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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.

Network70.2.80.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
70.2.80.0
Broadcast address
70.2.95.255
First usable
70.2.80.1
Last usable
70.2.95.254
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 46025000 · Integer 1174556672 to 1174560767
Reverse DNS zones
80.2.70.in-addr.arpa
81.2.70.in-addr.arpa
82.2.70.in-addr.arpa
83.2.70.in-addr.arpa
84.2.70.in-addr.arpa
85.2.70.in-addr.arpa
86.2.70.in-addr.arpa
87.2.70.in-addr.arpa
88.2.70.in-addr.arpa
89.2.70.in-addr.arpa
90.2.70.in-addr.arpa
91.2.70.in-addr.arpa
92.2.70.in-addr.arpa
93.2.70.in-addr.arpa
94.2.70.in-addr.arpa
95.2.70.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
Address01000110.00000010.01010000.0000000070.2.80.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network01000110.00000010.01010000.0000000070.2.80.0
Broadcast01000110.00000010.01011111.1111111170.2.95.255
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)

70.2.80.0/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
170.2.80.0/3270.2.80.0 to 70.2.80.0—1
270.2.80.1/3270.2.80.1 to 70.2.80.1—1
370.2.80.2/3270.2.80.2 to 70.2.80.2—1
470.2.80.3/3270.2.80.3 to 70.2.80.3—1
570.2.80.4/3270.2.80.4 to 70.2.80.4—1
670.2.80.5/3270.2.80.5 to 70.2.80.5—1
770.2.80.6/3270.2.80.6 to 70.2.80.6—1
870.2.80.7/3270.2.80.7 to 70.2.80.7—1
970.2.80.8/3270.2.80.8 to 70.2.80.8—1
1070.2.80.9/3270.2.80.9 to 70.2.80.9—1
1170.2.80.10/3270.2.80.10 to 70.2.80.10—1
1270.2.80.11/3270.2.80.11 to 70.2.80.11—1
1370.2.80.12/3270.2.80.12 to 70.2.80.12—1
1470.2.80.13/3270.2.80.13 to 70.2.80.13—1
1570.2.80.14/3270.2.80.14 to 70.2.80.14—1
1670.2.80.15/3270.2.80.15 to 70.2.80.15—1
1770.2.80.16/3270.2.80.16 to 70.2.80.16—1
1870.2.80.17/3270.2.80.17 to 70.2.80.17—1
1970.2.80.18/3270.2.80.18 to 70.2.80.18—1
2070.2.80.19/3270.2.80.19 to 70.2.80.19—1
2170.2.80.20/3270.2.80.20 to 70.2.80.20—1
2270.2.80.21/3270.2.80.21 to 70.2.80.21—1
2370.2.80.22/3270.2.80.22 to 70.2.80.22—1
2470.2.80.23/3270.2.80.23 to 70.2.80.23—1
2570.2.80.24/3270.2.80.24 to 70.2.80.24—1
2670.2.80.25/3270.2.80.25 to 70.2.80.25—1
2770.2.80.26/3270.2.80.26 to 70.2.80.26—1
2870.2.80.27/3270.2.80.27 to 70.2.80.27—1
2970.2.80.28/3270.2.80.28 to 70.2.80.28—1
3070.2.80.29/3270.2.80.29 to 70.2.80.29—1
3170.2.80.30/3270.2.80.30 to 70.2.80.30—1
3270.2.80.31/3270.2.80.31 to 70.2.80.31—1
3370.2.80.32/3270.2.80.32 to 70.2.80.32—1
3470.2.80.33/3270.2.80.33 to 70.2.80.33—1
3570.2.80.34/3270.2.80.34 to 70.2.80.34—1
3670.2.80.35/3270.2.80.35 to 70.2.80.35—1
3770.2.80.36/3270.2.80.36 to 70.2.80.36—1
3870.2.80.37/3270.2.80.37 to 70.2.80.37—1
3970.2.80.38/3270.2.80.38 to 70.2.80.38—1
4070.2.80.39/3270.2.80.39 to 70.2.80.39—1
4170.2.80.40/3270.2.80.40 to 70.2.80.40—1
4270.2.80.41/3270.2.80.41 to 70.2.80.41—1
4370.2.80.42/3270.2.80.42 to 70.2.80.42—1
4470.2.80.43/3270.2.80.43 to 70.2.80.43—1
4570.2.80.44/3270.2.80.44 to 70.2.80.44—1
4670.2.80.45/3270.2.80.45 to 70.2.80.45—1
4770.2.80.46/3270.2.80.46 to 70.2.80.46—1
4870.2.80.47/3270.2.80.47 to 70.2.80.47—1
4970.2.80.48/3270.2.80.48 to 70.2.80.48—1
5070.2.80.49/3270.2.80.49 to 70.2.80.49—1
5170.2.80.50/3270.2.80.50 to 70.2.80.50—1
5270.2.80.51/3270.2.80.51 to 70.2.80.51—1
5370.2.80.52/3270.2.80.52 to 70.2.80.52—1
5470.2.80.53/3270.2.80.53 to 70.2.80.53—1
5570.2.80.54/3270.2.80.54 to 70.2.80.54—1
5670.2.80.55/3270.2.80.55 to 70.2.80.55—1
5770.2.80.56/3270.2.80.56 to 70.2.80.56—1
5870.2.80.57/3270.2.80.57 to 70.2.80.57—1
5970.2.80.58/3270.2.80.58 to 70.2.80.58—1
6070.2.80.59/3270.2.80.59 to 70.2.80.59—1
6170.2.80.60/3270.2.80.60 to 70.2.80.60—1
6270.2.80.61/3270.2.80.61 to 70.2.80.61—1
6370.2.80.62/3270.2.80.62 to 70.2.80.62—1
6470.2.80.63/3270.2.80.63 to 70.2.80.63—1
6570.2.80.64/3270.2.80.64 to 70.2.80.64—1
6670.2.80.65/3270.2.80.65 to 70.2.80.65—1
6770.2.80.66/3270.2.80.66 to 70.2.80.66—1
6870.2.80.67/3270.2.80.67 to 70.2.80.67—1
6970.2.80.68/3270.2.80.68 to 70.2.80.68—1
7070.2.80.69/3270.2.80.69 to 70.2.80.69—1
7170.2.80.70/3270.2.80.70 to 70.2.80.70—1
7270.2.80.71/3270.2.80.71 to 70.2.80.71—1
7370.2.80.72/3270.2.80.72 to 70.2.80.72—1
7470.2.80.73/3270.2.80.73 to 70.2.80.73—1
7570.2.80.74/3270.2.80.74 to 70.2.80.74—1
7670.2.80.75/3270.2.80.75 to 70.2.80.75—1
7770.2.80.76/3270.2.80.76 to 70.2.80.76—1
7870.2.80.77/3270.2.80.77 to 70.2.80.77—1
7970.2.80.78/3270.2.80.78 to 70.2.80.78—1
8070.2.80.79/3270.2.80.79 to 70.2.80.79—1
8170.2.80.80/3270.2.80.80 to 70.2.80.80—1
8270.2.80.81/3270.2.80.81 to 70.2.80.81—1
8370.2.80.82/3270.2.80.82 to 70.2.80.82—1
8470.2.80.83/3270.2.80.83 to 70.2.80.83—1
8570.2.80.84/3270.2.80.84 to 70.2.80.84—1
8670.2.80.85/3270.2.80.85 to 70.2.80.85—1
8770.2.80.86/3270.2.80.86 to 70.2.80.86—1
8870.2.80.87/3270.2.80.87 to 70.2.80.87—1
8970.2.80.88/3270.2.80.88 to 70.2.80.88—1
9070.2.80.89/3270.2.80.89 to 70.2.80.89—1
9170.2.80.90/3270.2.80.90 to 70.2.80.90—1
9270.2.80.91/3270.2.80.91 to 70.2.80.91—1
9370.2.80.92/3270.2.80.92 to 70.2.80.92—1
9470.2.80.93/3270.2.80.93 to 70.2.80.93—1
9570.2.80.94/3270.2.80.94 to 70.2.80.94—1
9670.2.80.95/3270.2.80.95 to 70.2.80.95—1
9770.2.80.96/3270.2.80.96 to 70.2.80.96—1
9870.2.80.97/3270.2.80.97 to 70.2.80.97—1
9970.2.80.98/3270.2.80.98 to 70.2.80.98—1
10070.2.80.99/3270.2.80.99 to 70.2.80.99—1
10170.2.80.100/3270.2.80.100 to 70.2.80.100—1
10270.2.80.101/3270.2.80.101 to 70.2.80.101—1
10370.2.80.102/3270.2.80.102 to 70.2.80.102—1
10470.2.80.103/3270.2.80.103 to 70.2.80.103—1
10570.2.80.104/3270.2.80.104 to 70.2.80.104—1
10670.2.80.105/3270.2.80.105 to 70.2.80.105—1
10770.2.80.106/3270.2.80.106 to 70.2.80.106—1
10870.2.80.107/3270.2.80.107 to 70.2.80.107—1
10970.2.80.108/3270.2.80.108 to 70.2.80.108—1
11070.2.80.109/3270.2.80.109 to 70.2.80.109—1
11170.2.80.110/3270.2.80.110 to 70.2.80.110—1
11270.2.80.111/3270.2.80.111 to 70.2.80.111—1
11370.2.80.112/3270.2.80.112 to 70.2.80.112—1
11470.2.80.113/3270.2.80.113 to 70.2.80.113—1
11570.2.80.114/3270.2.80.114 to 70.2.80.114—1
11670.2.80.115/3270.2.80.115 to 70.2.80.115—1
11770.2.80.116/3270.2.80.116 to 70.2.80.116—1
11870.2.80.117/3270.2.80.117 to 70.2.80.117—1
11970.2.80.118/3270.2.80.118 to 70.2.80.118—1
12070.2.80.119/3270.2.80.119 to 70.2.80.119—1
12170.2.80.120/3270.2.80.120 to 70.2.80.120—1
12270.2.80.121/3270.2.80.121 to 70.2.80.121—1
12370.2.80.122/3270.2.80.122 to 70.2.80.122—1
12470.2.80.123/3270.2.80.123 to 70.2.80.123—1
12570.2.80.124/3270.2.80.124 to 70.2.80.124—1
12670.2.80.125/3270.2.80.125 to 70.2.80.125—1
12770.2.80.126/3270.2.80.126 to 70.2.80.126—1
12870.2.80.127/3270.2.80.127 to 70.2.80.127—1
12970.2.80.128/3270.2.80.128 to 70.2.80.128—1
13070.2.80.129/3270.2.80.129 to 70.2.80.129—1
13170.2.80.130/3270.2.80.130 to 70.2.80.130—1
13270.2.80.131/3270.2.80.131 to 70.2.80.131—1
13370.2.80.132/3270.2.80.132 to 70.2.80.132—1
13470.2.80.133/3270.2.80.133 to 70.2.80.133—1
13570.2.80.134/3270.2.80.134 to 70.2.80.134—1
13670.2.80.135/3270.2.80.135 to 70.2.80.135—1
13770.2.80.136/3270.2.80.136 to 70.2.80.136—1
13870.2.80.137/3270.2.80.137 to 70.2.80.137—1
13970.2.80.138/3270.2.80.138 to 70.2.80.138—1
14070.2.80.139/3270.2.80.139 to 70.2.80.139—1
14170.2.80.140/3270.2.80.140 to 70.2.80.140—1
14270.2.80.141/3270.2.80.141 to 70.2.80.141—1
14370.2.80.142/3270.2.80.142 to 70.2.80.142—1
14470.2.80.143/3270.2.80.143 to 70.2.80.143—1
14570.2.80.144/3270.2.80.144 to 70.2.80.144—1
14670.2.80.145/3270.2.80.145 to 70.2.80.145—1
14770.2.80.146/3270.2.80.146 to 70.2.80.146—1
14870.2.80.147/3270.2.80.147 to 70.2.80.147—1
14970.2.80.148/3270.2.80.148 to 70.2.80.148—1
15070.2.80.149/3270.2.80.149 to 70.2.80.149—1
15170.2.80.150/3270.2.80.150 to 70.2.80.150—1
15270.2.80.151/3270.2.80.151 to 70.2.80.151—1
15370.2.80.152/3270.2.80.152 to 70.2.80.152—1
15470.2.80.153/3270.2.80.153 to 70.2.80.153—1
15570.2.80.154/3270.2.80.154 to 70.2.80.154—1
15670.2.80.155/3270.2.80.155 to 70.2.80.155—1
15770.2.80.156/3270.2.80.156 to 70.2.80.156—1
15870.2.80.157/3270.2.80.157 to 70.2.80.157—1
15970.2.80.158/3270.2.80.158 to 70.2.80.158—1
16070.2.80.159/3270.2.80.159 to 70.2.80.159—1
16170.2.80.160/3270.2.80.160 to 70.2.80.160—1
16270.2.80.161/3270.2.80.161 to 70.2.80.161—1
16370.2.80.162/3270.2.80.162 to 70.2.80.162—1
16470.2.80.163/3270.2.80.163 to 70.2.80.163—1
16570.2.80.164/3270.2.80.164 to 70.2.80.164—1
16670.2.80.165/3270.2.80.165 to 70.2.80.165—1
16770.2.80.166/3270.2.80.166 to 70.2.80.166—1
16870.2.80.167/3270.2.80.167 to 70.2.80.167—1
16970.2.80.168/3270.2.80.168 to 70.2.80.168—1
17070.2.80.169/3270.2.80.169 to 70.2.80.169—1
17170.2.80.170/3270.2.80.170 to 70.2.80.170—1
17270.2.80.171/3270.2.80.171 to 70.2.80.171—1
17370.2.80.172/3270.2.80.172 to 70.2.80.172—1
17470.2.80.173/3270.2.80.173 to 70.2.80.173—1
17570.2.80.174/3270.2.80.174 to 70.2.80.174—1
17670.2.80.175/3270.2.80.175 to 70.2.80.175—1
17770.2.80.176/3270.2.80.176 to 70.2.80.176—1
17870.2.80.177/3270.2.80.177 to 70.2.80.177—1
17970.2.80.178/3270.2.80.178 to 70.2.80.178—1
18070.2.80.179/3270.2.80.179 to 70.2.80.179—1
18170.2.80.180/3270.2.80.180 to 70.2.80.180—1
18270.2.80.181/3270.2.80.181 to 70.2.80.181—1
18370.2.80.182/3270.2.80.182 to 70.2.80.182—1
18470.2.80.183/3270.2.80.183 to 70.2.80.183—1
18570.2.80.184/3270.2.80.184 to 70.2.80.184—1
18670.2.80.185/3270.2.80.185 to 70.2.80.185—1
18770.2.80.186/3270.2.80.186 to 70.2.80.186—1
18870.2.80.187/3270.2.80.187 to 70.2.80.187—1
18970.2.80.188/3270.2.80.188 to 70.2.80.188—1
19070.2.80.189/3270.2.80.189 to 70.2.80.189—1
19170.2.80.190/3270.2.80.190 to 70.2.80.190—1
19270.2.80.191/3270.2.80.191 to 70.2.80.191—1
19370.2.80.192/3270.2.80.192 to 70.2.80.192—1
19470.2.80.193/3270.2.80.193 to 70.2.80.193—1
19570.2.80.194/3270.2.80.194 to 70.2.80.194—1
19670.2.80.195/3270.2.80.195 to 70.2.80.195—1
19770.2.80.196/3270.2.80.196 to 70.2.80.196—1
19870.2.80.197/3270.2.80.197 to 70.2.80.197—1
19970.2.80.198/3270.2.80.198 to 70.2.80.198—1
20070.2.80.199/3270.2.80.199 to 70.2.80.199—1
20170.2.80.200/3270.2.80.200 to 70.2.80.200—1
20270.2.80.201/3270.2.80.201 to 70.2.80.201—1
20370.2.80.202/3270.2.80.202 to 70.2.80.202—1
20470.2.80.203/3270.2.80.203 to 70.2.80.203—1
20570.2.80.204/3270.2.80.204 to 70.2.80.204—1
20670.2.80.205/3270.2.80.205 to 70.2.80.205—1
20770.2.80.206/3270.2.80.206 to 70.2.80.206—1
20870.2.80.207/3270.2.80.207 to 70.2.80.207—1
20970.2.80.208/3270.2.80.208 to 70.2.80.208—1
21070.2.80.209/3270.2.80.209 to 70.2.80.209—1
21170.2.80.210/3270.2.80.210 to 70.2.80.210—1
21270.2.80.211/3270.2.80.211 to 70.2.80.211—1
21370.2.80.212/3270.2.80.212 to 70.2.80.212—1
21470.2.80.213/3270.2.80.213 to 70.2.80.213—1
21570.2.80.214/3270.2.80.214 to 70.2.80.214—1
21670.2.80.215/3270.2.80.215 to 70.2.80.215—1
21770.2.80.216/3270.2.80.216 to 70.2.80.216—1
21870.2.80.217/3270.2.80.217 to 70.2.80.217—1
21970.2.80.218/3270.2.80.218 to 70.2.80.218—1
22070.2.80.219/3270.2.80.219 to 70.2.80.219—1
22170.2.80.220/3270.2.80.220 to 70.2.80.220—1
22270.2.80.221/3270.2.80.221 to 70.2.80.221—1
22370.2.80.222/3270.2.80.222 to 70.2.80.222—1
22470.2.80.223/3270.2.80.223 to 70.2.80.223—1
22570.2.80.224/3270.2.80.224 to 70.2.80.224—1
22670.2.80.225/3270.2.80.225 to 70.2.80.225—1
22770.2.80.226/3270.2.80.226 to 70.2.80.226—1
22870.2.80.227/3270.2.80.227 to 70.2.80.227—1
22970.2.80.228/3270.2.80.228 to 70.2.80.228—1
23070.2.80.229/3270.2.80.229 to 70.2.80.229—1
23170.2.80.230/3270.2.80.230 to 70.2.80.230—1
23270.2.80.231/3270.2.80.231 to 70.2.80.231—1
23370.2.80.232/3270.2.80.232 to 70.2.80.232—1
23470.2.80.233/3270.2.80.233 to 70.2.80.233—1
23570.2.80.234/3270.2.80.234 to 70.2.80.234—1
23670.2.80.235/3270.2.80.235 to 70.2.80.235—1
23770.2.80.236/3270.2.80.236 to 70.2.80.236—1
23870.2.80.237/3270.2.80.237 to 70.2.80.237—1
23970.2.80.238/3270.2.80.238 to 70.2.80.238—1
24070.2.80.239/3270.2.80.239 to 70.2.80.239—1
24170.2.80.240/3270.2.80.240 to 70.2.80.240—1
24270.2.80.241/3270.2.80.241 to 70.2.80.241—1
24370.2.80.242/3270.2.80.242 to 70.2.80.242—1
24470.2.80.243/3270.2.80.243 to 70.2.80.243—1
24570.2.80.244/3270.2.80.244 to 70.2.80.244—1
24670.2.80.245/3270.2.80.245 to 70.2.80.245—1
24770.2.80.246/3270.2.80.246 to 70.2.80.246—1
24870.2.80.247/3270.2.80.247 to 70.2.80.247—1
24970.2.80.248/3270.2.80.248 to 70.2.80.248—1
25070.2.80.249/3270.2.80.249 to 70.2.80.249—1
25170.2.80.250/3270.2.80.250 to 70.2.80.250—1
25270.2.80.251/3270.2.80.251 to 70.2.80.251—1
25370.2.80.252/3270.2.80.252 to 70.2.80.252—1
25470.2.80.253/3270.2.80.253 to 70.2.80.253—1
25570.2.80.254/3270.2.80.254 to 70.2.80.254—1
25670.2.80.255/3270.2.80.255 to 70.2.80.255—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.