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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.

Network74.2.240.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
74.2.240.0
Broadcast address
74.2.255.255
First usable
74.2.240.1
Last usable
74.2.255.254
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 4A02F000 · Integer 1241706496 to 1241710591
Reverse DNS zones
240.2.74.in-addr.arpa
241.2.74.in-addr.arpa
242.2.74.in-addr.arpa
243.2.74.in-addr.arpa
244.2.74.in-addr.arpa
245.2.74.in-addr.arpa
246.2.74.in-addr.arpa
247.2.74.in-addr.arpa
248.2.74.in-addr.arpa
249.2.74.in-addr.arpa
250.2.74.in-addr.arpa
251.2.74.in-addr.arpa
252.2.74.in-addr.arpa
253.2.74.in-addr.arpa
254.2.74.in-addr.arpa
255.2.74.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
Address01001010.00000010.11110000.0000000074.2.240.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network01001010.00000010.11110000.0000000074.2.240.0
Broadcast01001010.00000010.11111111.1111111174.2.255.255
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)

74.2.240.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
174.2.240.0/3274.2.240.0 to 74.2.240.0—1
274.2.240.1/3274.2.240.1 to 74.2.240.1—1
374.2.240.2/3274.2.240.2 to 74.2.240.2—1
474.2.240.3/3274.2.240.3 to 74.2.240.3—1
574.2.240.4/3274.2.240.4 to 74.2.240.4—1
674.2.240.5/3274.2.240.5 to 74.2.240.5—1
774.2.240.6/3274.2.240.6 to 74.2.240.6—1
874.2.240.7/3274.2.240.7 to 74.2.240.7—1
974.2.240.8/3274.2.240.8 to 74.2.240.8—1
1074.2.240.9/3274.2.240.9 to 74.2.240.9—1
1174.2.240.10/3274.2.240.10 to 74.2.240.10—1
1274.2.240.11/3274.2.240.11 to 74.2.240.11—1
1374.2.240.12/3274.2.240.12 to 74.2.240.12—1
1474.2.240.13/3274.2.240.13 to 74.2.240.13—1
1574.2.240.14/3274.2.240.14 to 74.2.240.14—1
1674.2.240.15/3274.2.240.15 to 74.2.240.15—1
1774.2.240.16/3274.2.240.16 to 74.2.240.16—1
1874.2.240.17/3274.2.240.17 to 74.2.240.17—1
1974.2.240.18/3274.2.240.18 to 74.2.240.18—1
2074.2.240.19/3274.2.240.19 to 74.2.240.19—1
2174.2.240.20/3274.2.240.20 to 74.2.240.20—1
2274.2.240.21/3274.2.240.21 to 74.2.240.21—1
2374.2.240.22/3274.2.240.22 to 74.2.240.22—1
2474.2.240.23/3274.2.240.23 to 74.2.240.23—1
2574.2.240.24/3274.2.240.24 to 74.2.240.24—1
2674.2.240.25/3274.2.240.25 to 74.2.240.25—1
2774.2.240.26/3274.2.240.26 to 74.2.240.26—1
2874.2.240.27/3274.2.240.27 to 74.2.240.27—1
2974.2.240.28/3274.2.240.28 to 74.2.240.28—1
3074.2.240.29/3274.2.240.29 to 74.2.240.29—1
3174.2.240.30/3274.2.240.30 to 74.2.240.30—1
3274.2.240.31/3274.2.240.31 to 74.2.240.31—1
3374.2.240.32/3274.2.240.32 to 74.2.240.32—1
3474.2.240.33/3274.2.240.33 to 74.2.240.33—1
3574.2.240.34/3274.2.240.34 to 74.2.240.34—1
3674.2.240.35/3274.2.240.35 to 74.2.240.35—1
3774.2.240.36/3274.2.240.36 to 74.2.240.36—1
3874.2.240.37/3274.2.240.37 to 74.2.240.37—1
3974.2.240.38/3274.2.240.38 to 74.2.240.38—1
4074.2.240.39/3274.2.240.39 to 74.2.240.39—1
4174.2.240.40/3274.2.240.40 to 74.2.240.40—1
4274.2.240.41/3274.2.240.41 to 74.2.240.41—1
4374.2.240.42/3274.2.240.42 to 74.2.240.42—1
4474.2.240.43/3274.2.240.43 to 74.2.240.43—1
4574.2.240.44/3274.2.240.44 to 74.2.240.44—1
4674.2.240.45/3274.2.240.45 to 74.2.240.45—1
4774.2.240.46/3274.2.240.46 to 74.2.240.46—1
4874.2.240.47/3274.2.240.47 to 74.2.240.47—1
4974.2.240.48/3274.2.240.48 to 74.2.240.48—1
5074.2.240.49/3274.2.240.49 to 74.2.240.49—1
5174.2.240.50/3274.2.240.50 to 74.2.240.50—1
5274.2.240.51/3274.2.240.51 to 74.2.240.51—1
5374.2.240.52/3274.2.240.52 to 74.2.240.52—1
5474.2.240.53/3274.2.240.53 to 74.2.240.53—1
5574.2.240.54/3274.2.240.54 to 74.2.240.54—1
5674.2.240.55/3274.2.240.55 to 74.2.240.55—1
5774.2.240.56/3274.2.240.56 to 74.2.240.56—1
5874.2.240.57/3274.2.240.57 to 74.2.240.57—1
5974.2.240.58/3274.2.240.58 to 74.2.240.58—1
6074.2.240.59/3274.2.240.59 to 74.2.240.59—1
6174.2.240.60/3274.2.240.60 to 74.2.240.60—1
6274.2.240.61/3274.2.240.61 to 74.2.240.61—1
6374.2.240.62/3274.2.240.62 to 74.2.240.62—1
6474.2.240.63/3274.2.240.63 to 74.2.240.63—1
6574.2.240.64/3274.2.240.64 to 74.2.240.64—1
6674.2.240.65/3274.2.240.65 to 74.2.240.65—1
6774.2.240.66/3274.2.240.66 to 74.2.240.66—1
6874.2.240.67/3274.2.240.67 to 74.2.240.67—1
6974.2.240.68/3274.2.240.68 to 74.2.240.68—1
7074.2.240.69/3274.2.240.69 to 74.2.240.69—1
7174.2.240.70/3274.2.240.70 to 74.2.240.70—1
7274.2.240.71/3274.2.240.71 to 74.2.240.71—1
7374.2.240.72/3274.2.240.72 to 74.2.240.72—1
7474.2.240.73/3274.2.240.73 to 74.2.240.73—1
7574.2.240.74/3274.2.240.74 to 74.2.240.74—1
7674.2.240.75/3274.2.240.75 to 74.2.240.75—1
7774.2.240.76/3274.2.240.76 to 74.2.240.76—1
7874.2.240.77/3274.2.240.77 to 74.2.240.77—1
7974.2.240.78/3274.2.240.78 to 74.2.240.78—1
8074.2.240.79/3274.2.240.79 to 74.2.240.79—1
8174.2.240.80/3274.2.240.80 to 74.2.240.80—1
8274.2.240.81/3274.2.240.81 to 74.2.240.81—1
8374.2.240.82/3274.2.240.82 to 74.2.240.82—1
8474.2.240.83/3274.2.240.83 to 74.2.240.83—1
8574.2.240.84/3274.2.240.84 to 74.2.240.84—1
8674.2.240.85/3274.2.240.85 to 74.2.240.85—1
8774.2.240.86/3274.2.240.86 to 74.2.240.86—1
8874.2.240.87/3274.2.240.87 to 74.2.240.87—1
8974.2.240.88/3274.2.240.88 to 74.2.240.88—1
9074.2.240.89/3274.2.240.89 to 74.2.240.89—1
9174.2.240.90/3274.2.240.90 to 74.2.240.90—1
9274.2.240.91/3274.2.240.91 to 74.2.240.91—1
9374.2.240.92/3274.2.240.92 to 74.2.240.92—1
9474.2.240.93/3274.2.240.93 to 74.2.240.93—1
9574.2.240.94/3274.2.240.94 to 74.2.240.94—1
9674.2.240.95/3274.2.240.95 to 74.2.240.95—1
9774.2.240.96/3274.2.240.96 to 74.2.240.96—1
9874.2.240.97/3274.2.240.97 to 74.2.240.97—1
9974.2.240.98/3274.2.240.98 to 74.2.240.98—1
10074.2.240.99/3274.2.240.99 to 74.2.240.99—1
10174.2.240.100/3274.2.240.100 to 74.2.240.100—1
10274.2.240.101/3274.2.240.101 to 74.2.240.101—1
10374.2.240.102/3274.2.240.102 to 74.2.240.102—1
10474.2.240.103/3274.2.240.103 to 74.2.240.103—1
10574.2.240.104/3274.2.240.104 to 74.2.240.104—1
10674.2.240.105/3274.2.240.105 to 74.2.240.105—1
10774.2.240.106/3274.2.240.106 to 74.2.240.106—1
10874.2.240.107/3274.2.240.107 to 74.2.240.107—1
10974.2.240.108/3274.2.240.108 to 74.2.240.108—1
11074.2.240.109/3274.2.240.109 to 74.2.240.109—1
11174.2.240.110/3274.2.240.110 to 74.2.240.110—1
11274.2.240.111/3274.2.240.111 to 74.2.240.111—1
11374.2.240.112/3274.2.240.112 to 74.2.240.112—1
11474.2.240.113/3274.2.240.113 to 74.2.240.113—1
11574.2.240.114/3274.2.240.114 to 74.2.240.114—1
11674.2.240.115/3274.2.240.115 to 74.2.240.115—1
11774.2.240.116/3274.2.240.116 to 74.2.240.116—1
11874.2.240.117/3274.2.240.117 to 74.2.240.117—1
11974.2.240.118/3274.2.240.118 to 74.2.240.118—1
12074.2.240.119/3274.2.240.119 to 74.2.240.119—1
12174.2.240.120/3274.2.240.120 to 74.2.240.120—1
12274.2.240.121/3274.2.240.121 to 74.2.240.121—1
12374.2.240.122/3274.2.240.122 to 74.2.240.122—1
12474.2.240.123/3274.2.240.123 to 74.2.240.123—1
12574.2.240.124/3274.2.240.124 to 74.2.240.124—1
12674.2.240.125/3274.2.240.125 to 74.2.240.125—1
12774.2.240.126/3274.2.240.126 to 74.2.240.126—1
12874.2.240.127/3274.2.240.127 to 74.2.240.127—1
12974.2.240.128/3274.2.240.128 to 74.2.240.128—1
13074.2.240.129/3274.2.240.129 to 74.2.240.129—1
13174.2.240.130/3274.2.240.130 to 74.2.240.130—1
13274.2.240.131/3274.2.240.131 to 74.2.240.131—1
13374.2.240.132/3274.2.240.132 to 74.2.240.132—1
13474.2.240.133/3274.2.240.133 to 74.2.240.133—1
13574.2.240.134/3274.2.240.134 to 74.2.240.134—1
13674.2.240.135/3274.2.240.135 to 74.2.240.135—1
13774.2.240.136/3274.2.240.136 to 74.2.240.136—1
13874.2.240.137/3274.2.240.137 to 74.2.240.137—1
13974.2.240.138/3274.2.240.138 to 74.2.240.138—1
14074.2.240.139/3274.2.240.139 to 74.2.240.139—1
14174.2.240.140/3274.2.240.140 to 74.2.240.140—1
14274.2.240.141/3274.2.240.141 to 74.2.240.141—1
14374.2.240.142/3274.2.240.142 to 74.2.240.142—1
14474.2.240.143/3274.2.240.143 to 74.2.240.143—1
14574.2.240.144/3274.2.240.144 to 74.2.240.144—1
14674.2.240.145/3274.2.240.145 to 74.2.240.145—1
14774.2.240.146/3274.2.240.146 to 74.2.240.146—1
14874.2.240.147/3274.2.240.147 to 74.2.240.147—1
14974.2.240.148/3274.2.240.148 to 74.2.240.148—1
15074.2.240.149/3274.2.240.149 to 74.2.240.149—1
15174.2.240.150/3274.2.240.150 to 74.2.240.150—1
15274.2.240.151/3274.2.240.151 to 74.2.240.151—1
15374.2.240.152/3274.2.240.152 to 74.2.240.152—1
15474.2.240.153/3274.2.240.153 to 74.2.240.153—1
15574.2.240.154/3274.2.240.154 to 74.2.240.154—1
15674.2.240.155/3274.2.240.155 to 74.2.240.155—1
15774.2.240.156/3274.2.240.156 to 74.2.240.156—1
15874.2.240.157/3274.2.240.157 to 74.2.240.157—1
15974.2.240.158/3274.2.240.158 to 74.2.240.158—1
16074.2.240.159/3274.2.240.159 to 74.2.240.159—1
16174.2.240.160/3274.2.240.160 to 74.2.240.160—1
16274.2.240.161/3274.2.240.161 to 74.2.240.161—1
16374.2.240.162/3274.2.240.162 to 74.2.240.162—1
16474.2.240.163/3274.2.240.163 to 74.2.240.163—1
16574.2.240.164/3274.2.240.164 to 74.2.240.164—1
16674.2.240.165/3274.2.240.165 to 74.2.240.165—1
16774.2.240.166/3274.2.240.166 to 74.2.240.166—1
16874.2.240.167/3274.2.240.167 to 74.2.240.167—1
16974.2.240.168/3274.2.240.168 to 74.2.240.168—1
17074.2.240.169/3274.2.240.169 to 74.2.240.169—1
17174.2.240.170/3274.2.240.170 to 74.2.240.170—1
17274.2.240.171/3274.2.240.171 to 74.2.240.171—1
17374.2.240.172/3274.2.240.172 to 74.2.240.172—1
17474.2.240.173/3274.2.240.173 to 74.2.240.173—1
17574.2.240.174/3274.2.240.174 to 74.2.240.174—1
17674.2.240.175/3274.2.240.175 to 74.2.240.175—1
17774.2.240.176/3274.2.240.176 to 74.2.240.176—1
17874.2.240.177/3274.2.240.177 to 74.2.240.177—1
17974.2.240.178/3274.2.240.178 to 74.2.240.178—1
18074.2.240.179/3274.2.240.179 to 74.2.240.179—1
18174.2.240.180/3274.2.240.180 to 74.2.240.180—1
18274.2.240.181/3274.2.240.181 to 74.2.240.181—1
18374.2.240.182/3274.2.240.182 to 74.2.240.182—1
18474.2.240.183/3274.2.240.183 to 74.2.240.183—1
18574.2.240.184/3274.2.240.184 to 74.2.240.184—1
18674.2.240.185/3274.2.240.185 to 74.2.240.185—1
18774.2.240.186/3274.2.240.186 to 74.2.240.186—1
18874.2.240.187/3274.2.240.187 to 74.2.240.187—1
18974.2.240.188/3274.2.240.188 to 74.2.240.188—1
19074.2.240.189/3274.2.240.189 to 74.2.240.189—1
19174.2.240.190/3274.2.240.190 to 74.2.240.190—1
19274.2.240.191/3274.2.240.191 to 74.2.240.191—1
19374.2.240.192/3274.2.240.192 to 74.2.240.192—1
19474.2.240.193/3274.2.240.193 to 74.2.240.193—1
19574.2.240.194/3274.2.240.194 to 74.2.240.194—1
19674.2.240.195/3274.2.240.195 to 74.2.240.195—1
19774.2.240.196/3274.2.240.196 to 74.2.240.196—1
19874.2.240.197/3274.2.240.197 to 74.2.240.197—1
19974.2.240.198/3274.2.240.198 to 74.2.240.198—1
20074.2.240.199/3274.2.240.199 to 74.2.240.199—1
20174.2.240.200/3274.2.240.200 to 74.2.240.200—1
20274.2.240.201/3274.2.240.201 to 74.2.240.201—1
20374.2.240.202/3274.2.240.202 to 74.2.240.202—1
20474.2.240.203/3274.2.240.203 to 74.2.240.203—1
20574.2.240.204/3274.2.240.204 to 74.2.240.204—1
20674.2.240.205/3274.2.240.205 to 74.2.240.205—1
20774.2.240.206/3274.2.240.206 to 74.2.240.206—1
20874.2.240.207/3274.2.240.207 to 74.2.240.207—1
20974.2.240.208/3274.2.240.208 to 74.2.240.208—1
21074.2.240.209/3274.2.240.209 to 74.2.240.209—1
21174.2.240.210/3274.2.240.210 to 74.2.240.210—1
21274.2.240.211/3274.2.240.211 to 74.2.240.211—1
21374.2.240.212/3274.2.240.212 to 74.2.240.212—1
21474.2.240.213/3274.2.240.213 to 74.2.240.213—1
21574.2.240.214/3274.2.240.214 to 74.2.240.214—1
21674.2.240.215/3274.2.240.215 to 74.2.240.215—1
21774.2.240.216/3274.2.240.216 to 74.2.240.216—1
21874.2.240.217/3274.2.240.217 to 74.2.240.217—1
21974.2.240.218/3274.2.240.218 to 74.2.240.218—1
22074.2.240.219/3274.2.240.219 to 74.2.240.219—1
22174.2.240.220/3274.2.240.220 to 74.2.240.220—1
22274.2.240.221/3274.2.240.221 to 74.2.240.221—1
22374.2.240.222/3274.2.240.222 to 74.2.240.222—1
22474.2.240.223/3274.2.240.223 to 74.2.240.223—1
22574.2.240.224/3274.2.240.224 to 74.2.240.224—1
22674.2.240.225/3274.2.240.225 to 74.2.240.225—1
22774.2.240.226/3274.2.240.226 to 74.2.240.226—1
22874.2.240.227/3274.2.240.227 to 74.2.240.227—1
22974.2.240.228/3274.2.240.228 to 74.2.240.228—1
23074.2.240.229/3274.2.240.229 to 74.2.240.229—1
23174.2.240.230/3274.2.240.230 to 74.2.240.230—1
23274.2.240.231/3274.2.240.231 to 74.2.240.231—1
23374.2.240.232/3274.2.240.232 to 74.2.240.232—1
23474.2.240.233/3274.2.240.233 to 74.2.240.233—1
23574.2.240.234/3274.2.240.234 to 74.2.240.234—1
23674.2.240.235/3274.2.240.235 to 74.2.240.235—1
23774.2.240.236/3274.2.240.236 to 74.2.240.236—1
23874.2.240.237/3274.2.240.237 to 74.2.240.237—1
23974.2.240.238/3274.2.240.238 to 74.2.240.238—1
24074.2.240.239/3274.2.240.239 to 74.2.240.239—1
24174.2.240.240/3274.2.240.240 to 74.2.240.240—1
24274.2.240.241/3274.2.240.241 to 74.2.240.241—1
24374.2.240.242/3274.2.240.242 to 74.2.240.242—1
24474.2.240.243/3274.2.240.243 to 74.2.240.243—1
24574.2.240.244/3274.2.240.244 to 74.2.240.244—1
24674.2.240.245/3274.2.240.245 to 74.2.240.245—1
24774.2.240.246/3274.2.240.246 to 74.2.240.246—1
24874.2.240.247/3274.2.240.247 to 74.2.240.247—1
24974.2.240.248/3274.2.240.248 to 74.2.240.248—1
25074.2.240.249/3274.2.240.249 to 74.2.240.249—1
25174.2.240.250/3274.2.240.250 to 74.2.240.250—1
25274.2.240.251/3274.2.240.251 to 74.2.240.251—1
25374.2.240.252/3274.2.240.252 to 74.2.240.252—1
25474.2.240.253/3274.2.240.253 to 74.2.240.253—1
25574.2.240.254/3274.2.240.254 to 74.2.240.254—1
25674.2.240.255/3274.2.240.255 to 74.2.240.255—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.