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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.

Network184.3.0.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
184.3.0.0
Broadcast address
184.3.15.255
First usable
184.3.0.1
Last usable
184.3.15.254
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 B8030000 · Integer 3087204352 to 3087208447
Reverse DNS zones
0.3.184.in-addr.arpa
1.3.184.in-addr.arpa
2.3.184.in-addr.arpa
3.3.184.in-addr.arpa
4.3.184.in-addr.arpa
5.3.184.in-addr.arpa
6.3.184.in-addr.arpa
7.3.184.in-addr.arpa
8.3.184.in-addr.arpa
9.3.184.in-addr.arpa
10.3.184.in-addr.arpa
11.3.184.in-addr.arpa
12.3.184.in-addr.arpa
13.3.184.in-addr.arpa
14.3.184.in-addr.arpa
15.3.184.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
Address10111000.00000011.00000000.00000000184.3.0.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network10111000.00000011.00000000.00000000184.3.0.0
Broadcast10111000.00000011.00001111.11111111184.3.15.255
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)

184.3.0.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1184.3.0.0/32184.3.0.0 to 184.3.0.0—1
2184.3.0.1/32184.3.0.1 to 184.3.0.1—1
3184.3.0.2/32184.3.0.2 to 184.3.0.2—1
4184.3.0.3/32184.3.0.3 to 184.3.0.3—1
5184.3.0.4/32184.3.0.4 to 184.3.0.4—1
6184.3.0.5/32184.3.0.5 to 184.3.0.5—1
7184.3.0.6/32184.3.0.6 to 184.3.0.6—1
8184.3.0.7/32184.3.0.7 to 184.3.0.7—1
9184.3.0.8/32184.3.0.8 to 184.3.0.8—1
10184.3.0.9/32184.3.0.9 to 184.3.0.9—1
11184.3.0.10/32184.3.0.10 to 184.3.0.10—1
12184.3.0.11/32184.3.0.11 to 184.3.0.11—1
13184.3.0.12/32184.3.0.12 to 184.3.0.12—1
14184.3.0.13/32184.3.0.13 to 184.3.0.13—1
15184.3.0.14/32184.3.0.14 to 184.3.0.14—1
16184.3.0.15/32184.3.0.15 to 184.3.0.15—1
17184.3.0.16/32184.3.0.16 to 184.3.0.16—1
18184.3.0.17/32184.3.0.17 to 184.3.0.17—1
19184.3.0.18/32184.3.0.18 to 184.3.0.18—1
20184.3.0.19/32184.3.0.19 to 184.3.0.19—1
21184.3.0.20/32184.3.0.20 to 184.3.0.20—1
22184.3.0.21/32184.3.0.21 to 184.3.0.21—1
23184.3.0.22/32184.3.0.22 to 184.3.0.22—1
24184.3.0.23/32184.3.0.23 to 184.3.0.23—1
25184.3.0.24/32184.3.0.24 to 184.3.0.24—1
26184.3.0.25/32184.3.0.25 to 184.3.0.25—1
27184.3.0.26/32184.3.0.26 to 184.3.0.26—1
28184.3.0.27/32184.3.0.27 to 184.3.0.27—1
29184.3.0.28/32184.3.0.28 to 184.3.0.28—1
30184.3.0.29/32184.3.0.29 to 184.3.0.29—1
31184.3.0.30/32184.3.0.30 to 184.3.0.30—1
32184.3.0.31/32184.3.0.31 to 184.3.0.31—1
33184.3.0.32/32184.3.0.32 to 184.3.0.32—1
34184.3.0.33/32184.3.0.33 to 184.3.0.33—1
35184.3.0.34/32184.3.0.34 to 184.3.0.34—1
36184.3.0.35/32184.3.0.35 to 184.3.0.35—1
37184.3.0.36/32184.3.0.36 to 184.3.0.36—1
38184.3.0.37/32184.3.0.37 to 184.3.0.37—1
39184.3.0.38/32184.3.0.38 to 184.3.0.38—1
40184.3.0.39/32184.3.0.39 to 184.3.0.39—1
41184.3.0.40/32184.3.0.40 to 184.3.0.40—1
42184.3.0.41/32184.3.0.41 to 184.3.0.41—1
43184.3.0.42/32184.3.0.42 to 184.3.0.42—1
44184.3.0.43/32184.3.0.43 to 184.3.0.43—1
45184.3.0.44/32184.3.0.44 to 184.3.0.44—1
46184.3.0.45/32184.3.0.45 to 184.3.0.45—1
47184.3.0.46/32184.3.0.46 to 184.3.0.46—1
48184.3.0.47/32184.3.0.47 to 184.3.0.47—1
49184.3.0.48/32184.3.0.48 to 184.3.0.48—1
50184.3.0.49/32184.3.0.49 to 184.3.0.49—1
51184.3.0.50/32184.3.0.50 to 184.3.0.50—1
52184.3.0.51/32184.3.0.51 to 184.3.0.51—1
53184.3.0.52/32184.3.0.52 to 184.3.0.52—1
54184.3.0.53/32184.3.0.53 to 184.3.0.53—1
55184.3.0.54/32184.3.0.54 to 184.3.0.54—1
56184.3.0.55/32184.3.0.55 to 184.3.0.55—1
57184.3.0.56/32184.3.0.56 to 184.3.0.56—1
58184.3.0.57/32184.3.0.57 to 184.3.0.57—1
59184.3.0.58/32184.3.0.58 to 184.3.0.58—1
60184.3.0.59/32184.3.0.59 to 184.3.0.59—1
61184.3.0.60/32184.3.0.60 to 184.3.0.60—1
62184.3.0.61/32184.3.0.61 to 184.3.0.61—1
63184.3.0.62/32184.3.0.62 to 184.3.0.62—1
64184.3.0.63/32184.3.0.63 to 184.3.0.63—1
65184.3.0.64/32184.3.0.64 to 184.3.0.64—1
66184.3.0.65/32184.3.0.65 to 184.3.0.65—1
67184.3.0.66/32184.3.0.66 to 184.3.0.66—1
68184.3.0.67/32184.3.0.67 to 184.3.0.67—1
69184.3.0.68/32184.3.0.68 to 184.3.0.68—1
70184.3.0.69/32184.3.0.69 to 184.3.0.69—1
71184.3.0.70/32184.3.0.70 to 184.3.0.70—1
72184.3.0.71/32184.3.0.71 to 184.3.0.71—1
73184.3.0.72/32184.3.0.72 to 184.3.0.72—1
74184.3.0.73/32184.3.0.73 to 184.3.0.73—1
75184.3.0.74/32184.3.0.74 to 184.3.0.74—1
76184.3.0.75/32184.3.0.75 to 184.3.0.75—1
77184.3.0.76/32184.3.0.76 to 184.3.0.76—1
78184.3.0.77/32184.3.0.77 to 184.3.0.77—1
79184.3.0.78/32184.3.0.78 to 184.3.0.78—1
80184.3.0.79/32184.3.0.79 to 184.3.0.79—1
81184.3.0.80/32184.3.0.80 to 184.3.0.80—1
82184.3.0.81/32184.3.0.81 to 184.3.0.81—1
83184.3.0.82/32184.3.0.82 to 184.3.0.82—1
84184.3.0.83/32184.3.0.83 to 184.3.0.83—1
85184.3.0.84/32184.3.0.84 to 184.3.0.84—1
86184.3.0.85/32184.3.0.85 to 184.3.0.85—1
87184.3.0.86/32184.3.0.86 to 184.3.0.86—1
88184.3.0.87/32184.3.0.87 to 184.3.0.87—1
89184.3.0.88/32184.3.0.88 to 184.3.0.88—1
90184.3.0.89/32184.3.0.89 to 184.3.0.89—1
91184.3.0.90/32184.3.0.90 to 184.3.0.90—1
92184.3.0.91/32184.3.0.91 to 184.3.0.91—1
93184.3.0.92/32184.3.0.92 to 184.3.0.92—1
94184.3.0.93/32184.3.0.93 to 184.3.0.93—1
95184.3.0.94/32184.3.0.94 to 184.3.0.94—1
96184.3.0.95/32184.3.0.95 to 184.3.0.95—1
97184.3.0.96/32184.3.0.96 to 184.3.0.96—1
98184.3.0.97/32184.3.0.97 to 184.3.0.97—1
99184.3.0.98/32184.3.0.98 to 184.3.0.98—1
100184.3.0.99/32184.3.0.99 to 184.3.0.99—1
101184.3.0.100/32184.3.0.100 to 184.3.0.100—1
102184.3.0.101/32184.3.0.101 to 184.3.0.101—1
103184.3.0.102/32184.3.0.102 to 184.3.0.102—1
104184.3.0.103/32184.3.0.103 to 184.3.0.103—1
105184.3.0.104/32184.3.0.104 to 184.3.0.104—1
106184.3.0.105/32184.3.0.105 to 184.3.0.105—1
107184.3.0.106/32184.3.0.106 to 184.3.0.106—1
108184.3.0.107/32184.3.0.107 to 184.3.0.107—1
109184.3.0.108/32184.3.0.108 to 184.3.0.108—1
110184.3.0.109/32184.3.0.109 to 184.3.0.109—1
111184.3.0.110/32184.3.0.110 to 184.3.0.110—1
112184.3.0.111/32184.3.0.111 to 184.3.0.111—1
113184.3.0.112/32184.3.0.112 to 184.3.0.112—1
114184.3.0.113/32184.3.0.113 to 184.3.0.113—1
115184.3.0.114/32184.3.0.114 to 184.3.0.114—1
116184.3.0.115/32184.3.0.115 to 184.3.0.115—1
117184.3.0.116/32184.3.0.116 to 184.3.0.116—1
118184.3.0.117/32184.3.0.117 to 184.3.0.117—1
119184.3.0.118/32184.3.0.118 to 184.3.0.118—1
120184.3.0.119/32184.3.0.119 to 184.3.0.119—1
121184.3.0.120/32184.3.0.120 to 184.3.0.120—1
122184.3.0.121/32184.3.0.121 to 184.3.0.121—1
123184.3.0.122/32184.3.0.122 to 184.3.0.122—1
124184.3.0.123/32184.3.0.123 to 184.3.0.123—1
125184.3.0.124/32184.3.0.124 to 184.3.0.124—1
126184.3.0.125/32184.3.0.125 to 184.3.0.125—1
127184.3.0.126/32184.3.0.126 to 184.3.0.126—1
128184.3.0.127/32184.3.0.127 to 184.3.0.127—1
129184.3.0.128/32184.3.0.128 to 184.3.0.128—1
130184.3.0.129/32184.3.0.129 to 184.3.0.129—1
131184.3.0.130/32184.3.0.130 to 184.3.0.130—1
132184.3.0.131/32184.3.0.131 to 184.3.0.131—1
133184.3.0.132/32184.3.0.132 to 184.3.0.132—1
134184.3.0.133/32184.3.0.133 to 184.3.0.133—1
135184.3.0.134/32184.3.0.134 to 184.3.0.134—1
136184.3.0.135/32184.3.0.135 to 184.3.0.135—1
137184.3.0.136/32184.3.0.136 to 184.3.0.136—1
138184.3.0.137/32184.3.0.137 to 184.3.0.137—1
139184.3.0.138/32184.3.0.138 to 184.3.0.138—1
140184.3.0.139/32184.3.0.139 to 184.3.0.139—1
141184.3.0.140/32184.3.0.140 to 184.3.0.140—1
142184.3.0.141/32184.3.0.141 to 184.3.0.141—1
143184.3.0.142/32184.3.0.142 to 184.3.0.142—1
144184.3.0.143/32184.3.0.143 to 184.3.0.143—1
145184.3.0.144/32184.3.0.144 to 184.3.0.144—1
146184.3.0.145/32184.3.0.145 to 184.3.0.145—1
147184.3.0.146/32184.3.0.146 to 184.3.0.146—1
148184.3.0.147/32184.3.0.147 to 184.3.0.147—1
149184.3.0.148/32184.3.0.148 to 184.3.0.148—1
150184.3.0.149/32184.3.0.149 to 184.3.0.149—1
151184.3.0.150/32184.3.0.150 to 184.3.0.150—1
152184.3.0.151/32184.3.0.151 to 184.3.0.151—1
153184.3.0.152/32184.3.0.152 to 184.3.0.152—1
154184.3.0.153/32184.3.0.153 to 184.3.0.153—1
155184.3.0.154/32184.3.0.154 to 184.3.0.154—1
156184.3.0.155/32184.3.0.155 to 184.3.0.155—1
157184.3.0.156/32184.3.0.156 to 184.3.0.156—1
158184.3.0.157/32184.3.0.157 to 184.3.0.157—1
159184.3.0.158/32184.3.0.158 to 184.3.0.158—1
160184.3.0.159/32184.3.0.159 to 184.3.0.159—1
161184.3.0.160/32184.3.0.160 to 184.3.0.160—1
162184.3.0.161/32184.3.0.161 to 184.3.0.161—1
163184.3.0.162/32184.3.0.162 to 184.3.0.162—1
164184.3.0.163/32184.3.0.163 to 184.3.0.163—1
165184.3.0.164/32184.3.0.164 to 184.3.0.164—1
166184.3.0.165/32184.3.0.165 to 184.3.0.165—1
167184.3.0.166/32184.3.0.166 to 184.3.0.166—1
168184.3.0.167/32184.3.0.167 to 184.3.0.167—1
169184.3.0.168/32184.3.0.168 to 184.3.0.168—1
170184.3.0.169/32184.3.0.169 to 184.3.0.169—1
171184.3.0.170/32184.3.0.170 to 184.3.0.170—1
172184.3.0.171/32184.3.0.171 to 184.3.0.171—1
173184.3.0.172/32184.3.0.172 to 184.3.0.172—1
174184.3.0.173/32184.3.0.173 to 184.3.0.173—1
175184.3.0.174/32184.3.0.174 to 184.3.0.174—1
176184.3.0.175/32184.3.0.175 to 184.3.0.175—1
177184.3.0.176/32184.3.0.176 to 184.3.0.176—1
178184.3.0.177/32184.3.0.177 to 184.3.0.177—1
179184.3.0.178/32184.3.0.178 to 184.3.0.178—1
180184.3.0.179/32184.3.0.179 to 184.3.0.179—1
181184.3.0.180/32184.3.0.180 to 184.3.0.180—1
182184.3.0.181/32184.3.0.181 to 184.3.0.181—1
183184.3.0.182/32184.3.0.182 to 184.3.0.182—1
184184.3.0.183/32184.3.0.183 to 184.3.0.183—1
185184.3.0.184/32184.3.0.184 to 184.3.0.184—1
186184.3.0.185/32184.3.0.185 to 184.3.0.185—1
187184.3.0.186/32184.3.0.186 to 184.3.0.186—1
188184.3.0.187/32184.3.0.187 to 184.3.0.187—1
189184.3.0.188/32184.3.0.188 to 184.3.0.188—1
190184.3.0.189/32184.3.0.189 to 184.3.0.189—1
191184.3.0.190/32184.3.0.190 to 184.3.0.190—1
192184.3.0.191/32184.3.0.191 to 184.3.0.191—1
193184.3.0.192/32184.3.0.192 to 184.3.0.192—1
194184.3.0.193/32184.3.0.193 to 184.3.0.193—1
195184.3.0.194/32184.3.0.194 to 184.3.0.194—1
196184.3.0.195/32184.3.0.195 to 184.3.0.195—1
197184.3.0.196/32184.3.0.196 to 184.3.0.196—1
198184.3.0.197/32184.3.0.197 to 184.3.0.197—1
199184.3.0.198/32184.3.0.198 to 184.3.0.198—1
200184.3.0.199/32184.3.0.199 to 184.3.0.199—1
201184.3.0.200/32184.3.0.200 to 184.3.0.200—1
202184.3.0.201/32184.3.0.201 to 184.3.0.201—1
203184.3.0.202/32184.3.0.202 to 184.3.0.202—1
204184.3.0.203/32184.3.0.203 to 184.3.0.203—1
205184.3.0.204/32184.3.0.204 to 184.3.0.204—1
206184.3.0.205/32184.3.0.205 to 184.3.0.205—1
207184.3.0.206/32184.3.0.206 to 184.3.0.206—1
208184.3.0.207/32184.3.0.207 to 184.3.0.207—1
209184.3.0.208/32184.3.0.208 to 184.3.0.208—1
210184.3.0.209/32184.3.0.209 to 184.3.0.209—1
211184.3.0.210/32184.3.0.210 to 184.3.0.210—1
212184.3.0.211/32184.3.0.211 to 184.3.0.211—1
213184.3.0.212/32184.3.0.212 to 184.3.0.212—1
214184.3.0.213/32184.3.0.213 to 184.3.0.213—1
215184.3.0.214/32184.3.0.214 to 184.3.0.214—1
216184.3.0.215/32184.3.0.215 to 184.3.0.215—1
217184.3.0.216/32184.3.0.216 to 184.3.0.216—1
218184.3.0.217/32184.3.0.217 to 184.3.0.217—1
219184.3.0.218/32184.3.0.218 to 184.3.0.218—1
220184.3.0.219/32184.3.0.219 to 184.3.0.219—1
221184.3.0.220/32184.3.0.220 to 184.3.0.220—1
222184.3.0.221/32184.3.0.221 to 184.3.0.221—1
223184.3.0.222/32184.3.0.222 to 184.3.0.222—1
224184.3.0.223/32184.3.0.223 to 184.3.0.223—1
225184.3.0.224/32184.3.0.224 to 184.3.0.224—1
226184.3.0.225/32184.3.0.225 to 184.3.0.225—1
227184.3.0.226/32184.3.0.226 to 184.3.0.226—1
228184.3.0.227/32184.3.0.227 to 184.3.0.227—1
229184.3.0.228/32184.3.0.228 to 184.3.0.228—1
230184.3.0.229/32184.3.0.229 to 184.3.0.229—1
231184.3.0.230/32184.3.0.230 to 184.3.0.230—1
232184.3.0.231/32184.3.0.231 to 184.3.0.231—1
233184.3.0.232/32184.3.0.232 to 184.3.0.232—1
234184.3.0.233/32184.3.0.233 to 184.3.0.233—1
235184.3.0.234/32184.3.0.234 to 184.3.0.234—1
236184.3.0.235/32184.3.0.235 to 184.3.0.235—1
237184.3.0.236/32184.3.0.236 to 184.3.0.236—1
238184.3.0.237/32184.3.0.237 to 184.3.0.237—1
239184.3.0.238/32184.3.0.238 to 184.3.0.238—1
240184.3.0.239/32184.3.0.239 to 184.3.0.239—1
241184.3.0.240/32184.3.0.240 to 184.3.0.240—1
242184.3.0.241/32184.3.0.241 to 184.3.0.241—1
243184.3.0.242/32184.3.0.242 to 184.3.0.242—1
244184.3.0.243/32184.3.0.243 to 184.3.0.243—1
245184.3.0.244/32184.3.0.244 to 184.3.0.244—1
246184.3.0.245/32184.3.0.245 to 184.3.0.245—1
247184.3.0.246/32184.3.0.246 to 184.3.0.246—1
248184.3.0.247/32184.3.0.247 to 184.3.0.247—1
249184.3.0.248/32184.3.0.248 to 184.3.0.248—1
250184.3.0.249/32184.3.0.249 to 184.3.0.249—1
251184.3.0.250/32184.3.0.250 to 184.3.0.250—1
252184.3.0.251/32184.3.0.251 to 184.3.0.251—1
253184.3.0.252/32184.3.0.252 to 184.3.0.252—1
254184.3.0.253/32184.3.0.253 to 184.3.0.253—1
255184.3.0.254/32184.3.0.254 to 184.3.0.254—1
256184.3.0.255/32184.3.0.255 to 184.3.0.255—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.