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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.

Network166.167.78.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
166.167.78.0
Broadcast address
166.167.79.255
First usable
166.167.78.1
Last usable
166.167.79.254
Usable hosts
510 (512 less the network and broadcast addresses)
Subnet mask
255.255.254.0
Wildcard mask
0.0.1.255 (Cisco ACLs, OSPF)
Prefix length
/23
Type
Public public
Old class
B (default /16)
As numbers
Hex A6A74E00 · Integer 2795982336 to 2795982847
Reverse DNS zones
78.167.166.in-addr.arpa
79.167.166.in-addr.arpa
/23 is not on a 8-bit boundary, so it takes 2 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100110.10100111.01001110.00000000166.167.78.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network10100110.10100111.01001110.00000000166.167.78.0
Broadcast10100110.10100111.01001111.11111111166.167.79.255
Split into smaller subnets/32
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

166.167.78.0/23 makes 512 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1166.167.78.0/32166.167.78.0 to 166.167.78.0—1
2166.167.78.1/32166.167.78.1 to 166.167.78.1—1
3166.167.78.2/32166.167.78.2 to 166.167.78.2—1
4166.167.78.3/32166.167.78.3 to 166.167.78.3—1
5166.167.78.4/32166.167.78.4 to 166.167.78.4—1
6166.167.78.5/32166.167.78.5 to 166.167.78.5—1
7166.167.78.6/32166.167.78.6 to 166.167.78.6—1
8166.167.78.7/32166.167.78.7 to 166.167.78.7—1
9166.167.78.8/32166.167.78.8 to 166.167.78.8—1
10166.167.78.9/32166.167.78.9 to 166.167.78.9—1
11166.167.78.10/32166.167.78.10 to 166.167.78.10—1
12166.167.78.11/32166.167.78.11 to 166.167.78.11—1
13166.167.78.12/32166.167.78.12 to 166.167.78.12—1
14166.167.78.13/32166.167.78.13 to 166.167.78.13—1
15166.167.78.14/32166.167.78.14 to 166.167.78.14—1
16166.167.78.15/32166.167.78.15 to 166.167.78.15—1
17166.167.78.16/32166.167.78.16 to 166.167.78.16—1
18166.167.78.17/32166.167.78.17 to 166.167.78.17—1
19166.167.78.18/32166.167.78.18 to 166.167.78.18—1
20166.167.78.19/32166.167.78.19 to 166.167.78.19—1
21166.167.78.20/32166.167.78.20 to 166.167.78.20—1
22166.167.78.21/32166.167.78.21 to 166.167.78.21—1
23166.167.78.22/32166.167.78.22 to 166.167.78.22—1
24166.167.78.23/32166.167.78.23 to 166.167.78.23—1
25166.167.78.24/32166.167.78.24 to 166.167.78.24—1
26166.167.78.25/32166.167.78.25 to 166.167.78.25—1
27166.167.78.26/32166.167.78.26 to 166.167.78.26—1
28166.167.78.27/32166.167.78.27 to 166.167.78.27—1
29166.167.78.28/32166.167.78.28 to 166.167.78.28—1
30166.167.78.29/32166.167.78.29 to 166.167.78.29—1
31166.167.78.30/32166.167.78.30 to 166.167.78.30—1
32166.167.78.31/32166.167.78.31 to 166.167.78.31—1
33166.167.78.32/32166.167.78.32 to 166.167.78.32—1
34166.167.78.33/32166.167.78.33 to 166.167.78.33—1
35166.167.78.34/32166.167.78.34 to 166.167.78.34—1
36166.167.78.35/32166.167.78.35 to 166.167.78.35—1
37166.167.78.36/32166.167.78.36 to 166.167.78.36—1
38166.167.78.37/32166.167.78.37 to 166.167.78.37—1
39166.167.78.38/32166.167.78.38 to 166.167.78.38—1
40166.167.78.39/32166.167.78.39 to 166.167.78.39—1
41166.167.78.40/32166.167.78.40 to 166.167.78.40—1
42166.167.78.41/32166.167.78.41 to 166.167.78.41—1
43166.167.78.42/32166.167.78.42 to 166.167.78.42—1
44166.167.78.43/32166.167.78.43 to 166.167.78.43—1
45166.167.78.44/32166.167.78.44 to 166.167.78.44—1
46166.167.78.45/32166.167.78.45 to 166.167.78.45—1
47166.167.78.46/32166.167.78.46 to 166.167.78.46—1
48166.167.78.47/32166.167.78.47 to 166.167.78.47—1
49166.167.78.48/32166.167.78.48 to 166.167.78.48—1
50166.167.78.49/32166.167.78.49 to 166.167.78.49—1
51166.167.78.50/32166.167.78.50 to 166.167.78.50—1
52166.167.78.51/32166.167.78.51 to 166.167.78.51—1
53166.167.78.52/32166.167.78.52 to 166.167.78.52—1
54166.167.78.53/32166.167.78.53 to 166.167.78.53—1
55166.167.78.54/32166.167.78.54 to 166.167.78.54—1
56166.167.78.55/32166.167.78.55 to 166.167.78.55—1
57166.167.78.56/32166.167.78.56 to 166.167.78.56—1
58166.167.78.57/32166.167.78.57 to 166.167.78.57—1
59166.167.78.58/32166.167.78.58 to 166.167.78.58—1
60166.167.78.59/32166.167.78.59 to 166.167.78.59—1
61166.167.78.60/32166.167.78.60 to 166.167.78.60—1
62166.167.78.61/32166.167.78.61 to 166.167.78.61—1
63166.167.78.62/32166.167.78.62 to 166.167.78.62—1
64166.167.78.63/32166.167.78.63 to 166.167.78.63—1
65166.167.78.64/32166.167.78.64 to 166.167.78.64—1
66166.167.78.65/32166.167.78.65 to 166.167.78.65—1
67166.167.78.66/32166.167.78.66 to 166.167.78.66—1
68166.167.78.67/32166.167.78.67 to 166.167.78.67—1
69166.167.78.68/32166.167.78.68 to 166.167.78.68—1
70166.167.78.69/32166.167.78.69 to 166.167.78.69—1
71166.167.78.70/32166.167.78.70 to 166.167.78.70—1
72166.167.78.71/32166.167.78.71 to 166.167.78.71—1
73166.167.78.72/32166.167.78.72 to 166.167.78.72—1
74166.167.78.73/32166.167.78.73 to 166.167.78.73—1
75166.167.78.74/32166.167.78.74 to 166.167.78.74—1
76166.167.78.75/32166.167.78.75 to 166.167.78.75—1
77166.167.78.76/32166.167.78.76 to 166.167.78.76—1
78166.167.78.77/32166.167.78.77 to 166.167.78.77—1
79166.167.78.78/32166.167.78.78 to 166.167.78.78—1
80166.167.78.79/32166.167.78.79 to 166.167.78.79—1
81166.167.78.80/32166.167.78.80 to 166.167.78.80—1
82166.167.78.81/32166.167.78.81 to 166.167.78.81—1
83166.167.78.82/32166.167.78.82 to 166.167.78.82—1
84166.167.78.83/32166.167.78.83 to 166.167.78.83—1
85166.167.78.84/32166.167.78.84 to 166.167.78.84—1
86166.167.78.85/32166.167.78.85 to 166.167.78.85—1
87166.167.78.86/32166.167.78.86 to 166.167.78.86—1
88166.167.78.87/32166.167.78.87 to 166.167.78.87—1
89166.167.78.88/32166.167.78.88 to 166.167.78.88—1
90166.167.78.89/32166.167.78.89 to 166.167.78.89—1
91166.167.78.90/32166.167.78.90 to 166.167.78.90—1
92166.167.78.91/32166.167.78.91 to 166.167.78.91—1
93166.167.78.92/32166.167.78.92 to 166.167.78.92—1
94166.167.78.93/32166.167.78.93 to 166.167.78.93—1
95166.167.78.94/32166.167.78.94 to 166.167.78.94—1
96166.167.78.95/32166.167.78.95 to 166.167.78.95—1
97166.167.78.96/32166.167.78.96 to 166.167.78.96—1
98166.167.78.97/32166.167.78.97 to 166.167.78.97—1
99166.167.78.98/32166.167.78.98 to 166.167.78.98—1
100166.167.78.99/32166.167.78.99 to 166.167.78.99—1
101166.167.78.100/32166.167.78.100 to 166.167.78.100—1
102166.167.78.101/32166.167.78.101 to 166.167.78.101—1
103166.167.78.102/32166.167.78.102 to 166.167.78.102—1
104166.167.78.103/32166.167.78.103 to 166.167.78.103—1
105166.167.78.104/32166.167.78.104 to 166.167.78.104—1
106166.167.78.105/32166.167.78.105 to 166.167.78.105—1
107166.167.78.106/32166.167.78.106 to 166.167.78.106—1
108166.167.78.107/32166.167.78.107 to 166.167.78.107—1
109166.167.78.108/32166.167.78.108 to 166.167.78.108—1
110166.167.78.109/32166.167.78.109 to 166.167.78.109—1
111166.167.78.110/32166.167.78.110 to 166.167.78.110—1
112166.167.78.111/32166.167.78.111 to 166.167.78.111—1
113166.167.78.112/32166.167.78.112 to 166.167.78.112—1
114166.167.78.113/32166.167.78.113 to 166.167.78.113—1
115166.167.78.114/32166.167.78.114 to 166.167.78.114—1
116166.167.78.115/32166.167.78.115 to 166.167.78.115—1
117166.167.78.116/32166.167.78.116 to 166.167.78.116—1
118166.167.78.117/32166.167.78.117 to 166.167.78.117—1
119166.167.78.118/32166.167.78.118 to 166.167.78.118—1
120166.167.78.119/32166.167.78.119 to 166.167.78.119—1
121166.167.78.120/32166.167.78.120 to 166.167.78.120—1
122166.167.78.121/32166.167.78.121 to 166.167.78.121—1
123166.167.78.122/32166.167.78.122 to 166.167.78.122—1
124166.167.78.123/32166.167.78.123 to 166.167.78.123—1
125166.167.78.124/32166.167.78.124 to 166.167.78.124—1
126166.167.78.125/32166.167.78.125 to 166.167.78.125—1
127166.167.78.126/32166.167.78.126 to 166.167.78.126—1
128166.167.78.127/32166.167.78.127 to 166.167.78.127—1
129166.167.78.128/32166.167.78.128 to 166.167.78.128—1
130166.167.78.129/32166.167.78.129 to 166.167.78.129—1
131166.167.78.130/32166.167.78.130 to 166.167.78.130—1
132166.167.78.131/32166.167.78.131 to 166.167.78.131—1
133166.167.78.132/32166.167.78.132 to 166.167.78.132—1
134166.167.78.133/32166.167.78.133 to 166.167.78.133—1
135166.167.78.134/32166.167.78.134 to 166.167.78.134—1
136166.167.78.135/32166.167.78.135 to 166.167.78.135—1
137166.167.78.136/32166.167.78.136 to 166.167.78.136—1
138166.167.78.137/32166.167.78.137 to 166.167.78.137—1
139166.167.78.138/32166.167.78.138 to 166.167.78.138—1
140166.167.78.139/32166.167.78.139 to 166.167.78.139—1
141166.167.78.140/32166.167.78.140 to 166.167.78.140—1
142166.167.78.141/32166.167.78.141 to 166.167.78.141—1
143166.167.78.142/32166.167.78.142 to 166.167.78.142—1
144166.167.78.143/32166.167.78.143 to 166.167.78.143—1
145166.167.78.144/32166.167.78.144 to 166.167.78.144—1
146166.167.78.145/32166.167.78.145 to 166.167.78.145—1
147166.167.78.146/32166.167.78.146 to 166.167.78.146—1
148166.167.78.147/32166.167.78.147 to 166.167.78.147—1
149166.167.78.148/32166.167.78.148 to 166.167.78.148—1
150166.167.78.149/32166.167.78.149 to 166.167.78.149—1
151166.167.78.150/32166.167.78.150 to 166.167.78.150—1
152166.167.78.151/32166.167.78.151 to 166.167.78.151—1
153166.167.78.152/32166.167.78.152 to 166.167.78.152—1
154166.167.78.153/32166.167.78.153 to 166.167.78.153—1
155166.167.78.154/32166.167.78.154 to 166.167.78.154—1
156166.167.78.155/32166.167.78.155 to 166.167.78.155—1
157166.167.78.156/32166.167.78.156 to 166.167.78.156—1
158166.167.78.157/32166.167.78.157 to 166.167.78.157—1
159166.167.78.158/32166.167.78.158 to 166.167.78.158—1
160166.167.78.159/32166.167.78.159 to 166.167.78.159—1
161166.167.78.160/32166.167.78.160 to 166.167.78.160—1
162166.167.78.161/32166.167.78.161 to 166.167.78.161—1
163166.167.78.162/32166.167.78.162 to 166.167.78.162—1
164166.167.78.163/32166.167.78.163 to 166.167.78.163—1
165166.167.78.164/32166.167.78.164 to 166.167.78.164—1
166166.167.78.165/32166.167.78.165 to 166.167.78.165—1
167166.167.78.166/32166.167.78.166 to 166.167.78.166—1
168166.167.78.167/32166.167.78.167 to 166.167.78.167—1
169166.167.78.168/32166.167.78.168 to 166.167.78.168—1
170166.167.78.169/32166.167.78.169 to 166.167.78.169—1
171166.167.78.170/32166.167.78.170 to 166.167.78.170—1
172166.167.78.171/32166.167.78.171 to 166.167.78.171—1
173166.167.78.172/32166.167.78.172 to 166.167.78.172—1
174166.167.78.173/32166.167.78.173 to 166.167.78.173—1
175166.167.78.174/32166.167.78.174 to 166.167.78.174—1
176166.167.78.175/32166.167.78.175 to 166.167.78.175—1
177166.167.78.176/32166.167.78.176 to 166.167.78.176—1
178166.167.78.177/32166.167.78.177 to 166.167.78.177—1
179166.167.78.178/32166.167.78.178 to 166.167.78.178—1
180166.167.78.179/32166.167.78.179 to 166.167.78.179—1
181166.167.78.180/32166.167.78.180 to 166.167.78.180—1
182166.167.78.181/32166.167.78.181 to 166.167.78.181—1
183166.167.78.182/32166.167.78.182 to 166.167.78.182—1
184166.167.78.183/32166.167.78.183 to 166.167.78.183—1
185166.167.78.184/32166.167.78.184 to 166.167.78.184—1
186166.167.78.185/32166.167.78.185 to 166.167.78.185—1
187166.167.78.186/32166.167.78.186 to 166.167.78.186—1
188166.167.78.187/32166.167.78.187 to 166.167.78.187—1
189166.167.78.188/32166.167.78.188 to 166.167.78.188—1
190166.167.78.189/32166.167.78.189 to 166.167.78.189—1
191166.167.78.190/32166.167.78.190 to 166.167.78.190—1
192166.167.78.191/32166.167.78.191 to 166.167.78.191—1
193166.167.78.192/32166.167.78.192 to 166.167.78.192—1
194166.167.78.193/32166.167.78.193 to 166.167.78.193—1
195166.167.78.194/32166.167.78.194 to 166.167.78.194—1
196166.167.78.195/32166.167.78.195 to 166.167.78.195—1
197166.167.78.196/32166.167.78.196 to 166.167.78.196—1
198166.167.78.197/32166.167.78.197 to 166.167.78.197—1
199166.167.78.198/32166.167.78.198 to 166.167.78.198—1
200166.167.78.199/32166.167.78.199 to 166.167.78.199—1
201166.167.78.200/32166.167.78.200 to 166.167.78.200—1
202166.167.78.201/32166.167.78.201 to 166.167.78.201—1
203166.167.78.202/32166.167.78.202 to 166.167.78.202—1
204166.167.78.203/32166.167.78.203 to 166.167.78.203—1
205166.167.78.204/32166.167.78.204 to 166.167.78.204—1
206166.167.78.205/32166.167.78.205 to 166.167.78.205—1
207166.167.78.206/32166.167.78.206 to 166.167.78.206—1
208166.167.78.207/32166.167.78.207 to 166.167.78.207—1
209166.167.78.208/32166.167.78.208 to 166.167.78.208—1
210166.167.78.209/32166.167.78.209 to 166.167.78.209—1
211166.167.78.210/32166.167.78.210 to 166.167.78.210—1
212166.167.78.211/32166.167.78.211 to 166.167.78.211—1
213166.167.78.212/32166.167.78.212 to 166.167.78.212—1
214166.167.78.213/32166.167.78.213 to 166.167.78.213—1
215166.167.78.214/32166.167.78.214 to 166.167.78.214—1
216166.167.78.215/32166.167.78.215 to 166.167.78.215—1
217166.167.78.216/32166.167.78.216 to 166.167.78.216—1
218166.167.78.217/32166.167.78.217 to 166.167.78.217—1
219166.167.78.218/32166.167.78.218 to 166.167.78.218—1
220166.167.78.219/32166.167.78.219 to 166.167.78.219—1
221166.167.78.220/32166.167.78.220 to 166.167.78.220—1
222166.167.78.221/32166.167.78.221 to 166.167.78.221—1
223166.167.78.222/32166.167.78.222 to 166.167.78.222—1
224166.167.78.223/32166.167.78.223 to 166.167.78.223—1
225166.167.78.224/32166.167.78.224 to 166.167.78.224—1
226166.167.78.225/32166.167.78.225 to 166.167.78.225—1
227166.167.78.226/32166.167.78.226 to 166.167.78.226—1
228166.167.78.227/32166.167.78.227 to 166.167.78.227—1
229166.167.78.228/32166.167.78.228 to 166.167.78.228—1
230166.167.78.229/32166.167.78.229 to 166.167.78.229—1
231166.167.78.230/32166.167.78.230 to 166.167.78.230—1
232166.167.78.231/32166.167.78.231 to 166.167.78.231—1
233166.167.78.232/32166.167.78.232 to 166.167.78.232—1
234166.167.78.233/32166.167.78.233 to 166.167.78.233—1
235166.167.78.234/32166.167.78.234 to 166.167.78.234—1
236166.167.78.235/32166.167.78.235 to 166.167.78.235—1
237166.167.78.236/32166.167.78.236 to 166.167.78.236—1
238166.167.78.237/32166.167.78.237 to 166.167.78.237—1
239166.167.78.238/32166.167.78.238 to 166.167.78.238—1
240166.167.78.239/32166.167.78.239 to 166.167.78.239—1
241166.167.78.240/32166.167.78.240 to 166.167.78.240—1
242166.167.78.241/32166.167.78.241 to 166.167.78.241—1
243166.167.78.242/32166.167.78.242 to 166.167.78.242—1
244166.167.78.243/32166.167.78.243 to 166.167.78.243—1
245166.167.78.244/32166.167.78.244 to 166.167.78.244—1
246166.167.78.245/32166.167.78.245 to 166.167.78.245—1
247166.167.78.246/32166.167.78.246 to 166.167.78.246—1
248166.167.78.247/32166.167.78.247 to 166.167.78.247—1
249166.167.78.248/32166.167.78.248 to 166.167.78.248—1
250166.167.78.249/32166.167.78.249 to 166.167.78.249—1
251166.167.78.250/32166.167.78.250 to 166.167.78.250—1
252166.167.78.251/32166.167.78.251 to 166.167.78.251—1
253166.167.78.252/32166.167.78.252 to 166.167.78.252—1
254166.167.78.253/32166.167.78.253 to 166.167.78.253—1
255166.167.78.254/32166.167.78.254 to 166.167.78.254—1
256166.167.78.255/32166.167.78.255 to 166.167.78.255—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.