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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.

Network170.2.32.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
170.2.32.0
Broadcast address
170.2.47.255
First usable
170.2.32.1
Last usable
170.2.47.254
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 AA022000 · Integer 2852265984 to 2852270079
Reverse DNS zones
32.2.170.in-addr.arpa
33.2.170.in-addr.arpa
34.2.170.in-addr.arpa
35.2.170.in-addr.arpa
36.2.170.in-addr.arpa
37.2.170.in-addr.arpa
38.2.170.in-addr.arpa
39.2.170.in-addr.arpa
40.2.170.in-addr.arpa
41.2.170.in-addr.arpa
42.2.170.in-addr.arpa
43.2.170.in-addr.arpa
44.2.170.in-addr.arpa
45.2.170.in-addr.arpa
46.2.170.in-addr.arpa
47.2.170.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
Address10101010.00000010.00100000.00000000170.2.32.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network10101010.00000010.00100000.00000000170.2.32.0
Broadcast10101010.00000010.00101111.11111111170.2.47.255
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)

170.2.32.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1170.2.32.0/32170.2.32.0 to 170.2.32.0—1
2170.2.32.1/32170.2.32.1 to 170.2.32.1—1
3170.2.32.2/32170.2.32.2 to 170.2.32.2—1
4170.2.32.3/32170.2.32.3 to 170.2.32.3—1
5170.2.32.4/32170.2.32.4 to 170.2.32.4—1
6170.2.32.5/32170.2.32.5 to 170.2.32.5—1
7170.2.32.6/32170.2.32.6 to 170.2.32.6—1
8170.2.32.7/32170.2.32.7 to 170.2.32.7—1
9170.2.32.8/32170.2.32.8 to 170.2.32.8—1
10170.2.32.9/32170.2.32.9 to 170.2.32.9—1
11170.2.32.10/32170.2.32.10 to 170.2.32.10—1
12170.2.32.11/32170.2.32.11 to 170.2.32.11—1
13170.2.32.12/32170.2.32.12 to 170.2.32.12—1
14170.2.32.13/32170.2.32.13 to 170.2.32.13—1
15170.2.32.14/32170.2.32.14 to 170.2.32.14—1
16170.2.32.15/32170.2.32.15 to 170.2.32.15—1
17170.2.32.16/32170.2.32.16 to 170.2.32.16—1
18170.2.32.17/32170.2.32.17 to 170.2.32.17—1
19170.2.32.18/32170.2.32.18 to 170.2.32.18—1
20170.2.32.19/32170.2.32.19 to 170.2.32.19—1
21170.2.32.20/32170.2.32.20 to 170.2.32.20—1
22170.2.32.21/32170.2.32.21 to 170.2.32.21—1
23170.2.32.22/32170.2.32.22 to 170.2.32.22—1
24170.2.32.23/32170.2.32.23 to 170.2.32.23—1
25170.2.32.24/32170.2.32.24 to 170.2.32.24—1
26170.2.32.25/32170.2.32.25 to 170.2.32.25—1
27170.2.32.26/32170.2.32.26 to 170.2.32.26—1
28170.2.32.27/32170.2.32.27 to 170.2.32.27—1
29170.2.32.28/32170.2.32.28 to 170.2.32.28—1
30170.2.32.29/32170.2.32.29 to 170.2.32.29—1
31170.2.32.30/32170.2.32.30 to 170.2.32.30—1
32170.2.32.31/32170.2.32.31 to 170.2.32.31—1
33170.2.32.32/32170.2.32.32 to 170.2.32.32—1
34170.2.32.33/32170.2.32.33 to 170.2.32.33—1
35170.2.32.34/32170.2.32.34 to 170.2.32.34—1
36170.2.32.35/32170.2.32.35 to 170.2.32.35—1
37170.2.32.36/32170.2.32.36 to 170.2.32.36—1
38170.2.32.37/32170.2.32.37 to 170.2.32.37—1
39170.2.32.38/32170.2.32.38 to 170.2.32.38—1
40170.2.32.39/32170.2.32.39 to 170.2.32.39—1
41170.2.32.40/32170.2.32.40 to 170.2.32.40—1
42170.2.32.41/32170.2.32.41 to 170.2.32.41—1
43170.2.32.42/32170.2.32.42 to 170.2.32.42—1
44170.2.32.43/32170.2.32.43 to 170.2.32.43—1
45170.2.32.44/32170.2.32.44 to 170.2.32.44—1
46170.2.32.45/32170.2.32.45 to 170.2.32.45—1
47170.2.32.46/32170.2.32.46 to 170.2.32.46—1
48170.2.32.47/32170.2.32.47 to 170.2.32.47—1
49170.2.32.48/32170.2.32.48 to 170.2.32.48—1
50170.2.32.49/32170.2.32.49 to 170.2.32.49—1
51170.2.32.50/32170.2.32.50 to 170.2.32.50—1
52170.2.32.51/32170.2.32.51 to 170.2.32.51—1
53170.2.32.52/32170.2.32.52 to 170.2.32.52—1
54170.2.32.53/32170.2.32.53 to 170.2.32.53—1
55170.2.32.54/32170.2.32.54 to 170.2.32.54—1
56170.2.32.55/32170.2.32.55 to 170.2.32.55—1
57170.2.32.56/32170.2.32.56 to 170.2.32.56—1
58170.2.32.57/32170.2.32.57 to 170.2.32.57—1
59170.2.32.58/32170.2.32.58 to 170.2.32.58—1
60170.2.32.59/32170.2.32.59 to 170.2.32.59—1
61170.2.32.60/32170.2.32.60 to 170.2.32.60—1
62170.2.32.61/32170.2.32.61 to 170.2.32.61—1
63170.2.32.62/32170.2.32.62 to 170.2.32.62—1
64170.2.32.63/32170.2.32.63 to 170.2.32.63—1
65170.2.32.64/32170.2.32.64 to 170.2.32.64—1
66170.2.32.65/32170.2.32.65 to 170.2.32.65—1
67170.2.32.66/32170.2.32.66 to 170.2.32.66—1
68170.2.32.67/32170.2.32.67 to 170.2.32.67—1
69170.2.32.68/32170.2.32.68 to 170.2.32.68—1
70170.2.32.69/32170.2.32.69 to 170.2.32.69—1
71170.2.32.70/32170.2.32.70 to 170.2.32.70—1
72170.2.32.71/32170.2.32.71 to 170.2.32.71—1
73170.2.32.72/32170.2.32.72 to 170.2.32.72—1
74170.2.32.73/32170.2.32.73 to 170.2.32.73—1
75170.2.32.74/32170.2.32.74 to 170.2.32.74—1
76170.2.32.75/32170.2.32.75 to 170.2.32.75—1
77170.2.32.76/32170.2.32.76 to 170.2.32.76—1
78170.2.32.77/32170.2.32.77 to 170.2.32.77—1
79170.2.32.78/32170.2.32.78 to 170.2.32.78—1
80170.2.32.79/32170.2.32.79 to 170.2.32.79—1
81170.2.32.80/32170.2.32.80 to 170.2.32.80—1
82170.2.32.81/32170.2.32.81 to 170.2.32.81—1
83170.2.32.82/32170.2.32.82 to 170.2.32.82—1
84170.2.32.83/32170.2.32.83 to 170.2.32.83—1
85170.2.32.84/32170.2.32.84 to 170.2.32.84—1
86170.2.32.85/32170.2.32.85 to 170.2.32.85—1
87170.2.32.86/32170.2.32.86 to 170.2.32.86—1
88170.2.32.87/32170.2.32.87 to 170.2.32.87—1
89170.2.32.88/32170.2.32.88 to 170.2.32.88—1
90170.2.32.89/32170.2.32.89 to 170.2.32.89—1
91170.2.32.90/32170.2.32.90 to 170.2.32.90—1
92170.2.32.91/32170.2.32.91 to 170.2.32.91—1
93170.2.32.92/32170.2.32.92 to 170.2.32.92—1
94170.2.32.93/32170.2.32.93 to 170.2.32.93—1
95170.2.32.94/32170.2.32.94 to 170.2.32.94—1
96170.2.32.95/32170.2.32.95 to 170.2.32.95—1
97170.2.32.96/32170.2.32.96 to 170.2.32.96—1
98170.2.32.97/32170.2.32.97 to 170.2.32.97—1
99170.2.32.98/32170.2.32.98 to 170.2.32.98—1
100170.2.32.99/32170.2.32.99 to 170.2.32.99—1
101170.2.32.100/32170.2.32.100 to 170.2.32.100—1
102170.2.32.101/32170.2.32.101 to 170.2.32.101—1
103170.2.32.102/32170.2.32.102 to 170.2.32.102—1
104170.2.32.103/32170.2.32.103 to 170.2.32.103—1
105170.2.32.104/32170.2.32.104 to 170.2.32.104—1
106170.2.32.105/32170.2.32.105 to 170.2.32.105—1
107170.2.32.106/32170.2.32.106 to 170.2.32.106—1
108170.2.32.107/32170.2.32.107 to 170.2.32.107—1
109170.2.32.108/32170.2.32.108 to 170.2.32.108—1
110170.2.32.109/32170.2.32.109 to 170.2.32.109—1
111170.2.32.110/32170.2.32.110 to 170.2.32.110—1
112170.2.32.111/32170.2.32.111 to 170.2.32.111—1
113170.2.32.112/32170.2.32.112 to 170.2.32.112—1
114170.2.32.113/32170.2.32.113 to 170.2.32.113—1
115170.2.32.114/32170.2.32.114 to 170.2.32.114—1
116170.2.32.115/32170.2.32.115 to 170.2.32.115—1
117170.2.32.116/32170.2.32.116 to 170.2.32.116—1
118170.2.32.117/32170.2.32.117 to 170.2.32.117—1
119170.2.32.118/32170.2.32.118 to 170.2.32.118—1
120170.2.32.119/32170.2.32.119 to 170.2.32.119—1
121170.2.32.120/32170.2.32.120 to 170.2.32.120—1
122170.2.32.121/32170.2.32.121 to 170.2.32.121—1
123170.2.32.122/32170.2.32.122 to 170.2.32.122—1
124170.2.32.123/32170.2.32.123 to 170.2.32.123—1
125170.2.32.124/32170.2.32.124 to 170.2.32.124—1
126170.2.32.125/32170.2.32.125 to 170.2.32.125—1
127170.2.32.126/32170.2.32.126 to 170.2.32.126—1
128170.2.32.127/32170.2.32.127 to 170.2.32.127—1
129170.2.32.128/32170.2.32.128 to 170.2.32.128—1
130170.2.32.129/32170.2.32.129 to 170.2.32.129—1
131170.2.32.130/32170.2.32.130 to 170.2.32.130—1
132170.2.32.131/32170.2.32.131 to 170.2.32.131—1
133170.2.32.132/32170.2.32.132 to 170.2.32.132—1
134170.2.32.133/32170.2.32.133 to 170.2.32.133—1
135170.2.32.134/32170.2.32.134 to 170.2.32.134—1
136170.2.32.135/32170.2.32.135 to 170.2.32.135—1
137170.2.32.136/32170.2.32.136 to 170.2.32.136—1
138170.2.32.137/32170.2.32.137 to 170.2.32.137—1
139170.2.32.138/32170.2.32.138 to 170.2.32.138—1
140170.2.32.139/32170.2.32.139 to 170.2.32.139—1
141170.2.32.140/32170.2.32.140 to 170.2.32.140—1
142170.2.32.141/32170.2.32.141 to 170.2.32.141—1
143170.2.32.142/32170.2.32.142 to 170.2.32.142—1
144170.2.32.143/32170.2.32.143 to 170.2.32.143—1
145170.2.32.144/32170.2.32.144 to 170.2.32.144—1
146170.2.32.145/32170.2.32.145 to 170.2.32.145—1
147170.2.32.146/32170.2.32.146 to 170.2.32.146—1
148170.2.32.147/32170.2.32.147 to 170.2.32.147—1
149170.2.32.148/32170.2.32.148 to 170.2.32.148—1
150170.2.32.149/32170.2.32.149 to 170.2.32.149—1
151170.2.32.150/32170.2.32.150 to 170.2.32.150—1
152170.2.32.151/32170.2.32.151 to 170.2.32.151—1
153170.2.32.152/32170.2.32.152 to 170.2.32.152—1
154170.2.32.153/32170.2.32.153 to 170.2.32.153—1
155170.2.32.154/32170.2.32.154 to 170.2.32.154—1
156170.2.32.155/32170.2.32.155 to 170.2.32.155—1
157170.2.32.156/32170.2.32.156 to 170.2.32.156—1
158170.2.32.157/32170.2.32.157 to 170.2.32.157—1
159170.2.32.158/32170.2.32.158 to 170.2.32.158—1
160170.2.32.159/32170.2.32.159 to 170.2.32.159—1
161170.2.32.160/32170.2.32.160 to 170.2.32.160—1
162170.2.32.161/32170.2.32.161 to 170.2.32.161—1
163170.2.32.162/32170.2.32.162 to 170.2.32.162—1
164170.2.32.163/32170.2.32.163 to 170.2.32.163—1
165170.2.32.164/32170.2.32.164 to 170.2.32.164—1
166170.2.32.165/32170.2.32.165 to 170.2.32.165—1
167170.2.32.166/32170.2.32.166 to 170.2.32.166—1
168170.2.32.167/32170.2.32.167 to 170.2.32.167—1
169170.2.32.168/32170.2.32.168 to 170.2.32.168—1
170170.2.32.169/32170.2.32.169 to 170.2.32.169—1
171170.2.32.170/32170.2.32.170 to 170.2.32.170—1
172170.2.32.171/32170.2.32.171 to 170.2.32.171—1
173170.2.32.172/32170.2.32.172 to 170.2.32.172—1
174170.2.32.173/32170.2.32.173 to 170.2.32.173—1
175170.2.32.174/32170.2.32.174 to 170.2.32.174—1
176170.2.32.175/32170.2.32.175 to 170.2.32.175—1
177170.2.32.176/32170.2.32.176 to 170.2.32.176—1
178170.2.32.177/32170.2.32.177 to 170.2.32.177—1
179170.2.32.178/32170.2.32.178 to 170.2.32.178—1
180170.2.32.179/32170.2.32.179 to 170.2.32.179—1
181170.2.32.180/32170.2.32.180 to 170.2.32.180—1
182170.2.32.181/32170.2.32.181 to 170.2.32.181—1
183170.2.32.182/32170.2.32.182 to 170.2.32.182—1
184170.2.32.183/32170.2.32.183 to 170.2.32.183—1
185170.2.32.184/32170.2.32.184 to 170.2.32.184—1
186170.2.32.185/32170.2.32.185 to 170.2.32.185—1
187170.2.32.186/32170.2.32.186 to 170.2.32.186—1
188170.2.32.187/32170.2.32.187 to 170.2.32.187—1
189170.2.32.188/32170.2.32.188 to 170.2.32.188—1
190170.2.32.189/32170.2.32.189 to 170.2.32.189—1
191170.2.32.190/32170.2.32.190 to 170.2.32.190—1
192170.2.32.191/32170.2.32.191 to 170.2.32.191—1
193170.2.32.192/32170.2.32.192 to 170.2.32.192—1
194170.2.32.193/32170.2.32.193 to 170.2.32.193—1
195170.2.32.194/32170.2.32.194 to 170.2.32.194—1
196170.2.32.195/32170.2.32.195 to 170.2.32.195—1
197170.2.32.196/32170.2.32.196 to 170.2.32.196—1
198170.2.32.197/32170.2.32.197 to 170.2.32.197—1
199170.2.32.198/32170.2.32.198 to 170.2.32.198—1
200170.2.32.199/32170.2.32.199 to 170.2.32.199—1
201170.2.32.200/32170.2.32.200 to 170.2.32.200—1
202170.2.32.201/32170.2.32.201 to 170.2.32.201—1
203170.2.32.202/32170.2.32.202 to 170.2.32.202—1
204170.2.32.203/32170.2.32.203 to 170.2.32.203—1
205170.2.32.204/32170.2.32.204 to 170.2.32.204—1
206170.2.32.205/32170.2.32.205 to 170.2.32.205—1
207170.2.32.206/32170.2.32.206 to 170.2.32.206—1
208170.2.32.207/32170.2.32.207 to 170.2.32.207—1
209170.2.32.208/32170.2.32.208 to 170.2.32.208—1
210170.2.32.209/32170.2.32.209 to 170.2.32.209—1
211170.2.32.210/32170.2.32.210 to 170.2.32.210—1
212170.2.32.211/32170.2.32.211 to 170.2.32.211—1
213170.2.32.212/32170.2.32.212 to 170.2.32.212—1
214170.2.32.213/32170.2.32.213 to 170.2.32.213—1
215170.2.32.214/32170.2.32.214 to 170.2.32.214—1
216170.2.32.215/32170.2.32.215 to 170.2.32.215—1
217170.2.32.216/32170.2.32.216 to 170.2.32.216—1
218170.2.32.217/32170.2.32.217 to 170.2.32.217—1
219170.2.32.218/32170.2.32.218 to 170.2.32.218—1
220170.2.32.219/32170.2.32.219 to 170.2.32.219—1
221170.2.32.220/32170.2.32.220 to 170.2.32.220—1
222170.2.32.221/32170.2.32.221 to 170.2.32.221—1
223170.2.32.222/32170.2.32.222 to 170.2.32.222—1
224170.2.32.223/32170.2.32.223 to 170.2.32.223—1
225170.2.32.224/32170.2.32.224 to 170.2.32.224—1
226170.2.32.225/32170.2.32.225 to 170.2.32.225—1
227170.2.32.226/32170.2.32.226 to 170.2.32.226—1
228170.2.32.227/32170.2.32.227 to 170.2.32.227—1
229170.2.32.228/32170.2.32.228 to 170.2.32.228—1
230170.2.32.229/32170.2.32.229 to 170.2.32.229—1
231170.2.32.230/32170.2.32.230 to 170.2.32.230—1
232170.2.32.231/32170.2.32.231 to 170.2.32.231—1
233170.2.32.232/32170.2.32.232 to 170.2.32.232—1
234170.2.32.233/32170.2.32.233 to 170.2.32.233—1
235170.2.32.234/32170.2.32.234 to 170.2.32.234—1
236170.2.32.235/32170.2.32.235 to 170.2.32.235—1
237170.2.32.236/32170.2.32.236 to 170.2.32.236—1
238170.2.32.237/32170.2.32.237 to 170.2.32.237—1
239170.2.32.238/32170.2.32.238 to 170.2.32.238—1
240170.2.32.239/32170.2.32.239 to 170.2.32.239—1
241170.2.32.240/32170.2.32.240 to 170.2.32.240—1
242170.2.32.241/32170.2.32.241 to 170.2.32.241—1
243170.2.32.242/32170.2.32.242 to 170.2.32.242—1
244170.2.32.243/32170.2.32.243 to 170.2.32.243—1
245170.2.32.244/32170.2.32.244 to 170.2.32.244—1
246170.2.32.245/32170.2.32.245 to 170.2.32.245—1
247170.2.32.246/32170.2.32.246 to 170.2.32.246—1
248170.2.32.247/32170.2.32.247 to 170.2.32.247—1
249170.2.32.248/32170.2.32.248 to 170.2.32.248—1
250170.2.32.249/32170.2.32.249 to 170.2.32.249—1
251170.2.32.250/32170.2.32.250 to 170.2.32.250—1
252170.2.32.251/32170.2.32.251 to 170.2.32.251—1
253170.2.32.252/32170.2.32.252 to 170.2.32.252—1
254170.2.32.253/32170.2.32.253 to 170.2.32.253—1
255170.2.32.254/32170.2.32.254 to 170.2.32.254—1
256170.2.32.255/32170.2.32.255 to 170.2.32.255—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.