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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.

Network16.2.80.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
16.2.80.0
Broadcast address
16.2.95.255
First usable
16.2.80.1
Last usable
16.2.95.254
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 10025000 · Integer 268587008 to 268591103
Reverse DNS zones
80.2.16.in-addr.arpa
81.2.16.in-addr.arpa
82.2.16.in-addr.arpa
83.2.16.in-addr.arpa
84.2.16.in-addr.arpa
85.2.16.in-addr.arpa
86.2.16.in-addr.arpa
87.2.16.in-addr.arpa
88.2.16.in-addr.arpa
89.2.16.in-addr.arpa
90.2.16.in-addr.arpa
91.2.16.in-addr.arpa
92.2.16.in-addr.arpa
93.2.16.in-addr.arpa
94.2.16.in-addr.arpa
95.2.16.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
Address00010000.00000010.01010000.0000000016.2.80.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network00010000.00000010.01010000.0000000016.2.80.0
Broadcast00010000.00000010.01011111.1111111116.2.95.255
Split into smaller subnets/31
/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)

16.2.80.0/20 makes 2,048 subnets of /31; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
116.2.80.0/3116.2.80.0 to 16.2.80.1—2
216.2.80.2/3116.2.80.2 to 16.2.80.3—2
316.2.80.4/3116.2.80.4 to 16.2.80.5—2
416.2.80.6/3116.2.80.6 to 16.2.80.7—2
516.2.80.8/3116.2.80.8 to 16.2.80.9—2
616.2.80.10/3116.2.80.10 to 16.2.80.11—2
716.2.80.12/3116.2.80.12 to 16.2.80.13—2
816.2.80.14/3116.2.80.14 to 16.2.80.15—2
916.2.80.16/3116.2.80.16 to 16.2.80.17—2
1016.2.80.18/3116.2.80.18 to 16.2.80.19—2
1116.2.80.20/3116.2.80.20 to 16.2.80.21—2
1216.2.80.22/3116.2.80.22 to 16.2.80.23—2
1316.2.80.24/3116.2.80.24 to 16.2.80.25—2
1416.2.80.26/3116.2.80.26 to 16.2.80.27—2
1516.2.80.28/3116.2.80.28 to 16.2.80.29—2
1616.2.80.30/3116.2.80.30 to 16.2.80.31—2
1716.2.80.32/3116.2.80.32 to 16.2.80.33—2
1816.2.80.34/3116.2.80.34 to 16.2.80.35—2
1916.2.80.36/3116.2.80.36 to 16.2.80.37—2
2016.2.80.38/3116.2.80.38 to 16.2.80.39—2
2116.2.80.40/3116.2.80.40 to 16.2.80.41—2
2216.2.80.42/3116.2.80.42 to 16.2.80.43—2
2316.2.80.44/3116.2.80.44 to 16.2.80.45—2
2416.2.80.46/3116.2.80.46 to 16.2.80.47—2
2516.2.80.48/3116.2.80.48 to 16.2.80.49—2
2616.2.80.50/3116.2.80.50 to 16.2.80.51—2
2716.2.80.52/3116.2.80.52 to 16.2.80.53—2
2816.2.80.54/3116.2.80.54 to 16.2.80.55—2
2916.2.80.56/3116.2.80.56 to 16.2.80.57—2
3016.2.80.58/3116.2.80.58 to 16.2.80.59—2
3116.2.80.60/3116.2.80.60 to 16.2.80.61—2
3216.2.80.62/3116.2.80.62 to 16.2.80.63—2
3316.2.80.64/3116.2.80.64 to 16.2.80.65—2
3416.2.80.66/3116.2.80.66 to 16.2.80.67—2
3516.2.80.68/3116.2.80.68 to 16.2.80.69—2
3616.2.80.70/3116.2.80.70 to 16.2.80.71—2
3716.2.80.72/3116.2.80.72 to 16.2.80.73—2
3816.2.80.74/3116.2.80.74 to 16.2.80.75—2
3916.2.80.76/3116.2.80.76 to 16.2.80.77—2
4016.2.80.78/3116.2.80.78 to 16.2.80.79—2
4116.2.80.80/3116.2.80.80 to 16.2.80.81—2
4216.2.80.82/3116.2.80.82 to 16.2.80.83—2
4316.2.80.84/3116.2.80.84 to 16.2.80.85—2
4416.2.80.86/3116.2.80.86 to 16.2.80.87—2
4516.2.80.88/3116.2.80.88 to 16.2.80.89—2
4616.2.80.90/3116.2.80.90 to 16.2.80.91—2
4716.2.80.92/3116.2.80.92 to 16.2.80.93—2
4816.2.80.94/3116.2.80.94 to 16.2.80.95—2
4916.2.80.96/3116.2.80.96 to 16.2.80.97—2
5016.2.80.98/3116.2.80.98 to 16.2.80.99—2
5116.2.80.100/3116.2.80.100 to 16.2.80.101—2
5216.2.80.102/3116.2.80.102 to 16.2.80.103—2
5316.2.80.104/3116.2.80.104 to 16.2.80.105—2
5416.2.80.106/3116.2.80.106 to 16.2.80.107—2
5516.2.80.108/3116.2.80.108 to 16.2.80.109—2
5616.2.80.110/3116.2.80.110 to 16.2.80.111—2
5716.2.80.112/3116.2.80.112 to 16.2.80.113—2
5816.2.80.114/3116.2.80.114 to 16.2.80.115—2
5916.2.80.116/3116.2.80.116 to 16.2.80.117—2
6016.2.80.118/3116.2.80.118 to 16.2.80.119—2
6116.2.80.120/3116.2.80.120 to 16.2.80.121—2
6216.2.80.122/3116.2.80.122 to 16.2.80.123—2
6316.2.80.124/3116.2.80.124 to 16.2.80.125—2
6416.2.80.126/3116.2.80.126 to 16.2.80.127—2
6516.2.80.128/3116.2.80.128 to 16.2.80.129—2
6616.2.80.130/3116.2.80.130 to 16.2.80.131—2
6716.2.80.132/3116.2.80.132 to 16.2.80.133—2
6816.2.80.134/3116.2.80.134 to 16.2.80.135—2
6916.2.80.136/3116.2.80.136 to 16.2.80.137—2
7016.2.80.138/3116.2.80.138 to 16.2.80.139—2
7116.2.80.140/3116.2.80.140 to 16.2.80.141—2
7216.2.80.142/3116.2.80.142 to 16.2.80.143—2
7316.2.80.144/3116.2.80.144 to 16.2.80.145—2
7416.2.80.146/3116.2.80.146 to 16.2.80.147—2
7516.2.80.148/3116.2.80.148 to 16.2.80.149—2
7616.2.80.150/3116.2.80.150 to 16.2.80.151—2
7716.2.80.152/3116.2.80.152 to 16.2.80.153—2
7816.2.80.154/3116.2.80.154 to 16.2.80.155—2
7916.2.80.156/3116.2.80.156 to 16.2.80.157—2
8016.2.80.158/3116.2.80.158 to 16.2.80.159—2
8116.2.80.160/3116.2.80.160 to 16.2.80.161—2
8216.2.80.162/3116.2.80.162 to 16.2.80.163—2
8316.2.80.164/3116.2.80.164 to 16.2.80.165—2
8416.2.80.166/3116.2.80.166 to 16.2.80.167—2
8516.2.80.168/3116.2.80.168 to 16.2.80.169—2
8616.2.80.170/3116.2.80.170 to 16.2.80.171—2
8716.2.80.172/3116.2.80.172 to 16.2.80.173—2
8816.2.80.174/3116.2.80.174 to 16.2.80.175—2
8916.2.80.176/3116.2.80.176 to 16.2.80.177—2
9016.2.80.178/3116.2.80.178 to 16.2.80.179—2
9116.2.80.180/3116.2.80.180 to 16.2.80.181—2
9216.2.80.182/3116.2.80.182 to 16.2.80.183—2
9316.2.80.184/3116.2.80.184 to 16.2.80.185—2
9416.2.80.186/3116.2.80.186 to 16.2.80.187—2
9516.2.80.188/3116.2.80.188 to 16.2.80.189—2
9616.2.80.190/3116.2.80.190 to 16.2.80.191—2
9716.2.80.192/3116.2.80.192 to 16.2.80.193—2
9816.2.80.194/3116.2.80.194 to 16.2.80.195—2
9916.2.80.196/3116.2.80.196 to 16.2.80.197—2
10016.2.80.198/3116.2.80.198 to 16.2.80.199—2
10116.2.80.200/3116.2.80.200 to 16.2.80.201—2
10216.2.80.202/3116.2.80.202 to 16.2.80.203—2
10316.2.80.204/3116.2.80.204 to 16.2.80.205—2
10416.2.80.206/3116.2.80.206 to 16.2.80.207—2
10516.2.80.208/3116.2.80.208 to 16.2.80.209—2
10616.2.80.210/3116.2.80.210 to 16.2.80.211—2
10716.2.80.212/3116.2.80.212 to 16.2.80.213—2
10816.2.80.214/3116.2.80.214 to 16.2.80.215—2
10916.2.80.216/3116.2.80.216 to 16.2.80.217—2
11016.2.80.218/3116.2.80.218 to 16.2.80.219—2
11116.2.80.220/3116.2.80.220 to 16.2.80.221—2
11216.2.80.222/3116.2.80.222 to 16.2.80.223—2
11316.2.80.224/3116.2.80.224 to 16.2.80.225—2
11416.2.80.226/3116.2.80.226 to 16.2.80.227—2
11516.2.80.228/3116.2.80.228 to 16.2.80.229—2
11616.2.80.230/3116.2.80.230 to 16.2.80.231—2
11716.2.80.232/3116.2.80.232 to 16.2.80.233—2
11816.2.80.234/3116.2.80.234 to 16.2.80.235—2
11916.2.80.236/3116.2.80.236 to 16.2.80.237—2
12016.2.80.238/3116.2.80.238 to 16.2.80.239—2
12116.2.80.240/3116.2.80.240 to 16.2.80.241—2
12216.2.80.242/3116.2.80.242 to 16.2.80.243—2
12316.2.80.244/3116.2.80.244 to 16.2.80.245—2
12416.2.80.246/3116.2.80.246 to 16.2.80.247—2
12516.2.80.248/3116.2.80.248 to 16.2.80.249—2
12616.2.80.250/3116.2.80.250 to 16.2.80.251—2
12716.2.80.252/3116.2.80.252 to 16.2.80.253—2
12816.2.80.254/3116.2.80.254 to 16.2.80.255—2
12916.2.81.0/3116.2.81.0 to 16.2.81.1—2
13016.2.81.2/3116.2.81.2 to 16.2.81.3—2
13116.2.81.4/3116.2.81.4 to 16.2.81.5—2
13216.2.81.6/3116.2.81.6 to 16.2.81.7—2
13316.2.81.8/3116.2.81.8 to 16.2.81.9—2
13416.2.81.10/3116.2.81.10 to 16.2.81.11—2
13516.2.81.12/3116.2.81.12 to 16.2.81.13—2
13616.2.81.14/3116.2.81.14 to 16.2.81.15—2
13716.2.81.16/3116.2.81.16 to 16.2.81.17—2
13816.2.81.18/3116.2.81.18 to 16.2.81.19—2
13916.2.81.20/3116.2.81.20 to 16.2.81.21—2
14016.2.81.22/3116.2.81.22 to 16.2.81.23—2
14116.2.81.24/3116.2.81.24 to 16.2.81.25—2
14216.2.81.26/3116.2.81.26 to 16.2.81.27—2
14316.2.81.28/3116.2.81.28 to 16.2.81.29—2
14416.2.81.30/3116.2.81.30 to 16.2.81.31—2
14516.2.81.32/3116.2.81.32 to 16.2.81.33—2
14616.2.81.34/3116.2.81.34 to 16.2.81.35—2
14716.2.81.36/3116.2.81.36 to 16.2.81.37—2
14816.2.81.38/3116.2.81.38 to 16.2.81.39—2
14916.2.81.40/3116.2.81.40 to 16.2.81.41—2
15016.2.81.42/3116.2.81.42 to 16.2.81.43—2
15116.2.81.44/3116.2.81.44 to 16.2.81.45—2
15216.2.81.46/3116.2.81.46 to 16.2.81.47—2
15316.2.81.48/3116.2.81.48 to 16.2.81.49—2
15416.2.81.50/3116.2.81.50 to 16.2.81.51—2
15516.2.81.52/3116.2.81.52 to 16.2.81.53—2
15616.2.81.54/3116.2.81.54 to 16.2.81.55—2
15716.2.81.56/3116.2.81.56 to 16.2.81.57—2
15816.2.81.58/3116.2.81.58 to 16.2.81.59—2
15916.2.81.60/3116.2.81.60 to 16.2.81.61—2
16016.2.81.62/3116.2.81.62 to 16.2.81.63—2
16116.2.81.64/3116.2.81.64 to 16.2.81.65—2
16216.2.81.66/3116.2.81.66 to 16.2.81.67—2
16316.2.81.68/3116.2.81.68 to 16.2.81.69—2
16416.2.81.70/3116.2.81.70 to 16.2.81.71—2
16516.2.81.72/3116.2.81.72 to 16.2.81.73—2
16616.2.81.74/3116.2.81.74 to 16.2.81.75—2
16716.2.81.76/3116.2.81.76 to 16.2.81.77—2
16816.2.81.78/3116.2.81.78 to 16.2.81.79—2
16916.2.81.80/3116.2.81.80 to 16.2.81.81—2
17016.2.81.82/3116.2.81.82 to 16.2.81.83—2
17116.2.81.84/3116.2.81.84 to 16.2.81.85—2
17216.2.81.86/3116.2.81.86 to 16.2.81.87—2
17316.2.81.88/3116.2.81.88 to 16.2.81.89—2
17416.2.81.90/3116.2.81.90 to 16.2.81.91—2
17516.2.81.92/3116.2.81.92 to 16.2.81.93—2
17616.2.81.94/3116.2.81.94 to 16.2.81.95—2
17716.2.81.96/3116.2.81.96 to 16.2.81.97—2
17816.2.81.98/3116.2.81.98 to 16.2.81.99—2
17916.2.81.100/3116.2.81.100 to 16.2.81.101—2
18016.2.81.102/3116.2.81.102 to 16.2.81.103—2
18116.2.81.104/3116.2.81.104 to 16.2.81.105—2
18216.2.81.106/3116.2.81.106 to 16.2.81.107—2
18316.2.81.108/3116.2.81.108 to 16.2.81.109—2
18416.2.81.110/3116.2.81.110 to 16.2.81.111—2
18516.2.81.112/3116.2.81.112 to 16.2.81.113—2
18616.2.81.114/3116.2.81.114 to 16.2.81.115—2
18716.2.81.116/3116.2.81.116 to 16.2.81.117—2
18816.2.81.118/3116.2.81.118 to 16.2.81.119—2
18916.2.81.120/3116.2.81.120 to 16.2.81.121—2
19016.2.81.122/3116.2.81.122 to 16.2.81.123—2
19116.2.81.124/3116.2.81.124 to 16.2.81.125—2
19216.2.81.126/3116.2.81.126 to 16.2.81.127—2
19316.2.81.128/3116.2.81.128 to 16.2.81.129—2
19416.2.81.130/3116.2.81.130 to 16.2.81.131—2
19516.2.81.132/3116.2.81.132 to 16.2.81.133—2
19616.2.81.134/3116.2.81.134 to 16.2.81.135—2
19716.2.81.136/3116.2.81.136 to 16.2.81.137—2
19816.2.81.138/3116.2.81.138 to 16.2.81.139—2
19916.2.81.140/3116.2.81.140 to 16.2.81.141—2
20016.2.81.142/3116.2.81.142 to 16.2.81.143—2
20116.2.81.144/3116.2.81.144 to 16.2.81.145—2
20216.2.81.146/3116.2.81.146 to 16.2.81.147—2
20316.2.81.148/3116.2.81.148 to 16.2.81.149—2
20416.2.81.150/3116.2.81.150 to 16.2.81.151—2
20516.2.81.152/3116.2.81.152 to 16.2.81.153—2
20616.2.81.154/3116.2.81.154 to 16.2.81.155—2
20716.2.81.156/3116.2.81.156 to 16.2.81.157—2
20816.2.81.158/3116.2.81.158 to 16.2.81.159—2
20916.2.81.160/3116.2.81.160 to 16.2.81.161—2
21016.2.81.162/3116.2.81.162 to 16.2.81.163—2
21116.2.81.164/3116.2.81.164 to 16.2.81.165—2
21216.2.81.166/3116.2.81.166 to 16.2.81.167—2
21316.2.81.168/3116.2.81.168 to 16.2.81.169—2
21416.2.81.170/3116.2.81.170 to 16.2.81.171—2
21516.2.81.172/3116.2.81.172 to 16.2.81.173—2
21616.2.81.174/3116.2.81.174 to 16.2.81.175—2
21716.2.81.176/3116.2.81.176 to 16.2.81.177—2
21816.2.81.178/3116.2.81.178 to 16.2.81.179—2
21916.2.81.180/3116.2.81.180 to 16.2.81.181—2
22016.2.81.182/3116.2.81.182 to 16.2.81.183—2
22116.2.81.184/3116.2.81.184 to 16.2.81.185—2
22216.2.81.186/3116.2.81.186 to 16.2.81.187—2
22316.2.81.188/3116.2.81.188 to 16.2.81.189—2
22416.2.81.190/3116.2.81.190 to 16.2.81.191—2
22516.2.81.192/3116.2.81.192 to 16.2.81.193—2
22616.2.81.194/3116.2.81.194 to 16.2.81.195—2
22716.2.81.196/3116.2.81.196 to 16.2.81.197—2
22816.2.81.198/3116.2.81.198 to 16.2.81.199—2
22916.2.81.200/3116.2.81.200 to 16.2.81.201—2
23016.2.81.202/3116.2.81.202 to 16.2.81.203—2
23116.2.81.204/3116.2.81.204 to 16.2.81.205—2
23216.2.81.206/3116.2.81.206 to 16.2.81.207—2
23316.2.81.208/3116.2.81.208 to 16.2.81.209—2
23416.2.81.210/3116.2.81.210 to 16.2.81.211—2
23516.2.81.212/3116.2.81.212 to 16.2.81.213—2
23616.2.81.214/3116.2.81.214 to 16.2.81.215—2
23716.2.81.216/3116.2.81.216 to 16.2.81.217—2
23816.2.81.218/3116.2.81.218 to 16.2.81.219—2
23916.2.81.220/3116.2.81.220 to 16.2.81.221—2
24016.2.81.222/3116.2.81.222 to 16.2.81.223—2
24116.2.81.224/3116.2.81.224 to 16.2.81.225—2
24216.2.81.226/3116.2.81.226 to 16.2.81.227—2
24316.2.81.228/3116.2.81.228 to 16.2.81.229—2
24416.2.81.230/3116.2.81.230 to 16.2.81.231—2
24516.2.81.232/3116.2.81.232 to 16.2.81.233—2
24616.2.81.234/3116.2.81.234 to 16.2.81.235—2
24716.2.81.236/3116.2.81.236 to 16.2.81.237—2
24816.2.81.238/3116.2.81.238 to 16.2.81.239—2
24916.2.81.240/3116.2.81.240 to 16.2.81.241—2
25016.2.81.242/3116.2.81.242 to 16.2.81.243—2
25116.2.81.244/3116.2.81.244 to 16.2.81.245—2
25216.2.81.246/3116.2.81.246 to 16.2.81.247—2
25316.2.81.248/3116.2.81.248 to 16.2.81.249—2
25416.2.81.250/3116.2.81.250 to 16.2.81.251—2
25516.2.81.252/3116.2.81.252 to 16.2.81.253—2
25616.2.81.254/3116.2.81.254 to 16.2.81.255—2

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.