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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.

Network243.232.2.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
243.232.2.0
Broadcast address
243.232.3.255
First usable
243.232.2.1
Last usable
243.232.3.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F3E80200 · Integer 4092068352 to 4092068863
Reverse DNS zones
2.232.243.in-addr.arpa
3.232.243.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
Address11110011.11101000.00000010.00000000243.232.2.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network11110011.11101000.00000010.00000000243.232.2.0
Broadcast11110011.11101000.00000011.11111111243.232.3.255
Split into smaller subnets/32
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

243.232.2.0/23 makes 512 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1243.232.2.0/32243.232.2.0 to 243.232.2.0—1
2243.232.2.1/32243.232.2.1 to 243.232.2.1—1
3243.232.2.2/32243.232.2.2 to 243.232.2.2—1
4243.232.2.3/32243.232.2.3 to 243.232.2.3—1
5243.232.2.4/32243.232.2.4 to 243.232.2.4—1
6243.232.2.5/32243.232.2.5 to 243.232.2.5—1
7243.232.2.6/32243.232.2.6 to 243.232.2.6—1
8243.232.2.7/32243.232.2.7 to 243.232.2.7—1
9243.232.2.8/32243.232.2.8 to 243.232.2.8—1
10243.232.2.9/32243.232.2.9 to 243.232.2.9—1
11243.232.2.10/32243.232.2.10 to 243.232.2.10—1
12243.232.2.11/32243.232.2.11 to 243.232.2.11—1
13243.232.2.12/32243.232.2.12 to 243.232.2.12—1
14243.232.2.13/32243.232.2.13 to 243.232.2.13—1
15243.232.2.14/32243.232.2.14 to 243.232.2.14—1
16243.232.2.15/32243.232.2.15 to 243.232.2.15—1
17243.232.2.16/32243.232.2.16 to 243.232.2.16—1
18243.232.2.17/32243.232.2.17 to 243.232.2.17—1
19243.232.2.18/32243.232.2.18 to 243.232.2.18—1
20243.232.2.19/32243.232.2.19 to 243.232.2.19—1
21243.232.2.20/32243.232.2.20 to 243.232.2.20—1
22243.232.2.21/32243.232.2.21 to 243.232.2.21—1
23243.232.2.22/32243.232.2.22 to 243.232.2.22—1
24243.232.2.23/32243.232.2.23 to 243.232.2.23—1
25243.232.2.24/32243.232.2.24 to 243.232.2.24—1
26243.232.2.25/32243.232.2.25 to 243.232.2.25—1
27243.232.2.26/32243.232.2.26 to 243.232.2.26—1
28243.232.2.27/32243.232.2.27 to 243.232.2.27—1
29243.232.2.28/32243.232.2.28 to 243.232.2.28—1
30243.232.2.29/32243.232.2.29 to 243.232.2.29—1
31243.232.2.30/32243.232.2.30 to 243.232.2.30—1
32243.232.2.31/32243.232.2.31 to 243.232.2.31—1
33243.232.2.32/32243.232.2.32 to 243.232.2.32—1
34243.232.2.33/32243.232.2.33 to 243.232.2.33—1
35243.232.2.34/32243.232.2.34 to 243.232.2.34—1
36243.232.2.35/32243.232.2.35 to 243.232.2.35—1
37243.232.2.36/32243.232.2.36 to 243.232.2.36—1
38243.232.2.37/32243.232.2.37 to 243.232.2.37—1
39243.232.2.38/32243.232.2.38 to 243.232.2.38—1
40243.232.2.39/32243.232.2.39 to 243.232.2.39—1
41243.232.2.40/32243.232.2.40 to 243.232.2.40—1
42243.232.2.41/32243.232.2.41 to 243.232.2.41—1
43243.232.2.42/32243.232.2.42 to 243.232.2.42—1
44243.232.2.43/32243.232.2.43 to 243.232.2.43—1
45243.232.2.44/32243.232.2.44 to 243.232.2.44—1
46243.232.2.45/32243.232.2.45 to 243.232.2.45—1
47243.232.2.46/32243.232.2.46 to 243.232.2.46—1
48243.232.2.47/32243.232.2.47 to 243.232.2.47—1
49243.232.2.48/32243.232.2.48 to 243.232.2.48—1
50243.232.2.49/32243.232.2.49 to 243.232.2.49—1
51243.232.2.50/32243.232.2.50 to 243.232.2.50—1
52243.232.2.51/32243.232.2.51 to 243.232.2.51—1
53243.232.2.52/32243.232.2.52 to 243.232.2.52—1
54243.232.2.53/32243.232.2.53 to 243.232.2.53—1
55243.232.2.54/32243.232.2.54 to 243.232.2.54—1
56243.232.2.55/32243.232.2.55 to 243.232.2.55—1
57243.232.2.56/32243.232.2.56 to 243.232.2.56—1
58243.232.2.57/32243.232.2.57 to 243.232.2.57—1
59243.232.2.58/32243.232.2.58 to 243.232.2.58—1
60243.232.2.59/32243.232.2.59 to 243.232.2.59—1
61243.232.2.60/32243.232.2.60 to 243.232.2.60—1
62243.232.2.61/32243.232.2.61 to 243.232.2.61—1
63243.232.2.62/32243.232.2.62 to 243.232.2.62—1
64243.232.2.63/32243.232.2.63 to 243.232.2.63—1
65243.232.2.64/32243.232.2.64 to 243.232.2.64—1
66243.232.2.65/32243.232.2.65 to 243.232.2.65—1
67243.232.2.66/32243.232.2.66 to 243.232.2.66—1
68243.232.2.67/32243.232.2.67 to 243.232.2.67—1
69243.232.2.68/32243.232.2.68 to 243.232.2.68—1
70243.232.2.69/32243.232.2.69 to 243.232.2.69—1
71243.232.2.70/32243.232.2.70 to 243.232.2.70—1
72243.232.2.71/32243.232.2.71 to 243.232.2.71—1
73243.232.2.72/32243.232.2.72 to 243.232.2.72—1
74243.232.2.73/32243.232.2.73 to 243.232.2.73—1
75243.232.2.74/32243.232.2.74 to 243.232.2.74—1
76243.232.2.75/32243.232.2.75 to 243.232.2.75—1
77243.232.2.76/32243.232.2.76 to 243.232.2.76—1
78243.232.2.77/32243.232.2.77 to 243.232.2.77—1
79243.232.2.78/32243.232.2.78 to 243.232.2.78—1
80243.232.2.79/32243.232.2.79 to 243.232.2.79—1
81243.232.2.80/32243.232.2.80 to 243.232.2.80—1
82243.232.2.81/32243.232.2.81 to 243.232.2.81—1
83243.232.2.82/32243.232.2.82 to 243.232.2.82—1
84243.232.2.83/32243.232.2.83 to 243.232.2.83—1
85243.232.2.84/32243.232.2.84 to 243.232.2.84—1
86243.232.2.85/32243.232.2.85 to 243.232.2.85—1
87243.232.2.86/32243.232.2.86 to 243.232.2.86—1
88243.232.2.87/32243.232.2.87 to 243.232.2.87—1
89243.232.2.88/32243.232.2.88 to 243.232.2.88—1
90243.232.2.89/32243.232.2.89 to 243.232.2.89—1
91243.232.2.90/32243.232.2.90 to 243.232.2.90—1
92243.232.2.91/32243.232.2.91 to 243.232.2.91—1
93243.232.2.92/32243.232.2.92 to 243.232.2.92—1
94243.232.2.93/32243.232.2.93 to 243.232.2.93—1
95243.232.2.94/32243.232.2.94 to 243.232.2.94—1
96243.232.2.95/32243.232.2.95 to 243.232.2.95—1
97243.232.2.96/32243.232.2.96 to 243.232.2.96—1
98243.232.2.97/32243.232.2.97 to 243.232.2.97—1
99243.232.2.98/32243.232.2.98 to 243.232.2.98—1
100243.232.2.99/32243.232.2.99 to 243.232.2.99—1
101243.232.2.100/32243.232.2.100 to 243.232.2.100—1
102243.232.2.101/32243.232.2.101 to 243.232.2.101—1
103243.232.2.102/32243.232.2.102 to 243.232.2.102—1
104243.232.2.103/32243.232.2.103 to 243.232.2.103—1
105243.232.2.104/32243.232.2.104 to 243.232.2.104—1
106243.232.2.105/32243.232.2.105 to 243.232.2.105—1
107243.232.2.106/32243.232.2.106 to 243.232.2.106—1
108243.232.2.107/32243.232.2.107 to 243.232.2.107—1
109243.232.2.108/32243.232.2.108 to 243.232.2.108—1
110243.232.2.109/32243.232.2.109 to 243.232.2.109—1
111243.232.2.110/32243.232.2.110 to 243.232.2.110—1
112243.232.2.111/32243.232.2.111 to 243.232.2.111—1
113243.232.2.112/32243.232.2.112 to 243.232.2.112—1
114243.232.2.113/32243.232.2.113 to 243.232.2.113—1
115243.232.2.114/32243.232.2.114 to 243.232.2.114—1
116243.232.2.115/32243.232.2.115 to 243.232.2.115—1
117243.232.2.116/32243.232.2.116 to 243.232.2.116—1
118243.232.2.117/32243.232.2.117 to 243.232.2.117—1
119243.232.2.118/32243.232.2.118 to 243.232.2.118—1
120243.232.2.119/32243.232.2.119 to 243.232.2.119—1
121243.232.2.120/32243.232.2.120 to 243.232.2.120—1
122243.232.2.121/32243.232.2.121 to 243.232.2.121—1
123243.232.2.122/32243.232.2.122 to 243.232.2.122—1
124243.232.2.123/32243.232.2.123 to 243.232.2.123—1
125243.232.2.124/32243.232.2.124 to 243.232.2.124—1
126243.232.2.125/32243.232.2.125 to 243.232.2.125—1
127243.232.2.126/32243.232.2.126 to 243.232.2.126—1
128243.232.2.127/32243.232.2.127 to 243.232.2.127—1
129243.232.2.128/32243.232.2.128 to 243.232.2.128—1
130243.232.2.129/32243.232.2.129 to 243.232.2.129—1
131243.232.2.130/32243.232.2.130 to 243.232.2.130—1
132243.232.2.131/32243.232.2.131 to 243.232.2.131—1
133243.232.2.132/32243.232.2.132 to 243.232.2.132—1
134243.232.2.133/32243.232.2.133 to 243.232.2.133—1
135243.232.2.134/32243.232.2.134 to 243.232.2.134—1
136243.232.2.135/32243.232.2.135 to 243.232.2.135—1
137243.232.2.136/32243.232.2.136 to 243.232.2.136—1
138243.232.2.137/32243.232.2.137 to 243.232.2.137—1
139243.232.2.138/32243.232.2.138 to 243.232.2.138—1
140243.232.2.139/32243.232.2.139 to 243.232.2.139—1
141243.232.2.140/32243.232.2.140 to 243.232.2.140—1
142243.232.2.141/32243.232.2.141 to 243.232.2.141—1
143243.232.2.142/32243.232.2.142 to 243.232.2.142—1
144243.232.2.143/32243.232.2.143 to 243.232.2.143—1
145243.232.2.144/32243.232.2.144 to 243.232.2.144—1
146243.232.2.145/32243.232.2.145 to 243.232.2.145—1
147243.232.2.146/32243.232.2.146 to 243.232.2.146—1
148243.232.2.147/32243.232.2.147 to 243.232.2.147—1
149243.232.2.148/32243.232.2.148 to 243.232.2.148—1
150243.232.2.149/32243.232.2.149 to 243.232.2.149—1
151243.232.2.150/32243.232.2.150 to 243.232.2.150—1
152243.232.2.151/32243.232.2.151 to 243.232.2.151—1
153243.232.2.152/32243.232.2.152 to 243.232.2.152—1
154243.232.2.153/32243.232.2.153 to 243.232.2.153—1
155243.232.2.154/32243.232.2.154 to 243.232.2.154—1
156243.232.2.155/32243.232.2.155 to 243.232.2.155—1
157243.232.2.156/32243.232.2.156 to 243.232.2.156—1
158243.232.2.157/32243.232.2.157 to 243.232.2.157—1
159243.232.2.158/32243.232.2.158 to 243.232.2.158—1
160243.232.2.159/32243.232.2.159 to 243.232.2.159—1
161243.232.2.160/32243.232.2.160 to 243.232.2.160—1
162243.232.2.161/32243.232.2.161 to 243.232.2.161—1
163243.232.2.162/32243.232.2.162 to 243.232.2.162—1
164243.232.2.163/32243.232.2.163 to 243.232.2.163—1
165243.232.2.164/32243.232.2.164 to 243.232.2.164—1
166243.232.2.165/32243.232.2.165 to 243.232.2.165—1
167243.232.2.166/32243.232.2.166 to 243.232.2.166—1
168243.232.2.167/32243.232.2.167 to 243.232.2.167—1
169243.232.2.168/32243.232.2.168 to 243.232.2.168—1
170243.232.2.169/32243.232.2.169 to 243.232.2.169—1
171243.232.2.170/32243.232.2.170 to 243.232.2.170—1
172243.232.2.171/32243.232.2.171 to 243.232.2.171—1
173243.232.2.172/32243.232.2.172 to 243.232.2.172—1
174243.232.2.173/32243.232.2.173 to 243.232.2.173—1
175243.232.2.174/32243.232.2.174 to 243.232.2.174—1
176243.232.2.175/32243.232.2.175 to 243.232.2.175—1
177243.232.2.176/32243.232.2.176 to 243.232.2.176—1
178243.232.2.177/32243.232.2.177 to 243.232.2.177—1
179243.232.2.178/32243.232.2.178 to 243.232.2.178—1
180243.232.2.179/32243.232.2.179 to 243.232.2.179—1
181243.232.2.180/32243.232.2.180 to 243.232.2.180—1
182243.232.2.181/32243.232.2.181 to 243.232.2.181—1
183243.232.2.182/32243.232.2.182 to 243.232.2.182—1
184243.232.2.183/32243.232.2.183 to 243.232.2.183—1
185243.232.2.184/32243.232.2.184 to 243.232.2.184—1
186243.232.2.185/32243.232.2.185 to 243.232.2.185—1
187243.232.2.186/32243.232.2.186 to 243.232.2.186—1
188243.232.2.187/32243.232.2.187 to 243.232.2.187—1
189243.232.2.188/32243.232.2.188 to 243.232.2.188—1
190243.232.2.189/32243.232.2.189 to 243.232.2.189—1
191243.232.2.190/32243.232.2.190 to 243.232.2.190—1
192243.232.2.191/32243.232.2.191 to 243.232.2.191—1
193243.232.2.192/32243.232.2.192 to 243.232.2.192—1
194243.232.2.193/32243.232.2.193 to 243.232.2.193—1
195243.232.2.194/32243.232.2.194 to 243.232.2.194—1
196243.232.2.195/32243.232.2.195 to 243.232.2.195—1
197243.232.2.196/32243.232.2.196 to 243.232.2.196—1
198243.232.2.197/32243.232.2.197 to 243.232.2.197—1
199243.232.2.198/32243.232.2.198 to 243.232.2.198—1
200243.232.2.199/32243.232.2.199 to 243.232.2.199—1
201243.232.2.200/32243.232.2.200 to 243.232.2.200—1
202243.232.2.201/32243.232.2.201 to 243.232.2.201—1
203243.232.2.202/32243.232.2.202 to 243.232.2.202—1
204243.232.2.203/32243.232.2.203 to 243.232.2.203—1
205243.232.2.204/32243.232.2.204 to 243.232.2.204—1
206243.232.2.205/32243.232.2.205 to 243.232.2.205—1
207243.232.2.206/32243.232.2.206 to 243.232.2.206—1
208243.232.2.207/32243.232.2.207 to 243.232.2.207—1
209243.232.2.208/32243.232.2.208 to 243.232.2.208—1
210243.232.2.209/32243.232.2.209 to 243.232.2.209—1
211243.232.2.210/32243.232.2.210 to 243.232.2.210—1
212243.232.2.211/32243.232.2.211 to 243.232.2.211—1
213243.232.2.212/32243.232.2.212 to 243.232.2.212—1
214243.232.2.213/32243.232.2.213 to 243.232.2.213—1
215243.232.2.214/32243.232.2.214 to 243.232.2.214—1
216243.232.2.215/32243.232.2.215 to 243.232.2.215—1
217243.232.2.216/32243.232.2.216 to 243.232.2.216—1
218243.232.2.217/32243.232.2.217 to 243.232.2.217—1
219243.232.2.218/32243.232.2.218 to 243.232.2.218—1
220243.232.2.219/32243.232.2.219 to 243.232.2.219—1
221243.232.2.220/32243.232.2.220 to 243.232.2.220—1
222243.232.2.221/32243.232.2.221 to 243.232.2.221—1
223243.232.2.222/32243.232.2.222 to 243.232.2.222—1
224243.232.2.223/32243.232.2.223 to 243.232.2.223—1
225243.232.2.224/32243.232.2.224 to 243.232.2.224—1
226243.232.2.225/32243.232.2.225 to 243.232.2.225—1
227243.232.2.226/32243.232.2.226 to 243.232.2.226—1
228243.232.2.227/32243.232.2.227 to 243.232.2.227—1
229243.232.2.228/32243.232.2.228 to 243.232.2.228—1
230243.232.2.229/32243.232.2.229 to 243.232.2.229—1
231243.232.2.230/32243.232.2.230 to 243.232.2.230—1
232243.232.2.231/32243.232.2.231 to 243.232.2.231—1
233243.232.2.232/32243.232.2.232 to 243.232.2.232—1
234243.232.2.233/32243.232.2.233 to 243.232.2.233—1
235243.232.2.234/32243.232.2.234 to 243.232.2.234—1
236243.232.2.235/32243.232.2.235 to 243.232.2.235—1
237243.232.2.236/32243.232.2.236 to 243.232.2.236—1
238243.232.2.237/32243.232.2.237 to 243.232.2.237—1
239243.232.2.238/32243.232.2.238 to 243.232.2.238—1
240243.232.2.239/32243.232.2.239 to 243.232.2.239—1
241243.232.2.240/32243.232.2.240 to 243.232.2.240—1
242243.232.2.241/32243.232.2.241 to 243.232.2.241—1
243243.232.2.242/32243.232.2.242 to 243.232.2.242—1
244243.232.2.243/32243.232.2.243 to 243.232.2.243—1
245243.232.2.244/32243.232.2.244 to 243.232.2.244—1
246243.232.2.245/32243.232.2.245 to 243.232.2.245—1
247243.232.2.246/32243.232.2.246 to 243.232.2.246—1
248243.232.2.247/32243.232.2.247 to 243.232.2.247—1
249243.232.2.248/32243.232.2.248 to 243.232.2.248—1
250243.232.2.249/32243.232.2.249 to 243.232.2.249—1
251243.232.2.250/32243.232.2.250 to 243.232.2.250—1
252243.232.2.251/32243.232.2.251 to 243.232.2.251—1
253243.232.2.252/32243.232.2.252 to 243.232.2.252—1
254243.232.2.253/32243.232.2.253 to 243.232.2.253—1
255243.232.2.254/32243.232.2.254 to 243.232.2.254—1
256243.232.2.255/32243.232.2.255 to 243.232.2.255—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.