1
130254.2.80.129/32254.2.80.129 to 254.2.80.129—1
131254.2.80.130/32254.2.80.130 to 254.2.80.130—1
132254.2.80.131/32254.2.80.131 to 254.2.80.131—1
133254.2.80.132/32254.2.80.132 to 254.2.80.132—1
134254.2.80.133/32254.2.80.133 to 254.2.80.133—1
135254.2.80.134/32254.2.80.134 to 254.2.80.134—1
136254.2.80.135/32254.2.80.135 to 254.2.80.135—1
137254.2.80.136/32254.2.80.136 to 254.2.80.136—1
138254.2.80.137/32254.2.80.137 to 254.2.80.137—1
139254.2.80.138/32254.2.80.138 to 254.2.80.138—1
140254.2.80.139/32254.2.80.139 to 254.2.80.139—1
141254.2.80.140/32254.2.80.140 to 254.2.80.140—1
142254.2.80.141/32254.2.80.141 to 254.2.80.141—1
143254.2.80.142/32254.2.80.142 to 254.2.80.142—1
144254.2.80.143/32254.2.80.143 to 254.2.80.143—1
145254.2.80.144/32254.2.80.144 to 254.2.80.144—1
146254.2.80.145/32254.2.80.145 to 254.2.80.145—1
147254.2.80.146/32254.2.80.146 to 254.2.80.146—1
148254.2.80.147/32254.2.80.147 to 254.2.80.147—1
149254.2.80.148/32254.2.80.148 to 254.2.80.148—1
150254.2.80.149/32254.2.80.149 to 254.2.80.149—1
151254.2.80.150/32254.2.80.150 to 254.2.80.150—1
152254.2.80.151/32254.2.80.151 to 254.2.80.151—1
153254.2.80.152/32254.2.80.152 to 254.2.80.152—1
154254.2.80.153/32254.2.80.153 to 254.2.80.153—1
155254.2.80.154/32254.2.80.154 to 254.2.80.154—1
156254.2.80.155/32254.2.80.155 to 254.2.80.155—1
157254.2.80.156/32254.2.80.156 to 254.2.80.156—1
158254.2.80.157/32254.2.80.157 to 254.2.80.157—1
159254.2.80.158/32254.2.80.158 to 254.2.80.158—1
160254.2.80.159/32254.2.80.159 to 254.2.80.159—1
161254.2.80.160/32254.2.80.160 to 254.2.80.160—1
162254.2.80.161/32254.2.80.161 to 254.2.80.161—1
163254.2.80.162/32254.2.80.162 to 254.2.80.162—1
164254.2.80.163/32254.2.80.163 to 254.2.80.163—1
165254.2.80.164/32254.2.80.164 to 254.2.80.164—1
166254.2.80.165/32254.2.80.165 to 254.2.80.165—1
167254.2.80.166/32254.2.80.166 to 254.2.80.166—1
168254.2.80.167/32254.2.80.167 to 254.2.80.167—1
169254.2.80.168/32254.2.80.168 to 254.2.80.168—1
170254.2.80.169/32254.2.80.169 to 254.2.80.169—1
171254.2.80.170/32254.2.80.170 to 254.2.80.170—1
172254.2.80.171/32254.2.80.171 to 254.2.80.171—1
173254.2.80.172/32254.2.80.172 to 254.2.80.172—1
174254.2.80.173/32254.2.80.173 to 254.2.80.173—1
175254.2.80.174/32254.2.80.174 to 254.2.80.174—1
176254.2.80.175/32254.2.80.175 to 254.2.80.175—1
177254.2.80.176/32254.2.80.176 to 254.2.80.176—1
178254.2.80.177/32254.2.80.177 to 254.2.80.177—1
179254.2.80.178/32254.2.80.178 to 254.2.80.178—1
180254.2.80.179/32254.2.80.179 to 254.2.80.179—1
181254.2.80.180/32254.2.80.180 to 254.2.80.180—1
182254.2.80.181/32254.2.80.181 to 254.2.80.181—1
183254.2.80.182/32254.2.80.182 to 254.2.80.182—1
184254.2.80.183/32254.2.80.183 to 254.2.80.183—1
185254.2.80.184/32254.2.80.184 to 254.2.80.184—1
186254.2.80.185/32254.2.80.185 to 254.2.80.185—1
187254.2.80.186/32254.2.80.186 to 254.2.80.186—1
188254.2.80.187/32254.2.80.187 to 254.2.80.187—1
189254.2.80.188/32254.2.80.188 to 254.2.80.188—1
190254.2.80.189/32254.2.80.189 to 254.2.80.189—1
191254.2.80.190/32254.2.80.190 to 254.2.80.190—1
192254.2.80.191/32254.2.80.191 to 254.2.80.191—1
193254.2.80.192/32254.2.80.192 to 254.2.80.192—1
194254.2.80.193/32254.2.80.193 to 254.2.80.193—1
195254.2.80.194/32254.2.80.194 to 254.2.80.194—1
196254.2.80.195/32254.2.80.195 to 254.2.80.195—1
197254.2.80.196/32254.2.80.196 to 254.2.80.196—1
198254.2.80.197/32254.2.80.197 to 254.2.80.197—1
199254.2.80.198/32254.2.80.198 to 254.2.80.198—1
200254.2.80.199/32254.2.80.199 to 254.2.80.199—1
201254.2.80.200/32254.2.80.200 to 254.2.80.200—1
202254.2.80.201/32254.2.80.201 to 254.2.80.201—1
203254.2.80.202/32254.2.80.202 to 254.2.80.202—1
204254.2.80.203/32254.2.80.203 to 254.2.80.203—1
205254.2.80.204/32254.2.80.204 to 254.2.80.204—1
206254.2.80.205/32254.2.80.205 to 254.2.80.205—1
207254.2.80.206/32254.2.80.206 to 254.2.80.206—1
208254.2.80.207/32254.2.80.207 to 254.2.80.207—1
209254.2.80.208/32254.2.80.208 to 254.2.80.208—1
210254.2.80.209/32254.2.80.209 to 254.2.80.209—1
211254.2.80.210/32254.2.80.210 to 254.2.80.210—1
212254.2.80.211/32254.2.80.211 to 254.2.80.211—1
213254.2.80.212/32254.2.80.212 to 254.2.80.212—1
214254.2.80.213/32254.2.80.213 to 254.2.80.213—1
215254.2.80.214/32254.2.80.214 to 254.2.80.214—1
216254.2.80.215/32254.2.80.215 to 254.2.80.215—1
217254.2.80.216/32254.2.80.216 to 254.2.80.216—1
218254.2.80.217/32254.2.80.217 to 254.2.80.217—1
219254.2.80.218/32254.2.80.218 to 254.2.80.218—1
220254.2.80.219/32254.2.80.219 to 254.2.80.219—1
221254.2.80.220/32254.2.80.220 to 254.2.80.220—1
222254.2.80.221/32254.2.80.221 to 254.2.80.221—1
223254.2.80.222/32254.2.80.222 to 254.2.80.222—1
224254.2.80.223/32254.2.80.223 to 254.2.80.223—1
225254.2.80.224/32254.2.80.224 to 254.2.80.224—1
226254.2.80.225/32254.2.80.225 to 254.2.80.225—1
227254.2.80.226/32254.2.80.226 to 254.2.80.226—1
228254.2.80.227/32254.2.80.227 to 254.2.80.227—1
229254.2.80.228/32254.2.80.228 to 254.2.80.228—1
230254.2.80.229/32254.2.80.229 to 254.2.80.229—1
231254.2.80.230/32254.2.80.230 to 254.2.80.230—1
232254.2.80.231/32254.2.80.231 to 254.2.80.231—1
233254.2.80.232/32254.2.80.232 to 254.2.80.232—1
234254.2.80.233/32254.2.80.233 to 254.2.80.233—1
235254.2.80.234/32254.2.80.234 to 254.2.80.234—1
236254.2.80.235/32254.2.80.235 to 254.2.80.235—1
237254.2.80.236/32254.2.80.236 to 254.2.80.236—1
238254.2.80.237/32254.2.80.237 to 254.2.80.237—1
239254.2.80.238/32254.2.80.238 to 254.2.80.238—1
240254.2.80.239/32254.2.80.239 to 254.2.80.239—1
241254.2.80.240/32254.2.80.240 to 254.2.80.240—1
242254.2.80.241/32254.2.80.241 to 254.2.80.241—1
243254.2.80.242/32254.2.80.242 to 254.2.80.242—1
244254.2.80.243/32254.2.80.243 to 254.2.80.243—1
245254.2.80.244/32254.2.80.244 to 254.2.80.244—1
246254.2.80.245/32254.2.80.245 to 254.2.80.245—1
247254.2.80.246/32254.2.80.246 to 254.2.80.246—1
248254.2.80.247/32254.2.80.247 to 254.2.80.247—1
249254.2.80.248/32254.2.80.248 to 254.2.80.248—1
250254.2.80.249/32254.2.80.249 to 254.2.80.249—1
251254.2.80.250/32254.2.80.250 to 254.2.80.250—1
252254.2.80.251/32254.2.80.251 to 254.2.80.251—1
253254.2.80.252/32254.2.80.252 to 254.2.80.252—1
254254.2.80.253/32254.2.80.253 to 254.2.80.253—1
255254.2.80.254/32254.2.80.254 to 254.2.80.254—1
256254.2.80.255/32254.2.80.255 to 254.2.80.255—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.