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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.

Network145.3.32.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
145.3.32.0
Broadcast address
145.3.47.255
First usable
145.3.32.1
Last usable
145.3.47.254
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 91032000 · Integer 2432901120 to 2432905215
Reverse DNS zones
32.3.145.in-addr.arpa
33.3.145.in-addr.arpa
34.3.145.in-addr.arpa
35.3.145.in-addr.arpa
36.3.145.in-addr.arpa
37.3.145.in-addr.arpa
38.3.145.in-addr.arpa
39.3.145.in-addr.arpa
40.3.145.in-addr.arpa
41.3.145.in-addr.arpa
42.3.145.in-addr.arpa
43.3.145.in-addr.arpa
44.3.145.in-addr.arpa
45.3.145.in-addr.arpa
46.3.145.in-addr.arpa
47.3.145.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
Address10010001.00000011.00100000.00000000145.3.32.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network10010001.00000011.00100000.00000000145.3.32.0
Broadcast10010001.00000011.00101111.11111111145.3.47.255
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)

145.3.32.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1145.3.32.0/32145.3.32.0 to 145.3.32.0—1
2145.3.32.1/32145.3.32.1 to 145.3.32.1—1
3145.3.32.2/32145.3.32.2 to 145.3.32.2—1
4145.3.32.3/32145.3.32.3 to 145.3.32.3—1
5145.3.32.4/32145.3.32.4 to 145.3.32.4—1
6145.3.32.5/32145.3.32.5 to 145.3.32.5—1
7145.3.32.6/32145.3.32.6 to 145.3.32.6—1
8145.3.32.7/32145.3.32.7 to 145.3.32.7—1
9145.3.32.8/32145.3.32.8 to 145.3.32.8—1
10145.3.32.9/32145.3.32.9 to 145.3.32.9—1
11145.3.32.10/32145.3.32.10 to 145.3.32.10—1
12145.3.32.11/32145.3.32.11 to 145.3.32.11—1
13145.3.32.12/32145.3.32.12 to 145.3.32.12—1
14145.3.32.13/32145.3.32.13 to 145.3.32.13—1
15145.3.32.14/32145.3.32.14 to 145.3.32.14—1
16145.3.32.15/32145.3.32.15 to 145.3.32.15—1
17145.3.32.16/32145.3.32.16 to 145.3.32.16—1
18145.3.32.17/32145.3.32.17 to 145.3.32.17—1
19145.3.32.18/32145.3.32.18 to 145.3.32.18—1
20145.3.32.19/32145.3.32.19 to 145.3.32.19—1
21145.3.32.20/32145.3.32.20 to 145.3.32.20—1
22145.3.32.21/32145.3.32.21 to 145.3.32.21—1
23145.3.32.22/32145.3.32.22 to 145.3.32.22—1
24145.3.32.23/32145.3.32.23 to 145.3.32.23—1
25145.3.32.24/32145.3.32.24 to 145.3.32.24—1
26145.3.32.25/32145.3.32.25 to 145.3.32.25—1
27145.3.32.26/32145.3.32.26 to 145.3.32.26—1
28145.3.32.27/32145.3.32.27 to 145.3.32.27—1
29145.3.32.28/32145.3.32.28 to 145.3.32.28—1
30145.3.32.29/32145.3.32.29 to 145.3.32.29—1
31145.3.32.30/32145.3.32.30 to 145.3.32.30—1
32145.3.32.31/32145.3.32.31 to 145.3.32.31—1
33145.3.32.32/32145.3.32.32 to 145.3.32.32—1
34145.3.32.33/32145.3.32.33 to 145.3.32.33—1
35145.3.32.34/32145.3.32.34 to 145.3.32.34—1
36145.3.32.35/32145.3.32.35 to 145.3.32.35—1
37145.3.32.36/32145.3.32.36 to 145.3.32.36—1
38145.3.32.37/32145.3.32.37 to 145.3.32.37—1
39145.3.32.38/32145.3.32.38 to 145.3.32.38—1
40145.3.32.39/32145.3.32.39 to 145.3.32.39—1
41145.3.32.40/32145.3.32.40 to 145.3.32.40—1
42145.3.32.41/32145.3.32.41 to 145.3.32.41—1
43145.3.32.42/32145.3.32.42 to 145.3.32.42—1
44145.3.32.43/32145.3.32.43 to 145.3.32.43—1
45145.3.32.44/32145.3.32.44 to 145.3.32.44—1
46145.3.32.45/32145.3.32.45 to 145.3.32.45—1
47145.3.32.46/32145.3.32.46 to 145.3.32.46—1
48145.3.32.47/32145.3.32.47 to 145.3.32.47—1
49145.3.32.48/32145.3.32.48 to 145.3.32.48—1
50145.3.32.49/32145.3.32.49 to 145.3.32.49—1
51145.3.32.50/32145.3.32.50 to 145.3.32.50—1
52145.3.32.51/32145.3.32.51 to 145.3.32.51—1
53145.3.32.52/32145.3.32.52 to 145.3.32.52—1
54145.3.32.53/32145.3.32.53 to 145.3.32.53—1
55145.3.32.54/32145.3.32.54 to 145.3.32.54—1
56145.3.32.55/32145.3.32.55 to 145.3.32.55—1
57145.3.32.56/32145.3.32.56 to 145.3.32.56—1
58145.3.32.57/32145.3.32.57 to 145.3.32.57—1
59145.3.32.58/32145.3.32.58 to 145.3.32.58—1
60145.3.32.59/32145.3.32.59 to 145.3.32.59—1
61145.3.32.60/32145.3.32.60 to 145.3.32.60—1
62145.3.32.61/32145.3.32.61 to 145.3.32.61—1
63145.3.32.62/32145.3.32.62 to 145.3.32.62—1
64145.3.32.63/32145.3.32.63 to 145.3.32.63—1
65145.3.32.64/32145.3.32.64 to 145.3.32.64—1
66145.3.32.65/32145.3.32.65 to 145.3.32.65—1
67145.3.32.66/32145.3.32.66 to 145.3.32.66—1
68145.3.32.67/32145.3.32.67 to 145.3.32.67—1
69145.3.32.68/32145.3.32.68 to 145.3.32.68—1
70145.3.32.69/32145.3.32.69 to 145.3.32.69—1
71145.3.32.70/32145.3.32.70 to 145.3.32.70—1
72145.3.32.71/32145.3.32.71 to 145.3.32.71—1
73145.3.32.72/32145.3.32.72 to 145.3.32.72—1
74145.3.32.73/32145.3.32.73 to 145.3.32.73—1
75145.3.32.74/32145.3.32.74 to 145.3.32.74—1
76145.3.32.75/32145.3.32.75 to 145.3.32.75—1
77145.3.32.76/32145.3.32.76 to 145.3.32.76—1
78145.3.32.77/32145.3.32.77 to 145.3.32.77—1
79145.3.32.78/32145.3.32.78 to 145.3.32.78—1
80145.3.32.79/32145.3.32.79 to 145.3.32.79—1
81145.3.32.80/32145.3.32.80 to 145.3.32.80—1
82145.3.32.81/32145.3.32.81 to 145.3.32.81—1
83145.3.32.82/32145.3.32.82 to 145.3.32.82—1
84145.3.32.83/32145.3.32.83 to 145.3.32.83—1
85145.3.32.84/32145.3.32.84 to 145.3.32.84—1
86145.3.32.85/32145.3.32.85 to 145.3.32.85—1
87145.3.32.86/32145.3.32.86 to 145.3.32.86—1
88145.3.32.87/32145.3.32.87 to 145.3.32.87—1
89145.3.32.88/32145.3.32.88 to 145.3.32.88—1
90145.3.32.89/32145.3.32.89 to 145.3.32.89—1
91145.3.32.90/32145.3.32.90 to 145.3.32.90—1
92145.3.32.91/32145.3.32.91 to 145.3.32.91—1
93145.3.32.92/32145.3.32.92 to 145.3.32.92—1
94145.3.32.93/32145.3.32.93 to 145.3.32.93—1
95145.3.32.94/32145.3.32.94 to 145.3.32.94—1
96145.3.32.95/32145.3.32.95 to 145.3.32.95—1
97145.3.32.96/32145.3.32.96 to 145.3.32.96—1
98145.3.32.97/32145.3.32.97 to 145.3.32.97—1
99145.3.32.98/32145.3.32.98 to 145.3.32.98—1
100145.3.32.99/32145.3.32.99 to 145.3.32.99—1
101145.3.32.100/32145.3.32.100 to 145.3.32.100—1
102145.3.32.101/32145.3.32.101 to 145.3.32.101—1
103145.3.32.102/32145.3.32.102 to 145.3.32.102—1
104145.3.32.103/32145.3.32.103 to 145.3.32.103—1
105145.3.32.104/32145.3.32.104 to 145.3.32.104—1
106145.3.32.105/32145.3.32.105 to 145.3.32.105—1
107145.3.32.106/32145.3.32.106 to 145.3.32.106—1
108145.3.32.107/32145.3.32.107 to 145.3.32.107—1
109145.3.32.108/32145.3.32.108 to 145.3.32.108—1
110145.3.32.109/32145.3.32.109 to 145.3.32.109—1
111145.3.32.110/32145.3.32.110 to 145.3.32.110—1
112145.3.32.111/32145.3.32.111 to 145.3.32.111—1
113145.3.32.112/32145.3.32.112 to 145.3.32.112—1
114145.3.32.113/32145.3.32.113 to 145.3.32.113—1
115145.3.32.114/32145.3.32.114 to 145.3.32.114—1
116145.3.32.115/32145.3.32.115 to 145.3.32.115—1
117145.3.32.116/32145.3.32.116 to 145.3.32.116—1
118145.3.32.117/32145.3.32.117 to 145.3.32.117—1
119145.3.32.118/32145.3.32.118 to 145.3.32.118—1
120145.3.32.119/32145.3.32.119 to 145.3.32.119—1
121145.3.32.120/32145.3.32.120 to 145.3.32.120—1
122145.3.32.121/32145.3.32.121 to 145.3.32.121—1
123145.3.32.122/32145.3.32.122 to 145.3.32.122—1
124145.3.32.123/32145.3.32.123 to 145.3.32.123—1
125145.3.32.124/32145.3.32.124 to 145.3.32.124—1
126145.3.32.125/32145.3.32.125 to 145.3.32.125—1
127145.3.32.126/32145.3.32.126 to 145.3.32.126—1
128145.3.32.127/32145.3.32.127 to 145.3.32.127—1
129145.3.32.128/32145.3.32.128 to 145.3.32.128—1
130145.3.32.129/32145.3.32.129 to 145.3.32.129—1
131145.3.32.130/32145.3.32.130 to 145.3.32.130—1
132145.3.32.131/32145.3.32.131 to 145.3.32.131—1
133145.3.32.132/32145.3.32.132 to 145.3.32.132—1
134145.3.32.133/32145.3.32.133 to 145.3.32.133—1
135145.3.32.134/32145.3.32.134 to 145.3.32.134—1
136145.3.32.135/32145.3.32.135 to 145.3.32.135—1
137145.3.32.136/32145.3.32.136 to 145.3.32.136—1
138145.3.32.137/32145.3.32.137 to 145.3.32.137—1
139145.3.32.138/32145.3.32.138 to 145.3.32.138—1
140145.3.32.139/32145.3.32.139 to 145.3.32.139—1
141145.3.32.140/32145.3.32.140 to 145.3.32.140—1
142145.3.32.141/32145.3.32.141 to 145.3.32.141—1
143145.3.32.142/32145.3.32.142 to 145.3.32.142—1
144145.3.32.143/32145.3.32.143 to 145.3.32.143—1
145145.3.32.144/32145.3.32.144 to 145.3.32.144—1
146145.3.32.145/32145.3.32.145 to 145.3.32.145—1
147145.3.32.146/32145.3.32.146 to 145.3.32.146—1
148145.3.32.147/32145.3.32.147 to 145.3.32.147—1
149145.3.32.148/32145.3.32.148 to 145.3.32.148—1
150145.3.32.149/32145.3.32.149 to 145.3.32.149—1
151145.3.32.150/32145.3.32.150 to 145.3.32.150—1
152145.3.32.151/32145.3.32.151 to 145.3.32.151—1
153145.3.32.152/32145.3.32.152 to 145.3.32.152—1
154145.3.32.153/32145.3.32.153 to 145.3.32.153—1
155145.3.32.154/32145.3.32.154 to 145.3.32.154—1
156145.3.32.155/32145.3.32.155 to 145.3.32.155—1
157145.3.32.156/32145.3.32.156 to 145.3.32.156—1
158145.3.32.157/32145.3.32.157 to 145.3.32.157—1
159145.3.32.158/32145.3.32.158 to 145.3.32.158—1
160145.3.32.159/32145.3.32.159 to 145.3.32.159—1
161145.3.32.160/32145.3.32.160 to 145.3.32.160—1
162145.3.32.161/32145.3.32.161 to 145.3.32.161—1
163145.3.32.162/32145.3.32.162 to 145.3.32.162—1
164145.3.32.163/32145.3.32.163 to 145.3.32.163—1
165145.3.32.164/32145.3.32.164 to 145.3.32.164—1
166145.3.32.165/32145.3.32.165 to 145.3.32.165—1
167145.3.32.166/32145.3.32.166 to 145.3.32.166—1
168145.3.32.167/32145.3.32.167 to 145.3.32.167—1
169145.3.32.168/32145.3.32.168 to 145.3.32.168—1
170145.3.32.169/32145.3.32.169 to 145.3.32.169—1
171145.3.32.170/32145.3.32.170 to 145.3.32.170—1
172145.3.32.171/32145.3.32.171 to 145.3.32.171—1
173145.3.32.172/32145.3.32.172 to 145.3.32.172—1
174145.3.32.173/32145.3.32.173 to 145.3.32.173—1
175145.3.32.174/32145.3.32.174 to 145.3.32.174—1
176145.3.32.175/32145.3.32.175 to 145.3.32.175—1
177145.3.32.176/32145.3.32.176 to 145.3.32.176—1
178145.3.32.177/32145.3.32.177 to 145.3.32.177—1
179145.3.32.178/32145.3.32.178 to 145.3.32.178—1
180145.3.32.179/32145.3.32.179 to 145.3.32.179—1
181145.3.32.180/32145.3.32.180 to 145.3.32.180—1
182145.3.32.181/32145.3.32.181 to 145.3.32.181—1
183145.3.32.182/32145.3.32.182 to 145.3.32.182—1
184145.3.32.183/32145.3.32.183 to 145.3.32.183—1
185145.3.32.184/32145.3.32.184 to 145.3.32.184—1
186145.3.32.185/32145.3.32.185 to 145.3.32.185—1
187145.3.32.186/32145.3.32.186 to 145.3.32.186—1
188145.3.32.187/32145.3.32.187 to 145.3.32.187—1
189145.3.32.188/32145.3.32.188 to 145.3.32.188—1
190145.3.32.189/32145.3.32.189 to 145.3.32.189—1
191145.3.32.190/32145.3.32.190 to 145.3.32.190—1
192145.3.32.191/32145.3.32.191 to 145.3.32.191—1
193145.3.32.192/32145.3.32.192 to 145.3.32.192—1
194145.3.32.193/32145.3.32.193 to 145.3.32.193—1
195145.3.32.194/32145.3.32.194 to 145.3.32.194—1
196145.3.32.195/32145.3.32.195 to 145.3.32.195—1
197145.3.32.196/32145.3.32.196 to 145.3.32.196—1
198145.3.32.197/32145.3.32.197 to 145.3.32.197—1
199145.3.32.198/32145.3.32.198 to 145.3.32.198—1
200145.3.32.199/32145.3.32.199 to 145.3.32.199—1
201145.3.32.200/32145.3.32.200 to 145.3.32.200—1
202145.3.32.201/32145.3.32.201 to 145.3.32.201—1
203145.3.32.202/32145.3.32.202 to 145.3.32.202—1
204145.3.32.203/32145.3.32.203 to 145.3.32.203—1
205145.3.32.204/32145.3.32.204 to 145.3.32.204—1
206145.3.32.205/32145.3.32.205 to 145.3.32.205—1
207145.3.32.206/32145.3.32.206 to 145.3.32.206—1
208145.3.32.207/32145.3.32.207 to 145.3.32.207—1
209145.3.32.208/32145.3.32.208 to 145.3.32.208—1
210145.3.32.209/32145.3.32.209 to 145.3.32.209—1
211145.3.32.210/32145.3.32.210 to 145.3.32.210—1
212145.3.32.211/32145.3.32.211 to 145.3.32.211—1
213145.3.32.212/32145.3.32.212 to 145.3.32.212—1
214145.3.32.213/32145.3.32.213 to 145.3.32.213—1
215145.3.32.214/32145.3.32.214 to 145.3.32.214—1
216145.3.32.215/32145.3.32.215 to 145.3.32.215—1
217145.3.32.216/32145.3.32.216 to 145.3.32.216—1
218145.3.32.217/32145.3.32.217 to 145.3.32.217—1
219145.3.32.218/32145.3.32.218 to 145.3.32.218—1
220145.3.32.219/32145.3.32.219 to 145.3.32.219—1
221145.3.32.220/32145.3.32.220 to 145.3.32.220—1
222145.3.32.221/32145.3.32.221 to 145.3.32.221—1
223145.3.32.222/32145.3.32.222 to 145.3.32.222—1
224145.3.32.223/32145.3.32.223 to 145.3.32.223—1
225145.3.32.224/32145.3.32.224 to 145.3.32.224—1
226145.3.32.225/32145.3.32.225 to 145.3.32.225—1
227145.3.32.226/32145.3.32.226 to 145.3.32.226—1
228145.3.32.227/32145.3.32.227 to 145.3.32.227—1
229145.3.32.228/32145.3.32.228 to 145.3.32.228—1
230145.3.32.229/32145.3.32.229 to 145.3.32.229—1
231145.3.32.230/32145.3.32.230 to 145.3.32.230—1
232145.3.32.231/32145.3.32.231 to 145.3.32.231—1
233145.3.32.232/32145.3.32.232 to 145.3.32.232—1
234145.3.32.233/32145.3.32.233 to 145.3.32.233—1
235145.3.32.234/32145.3.32.234 to 145.3.32.234—1
236145.3.32.235/32145.3.32.235 to 145.3.32.235—1
237145.3.32.236/32145.3.32.236 to 145.3.32.236—1
238145.3.32.237/32145.3.32.237 to 145.3.32.237—1
239145.3.32.238/32145.3.32.238 to 145.3.32.238—1
240145.3.32.239/32145.3.32.239 to 145.3.32.239—1
241145.3.32.240/32145.3.32.240 to 145.3.32.240—1
242145.3.32.241/32145.3.32.241 to 145.3.32.241—1
243145.3.32.242/32145.3.32.242 to 145.3.32.242—1
244145.3.32.243/32145.3.32.243 to 145.3.32.243—1
245145.3.32.244/32145.3.32.244 to 145.3.32.244—1
246145.3.32.245/32145.3.32.245 to 145.3.32.245—1
247145.3.32.246/32145.3.32.246 to 145.3.32.246—1
248145.3.32.247/32145.3.32.247 to 145.3.32.247—1
249145.3.32.248/32145.3.32.248 to 145.3.32.248—1
250145.3.32.249/32145.3.32.249 to 145.3.32.249—1
251145.3.32.250/32145.3.32.250 to 145.3.32.250—1
252145.3.32.251/32145.3.32.251 to 145.3.32.251—1
253145.3.32.252/32145.3.32.252 to 145.3.32.252—1
254145.3.32.253/32145.3.32.253 to 145.3.32.253—1
255145.3.32.254/32145.3.32.254 to 145.3.32.254—1
256145.3.32.255/32145.3.32.255 to 145.3.32.255—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.