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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.

Network221.3.80.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
221.3.80.0
Broadcast address
221.3.95.255
First usable
221.3.80.1
Last usable
221.3.95.254
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
Public public
Old class
C (default /24)
As numbers
Hex DD035000 · Integer 3707981824 to 3707985919
Reverse DNS zones
80.3.221.in-addr.arpa
81.3.221.in-addr.arpa
82.3.221.in-addr.arpa
83.3.221.in-addr.arpa
84.3.221.in-addr.arpa
85.3.221.in-addr.arpa
86.3.221.in-addr.arpa
87.3.221.in-addr.arpa
88.3.221.in-addr.arpa
89.3.221.in-addr.arpa
90.3.221.in-addr.arpa
91.3.221.in-addr.arpa
92.3.221.in-addr.arpa
93.3.221.in-addr.arpa
94.3.221.in-addr.arpa
95.3.221.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
Address11011101.00000011.01010000.00000000221.3.80.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network11011101.00000011.01010000.00000000221.3.80.0
Broadcast11011101.00000011.01011111.11111111221.3.95.255
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)

221.3.80.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1221.3.80.0/32221.3.80.0 to 221.3.80.0—1
2221.3.80.1/32221.3.80.1 to 221.3.80.1—1
3221.3.80.2/32221.3.80.2 to 221.3.80.2—1
4221.3.80.3/32221.3.80.3 to 221.3.80.3—1
5221.3.80.4/32221.3.80.4 to 221.3.80.4—1
6221.3.80.5/32221.3.80.5 to 221.3.80.5—1
7221.3.80.6/32221.3.80.6 to 221.3.80.6—1
8221.3.80.7/32221.3.80.7 to 221.3.80.7—1
9221.3.80.8/32221.3.80.8 to 221.3.80.8—1
10221.3.80.9/32221.3.80.9 to 221.3.80.9—1
11221.3.80.10/32221.3.80.10 to 221.3.80.10—1
12221.3.80.11/32221.3.80.11 to 221.3.80.11—1
13221.3.80.12/32221.3.80.12 to 221.3.80.12—1
14221.3.80.13/32221.3.80.13 to 221.3.80.13—1
15221.3.80.14/32221.3.80.14 to 221.3.80.14—1
16221.3.80.15/32221.3.80.15 to 221.3.80.15—1
17221.3.80.16/32221.3.80.16 to 221.3.80.16—1
18221.3.80.17/32221.3.80.17 to 221.3.80.17—1
19221.3.80.18/32221.3.80.18 to 221.3.80.18—1
20221.3.80.19/32221.3.80.19 to 221.3.80.19—1
21221.3.80.20/32221.3.80.20 to 221.3.80.20—1
22221.3.80.21/32221.3.80.21 to 221.3.80.21—1
23221.3.80.22/32221.3.80.22 to 221.3.80.22—1
24221.3.80.23/32221.3.80.23 to 221.3.80.23—1
25221.3.80.24/32221.3.80.24 to 221.3.80.24—1
26221.3.80.25/32221.3.80.25 to 221.3.80.25—1
27221.3.80.26/32221.3.80.26 to 221.3.80.26—1
28221.3.80.27/32221.3.80.27 to 221.3.80.27—1
29221.3.80.28/32221.3.80.28 to 221.3.80.28—1
30221.3.80.29/32221.3.80.29 to 221.3.80.29—1
31221.3.80.30/32221.3.80.30 to 221.3.80.30—1
32221.3.80.31/32221.3.80.31 to 221.3.80.31—1
33221.3.80.32/32221.3.80.32 to 221.3.80.32—1
34221.3.80.33/32221.3.80.33 to 221.3.80.33—1
35221.3.80.34/32221.3.80.34 to 221.3.80.34—1
36221.3.80.35/32221.3.80.35 to 221.3.80.35—1
37221.3.80.36/32221.3.80.36 to 221.3.80.36—1
38221.3.80.37/32221.3.80.37 to 221.3.80.37—1
39221.3.80.38/32221.3.80.38 to 221.3.80.38—1
40221.3.80.39/32221.3.80.39 to 221.3.80.39—1
41221.3.80.40/32221.3.80.40 to 221.3.80.40—1
42221.3.80.41/32221.3.80.41 to 221.3.80.41—1
43221.3.80.42/32221.3.80.42 to 221.3.80.42—1
44221.3.80.43/32221.3.80.43 to 221.3.80.43—1
45221.3.80.44/32221.3.80.44 to 221.3.80.44—1
46221.3.80.45/32221.3.80.45 to 221.3.80.45—1
47221.3.80.46/32221.3.80.46 to 221.3.80.46—1
48221.3.80.47/32221.3.80.47 to 221.3.80.47—1
49221.3.80.48/32221.3.80.48 to 221.3.80.48—1
50221.3.80.49/32221.3.80.49 to 221.3.80.49—1
51221.3.80.50/32221.3.80.50 to 221.3.80.50—1
52221.3.80.51/32221.3.80.51 to 221.3.80.51—1
53221.3.80.52/32221.3.80.52 to 221.3.80.52—1
54221.3.80.53/32221.3.80.53 to 221.3.80.53—1
55221.3.80.54/32221.3.80.54 to 221.3.80.54—1
56221.3.80.55/32221.3.80.55 to 221.3.80.55—1
57221.3.80.56/32221.3.80.56 to 221.3.80.56—1
58221.3.80.57/32221.3.80.57 to 221.3.80.57—1
59221.3.80.58/32221.3.80.58 to 221.3.80.58—1
60221.3.80.59/32221.3.80.59 to 221.3.80.59—1
61221.3.80.60/32221.3.80.60 to 221.3.80.60—1
62221.3.80.61/32221.3.80.61 to 221.3.80.61—1
63221.3.80.62/32221.3.80.62 to 221.3.80.62—1
64221.3.80.63/32221.3.80.63 to 221.3.80.63—1
65221.3.80.64/32221.3.80.64 to 221.3.80.64—1
66221.3.80.65/32221.3.80.65 to 221.3.80.65—1
67221.3.80.66/32221.3.80.66 to 221.3.80.66—1
68221.3.80.67/32221.3.80.67 to 221.3.80.67—1
69221.3.80.68/32221.3.80.68 to 221.3.80.68—1
70221.3.80.69/32221.3.80.69 to 221.3.80.69—1
71221.3.80.70/32221.3.80.70 to 221.3.80.70—1
72221.3.80.71/32221.3.80.71 to 221.3.80.71—1
73221.3.80.72/32221.3.80.72 to 221.3.80.72—1
74221.3.80.73/32221.3.80.73 to 221.3.80.73—1
75221.3.80.74/32221.3.80.74 to 221.3.80.74—1
76221.3.80.75/32221.3.80.75 to 221.3.80.75—1
77221.3.80.76/32221.3.80.76 to 221.3.80.76—1
78221.3.80.77/32221.3.80.77 to 221.3.80.77—1
79221.3.80.78/32221.3.80.78 to 221.3.80.78—1
80221.3.80.79/32221.3.80.79 to 221.3.80.79—1
81221.3.80.80/32221.3.80.80 to 221.3.80.80—1
82221.3.80.81/32221.3.80.81 to 221.3.80.81—1
83221.3.80.82/32221.3.80.82 to 221.3.80.82—1
84221.3.80.83/32221.3.80.83 to 221.3.80.83—1
85221.3.80.84/32221.3.80.84 to 221.3.80.84—1
86221.3.80.85/32221.3.80.85 to 221.3.80.85—1
87221.3.80.86/32221.3.80.86 to 221.3.80.86—1
88221.3.80.87/32221.3.80.87 to 221.3.80.87—1
89221.3.80.88/32221.3.80.88 to 221.3.80.88—1
90221.3.80.89/32221.3.80.89 to 221.3.80.89—1
91221.3.80.90/32221.3.80.90 to 221.3.80.90—1
92221.3.80.91/32221.3.80.91 to 221.3.80.91—1
93221.3.80.92/32221.3.80.92 to 221.3.80.92—1
94221.3.80.93/32221.3.80.93 to 221.3.80.93—1
95221.3.80.94/32221.3.80.94 to 221.3.80.94—1
96221.3.80.95/32221.3.80.95 to 221.3.80.95—1
97221.3.80.96/32221.3.80.96 to 221.3.80.96—1
98221.3.80.97/32221.3.80.97 to 221.3.80.97—1
99221.3.80.98/32221.3.80.98 to 221.3.80.98—1
100221.3.80.99/32221.3.80.99 to 221.3.80.99—1
101221.3.80.100/32221.3.80.100 to 221.3.80.100—1
102221.3.80.101/32221.3.80.101 to 221.3.80.101—1
103221.3.80.102/32221.3.80.102 to 221.3.80.102—1
104221.3.80.103/32221.3.80.103 to 221.3.80.103—1
105221.3.80.104/32221.3.80.104 to 221.3.80.104—1
106221.3.80.105/32221.3.80.105 to 221.3.80.105—1
107221.3.80.106/32221.3.80.106 to 221.3.80.106—1
108221.3.80.107/32221.3.80.107 to 221.3.80.107—1
109221.3.80.108/32221.3.80.108 to 221.3.80.108—1
110221.3.80.109/32221.3.80.109 to 221.3.80.109—1
111221.3.80.110/32221.3.80.110 to 221.3.80.110—1
112221.3.80.111/32221.3.80.111 to 221.3.80.111—1
113221.3.80.112/32221.3.80.112 to 221.3.80.112—1
114221.3.80.113/32221.3.80.113 to 221.3.80.113—1
115221.3.80.114/32221.3.80.114 to 221.3.80.114—1
116221.3.80.115/32221.3.80.115 to 221.3.80.115—1
117221.3.80.116/32221.3.80.116 to 221.3.80.116—1
118221.3.80.117/32221.3.80.117 to 221.3.80.117—1
119221.3.80.118/32221.3.80.118 to 221.3.80.118—1
120221.3.80.119/32221.3.80.119 to 221.3.80.119—1
121221.3.80.120/32221.3.80.120 to 221.3.80.120—1
122221.3.80.121/32221.3.80.121 to 221.3.80.121—1
123221.3.80.122/32221.3.80.122 to 221.3.80.122—1
124221.3.80.123/32221.3.80.123 to 221.3.80.123—1
125221.3.80.124/32221.3.80.124 to 221.3.80.124—1
126221.3.80.125/32221.3.80.125 to 221.3.80.125—1
127221.3.80.126/32221.3.80.126 to 221.3.80.126—1
128221.3.80.127/32221.3.80.127 to 221.3.80.127—1
129221.3.80.128/32221.3.80.128 to 221.3.80.128—1
130221.3.80.129/32221.3.80.129 to 221.3.80.129—1
131221.3.80.130/32221.3.80.130 to 221.3.80.130—1
132221.3.80.131/32221.3.80.131 to 221.3.80.131—1
133221.3.80.132/32221.3.80.132 to 221.3.80.132—1
134221.3.80.133/32221.3.80.133 to 221.3.80.133—1
135221.3.80.134/32221.3.80.134 to 221.3.80.134—1
136221.3.80.135/32221.3.80.135 to 221.3.80.135—1
137221.3.80.136/32221.3.80.136 to 221.3.80.136—1
138221.3.80.137/32221.3.80.137 to 221.3.80.137—1
139221.3.80.138/32221.3.80.138 to 221.3.80.138—1
140221.3.80.139/32221.3.80.139 to 221.3.80.139—1
141221.3.80.140/32221.3.80.140 to 221.3.80.140—1
142221.3.80.141/32221.3.80.141 to 221.3.80.141—1
143221.3.80.142/32221.3.80.142 to 221.3.80.142—1
144221.3.80.143/32221.3.80.143 to 221.3.80.143—1
145221.3.80.144/32221.3.80.144 to 221.3.80.144—1
146221.3.80.145/32221.3.80.145 to 221.3.80.145—1
147221.3.80.146/32221.3.80.146 to 221.3.80.146—1
148221.3.80.147/32221.3.80.147 to 221.3.80.147—1
149221.3.80.148/32221.3.80.148 to 221.3.80.148—1
150221.3.80.149/32221.3.80.149 to 221.3.80.149—1
151221.3.80.150/32221.3.80.150 to 221.3.80.150—1
152221.3.80.151/32221.3.80.151 to 221.3.80.151—1
153221.3.80.152/32221.3.80.152 to 221.3.80.152—1
154221.3.80.153/32221.3.80.153 to 221.3.80.153—1
155221.3.80.154/32221.3.80.154 to 221.3.80.154—1
156221.3.80.155/32221.3.80.155 to 221.3.80.155—1
157221.3.80.156/32221.3.80.156 to 221.3.80.156—1
158221.3.80.157/32221.3.80.157 to 221.3.80.157—1
159221.3.80.158/32221.3.80.158 to 221.3.80.158—1
160221.3.80.159/32221.3.80.159 to 221.3.80.159—1
161221.3.80.160/32221.3.80.160 to 221.3.80.160—1
162221.3.80.161/32221.3.80.161 to 221.3.80.161—1
163221.3.80.162/32221.3.80.162 to 221.3.80.162—1
164221.3.80.163/32221.3.80.163 to 221.3.80.163—1
165221.3.80.164/32221.3.80.164 to 221.3.80.164—1
166221.3.80.165/32221.3.80.165 to 221.3.80.165—1
167221.3.80.166/32221.3.80.166 to 221.3.80.166—1
168221.3.80.167/32221.3.80.167 to 221.3.80.167—1
169221.3.80.168/32221.3.80.168 to 221.3.80.168—1
170221.3.80.169/32221.3.80.169 to 221.3.80.169—1
171221.3.80.170/32221.3.80.170 to 221.3.80.170—1
172221.3.80.171/32221.3.80.171 to 221.3.80.171—1
173221.3.80.172/32221.3.80.172 to 221.3.80.172—1
174221.3.80.173/32221.3.80.173 to 221.3.80.173—1
175221.3.80.174/32221.3.80.174 to 221.3.80.174—1
176221.3.80.175/32221.3.80.175 to 221.3.80.175—1
177221.3.80.176/32221.3.80.176 to 221.3.80.176—1
178221.3.80.177/32221.3.80.177 to 221.3.80.177—1
179221.3.80.178/32221.3.80.178 to 221.3.80.178—1
180221.3.80.179/32221.3.80.179 to 221.3.80.179—1
181221.3.80.180/32221.3.80.180 to 221.3.80.180—1
182221.3.80.181/32221.3.80.181 to 221.3.80.181—1
183221.3.80.182/32221.3.80.182 to 221.3.80.182—1
184221.3.80.183/32221.3.80.183 to 221.3.80.183—1
185221.3.80.184/32221.3.80.184 to 221.3.80.184—1
186221.3.80.185/32221.3.80.185 to 221.3.80.185—1
187221.3.80.186/32221.3.80.186 to 221.3.80.186—1
188221.3.80.187/32221.3.80.187 to 221.3.80.187—1
189221.3.80.188/32221.3.80.188 to 221.3.80.188—1
190221.3.80.189/32221.3.80.189 to 221.3.80.189—1
191221.3.80.190/32221.3.80.190 to 221.3.80.190—1
192221.3.80.191/32221.3.80.191 to 221.3.80.191—1
193221.3.80.192/32221.3.80.192 to 221.3.80.192—1
194221.3.80.193/32221.3.80.193 to 221.3.80.193—1
195221.3.80.194/32221.3.80.194 to 221.3.80.194—1
196221.3.80.195/32221.3.80.195 to 221.3.80.195—1
197221.3.80.196/32221.3.80.196 to 221.3.80.196—1
198221.3.80.197/32221.3.80.197 to 221.3.80.197—1
199221.3.80.198/32221.3.80.198 to 221.3.80.198—1
200221.3.80.199/32221.3.80.199 to 221.3.80.199—1
201221.3.80.200/32221.3.80.200 to 221.3.80.200—1
202221.3.80.201/32221.3.80.201 to 221.3.80.201—1
203221.3.80.202/32221.3.80.202 to 221.3.80.202—1
204221.3.80.203/32221.3.80.203 to 221.3.80.203—1
205221.3.80.204/32221.3.80.204 to 221.3.80.204—1
206221.3.80.205/32221.3.80.205 to 221.3.80.205—1
207221.3.80.206/32221.3.80.206 to 221.3.80.206—1
208221.3.80.207/32221.3.80.207 to 221.3.80.207—1
209221.3.80.208/32221.3.80.208 to 221.3.80.208—1
210221.3.80.209/32221.3.80.209 to 221.3.80.209—1
211221.3.80.210/32221.3.80.210 to 221.3.80.210—1
212221.3.80.211/32221.3.80.211 to 221.3.80.211—1
213221.3.80.212/32221.3.80.212 to 221.3.80.212—1
214221.3.80.213/32221.3.80.213 to 221.3.80.213—1
215221.3.80.214/32221.3.80.214 to 221.3.80.214—1
216221.3.80.215/32221.3.80.215 to 221.3.80.215—1
217221.3.80.216/32221.3.80.216 to 221.3.80.216—1
218221.3.80.217/32221.3.80.217 to 221.3.80.217—1
219221.3.80.218/32221.3.80.218 to 221.3.80.218—1
220221.3.80.219/32221.3.80.219 to 221.3.80.219—1
221221.3.80.220/32221.3.80.220 to 221.3.80.220—1
222221.3.80.221/32221.3.80.221 to 221.3.80.221—1
223221.3.80.222/32221.3.80.222 to 221.3.80.222—1
224221.3.80.223/32221.3.80.223 to 221.3.80.223—1
225221.3.80.224/32221.3.80.224 to 221.3.80.224—1
226221.3.80.225/32221.3.80.225 to 221.3.80.225—1
227221.3.80.226/32221.3.80.226 to 221.3.80.226—1
228221.3.80.227/32221.3.80.227 to 221.3.80.227—1
229221.3.80.228/32221.3.80.228 to 221.3.80.228—1
230221.3.80.229/32221.3.80.229 to 221.3.80.229—1
231221.3.80.230/32221.3.80.230 to 221.3.80.230—1
232221.3.80.231/32221.3.80.231 to 221.3.80.231—1
233221.3.80.232/32221.3.80.232 to 221.3.80.232—1
234221.3.80.233/32221.3.80.233 to 221.3.80.233—1
235221.3.80.234/32221.3.80.234 to 221.3.80.234—1
236221.3.80.235/32221.3.80.235 to 221.3.80.235—1
237221.3.80.236/32221.3.80.236 to 221.3.80.236—1
238221.3.80.237/32221.3.80.237 to 221.3.80.237—1
239221.3.80.238/32221.3.80.238 to 221.3.80.238—1
240221.3.80.239/32221.3.80.239 to 221.3.80.239—1
241221.3.80.240/32221.3.80.240 to 221.3.80.240—1
242221.3.80.241/32221.3.80.241 to 221.3.80.241—1
243221.3.80.242/32221.3.80.242 to 221.3.80.242—1
244221.3.80.243/32221.3.80.243 to 221.3.80.243—1
245221.3.80.244/32221.3.80.244 to 221.3.80.244—1
246221.3.80.245/32221.3.80.245 to 221.3.80.245—1
247221.3.80.246/32221.3.80.246 to 221.3.80.246—1
248221.3.80.247/32221.3.80.247 to 221.3.80.247—1
249221.3.80.248/32221.3.80.248 to 221.3.80.248—1
250221.3.80.249/32221.3.80.249 to 221.3.80.249—1
251221.3.80.250/32221.3.80.250 to 221.3.80.250—1
252221.3.80.251/32221.3.80.251 to 221.3.80.251—1
253221.3.80.252/32221.3.80.252 to 221.3.80.252—1
254221.3.80.253/32221.3.80.253 to 221.3.80.253—1
255221.3.80.254/32221.3.80.254 to 221.3.80.254—1
256221.3.80.255/32221.3.80.255 to 221.3.80.255—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.