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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.

Network20.4.64.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
20.4.64.0
Broadcast address
20.4.79.255
First usable
20.4.64.1
Last usable
20.4.79.254
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
A (default /8)
As numbers
Hex 14044000 · Integer 335822848 to 335826943
Reverse DNS zones
64.4.20.in-addr.arpa
65.4.20.in-addr.arpa
66.4.20.in-addr.arpa
67.4.20.in-addr.arpa
68.4.20.in-addr.arpa
69.4.20.in-addr.arpa
70.4.20.in-addr.arpa
71.4.20.in-addr.arpa
72.4.20.in-addr.arpa
73.4.20.in-addr.arpa
74.4.20.in-addr.arpa
75.4.20.in-addr.arpa
76.4.20.in-addr.arpa
77.4.20.in-addr.arpa
78.4.20.in-addr.arpa
79.4.20.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
Address00010100.00000100.01000000.0000000020.4.64.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network00010100.00000100.01000000.0000000020.4.64.0
Broadcast00010100.00000100.01001111.1111111120.4.79.255
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)

20.4.64.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
120.4.64.0/3220.4.64.0 to 20.4.64.0—1
220.4.64.1/3220.4.64.1 to 20.4.64.1—1
320.4.64.2/3220.4.64.2 to 20.4.64.2—1
420.4.64.3/3220.4.64.3 to 20.4.64.3—1
520.4.64.4/3220.4.64.4 to 20.4.64.4—1
620.4.64.5/3220.4.64.5 to 20.4.64.5—1
720.4.64.6/3220.4.64.6 to 20.4.64.6—1
820.4.64.7/3220.4.64.7 to 20.4.64.7—1
920.4.64.8/3220.4.64.8 to 20.4.64.8—1
1020.4.64.9/3220.4.64.9 to 20.4.64.9—1
1120.4.64.10/3220.4.64.10 to 20.4.64.10—1
1220.4.64.11/3220.4.64.11 to 20.4.64.11—1
1320.4.64.12/3220.4.64.12 to 20.4.64.12—1
1420.4.64.13/3220.4.64.13 to 20.4.64.13—1
1520.4.64.14/3220.4.64.14 to 20.4.64.14—1
1620.4.64.15/3220.4.64.15 to 20.4.64.15—1
1720.4.64.16/3220.4.64.16 to 20.4.64.16—1
1820.4.64.17/3220.4.64.17 to 20.4.64.17—1
1920.4.64.18/3220.4.64.18 to 20.4.64.18—1
2020.4.64.19/3220.4.64.19 to 20.4.64.19—1
2120.4.64.20/3220.4.64.20 to 20.4.64.20—1
2220.4.64.21/3220.4.64.21 to 20.4.64.21—1
2320.4.64.22/3220.4.64.22 to 20.4.64.22—1
2420.4.64.23/3220.4.64.23 to 20.4.64.23—1
2520.4.64.24/3220.4.64.24 to 20.4.64.24—1
2620.4.64.25/3220.4.64.25 to 20.4.64.25—1
2720.4.64.26/3220.4.64.26 to 20.4.64.26—1
2820.4.64.27/3220.4.64.27 to 20.4.64.27—1
2920.4.64.28/3220.4.64.28 to 20.4.64.28—1
3020.4.64.29/3220.4.64.29 to 20.4.64.29—1
3120.4.64.30/3220.4.64.30 to 20.4.64.30—1
3220.4.64.31/3220.4.64.31 to 20.4.64.31—1
3320.4.64.32/3220.4.64.32 to 20.4.64.32—1
3420.4.64.33/3220.4.64.33 to 20.4.64.33—1
3520.4.64.34/3220.4.64.34 to 20.4.64.34—1
3620.4.64.35/3220.4.64.35 to 20.4.64.35—1
3720.4.64.36/3220.4.64.36 to 20.4.64.36—1
3820.4.64.37/3220.4.64.37 to 20.4.64.37—1
3920.4.64.38/3220.4.64.38 to 20.4.64.38—1
4020.4.64.39/3220.4.64.39 to 20.4.64.39—1
4120.4.64.40/3220.4.64.40 to 20.4.64.40—1
4220.4.64.41/3220.4.64.41 to 20.4.64.41—1
4320.4.64.42/3220.4.64.42 to 20.4.64.42—1
4420.4.64.43/3220.4.64.43 to 20.4.64.43—1
4520.4.64.44/3220.4.64.44 to 20.4.64.44—1
4620.4.64.45/3220.4.64.45 to 20.4.64.45—1
4720.4.64.46/3220.4.64.46 to 20.4.64.46—1
4820.4.64.47/3220.4.64.47 to 20.4.64.47—1
4920.4.64.48/3220.4.64.48 to 20.4.64.48—1
5020.4.64.49/3220.4.64.49 to 20.4.64.49—1
5120.4.64.50/3220.4.64.50 to 20.4.64.50—1
5220.4.64.51/3220.4.64.51 to 20.4.64.51—1
5320.4.64.52/3220.4.64.52 to 20.4.64.52—1
5420.4.64.53/3220.4.64.53 to 20.4.64.53—1
5520.4.64.54/3220.4.64.54 to 20.4.64.54—1
5620.4.64.55/3220.4.64.55 to 20.4.64.55—1
5720.4.64.56/3220.4.64.56 to 20.4.64.56—1
5820.4.64.57/3220.4.64.57 to 20.4.64.57—1
5920.4.64.58/3220.4.64.58 to 20.4.64.58—1
6020.4.64.59/3220.4.64.59 to 20.4.64.59—1
6120.4.64.60/3220.4.64.60 to 20.4.64.60—1
6220.4.64.61/3220.4.64.61 to 20.4.64.61—1
6320.4.64.62/3220.4.64.62 to 20.4.64.62—1
6420.4.64.63/3220.4.64.63 to 20.4.64.63—1
6520.4.64.64/3220.4.64.64 to 20.4.64.64—1
6620.4.64.65/3220.4.64.65 to 20.4.64.65—1
6720.4.64.66/3220.4.64.66 to 20.4.64.66—1
6820.4.64.67/3220.4.64.67 to 20.4.64.67—1
6920.4.64.68/3220.4.64.68 to 20.4.64.68—1
7020.4.64.69/3220.4.64.69 to 20.4.64.69—1
7120.4.64.70/3220.4.64.70 to 20.4.64.70—1
7220.4.64.71/3220.4.64.71 to 20.4.64.71—1
7320.4.64.72/3220.4.64.72 to 20.4.64.72—1
7420.4.64.73/3220.4.64.73 to 20.4.64.73—1
7520.4.64.74/3220.4.64.74 to 20.4.64.74—1
7620.4.64.75/3220.4.64.75 to 20.4.64.75—1
7720.4.64.76/3220.4.64.76 to 20.4.64.76—1
7820.4.64.77/3220.4.64.77 to 20.4.64.77—1
7920.4.64.78/3220.4.64.78 to 20.4.64.78—1
8020.4.64.79/3220.4.64.79 to 20.4.64.79—1
8120.4.64.80/3220.4.64.80 to 20.4.64.80—1
8220.4.64.81/3220.4.64.81 to 20.4.64.81—1
8320.4.64.82/3220.4.64.82 to 20.4.64.82—1
8420.4.64.83/3220.4.64.83 to 20.4.64.83—1
8520.4.64.84/3220.4.64.84 to 20.4.64.84—1
8620.4.64.85/3220.4.64.85 to 20.4.64.85—1
8720.4.64.86/3220.4.64.86 to 20.4.64.86—1
8820.4.64.87/3220.4.64.87 to 20.4.64.87—1
8920.4.64.88/3220.4.64.88 to 20.4.64.88—1
9020.4.64.89/3220.4.64.89 to 20.4.64.89—1
9120.4.64.90/3220.4.64.90 to 20.4.64.90—1
9220.4.64.91/3220.4.64.91 to 20.4.64.91—1
9320.4.64.92/3220.4.64.92 to 20.4.64.92—1
9420.4.64.93/3220.4.64.93 to 20.4.64.93—1
9520.4.64.94/3220.4.64.94 to 20.4.64.94—1
9620.4.64.95/3220.4.64.95 to 20.4.64.95—1
9720.4.64.96/3220.4.64.96 to 20.4.64.96—1
9820.4.64.97/3220.4.64.97 to 20.4.64.97—1
9920.4.64.98/3220.4.64.98 to 20.4.64.98—1
10020.4.64.99/3220.4.64.99 to 20.4.64.99—1
10120.4.64.100/3220.4.64.100 to 20.4.64.100—1
10220.4.64.101/3220.4.64.101 to 20.4.64.101—1
10320.4.64.102/3220.4.64.102 to 20.4.64.102—1
10420.4.64.103/3220.4.64.103 to 20.4.64.103—1
10520.4.64.104/3220.4.64.104 to 20.4.64.104—1
10620.4.64.105/3220.4.64.105 to 20.4.64.105—1
10720.4.64.106/3220.4.64.106 to 20.4.64.106—1
10820.4.64.107/3220.4.64.107 to 20.4.64.107—1
10920.4.64.108/3220.4.64.108 to 20.4.64.108—1
11020.4.64.109/3220.4.64.109 to 20.4.64.109—1
11120.4.64.110/3220.4.64.110 to 20.4.64.110—1
11220.4.64.111/3220.4.64.111 to 20.4.64.111—1
11320.4.64.112/3220.4.64.112 to 20.4.64.112—1
11420.4.64.113/3220.4.64.113 to 20.4.64.113—1
11520.4.64.114/3220.4.64.114 to 20.4.64.114—1
11620.4.64.115/3220.4.64.115 to 20.4.64.115—1
11720.4.64.116/3220.4.64.116 to 20.4.64.116—1
11820.4.64.117/3220.4.64.117 to 20.4.64.117—1
11920.4.64.118/3220.4.64.118 to 20.4.64.118—1
12020.4.64.119/3220.4.64.119 to 20.4.64.119—1
12120.4.64.120/3220.4.64.120 to 20.4.64.120—1
12220.4.64.121/3220.4.64.121 to 20.4.64.121—1
12320.4.64.122/3220.4.64.122 to 20.4.64.122—1
12420.4.64.123/3220.4.64.123 to 20.4.64.123—1
12520.4.64.124/3220.4.64.124 to 20.4.64.124—1
12620.4.64.125/3220.4.64.125 to 20.4.64.125—1
12720.4.64.126/3220.4.64.126 to 20.4.64.126—1
12820.4.64.127/3220.4.64.127 to 20.4.64.127—1
12920.4.64.128/3220.4.64.128 to 20.4.64.128—1
13020.4.64.129/3220.4.64.129 to 20.4.64.129—1
13120.4.64.130/3220.4.64.130 to 20.4.64.130—1
13220.4.64.131/3220.4.64.131 to 20.4.64.131—1
13320.4.64.132/3220.4.64.132 to 20.4.64.132—1
13420.4.64.133/3220.4.64.133 to 20.4.64.133—1
13520.4.64.134/3220.4.64.134 to 20.4.64.134—1
13620.4.64.135/3220.4.64.135 to 20.4.64.135—1
13720.4.64.136/3220.4.64.136 to 20.4.64.136—1
13820.4.64.137/3220.4.64.137 to 20.4.64.137—1
13920.4.64.138/3220.4.64.138 to 20.4.64.138—1
14020.4.64.139/3220.4.64.139 to 20.4.64.139—1
14120.4.64.140/3220.4.64.140 to 20.4.64.140—1
14220.4.64.141/3220.4.64.141 to 20.4.64.141—1
14320.4.64.142/3220.4.64.142 to 20.4.64.142—1
14420.4.64.143/3220.4.64.143 to 20.4.64.143—1
14520.4.64.144/3220.4.64.144 to 20.4.64.144—1
14620.4.64.145/3220.4.64.145 to 20.4.64.145—1
14720.4.64.146/3220.4.64.146 to 20.4.64.146—1
14820.4.64.147/3220.4.64.147 to 20.4.64.147—1
14920.4.64.148/3220.4.64.148 to 20.4.64.148—1
15020.4.64.149/3220.4.64.149 to 20.4.64.149—1
15120.4.64.150/3220.4.64.150 to 20.4.64.150—1
15220.4.64.151/3220.4.64.151 to 20.4.64.151—1
15320.4.64.152/3220.4.64.152 to 20.4.64.152—1
15420.4.64.153/3220.4.64.153 to 20.4.64.153—1
15520.4.64.154/3220.4.64.154 to 20.4.64.154—1
15620.4.64.155/3220.4.64.155 to 20.4.64.155—1
15720.4.64.156/3220.4.64.156 to 20.4.64.156—1
15820.4.64.157/3220.4.64.157 to 20.4.64.157—1
15920.4.64.158/3220.4.64.158 to 20.4.64.158—1
16020.4.64.159/3220.4.64.159 to 20.4.64.159—1
16120.4.64.160/3220.4.64.160 to 20.4.64.160—1
16220.4.64.161/3220.4.64.161 to 20.4.64.161—1
16320.4.64.162/3220.4.64.162 to 20.4.64.162—1
16420.4.64.163/3220.4.64.163 to 20.4.64.163—1
16520.4.64.164/3220.4.64.164 to 20.4.64.164—1
16620.4.64.165/3220.4.64.165 to 20.4.64.165—1
16720.4.64.166/3220.4.64.166 to 20.4.64.166—1
16820.4.64.167/3220.4.64.167 to 20.4.64.167—1
16920.4.64.168/3220.4.64.168 to 20.4.64.168—1
17020.4.64.169/3220.4.64.169 to 20.4.64.169—1
17120.4.64.170/3220.4.64.170 to 20.4.64.170—1
17220.4.64.171/3220.4.64.171 to 20.4.64.171—1
17320.4.64.172/3220.4.64.172 to 20.4.64.172—1
17420.4.64.173/3220.4.64.173 to 20.4.64.173—1
17520.4.64.174/3220.4.64.174 to 20.4.64.174—1
17620.4.64.175/3220.4.64.175 to 20.4.64.175—1
17720.4.64.176/3220.4.64.176 to 20.4.64.176—1
17820.4.64.177/3220.4.64.177 to 20.4.64.177—1
17920.4.64.178/3220.4.64.178 to 20.4.64.178—1
18020.4.64.179/3220.4.64.179 to 20.4.64.179—1
18120.4.64.180/3220.4.64.180 to 20.4.64.180—1
18220.4.64.181/3220.4.64.181 to 20.4.64.181—1
18320.4.64.182/3220.4.64.182 to 20.4.64.182—1
18420.4.64.183/3220.4.64.183 to 20.4.64.183—1
18520.4.64.184/3220.4.64.184 to 20.4.64.184—1
18620.4.64.185/3220.4.64.185 to 20.4.64.185—1
18720.4.64.186/3220.4.64.186 to 20.4.64.186—1
18820.4.64.187/3220.4.64.187 to 20.4.64.187—1
18920.4.64.188/3220.4.64.188 to 20.4.64.188—1
19020.4.64.189/3220.4.64.189 to 20.4.64.189—1
19120.4.64.190/3220.4.64.190 to 20.4.64.190—1
19220.4.64.191/3220.4.64.191 to 20.4.64.191—1
19320.4.64.192/3220.4.64.192 to 20.4.64.192—1
19420.4.64.193/3220.4.64.193 to 20.4.64.193—1
19520.4.64.194/3220.4.64.194 to 20.4.64.194—1
19620.4.64.195/3220.4.64.195 to 20.4.64.195—1
19720.4.64.196/3220.4.64.196 to 20.4.64.196—1
19820.4.64.197/3220.4.64.197 to 20.4.64.197—1
19920.4.64.198/3220.4.64.198 to 20.4.64.198—1
20020.4.64.199/3220.4.64.199 to 20.4.64.199—1
20120.4.64.200/3220.4.64.200 to 20.4.64.200—1
20220.4.64.201/3220.4.64.201 to 20.4.64.201—1
20320.4.64.202/3220.4.64.202 to 20.4.64.202—1
20420.4.64.203/3220.4.64.203 to 20.4.64.203—1
20520.4.64.204/3220.4.64.204 to 20.4.64.204—1
20620.4.64.205/3220.4.64.205 to 20.4.64.205—1
20720.4.64.206/3220.4.64.206 to 20.4.64.206—1
20820.4.64.207/3220.4.64.207 to 20.4.64.207—1
20920.4.64.208/3220.4.64.208 to 20.4.64.208—1
21020.4.64.209/3220.4.64.209 to 20.4.64.209—1
21120.4.64.210/3220.4.64.210 to 20.4.64.210—1
21220.4.64.211/3220.4.64.211 to 20.4.64.211—1
21320.4.64.212/3220.4.64.212 to 20.4.64.212—1
21420.4.64.213/3220.4.64.213 to 20.4.64.213—1
21520.4.64.214/3220.4.64.214 to 20.4.64.214—1
21620.4.64.215/3220.4.64.215 to 20.4.64.215—1
21720.4.64.216/3220.4.64.216 to 20.4.64.216—1
21820.4.64.217/3220.4.64.217 to 20.4.64.217—1
21920.4.64.218/3220.4.64.218 to 20.4.64.218—1
22020.4.64.219/3220.4.64.219 to 20.4.64.219—1
22120.4.64.220/3220.4.64.220 to 20.4.64.220—1
22220.4.64.221/3220.4.64.221 to 20.4.64.221—1
22320.4.64.222/3220.4.64.222 to 20.4.64.222—1
22420.4.64.223/3220.4.64.223 to 20.4.64.223—1
22520.4.64.224/3220.4.64.224 to 20.4.64.224—1
22620.4.64.225/3220.4.64.225 to 20.4.64.225—1
22720.4.64.226/3220.4.64.226 to 20.4.64.226—1
22820.4.64.227/3220.4.64.227 to 20.4.64.227—1
22920.4.64.228/3220.4.64.228 to 20.4.64.228—1
23020.4.64.229/3220.4.64.229 to 20.4.64.229—1
23120.4.64.230/3220.4.64.230 to 20.4.64.230—1
23220.4.64.231/3220.4.64.231 to 20.4.64.231—1
23320.4.64.232/3220.4.64.232 to 20.4.64.232—1
23420.4.64.233/3220.4.64.233 to 20.4.64.233—1
23520.4.64.234/3220.4.64.234 to 20.4.64.234—1
23620.4.64.235/3220.4.64.235 to 20.4.64.235—1
23720.4.64.236/3220.4.64.236 to 20.4.64.236—1
23820.4.64.237/3220.4.64.237 to 20.4.64.237—1
23920.4.64.238/3220.4.64.238 to 20.4.64.238—1
24020.4.64.239/3220.4.64.239 to 20.4.64.239—1
24120.4.64.240/3220.4.64.240 to 20.4.64.240—1
24220.4.64.241/3220.4.64.241 to 20.4.64.241—1
24320.4.64.242/3220.4.64.242 to 20.4.64.242—1
24420.4.64.243/3220.4.64.243 to 20.4.64.243—1
24520.4.64.244/3220.4.64.244 to 20.4.64.244—1
24620.4.64.245/3220.4.64.245 to 20.4.64.245—1
24720.4.64.246/3220.4.64.246 to 20.4.64.246—1
24820.4.64.247/3220.4.64.247 to 20.4.64.247—1
24920.4.64.248/3220.4.64.248 to 20.4.64.248—1
25020.4.64.249/3220.4.64.249 to 20.4.64.249—1
25120.4.64.250/3220.4.64.250 to 20.4.64.250—1
25220.4.64.251/3220.4.64.251 to 20.4.64.251—1
25320.4.64.252/3220.4.64.252 to 20.4.64.252—1
25420.4.64.253/3220.4.64.253 to 20.4.64.253—1
25520.4.64.254/3220.4.64.254 to 20.4.64.254—1
25620.4.64.255/3220.4.64.255 to 20.4.64.255—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.