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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.

Network80.3.128.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
80.3.128.0
Broadcast address
80.3.143.255
First usable
80.3.128.1
Last usable
80.3.143.254
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 50038000 · Integer 1342406656 to 1342410751
Reverse DNS zones
128.3.80.in-addr.arpa
129.3.80.in-addr.arpa
130.3.80.in-addr.arpa
131.3.80.in-addr.arpa
132.3.80.in-addr.arpa
133.3.80.in-addr.arpa
134.3.80.in-addr.arpa
135.3.80.in-addr.arpa
136.3.80.in-addr.arpa
137.3.80.in-addr.arpa
138.3.80.in-addr.arpa
139.3.80.in-addr.arpa
140.3.80.in-addr.arpa
141.3.80.in-addr.arpa
142.3.80.in-addr.arpa
143.3.80.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
Address01010000.00000011.10000000.0000000080.3.128.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network01010000.00000011.10000000.0000000080.3.128.0
Broadcast01010000.00000011.10001111.1111111180.3.143.255
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)

80.3.128.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
180.3.128.0/3280.3.128.0 to 80.3.128.0—1
280.3.128.1/3280.3.128.1 to 80.3.128.1—1
380.3.128.2/3280.3.128.2 to 80.3.128.2—1
480.3.128.3/3280.3.128.3 to 80.3.128.3—1
580.3.128.4/3280.3.128.4 to 80.3.128.4—1
680.3.128.5/3280.3.128.5 to 80.3.128.5—1
780.3.128.6/3280.3.128.6 to 80.3.128.6—1
880.3.128.7/3280.3.128.7 to 80.3.128.7—1
980.3.128.8/3280.3.128.8 to 80.3.128.8—1
1080.3.128.9/3280.3.128.9 to 80.3.128.9—1
1180.3.128.10/3280.3.128.10 to 80.3.128.10—1
1280.3.128.11/3280.3.128.11 to 80.3.128.11—1
1380.3.128.12/3280.3.128.12 to 80.3.128.12—1
1480.3.128.13/3280.3.128.13 to 80.3.128.13—1
1580.3.128.14/3280.3.128.14 to 80.3.128.14—1
1680.3.128.15/3280.3.128.15 to 80.3.128.15—1
1780.3.128.16/3280.3.128.16 to 80.3.128.16—1
1880.3.128.17/3280.3.128.17 to 80.3.128.17—1
1980.3.128.18/3280.3.128.18 to 80.3.128.18—1
2080.3.128.19/3280.3.128.19 to 80.3.128.19—1
2180.3.128.20/3280.3.128.20 to 80.3.128.20—1
2280.3.128.21/3280.3.128.21 to 80.3.128.21—1
2380.3.128.22/3280.3.128.22 to 80.3.128.22—1
2480.3.128.23/3280.3.128.23 to 80.3.128.23—1
2580.3.128.24/3280.3.128.24 to 80.3.128.24—1
2680.3.128.25/3280.3.128.25 to 80.3.128.25—1
2780.3.128.26/3280.3.128.26 to 80.3.128.26—1
2880.3.128.27/3280.3.128.27 to 80.3.128.27—1
2980.3.128.28/3280.3.128.28 to 80.3.128.28—1
3080.3.128.29/3280.3.128.29 to 80.3.128.29—1
3180.3.128.30/3280.3.128.30 to 80.3.128.30—1
3280.3.128.31/3280.3.128.31 to 80.3.128.31—1
3380.3.128.32/3280.3.128.32 to 80.3.128.32—1
3480.3.128.33/3280.3.128.33 to 80.3.128.33—1
3580.3.128.34/3280.3.128.34 to 80.3.128.34—1
3680.3.128.35/3280.3.128.35 to 80.3.128.35—1
3780.3.128.36/3280.3.128.36 to 80.3.128.36—1
3880.3.128.37/3280.3.128.37 to 80.3.128.37—1
3980.3.128.38/3280.3.128.38 to 80.3.128.38—1
4080.3.128.39/3280.3.128.39 to 80.3.128.39—1
4180.3.128.40/3280.3.128.40 to 80.3.128.40—1
4280.3.128.41/3280.3.128.41 to 80.3.128.41—1
4380.3.128.42/3280.3.128.42 to 80.3.128.42—1
4480.3.128.43/3280.3.128.43 to 80.3.128.43—1
4580.3.128.44/3280.3.128.44 to 80.3.128.44—1
4680.3.128.45/3280.3.128.45 to 80.3.128.45—1
4780.3.128.46/3280.3.128.46 to 80.3.128.46—1
4880.3.128.47/3280.3.128.47 to 80.3.128.47—1
4980.3.128.48/3280.3.128.48 to 80.3.128.48—1
5080.3.128.49/3280.3.128.49 to 80.3.128.49—1
5180.3.128.50/3280.3.128.50 to 80.3.128.50—1
5280.3.128.51/3280.3.128.51 to 80.3.128.51—1
5380.3.128.52/3280.3.128.52 to 80.3.128.52—1
5480.3.128.53/3280.3.128.53 to 80.3.128.53—1
5580.3.128.54/3280.3.128.54 to 80.3.128.54—1
5680.3.128.55/3280.3.128.55 to 80.3.128.55—1
5780.3.128.56/3280.3.128.56 to 80.3.128.56—1
5880.3.128.57/3280.3.128.57 to 80.3.128.57—1
5980.3.128.58/3280.3.128.58 to 80.3.128.58—1
6080.3.128.59/3280.3.128.59 to 80.3.128.59—1
6180.3.128.60/3280.3.128.60 to 80.3.128.60—1
6280.3.128.61/3280.3.128.61 to 80.3.128.61—1
6380.3.128.62/3280.3.128.62 to 80.3.128.62—1
6480.3.128.63/3280.3.128.63 to 80.3.128.63—1
6580.3.128.64/3280.3.128.64 to 80.3.128.64—1
6680.3.128.65/3280.3.128.65 to 80.3.128.65—1
6780.3.128.66/3280.3.128.66 to 80.3.128.66—1
6880.3.128.67/3280.3.128.67 to 80.3.128.67—1
6980.3.128.68/3280.3.128.68 to 80.3.128.68—1
7080.3.128.69/3280.3.128.69 to 80.3.128.69—1
7180.3.128.70/3280.3.128.70 to 80.3.128.70—1
7280.3.128.71/3280.3.128.71 to 80.3.128.71—1
7380.3.128.72/3280.3.128.72 to 80.3.128.72—1
7480.3.128.73/3280.3.128.73 to 80.3.128.73—1
7580.3.128.74/3280.3.128.74 to 80.3.128.74—1
7680.3.128.75/3280.3.128.75 to 80.3.128.75—1
7780.3.128.76/3280.3.128.76 to 80.3.128.76—1
7880.3.128.77/3280.3.128.77 to 80.3.128.77—1
7980.3.128.78/3280.3.128.78 to 80.3.128.78—1
8080.3.128.79/3280.3.128.79 to 80.3.128.79—1
8180.3.128.80/3280.3.128.80 to 80.3.128.80—1
8280.3.128.81/3280.3.128.81 to 80.3.128.81—1
8380.3.128.82/3280.3.128.82 to 80.3.128.82—1
8480.3.128.83/3280.3.128.83 to 80.3.128.83—1
8580.3.128.84/3280.3.128.84 to 80.3.128.84—1
8680.3.128.85/3280.3.128.85 to 80.3.128.85—1
8780.3.128.86/3280.3.128.86 to 80.3.128.86—1
8880.3.128.87/3280.3.128.87 to 80.3.128.87—1
8980.3.128.88/3280.3.128.88 to 80.3.128.88—1
9080.3.128.89/3280.3.128.89 to 80.3.128.89—1
9180.3.128.90/3280.3.128.90 to 80.3.128.90—1
9280.3.128.91/3280.3.128.91 to 80.3.128.91—1
9380.3.128.92/3280.3.128.92 to 80.3.128.92—1
9480.3.128.93/3280.3.128.93 to 80.3.128.93—1
9580.3.128.94/3280.3.128.94 to 80.3.128.94—1
9680.3.128.95/3280.3.128.95 to 80.3.128.95—1
9780.3.128.96/3280.3.128.96 to 80.3.128.96—1
9880.3.128.97/3280.3.128.97 to 80.3.128.97—1
9980.3.128.98/3280.3.128.98 to 80.3.128.98—1
10080.3.128.99/3280.3.128.99 to 80.3.128.99—1
10180.3.128.100/3280.3.128.100 to 80.3.128.100—1
10280.3.128.101/3280.3.128.101 to 80.3.128.101—1
10380.3.128.102/3280.3.128.102 to 80.3.128.102—1
10480.3.128.103/3280.3.128.103 to 80.3.128.103—1
10580.3.128.104/3280.3.128.104 to 80.3.128.104—1
10680.3.128.105/3280.3.128.105 to 80.3.128.105—1
10780.3.128.106/3280.3.128.106 to 80.3.128.106—1
10880.3.128.107/3280.3.128.107 to 80.3.128.107—1
10980.3.128.108/3280.3.128.108 to 80.3.128.108—1
11080.3.128.109/3280.3.128.109 to 80.3.128.109—1
11180.3.128.110/3280.3.128.110 to 80.3.128.110—1
11280.3.128.111/3280.3.128.111 to 80.3.128.111—1
11380.3.128.112/3280.3.128.112 to 80.3.128.112—1
11480.3.128.113/3280.3.128.113 to 80.3.128.113—1
11580.3.128.114/3280.3.128.114 to 80.3.128.114—1
11680.3.128.115/3280.3.128.115 to 80.3.128.115—1
11780.3.128.116/3280.3.128.116 to 80.3.128.116—1
11880.3.128.117/3280.3.128.117 to 80.3.128.117—1
11980.3.128.118/3280.3.128.118 to 80.3.128.118—1
12080.3.128.119/3280.3.128.119 to 80.3.128.119—1
12180.3.128.120/3280.3.128.120 to 80.3.128.120—1
12280.3.128.121/3280.3.128.121 to 80.3.128.121—1
12380.3.128.122/3280.3.128.122 to 80.3.128.122—1
12480.3.128.123/3280.3.128.123 to 80.3.128.123—1
12580.3.128.124/3280.3.128.124 to 80.3.128.124—1
12680.3.128.125/3280.3.128.125 to 80.3.128.125—1
12780.3.128.126/3280.3.128.126 to 80.3.128.126—1
12880.3.128.127/3280.3.128.127 to 80.3.128.127—1
12980.3.128.128/3280.3.128.128 to 80.3.128.128—1
13080.3.128.129/3280.3.128.129 to 80.3.128.129—1
13180.3.128.130/3280.3.128.130 to 80.3.128.130—1
13280.3.128.131/3280.3.128.131 to 80.3.128.131—1
13380.3.128.132/3280.3.128.132 to 80.3.128.132—1
13480.3.128.133/3280.3.128.133 to 80.3.128.133—1
13580.3.128.134/3280.3.128.134 to 80.3.128.134—1
13680.3.128.135/3280.3.128.135 to 80.3.128.135—1
13780.3.128.136/3280.3.128.136 to 80.3.128.136—1
13880.3.128.137/3280.3.128.137 to 80.3.128.137—1
13980.3.128.138/3280.3.128.138 to 80.3.128.138—1
14080.3.128.139/3280.3.128.139 to 80.3.128.139—1
14180.3.128.140/3280.3.128.140 to 80.3.128.140—1
14280.3.128.141/3280.3.128.141 to 80.3.128.141—1
14380.3.128.142/3280.3.128.142 to 80.3.128.142—1
14480.3.128.143/3280.3.128.143 to 80.3.128.143—1
14580.3.128.144/3280.3.128.144 to 80.3.128.144—1
14680.3.128.145/3280.3.128.145 to 80.3.128.145—1
14780.3.128.146/3280.3.128.146 to 80.3.128.146—1
14880.3.128.147/3280.3.128.147 to 80.3.128.147—1
14980.3.128.148/3280.3.128.148 to 80.3.128.148—1
15080.3.128.149/3280.3.128.149 to 80.3.128.149—1
15180.3.128.150/3280.3.128.150 to 80.3.128.150—1
15280.3.128.151/3280.3.128.151 to 80.3.128.151—1
15380.3.128.152/3280.3.128.152 to 80.3.128.152—1
15480.3.128.153/3280.3.128.153 to 80.3.128.153—1
15580.3.128.154/3280.3.128.154 to 80.3.128.154—1
15680.3.128.155/3280.3.128.155 to 80.3.128.155—1
15780.3.128.156/3280.3.128.156 to 80.3.128.156—1
15880.3.128.157/3280.3.128.157 to 80.3.128.157—1
15980.3.128.158/3280.3.128.158 to 80.3.128.158—1
16080.3.128.159/3280.3.128.159 to 80.3.128.159—1
16180.3.128.160/3280.3.128.160 to 80.3.128.160—1
16280.3.128.161/3280.3.128.161 to 80.3.128.161—1
16380.3.128.162/3280.3.128.162 to 80.3.128.162—1
16480.3.128.163/3280.3.128.163 to 80.3.128.163—1
16580.3.128.164/3280.3.128.164 to 80.3.128.164—1
16680.3.128.165/3280.3.128.165 to 80.3.128.165—1
16780.3.128.166/3280.3.128.166 to 80.3.128.166—1
16880.3.128.167/3280.3.128.167 to 80.3.128.167—1
16980.3.128.168/3280.3.128.168 to 80.3.128.168—1
17080.3.128.169/3280.3.128.169 to 80.3.128.169—1
17180.3.128.170/3280.3.128.170 to 80.3.128.170—1
17280.3.128.171/3280.3.128.171 to 80.3.128.171—1
17380.3.128.172/3280.3.128.172 to 80.3.128.172—1
17480.3.128.173/3280.3.128.173 to 80.3.128.173—1
17580.3.128.174/3280.3.128.174 to 80.3.128.174—1
17680.3.128.175/3280.3.128.175 to 80.3.128.175—1
17780.3.128.176/3280.3.128.176 to 80.3.128.176—1
17880.3.128.177/3280.3.128.177 to 80.3.128.177—1
17980.3.128.178/3280.3.128.178 to 80.3.128.178—1
18080.3.128.179/3280.3.128.179 to 80.3.128.179—1
18180.3.128.180/3280.3.128.180 to 80.3.128.180—1
18280.3.128.181/3280.3.128.181 to 80.3.128.181—1
18380.3.128.182/3280.3.128.182 to 80.3.128.182—1
18480.3.128.183/3280.3.128.183 to 80.3.128.183—1
18580.3.128.184/3280.3.128.184 to 80.3.128.184—1
18680.3.128.185/3280.3.128.185 to 80.3.128.185—1
18780.3.128.186/3280.3.128.186 to 80.3.128.186—1
18880.3.128.187/3280.3.128.187 to 80.3.128.187—1
18980.3.128.188/3280.3.128.188 to 80.3.128.188—1
19080.3.128.189/3280.3.128.189 to 80.3.128.189—1
19180.3.128.190/3280.3.128.190 to 80.3.128.190—1
19280.3.128.191/3280.3.128.191 to 80.3.128.191—1
19380.3.128.192/3280.3.128.192 to 80.3.128.192—1
19480.3.128.193/3280.3.128.193 to 80.3.128.193—1
19580.3.128.194/3280.3.128.194 to 80.3.128.194—1
19680.3.128.195/3280.3.128.195 to 80.3.128.195—1
19780.3.128.196/3280.3.128.196 to 80.3.128.196—1
19880.3.128.197/3280.3.128.197 to 80.3.128.197—1
19980.3.128.198/3280.3.128.198 to 80.3.128.198—1
20080.3.128.199/3280.3.128.199 to 80.3.128.199—1
20180.3.128.200/3280.3.128.200 to 80.3.128.200—1
20280.3.128.201/3280.3.128.201 to 80.3.128.201—1
20380.3.128.202/3280.3.128.202 to 80.3.128.202—1
20480.3.128.203/3280.3.128.203 to 80.3.128.203—1
20580.3.128.204/3280.3.128.204 to 80.3.128.204—1
20680.3.128.205/3280.3.128.205 to 80.3.128.205—1
20780.3.128.206/3280.3.128.206 to 80.3.128.206—1
20880.3.128.207/3280.3.128.207 to 80.3.128.207—1
20980.3.128.208/3280.3.128.208 to 80.3.128.208—1
21080.3.128.209/3280.3.128.209 to 80.3.128.209—1
21180.3.128.210/3280.3.128.210 to 80.3.128.210—1
21280.3.128.211/3280.3.128.211 to 80.3.128.211—1
21380.3.128.212/3280.3.128.212 to 80.3.128.212—1
21480.3.128.213/3280.3.128.213 to 80.3.128.213—1
21580.3.128.214/3280.3.128.214 to 80.3.128.214—1
21680.3.128.215/3280.3.128.215 to 80.3.128.215—1
21780.3.128.216/3280.3.128.216 to 80.3.128.216—1
21880.3.128.217/3280.3.128.217 to 80.3.128.217—1
21980.3.128.218/3280.3.128.218 to 80.3.128.218—1
22080.3.128.219/3280.3.128.219 to 80.3.128.219—1
22180.3.128.220/3280.3.128.220 to 80.3.128.220—1
22280.3.128.221/3280.3.128.221 to 80.3.128.221—1
22380.3.128.222/3280.3.128.222 to 80.3.128.222—1
22480.3.128.223/3280.3.128.223 to 80.3.128.223—1
22580.3.128.224/3280.3.128.224 to 80.3.128.224—1
22680.3.128.225/3280.3.128.225 to 80.3.128.225—1
22780.3.128.226/3280.3.128.226 to 80.3.128.226—1
22880.3.128.227/3280.3.128.227 to 80.3.128.227—1
22980.3.128.228/3280.3.128.228 to 80.3.128.228—1
23080.3.128.229/3280.3.128.229 to 80.3.128.229—1
23180.3.128.230/3280.3.128.230 to 80.3.128.230—1
23280.3.128.231/3280.3.128.231 to 80.3.128.231—1
23380.3.128.232/3280.3.128.232 to 80.3.128.232—1
23480.3.128.233/3280.3.128.233 to 80.3.128.233—1
23580.3.128.234/3280.3.128.234 to 80.3.128.234—1
23680.3.128.235/3280.3.128.235 to 80.3.128.235—1
23780.3.128.236/3280.3.128.236 to 80.3.128.236—1
23880.3.128.237/3280.3.128.237 to 80.3.128.237—1
23980.3.128.238/3280.3.128.238 to 80.3.128.238—1
24080.3.128.239/3280.3.128.239 to 80.3.128.239—1
24180.3.128.240/3280.3.128.240 to 80.3.128.240—1
24280.3.128.241/3280.3.128.241 to 80.3.128.241—1
24380.3.128.242/3280.3.128.242 to 80.3.128.242—1
24480.3.128.243/3280.3.128.243 to 80.3.128.243—1
24580.3.128.244/3280.3.128.244 to 80.3.128.244—1
24680.3.128.245/3280.3.128.245 to 80.3.128.245—1
24780.3.128.246/3280.3.128.246 to 80.3.128.246—1
24880.3.128.247/3280.3.128.247 to 80.3.128.247—1
24980.3.128.248/3280.3.128.248 to 80.3.128.248—1
25080.3.128.249/3280.3.128.249 to 80.3.128.249—1
25180.3.128.250/3280.3.128.250 to 80.3.128.250—1
25280.3.128.251/3280.3.128.251 to 80.3.128.251—1
25380.3.128.252/3280.3.128.252 to 80.3.128.252—1
25480.3.128.253/3280.3.128.253 to 80.3.128.253—1
25580.3.128.254/3280.3.128.254 to 80.3.128.254—1
25680.3.128.255/3280.3.128.255 to 80.3.128.255—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.