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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.

Network202.4.64.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
202.4.64.0
Broadcast address
202.4.79.255
First usable
202.4.64.1
Last usable
202.4.79.254
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 CA044000 · Integer 3389276160 to 3389280255
Reverse DNS zones
64.4.202.in-addr.arpa
65.4.202.in-addr.arpa
66.4.202.in-addr.arpa
67.4.202.in-addr.arpa
68.4.202.in-addr.arpa
69.4.202.in-addr.arpa
70.4.202.in-addr.arpa
71.4.202.in-addr.arpa
72.4.202.in-addr.arpa
73.4.202.in-addr.arpa
74.4.202.in-addr.arpa
75.4.202.in-addr.arpa
76.4.202.in-addr.arpa
77.4.202.in-addr.arpa
78.4.202.in-addr.arpa
79.4.202.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
Address11001010.00000100.01000000.00000000202.4.64.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network11001010.00000100.01000000.00000000202.4.64.0
Broadcast11001010.00000100.01001111.11111111202.4.79.255
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)

202.4.64.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1202.4.64.0/32202.4.64.0 to 202.4.64.0—1
2202.4.64.1/32202.4.64.1 to 202.4.64.1—1
3202.4.64.2/32202.4.64.2 to 202.4.64.2—1
4202.4.64.3/32202.4.64.3 to 202.4.64.3—1
5202.4.64.4/32202.4.64.4 to 202.4.64.4—1
6202.4.64.5/32202.4.64.5 to 202.4.64.5—1
7202.4.64.6/32202.4.64.6 to 202.4.64.6—1
8202.4.64.7/32202.4.64.7 to 202.4.64.7—1
9202.4.64.8/32202.4.64.8 to 202.4.64.8—1
10202.4.64.9/32202.4.64.9 to 202.4.64.9—1
11202.4.64.10/32202.4.64.10 to 202.4.64.10—1
12202.4.64.11/32202.4.64.11 to 202.4.64.11—1
13202.4.64.12/32202.4.64.12 to 202.4.64.12—1
14202.4.64.13/32202.4.64.13 to 202.4.64.13—1
15202.4.64.14/32202.4.64.14 to 202.4.64.14—1
16202.4.64.15/32202.4.64.15 to 202.4.64.15—1
17202.4.64.16/32202.4.64.16 to 202.4.64.16—1
18202.4.64.17/32202.4.64.17 to 202.4.64.17—1
19202.4.64.18/32202.4.64.18 to 202.4.64.18—1
20202.4.64.19/32202.4.64.19 to 202.4.64.19—1
21202.4.64.20/32202.4.64.20 to 202.4.64.20—1
22202.4.64.21/32202.4.64.21 to 202.4.64.21—1
23202.4.64.22/32202.4.64.22 to 202.4.64.22—1
24202.4.64.23/32202.4.64.23 to 202.4.64.23—1
25202.4.64.24/32202.4.64.24 to 202.4.64.24—1
26202.4.64.25/32202.4.64.25 to 202.4.64.25—1
27202.4.64.26/32202.4.64.26 to 202.4.64.26—1
28202.4.64.27/32202.4.64.27 to 202.4.64.27—1
29202.4.64.28/32202.4.64.28 to 202.4.64.28—1
30202.4.64.29/32202.4.64.29 to 202.4.64.29—1
31202.4.64.30/32202.4.64.30 to 202.4.64.30—1
32202.4.64.31/32202.4.64.31 to 202.4.64.31—1
33202.4.64.32/32202.4.64.32 to 202.4.64.32—1
34202.4.64.33/32202.4.64.33 to 202.4.64.33—1
35202.4.64.34/32202.4.64.34 to 202.4.64.34—1
36202.4.64.35/32202.4.64.35 to 202.4.64.35—1
37202.4.64.36/32202.4.64.36 to 202.4.64.36—1
38202.4.64.37/32202.4.64.37 to 202.4.64.37—1
39202.4.64.38/32202.4.64.38 to 202.4.64.38—1
40202.4.64.39/32202.4.64.39 to 202.4.64.39—1
41202.4.64.40/32202.4.64.40 to 202.4.64.40—1
42202.4.64.41/32202.4.64.41 to 202.4.64.41—1
43202.4.64.42/32202.4.64.42 to 202.4.64.42—1
44202.4.64.43/32202.4.64.43 to 202.4.64.43—1
45202.4.64.44/32202.4.64.44 to 202.4.64.44—1
46202.4.64.45/32202.4.64.45 to 202.4.64.45—1
47202.4.64.46/32202.4.64.46 to 202.4.64.46—1
48202.4.64.47/32202.4.64.47 to 202.4.64.47—1
49202.4.64.48/32202.4.64.48 to 202.4.64.48—1
50202.4.64.49/32202.4.64.49 to 202.4.64.49—1
51202.4.64.50/32202.4.64.50 to 202.4.64.50—1
52202.4.64.51/32202.4.64.51 to 202.4.64.51—1
53202.4.64.52/32202.4.64.52 to 202.4.64.52—1
54202.4.64.53/32202.4.64.53 to 202.4.64.53—1
55202.4.64.54/32202.4.64.54 to 202.4.64.54—1
56202.4.64.55/32202.4.64.55 to 202.4.64.55—1
57202.4.64.56/32202.4.64.56 to 202.4.64.56—1
58202.4.64.57/32202.4.64.57 to 202.4.64.57—1
59202.4.64.58/32202.4.64.58 to 202.4.64.58—1
60202.4.64.59/32202.4.64.59 to 202.4.64.59—1
61202.4.64.60/32202.4.64.60 to 202.4.64.60—1
62202.4.64.61/32202.4.64.61 to 202.4.64.61—1
63202.4.64.62/32202.4.64.62 to 202.4.64.62—1
64202.4.64.63/32202.4.64.63 to 202.4.64.63—1
65202.4.64.64/32202.4.64.64 to 202.4.64.64—1
66202.4.64.65/32202.4.64.65 to 202.4.64.65—1
67202.4.64.66/32202.4.64.66 to 202.4.64.66—1
68202.4.64.67/32202.4.64.67 to 202.4.64.67—1
69202.4.64.68/32202.4.64.68 to 202.4.64.68—1
70202.4.64.69/32202.4.64.69 to 202.4.64.69—1
71202.4.64.70/32202.4.64.70 to 202.4.64.70—1
72202.4.64.71/32202.4.64.71 to 202.4.64.71—1
73202.4.64.72/32202.4.64.72 to 202.4.64.72—1
74202.4.64.73/32202.4.64.73 to 202.4.64.73—1
75202.4.64.74/32202.4.64.74 to 202.4.64.74—1
76202.4.64.75/32202.4.64.75 to 202.4.64.75—1
77202.4.64.76/32202.4.64.76 to 202.4.64.76—1
78202.4.64.77/32202.4.64.77 to 202.4.64.77—1
79202.4.64.78/32202.4.64.78 to 202.4.64.78—1
80202.4.64.79/32202.4.64.79 to 202.4.64.79—1
81202.4.64.80/32202.4.64.80 to 202.4.64.80—1
82202.4.64.81/32202.4.64.81 to 202.4.64.81—1
83202.4.64.82/32202.4.64.82 to 202.4.64.82—1
84202.4.64.83/32202.4.64.83 to 202.4.64.83—1
85202.4.64.84/32202.4.64.84 to 202.4.64.84—1
86202.4.64.85/32202.4.64.85 to 202.4.64.85—1
87202.4.64.86/32202.4.64.86 to 202.4.64.86—1
88202.4.64.87/32202.4.64.87 to 202.4.64.87—1
89202.4.64.88/32202.4.64.88 to 202.4.64.88—1
90202.4.64.89/32202.4.64.89 to 202.4.64.89—1
91202.4.64.90/32202.4.64.90 to 202.4.64.90—1
92202.4.64.91/32202.4.64.91 to 202.4.64.91—1
93202.4.64.92/32202.4.64.92 to 202.4.64.92—1
94202.4.64.93/32202.4.64.93 to 202.4.64.93—1
95202.4.64.94/32202.4.64.94 to 202.4.64.94—1
96202.4.64.95/32202.4.64.95 to 202.4.64.95—1
97202.4.64.96/32202.4.64.96 to 202.4.64.96—1
98202.4.64.97/32202.4.64.97 to 202.4.64.97—1
99202.4.64.98/32202.4.64.98 to 202.4.64.98—1
100202.4.64.99/32202.4.64.99 to 202.4.64.99—1
101202.4.64.100/32202.4.64.100 to 202.4.64.100—1
102202.4.64.101/32202.4.64.101 to 202.4.64.101—1
103202.4.64.102/32202.4.64.102 to 202.4.64.102—1
104202.4.64.103/32202.4.64.103 to 202.4.64.103—1
105202.4.64.104/32202.4.64.104 to 202.4.64.104—1
106202.4.64.105/32202.4.64.105 to 202.4.64.105—1
107202.4.64.106/32202.4.64.106 to 202.4.64.106—1
108202.4.64.107/32202.4.64.107 to 202.4.64.107—1
109202.4.64.108/32202.4.64.108 to 202.4.64.108—1
110202.4.64.109/32202.4.64.109 to 202.4.64.109—1
111202.4.64.110/32202.4.64.110 to 202.4.64.110—1
112202.4.64.111/32202.4.64.111 to 202.4.64.111—1
113202.4.64.112/32202.4.64.112 to 202.4.64.112—1
114202.4.64.113/32202.4.64.113 to 202.4.64.113—1
115202.4.64.114/32202.4.64.114 to 202.4.64.114—1
116202.4.64.115/32202.4.64.115 to 202.4.64.115—1
117202.4.64.116/32202.4.64.116 to 202.4.64.116—1
118202.4.64.117/32202.4.64.117 to 202.4.64.117—1
119202.4.64.118/32202.4.64.118 to 202.4.64.118—1
120202.4.64.119/32202.4.64.119 to 202.4.64.119—1
121202.4.64.120/32202.4.64.120 to 202.4.64.120—1
122202.4.64.121/32202.4.64.121 to 202.4.64.121—1
123202.4.64.122/32202.4.64.122 to 202.4.64.122—1
124202.4.64.123/32202.4.64.123 to 202.4.64.123—1
125202.4.64.124/32202.4.64.124 to 202.4.64.124—1
126202.4.64.125/32202.4.64.125 to 202.4.64.125—1
127202.4.64.126/32202.4.64.126 to 202.4.64.126—1
128202.4.64.127/32202.4.64.127 to 202.4.64.127—1
129202.4.64.128/32202.4.64.128 to 202.4.64.128—1
130202.4.64.129/32202.4.64.129 to 202.4.64.129—1
131202.4.64.130/32202.4.64.130 to 202.4.64.130—1
132202.4.64.131/32202.4.64.131 to 202.4.64.131—1
133202.4.64.132/32202.4.64.132 to 202.4.64.132—1
134202.4.64.133/32202.4.64.133 to 202.4.64.133—1
135202.4.64.134/32202.4.64.134 to 202.4.64.134—1
136202.4.64.135/32202.4.64.135 to 202.4.64.135—1
137202.4.64.136/32202.4.64.136 to 202.4.64.136—1
138202.4.64.137/32202.4.64.137 to 202.4.64.137—1
139202.4.64.138/32202.4.64.138 to 202.4.64.138—1
140202.4.64.139/32202.4.64.139 to 202.4.64.139—1
141202.4.64.140/32202.4.64.140 to 202.4.64.140—1
142202.4.64.141/32202.4.64.141 to 202.4.64.141—1
143202.4.64.142/32202.4.64.142 to 202.4.64.142—1
144202.4.64.143/32202.4.64.143 to 202.4.64.143—1
145202.4.64.144/32202.4.64.144 to 202.4.64.144—1
146202.4.64.145/32202.4.64.145 to 202.4.64.145—1
147202.4.64.146/32202.4.64.146 to 202.4.64.146—1
148202.4.64.147/32202.4.64.147 to 202.4.64.147—1
149202.4.64.148/32202.4.64.148 to 202.4.64.148—1
150202.4.64.149/32202.4.64.149 to 202.4.64.149—1
151202.4.64.150/32202.4.64.150 to 202.4.64.150—1
152202.4.64.151/32202.4.64.151 to 202.4.64.151—1
153202.4.64.152/32202.4.64.152 to 202.4.64.152—1
154202.4.64.153/32202.4.64.153 to 202.4.64.153—1
155202.4.64.154/32202.4.64.154 to 202.4.64.154—1
156202.4.64.155/32202.4.64.155 to 202.4.64.155—1
157202.4.64.156/32202.4.64.156 to 202.4.64.156—1
158202.4.64.157/32202.4.64.157 to 202.4.64.157—1
159202.4.64.158/32202.4.64.158 to 202.4.64.158—1
160202.4.64.159/32202.4.64.159 to 202.4.64.159—1
161202.4.64.160/32202.4.64.160 to 202.4.64.160—1
162202.4.64.161/32202.4.64.161 to 202.4.64.161—1
163202.4.64.162/32202.4.64.162 to 202.4.64.162—1
164202.4.64.163/32202.4.64.163 to 202.4.64.163—1
165202.4.64.164/32202.4.64.164 to 202.4.64.164—1
166202.4.64.165/32202.4.64.165 to 202.4.64.165—1
167202.4.64.166/32202.4.64.166 to 202.4.64.166—1
168202.4.64.167/32202.4.64.167 to 202.4.64.167—1
169202.4.64.168/32202.4.64.168 to 202.4.64.168—1
170202.4.64.169/32202.4.64.169 to 202.4.64.169—1
171202.4.64.170/32202.4.64.170 to 202.4.64.170—1
172202.4.64.171/32202.4.64.171 to 202.4.64.171—1
173202.4.64.172/32202.4.64.172 to 202.4.64.172—1
174202.4.64.173/32202.4.64.173 to 202.4.64.173—1
175202.4.64.174/32202.4.64.174 to 202.4.64.174—1
176202.4.64.175/32202.4.64.175 to 202.4.64.175—1
177202.4.64.176/32202.4.64.176 to 202.4.64.176—1
178202.4.64.177/32202.4.64.177 to 202.4.64.177—1
179202.4.64.178/32202.4.64.178 to 202.4.64.178—1
180202.4.64.179/32202.4.64.179 to 202.4.64.179—1
181202.4.64.180/32202.4.64.180 to 202.4.64.180—1
182202.4.64.181/32202.4.64.181 to 202.4.64.181—1
183202.4.64.182/32202.4.64.182 to 202.4.64.182—1
184202.4.64.183/32202.4.64.183 to 202.4.64.183—1
185202.4.64.184/32202.4.64.184 to 202.4.64.184—1
186202.4.64.185/32202.4.64.185 to 202.4.64.185—1
187202.4.64.186/32202.4.64.186 to 202.4.64.186—1
188202.4.64.187/32202.4.64.187 to 202.4.64.187—1
189202.4.64.188/32202.4.64.188 to 202.4.64.188—1
190202.4.64.189/32202.4.64.189 to 202.4.64.189—1
191202.4.64.190/32202.4.64.190 to 202.4.64.190—1
192202.4.64.191/32202.4.64.191 to 202.4.64.191—1
193202.4.64.192/32202.4.64.192 to 202.4.64.192—1
194202.4.64.193/32202.4.64.193 to 202.4.64.193—1
195202.4.64.194/32202.4.64.194 to 202.4.64.194—1
196202.4.64.195/32202.4.64.195 to 202.4.64.195—1
197202.4.64.196/32202.4.64.196 to 202.4.64.196—1
198202.4.64.197/32202.4.64.197 to 202.4.64.197—1
199202.4.64.198/32202.4.64.198 to 202.4.64.198—1
200202.4.64.199/32202.4.64.199 to 202.4.64.199—1
201202.4.64.200/32202.4.64.200 to 202.4.64.200—1
202202.4.64.201/32202.4.64.201 to 202.4.64.201—1
203202.4.64.202/32202.4.64.202 to 202.4.64.202—1
204202.4.64.203/32202.4.64.203 to 202.4.64.203—1
205202.4.64.204/32202.4.64.204 to 202.4.64.204—1
206202.4.64.205/32202.4.64.205 to 202.4.64.205—1
207202.4.64.206/32202.4.64.206 to 202.4.64.206—1
208202.4.64.207/32202.4.64.207 to 202.4.64.207—1
209202.4.64.208/32202.4.64.208 to 202.4.64.208—1
210202.4.64.209/32202.4.64.209 to 202.4.64.209—1
211202.4.64.210/32202.4.64.210 to 202.4.64.210—1
212202.4.64.211/32202.4.64.211 to 202.4.64.211—1
213202.4.64.212/32202.4.64.212 to 202.4.64.212—1
214202.4.64.213/32202.4.64.213 to 202.4.64.213—1
215202.4.64.214/32202.4.64.214 to 202.4.64.214—1
216202.4.64.215/32202.4.64.215 to 202.4.64.215—1
217202.4.64.216/32202.4.64.216 to 202.4.64.216—1
218202.4.64.217/32202.4.64.217 to 202.4.64.217—1
219202.4.64.218/32202.4.64.218 to 202.4.64.218—1
220202.4.64.219/32202.4.64.219 to 202.4.64.219—1
221202.4.64.220/32202.4.64.220 to 202.4.64.220—1
222202.4.64.221/32202.4.64.221 to 202.4.64.221—1
223202.4.64.222/32202.4.64.222 to 202.4.64.222—1
224202.4.64.223/32202.4.64.223 to 202.4.64.223—1
225202.4.64.224/32202.4.64.224 to 202.4.64.224—1
226202.4.64.225/32202.4.64.225 to 202.4.64.225—1
227202.4.64.226/32202.4.64.226 to 202.4.64.226—1
228202.4.64.227/32202.4.64.227 to 202.4.64.227—1
229202.4.64.228/32202.4.64.228 to 202.4.64.228—1
230202.4.64.229/32202.4.64.229 to 202.4.64.229—1
231202.4.64.230/32202.4.64.230 to 202.4.64.230—1
232202.4.64.231/32202.4.64.231 to 202.4.64.231—1
233202.4.64.232/32202.4.64.232 to 202.4.64.232—1
234202.4.64.233/32202.4.64.233 to 202.4.64.233—1
235202.4.64.234/32202.4.64.234 to 202.4.64.234—1
236202.4.64.235/32202.4.64.235 to 202.4.64.235—1
237202.4.64.236/32202.4.64.236 to 202.4.64.236—1
238202.4.64.237/32202.4.64.237 to 202.4.64.237—1
239202.4.64.238/32202.4.64.238 to 202.4.64.238—1
240202.4.64.239/32202.4.64.239 to 202.4.64.239—1
241202.4.64.240/32202.4.64.240 to 202.4.64.240—1
242202.4.64.241/32202.4.64.241 to 202.4.64.241—1
243202.4.64.242/32202.4.64.242 to 202.4.64.242—1
244202.4.64.243/32202.4.64.243 to 202.4.64.243—1
245202.4.64.244/32202.4.64.244 to 202.4.64.244—1
246202.4.64.245/32202.4.64.245 to 202.4.64.245—1
247202.4.64.246/32202.4.64.246 to 202.4.64.246—1
248202.4.64.247/32202.4.64.247 to 202.4.64.247—1
249202.4.64.248/32202.4.64.248 to 202.4.64.248—1
250202.4.64.249/32202.4.64.249 to 202.4.64.249—1
251202.4.64.250/32202.4.64.250 to 202.4.64.250—1
252202.4.64.251/32202.4.64.251 to 202.4.64.251—1
253202.4.64.252/32202.4.64.252 to 202.4.64.252—1
254202.4.64.253/32202.4.64.253 to 202.4.64.253—1
255202.4.64.254/32202.4.64.254 to 202.4.64.254—1
256202.4.64.255/32202.4.64.255 to 202.4.64.255—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.