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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.

Network17.166.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
17.166.0.0
Broadcast address
17.167.255.255
First usable
17.166.0.1
Last usable
17.167.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
A (default /8)
As numbers
Hex 11A60000 · Integer 296091648 to 296222719
Reverse DNS zones
166.17.in-addr.arpa
167.17.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010001.10100110.00000000.0000000017.166.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00010001.10100110.00000000.0000000017.166.0.0
Broadcast00010001.10100111.11111111.1111111117.167.255.255
Split into smaller subnets/27
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

17.166.0.0/15 makes 4,096 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
117.166.0.0/2717.166.0.1 to 17.166.0.3017.166.0.3130
217.166.0.32/2717.166.0.33 to 17.166.0.6217.166.0.6330
317.166.0.64/2717.166.0.65 to 17.166.0.9417.166.0.9530
417.166.0.96/2717.166.0.97 to 17.166.0.12617.166.0.12730
517.166.0.128/2717.166.0.129 to 17.166.0.15817.166.0.15930
617.166.0.160/2717.166.0.161 to 17.166.0.19017.166.0.19130
717.166.0.192/2717.166.0.193 to 17.166.0.22217.166.0.22330
817.166.0.224/2717.166.0.225 to 17.166.0.25417.166.0.25530
917.166.1.0/2717.166.1.1 to 17.166.1.3017.166.1.3130
1017.166.1.32/2717.166.1.33 to 17.166.1.6217.166.1.6330
1117.166.1.64/2717.166.1.65 to 17.166.1.9417.166.1.9530
1217.166.1.96/2717.166.1.97 to 17.166.1.12617.166.1.12730
1317.166.1.128/2717.166.1.129 to 17.166.1.15817.166.1.15930
1417.166.1.160/2717.166.1.161 to 17.166.1.19017.166.1.19130
1517.166.1.192/2717.166.1.193 to 17.166.1.22217.166.1.22330
1617.166.1.224/2717.166.1.225 to 17.166.1.25417.166.1.25530
1717.166.2.0/2717.166.2.1 to 17.166.2.3017.166.2.3130
1817.166.2.32/2717.166.2.33 to 17.166.2.6217.166.2.6330
1917.166.2.64/2717.166.2.65 to 17.166.2.9417.166.2.9530
2017.166.2.96/2717.166.2.97 to 17.166.2.12617.166.2.12730
2117.166.2.128/2717.166.2.129 to 17.166.2.15817.166.2.15930
2217.166.2.160/2717.166.2.161 to 17.166.2.19017.166.2.19130
2317.166.2.192/2717.166.2.193 to 17.166.2.22217.166.2.22330
2417.166.2.224/2717.166.2.225 to 17.166.2.25417.166.2.25530
2517.166.3.0/2717.166.3.1 to 17.166.3.3017.166.3.3130
2617.166.3.32/2717.166.3.33 to 17.166.3.6217.166.3.6330
2717.166.3.64/2717.166.3.65 to 17.166.3.9417.166.3.9530
2817.166.3.96/2717.166.3.97 to 17.166.3.12617.166.3.12730
2917.166.3.128/2717.166.3.129 to 17.166.3.15817.166.3.15930
3017.166.3.160/2717.166.3.161 to 17.166.3.19017.166.3.19130
3117.166.3.192/2717.166.3.193 to 17.166.3.22217.166.3.22330
3217.166.3.224/2717.166.3.225 to 17.166.3.25417.166.3.25530
3317.166.4.0/2717.166.4.1 to 17.166.4.3017.166.4.3130
3417.166.4.32/2717.166.4.33 to 17.166.4.6217.166.4.6330
3517.166.4.64/2717.166.4.65 to 17.166.4.9417.166.4.9530
3617.166.4.96/2717.166.4.97 to 17.166.4.12617.166.4.12730
3717.166.4.128/2717.166.4.129 to 17.166.4.15817.166.4.15930
3817.166.4.160/2717.166.4.161 to 17.166.4.19017.166.4.19130
3917.166.4.192/2717.166.4.193 to 17.166.4.22217.166.4.22330
4017.166.4.224/2717.166.4.225 to 17.166.4.25417.166.4.25530
4117.166.5.0/2717.166.5.1 to 17.166.5.3017.166.5.3130
4217.166.5.32/2717.166.5.33 to 17.166.5.6217.166.5.6330
4317.166.5.64/2717.166.5.65 to 17.166.5.9417.166.5.9530
4417.166.5.96/2717.166.5.97 to 17.166.5.12617.166.5.12730
4517.166.5.128/2717.166.5.129 to 17.166.5.15817.166.5.15930
4617.166.5.160/2717.166.5.161 to 17.166.5.19017.166.5.19130
4717.166.5.192/2717.166.5.193 to 17.166.5.22217.166.5.22330
4817.166.5.224/2717.166.5.225 to 17.166.5.25417.166.5.25530
4917.166.6.0/2717.166.6.1 to 17.166.6.3017.166.6.3130
5017.166.6.32/2717.166.6.33 to 17.166.6.6217.166.6.6330
5117.166.6.64/2717.166.6.65 to 17.166.6.9417.166.6.9530
5217.166.6.96/2717.166.6.97 to 17.166.6.12617.166.6.12730
5317.166.6.128/2717.166.6.129 to 17.166.6.15817.166.6.15930
5417.166.6.160/2717.166.6.161 to 17.166.6.19017.166.6.19130
5517.166.6.192/2717.166.6.193 to 17.166.6.22217.166.6.22330
5617.166.6.224/2717.166.6.225 to 17.166.6.25417.166.6.25530
5717.166.7.0/2717.166.7.1 to 17.166.7.3017.166.7.3130
5817.166.7.32/2717.166.7.33 to 17.166.7.6217.166.7.6330
5917.166.7.64/2717.166.7.65 to 17.166.7.9417.166.7.9530
6017.166.7.96/2717.166.7.97 to 17.166.7.12617.166.7.12730
6117.166.7.128/2717.166.7.129 to 17.166.7.15817.166.7.15930
6217.166.7.160/2717.166.7.161 to 17.166.7.19017.166.7.19130
6317.166.7.192/2717.166.7.193 to 17.166.7.22217.166.7.22330
6417.166.7.224/2717.166.7.225 to 17.166.7.25417.166.7.25530
6517.166.8.0/2717.166.8.1 to 17.166.8.3017.166.8.3130
6617.166.8.32/2717.166.8.33 to 17.166.8.6217.166.8.6330
6717.166.8.64/2717.166.8.65 to 17.166.8.9417.166.8.9530
6817.166.8.96/2717.166.8.97 to 17.166.8.12617.166.8.12730
6917.166.8.128/2717.166.8.129 to 17.166.8.15817.166.8.15930
7017.166.8.160/2717.166.8.161 to 17.166.8.19017.166.8.19130
7117.166.8.192/2717.166.8.193 to 17.166.8.22217.166.8.22330
7217.166.8.224/2717.166.8.225 to 17.166.8.25417.166.8.25530
7317.166.9.0/2717.166.9.1 to 17.166.9.3017.166.9.3130
7417.166.9.32/2717.166.9.33 to 17.166.9.6217.166.9.6330
7517.166.9.64/2717.166.9.65 to 17.166.9.9417.166.9.9530
7617.166.9.96/2717.166.9.97 to 17.166.9.12617.166.9.12730
7717.166.9.128/2717.166.9.129 to 17.166.9.15817.166.9.15930
7817.166.9.160/2717.166.9.161 to 17.166.9.19017.166.9.19130
7917.166.9.192/2717.166.9.193 to 17.166.9.22217.166.9.22330
8017.166.9.224/2717.166.9.225 to 17.166.9.25417.166.9.25530
8117.166.10.0/2717.166.10.1 to 17.166.10.3017.166.10.3130
8217.166.10.32/2717.166.10.33 to 17.166.10.6217.166.10.6330
8317.166.10.64/2717.166.10.65 to 17.166.10.9417.166.10.9530
8417.166.10.96/2717.166.10.97 to 17.166.10.12617.166.10.12730
8517.166.10.128/2717.166.10.129 to 17.166.10.15817.166.10.15930
8617.166.10.160/2717.166.10.161 to 17.166.10.19017.166.10.19130
8717.166.10.192/2717.166.10.193 to 17.166.10.22217.166.10.22330
8817.166.10.224/2717.166.10.225 to 17.166.10.25417.166.10.25530
8917.166.11.0/2717.166.11.1 to 17.166.11.3017.166.11.3130
9017.166.11.32/2717.166.11.33 to 17.166.11.6217.166.11.6330
9117.166.11.64/2717.166.11.65 to 17.166.11.9417.166.11.9530
9217.166.11.96/2717.166.11.97 to 17.166.11.12617.166.11.12730
9317.166.11.128/2717.166.11.129 to 17.166.11.15817.166.11.15930
9417.166.11.160/2717.166.11.161 to 17.166.11.19017.166.11.19130
9517.166.11.192/2717.166.11.193 to 17.166.11.22217.166.11.22330
9617.166.11.224/2717.166.11.225 to 17.166.11.25417.166.11.25530
9717.166.12.0/2717.166.12.1 to 17.166.12.3017.166.12.3130
9817.166.12.32/2717.166.12.33 to 17.166.12.6217.166.12.6330
9917.166.12.64/2717.166.12.65 to 17.166.12.9417.166.12.9530
10017.166.12.96/2717.166.12.97 to 17.166.12.12617.166.12.12730
10117.166.12.128/2717.166.12.129 to 17.166.12.15817.166.12.15930
10217.166.12.160/2717.166.12.161 to 17.166.12.19017.166.12.19130
10317.166.12.192/2717.166.12.193 to 17.166.12.22217.166.12.22330
10417.166.12.224/2717.166.12.225 to 17.166.12.25417.166.12.25530
10517.166.13.0/2717.166.13.1 to 17.166.13.3017.166.13.3130
10617.166.13.32/2717.166.13.33 to 17.166.13.6217.166.13.6330
10717.166.13.64/2717.166.13.65 to 17.166.13.9417.166.13.9530
10817.166.13.96/2717.166.13.97 to 17.166.13.12617.166.13.12730
10917.166.13.128/2717.166.13.129 to 17.166.13.15817.166.13.15930
11017.166.13.160/2717.166.13.161 to 17.166.13.19017.166.13.19130
11117.166.13.192/2717.166.13.193 to 17.166.13.22217.166.13.22330
11217.166.13.224/2717.166.13.225 to 17.166.13.25417.166.13.25530
11317.166.14.0/2717.166.14.1 to 17.166.14.3017.166.14.3130
11417.166.14.32/2717.166.14.33 to 17.166.14.6217.166.14.6330
11517.166.14.64/2717.166.14.65 to 17.166.14.9417.166.14.9530
11617.166.14.96/2717.166.14.97 to 17.166.14.12617.166.14.12730
11717.166.14.128/2717.166.14.129 to 17.166.14.15817.166.14.15930
11817.166.14.160/2717.166.14.161 to 17.166.14.19017.166.14.19130
11917.166.14.192/2717.166.14.193 to 17.166.14.22217.166.14.22330
12017.166.14.224/2717.166.14.225 to 17.166.14.25417.166.14.25530
12117.166.15.0/2717.166.15.1 to 17.166.15.3017.166.15.3130
12217.166.15.32/2717.166.15.33 to 17.166.15.6217.166.15.6330
12317.166.15.64/2717.166.15.65 to 17.166.15.9417.166.15.9530
12417.166.15.96/2717.166.15.97 to 17.166.15.12617.166.15.12730
12517.166.15.128/2717.166.15.129 to 17.166.15.15817.166.15.15930
12617.166.15.160/2717.166.15.161 to 17.166.15.19017.166.15.19130
12717.166.15.192/2717.166.15.193 to 17.166.15.22217.166.15.22330
12817.166.15.224/2717.166.15.225 to 17.166.15.25417.166.15.25530
12917.166.16.0/2717.166.16.1 to 17.166.16.3017.166.16.3130
13017.166.16.32/2717.166.16.33 to 17.166.16.6217.166.16.6330
13117.166.16.64/2717.166.16.65 to 17.166.16.9417.166.16.9530
13217.166.16.96/2717.166.16.97 to 17.166.16.12617.166.16.12730
13317.166.16.128/2717.166.16.129 to 17.166.16.15817.166.16.15930
13417.166.16.160/2717.166.16.161 to 17.166.16.19017.166.16.19130
13517.166.16.192/2717.166.16.193 to 17.166.16.22217.166.16.22330
13617.166.16.224/2717.166.16.225 to 17.166.16.25417.166.16.25530
13717.166.17.0/2717.166.17.1 to 17.166.17.3017.166.17.3130
13817.166.17.32/2717.166.17.33 to 17.166.17.6217.166.17.6330
13917.166.17.64/2717.166.17.65 to 17.166.17.9417.166.17.9530
14017.166.17.96/2717.166.17.97 to 17.166.17.12617.166.17.12730
14117.166.17.128/2717.166.17.129 to 17.166.17.15817.166.17.15930
14217.166.17.160/2717.166.17.161 to 17.166.17.19017.166.17.19130
14317.166.17.192/2717.166.17.193 to 17.166.17.22217.166.17.22330
14417.166.17.224/2717.166.17.225 to 17.166.17.25417.166.17.25530
14517.166.18.0/2717.166.18.1 to 17.166.18.3017.166.18.3130
14617.166.18.32/2717.166.18.33 to 17.166.18.6217.166.18.6330
14717.166.18.64/2717.166.18.65 to 17.166.18.9417.166.18.9530
14817.166.18.96/2717.166.18.97 to 17.166.18.12617.166.18.12730
14917.166.18.128/2717.166.18.129 to 17.166.18.15817.166.18.15930
15017.166.18.160/2717.166.18.161 to 17.166.18.19017.166.18.19130
15117.166.18.192/2717.166.18.193 to 17.166.18.22217.166.18.22330
15217.166.18.224/2717.166.18.225 to 17.166.18.25417.166.18.25530
15317.166.19.0/2717.166.19.1 to 17.166.19.3017.166.19.3130
15417.166.19.32/2717.166.19.33 to 17.166.19.6217.166.19.6330
15517.166.19.64/2717.166.19.65 to 17.166.19.9417.166.19.9530
15617.166.19.96/2717.166.19.97 to 17.166.19.12617.166.19.12730
15717.166.19.128/2717.166.19.129 to 17.166.19.15817.166.19.15930
15817.166.19.160/2717.166.19.161 to 17.166.19.19017.166.19.19130
15917.166.19.192/2717.166.19.193 to 17.166.19.22217.166.19.22330
16017.166.19.224/2717.166.19.225 to 17.166.19.25417.166.19.25530
16117.166.20.0/2717.166.20.1 to 17.166.20.3017.166.20.3130
16217.166.20.32/2717.166.20.33 to 17.166.20.6217.166.20.6330
16317.166.20.64/2717.166.20.65 to 17.166.20.9417.166.20.9530
16417.166.20.96/2717.166.20.97 to 17.166.20.12617.166.20.12730
16517.166.20.128/2717.166.20.129 to 17.166.20.15817.166.20.15930
16617.166.20.160/2717.166.20.161 to 17.166.20.19017.166.20.19130
16717.166.20.192/2717.166.20.193 to 17.166.20.22217.166.20.22330
16817.166.20.224/2717.166.20.225 to 17.166.20.25417.166.20.25530
16917.166.21.0/2717.166.21.1 to 17.166.21.3017.166.21.3130
17017.166.21.32/2717.166.21.33 to 17.166.21.6217.166.21.6330
17117.166.21.64/2717.166.21.65 to 17.166.21.9417.166.21.9530
17217.166.21.96/2717.166.21.97 to 17.166.21.12617.166.21.12730
17317.166.21.128/2717.166.21.129 to 17.166.21.15817.166.21.15930
17417.166.21.160/2717.166.21.161 to 17.166.21.19017.166.21.19130
17517.166.21.192/2717.166.21.193 to 17.166.21.22217.166.21.22330
17617.166.21.224/2717.166.21.225 to 17.166.21.25417.166.21.25530
17717.166.22.0/2717.166.22.1 to 17.166.22.3017.166.22.3130
17817.166.22.32/2717.166.22.33 to 17.166.22.6217.166.22.6330
17917.166.22.64/2717.166.22.65 to 17.166.22.9417.166.22.9530
18017.166.22.96/2717.166.22.97 to 17.166.22.12617.166.22.12730
18117.166.22.128/2717.166.22.129 to 17.166.22.15817.166.22.15930
18217.166.22.160/2717.166.22.161 to 17.166.22.19017.166.22.19130
18317.166.22.192/2717.166.22.193 to 17.166.22.22217.166.22.22330
18417.166.22.224/2717.166.22.225 to 17.166.22.25417.166.22.25530
18517.166.23.0/2717.166.23.1 to 17.166.23.3017.166.23.3130
18617.166.23.32/2717.166.23.33 to 17.166.23.6217.166.23.6330
18717.166.23.64/2717.166.23.65 to 17.166.23.9417.166.23.9530
18817.166.23.96/2717.166.23.97 to 17.166.23.12617.166.23.12730
18917.166.23.128/2717.166.23.129 to 17.166.23.15817.166.23.15930
19017.166.23.160/2717.166.23.161 to 17.166.23.19017.166.23.19130
19117.166.23.192/2717.166.23.193 to 17.166.23.22217.166.23.22330
19217.166.23.224/2717.166.23.225 to 17.166.23.25417.166.23.25530
19317.166.24.0/2717.166.24.1 to 17.166.24.3017.166.24.3130
19417.166.24.32/2717.166.24.33 to 17.166.24.6217.166.24.6330
19517.166.24.64/2717.166.24.65 to 17.166.24.9417.166.24.9530
19617.166.24.96/2717.166.24.97 to 17.166.24.12617.166.24.12730
19717.166.24.128/2717.166.24.129 to 17.166.24.15817.166.24.15930
19817.166.24.160/2717.166.24.161 to 17.166.24.19017.166.24.19130
19917.166.24.192/2717.166.24.193 to 17.166.24.22217.166.24.22330
20017.166.24.224/2717.166.24.225 to 17.166.24.25417.166.24.25530
20117.166.25.0/2717.166.25.1 to 17.166.25.3017.166.25.3130
20217.166.25.32/2717.166.25.33 to 17.166.25.6217.166.25.6330
20317.166.25.64/2717.166.25.65 to 17.166.25.9417.166.25.9530
20417.166.25.96/2717.166.25.97 to 17.166.25.12617.166.25.12730
20517.166.25.128/2717.166.25.129 to 17.166.25.15817.166.25.15930
20617.166.25.160/2717.166.25.161 to 17.166.25.19017.166.25.19130
20717.166.25.192/2717.166.25.193 to 17.166.25.22217.166.25.22330
20817.166.25.224/2717.166.25.225 to 17.166.25.25417.166.25.25530
20917.166.26.0/2717.166.26.1 to 17.166.26.3017.166.26.3130
21017.166.26.32/2717.166.26.33 to 17.166.26.6217.166.26.6330
21117.166.26.64/2717.166.26.65 to 17.166.26.9417.166.26.9530
21217.166.26.96/2717.166.26.97 to 17.166.26.12617.166.26.12730
21317.166.26.128/2717.166.26.129 to 17.166.26.15817.166.26.15930
21417.166.26.160/2717.166.26.161 to 17.166.26.19017.166.26.19130
21517.166.26.192/2717.166.26.193 to 17.166.26.22217.166.26.22330
21617.166.26.224/2717.166.26.225 to 17.166.26.25417.166.26.25530
21717.166.27.0/2717.166.27.1 to 17.166.27.3017.166.27.3130
21817.166.27.32/2717.166.27.33 to 17.166.27.6217.166.27.6330
21917.166.27.64/2717.166.27.65 to 17.166.27.9417.166.27.9530
22017.166.27.96/2717.166.27.97 to 17.166.27.12617.166.27.12730
22117.166.27.128/2717.166.27.129 to 17.166.27.15817.166.27.15930
22217.166.27.160/2717.166.27.161 to 17.166.27.19017.166.27.19130
22317.166.27.192/2717.166.27.193 to 17.166.27.22217.166.27.22330
22417.166.27.224/2717.166.27.225 to 17.166.27.25417.166.27.25530
22517.166.28.0/2717.166.28.1 to 17.166.28.3017.166.28.3130
22617.166.28.32/2717.166.28.33 to 17.166.28.6217.166.28.6330
22717.166.28.64/2717.166.28.65 to 17.166.28.9417.166.28.9530
22817.166.28.96/2717.166.28.97 to 17.166.28.12617.166.28.12730
22917.166.28.128/2717.166.28.129 to 17.166.28.15817.166.28.15930
23017.166.28.160/2717.166.28.161 to 17.166.28.19017.166.28.19130
23117.166.28.192/2717.166.28.193 to 17.166.28.22217.166.28.22330
23217.166.28.224/2717.166.28.225 to 17.166.28.25417.166.28.25530
23317.166.29.0/2717.166.29.1 to 17.166.29.3017.166.29.3130
23417.166.29.32/2717.166.29.33 to 17.166.29.6217.166.29.6330
23517.166.29.64/2717.166.29.65 to 17.166.29.9417.166.29.9530
23617.166.29.96/2717.166.29.97 to 17.166.29.12617.166.29.12730
23717.166.29.128/2717.166.29.129 to 17.166.29.15817.166.29.15930
23817.166.29.160/2717.166.29.161 to 17.166.29.19017.166.29.19130
23917.166.29.192/2717.166.29.193 to 17.166.29.22217.166.29.22330
24017.166.29.224/2717.166.29.225 to 17.166.29.25417.166.29.25530
24117.166.30.0/2717.166.30.1 to 17.166.30.3017.166.30.3130
24217.166.30.32/2717.166.30.33 to 17.166.30.6217.166.30.6330
24317.166.30.64/2717.166.30.65 to 17.166.30.9417.166.30.9530
24417.166.30.96/2717.166.30.97 to 17.166.30.12617.166.30.12730
24517.166.30.128/2717.166.30.129 to 17.166.30.15817.166.30.15930
24617.166.30.160/2717.166.30.161 to 17.166.30.19017.166.30.19130
24717.166.30.192/2717.166.30.193 to 17.166.30.22217.166.30.22330
24817.166.30.224/2717.166.30.225 to 17.166.30.25417.166.30.25530
24917.166.31.0/2717.166.31.1 to 17.166.31.3017.166.31.3130
25017.166.31.32/2717.166.31.33 to 17.166.31.6217.166.31.6330
25117.166.31.64/2717.166.31.65 to 17.166.31.9417.166.31.9530
25217.166.31.96/2717.166.31.97 to 17.166.31.12617.166.31.12730
25317.166.31.128/2717.166.31.129 to 17.166.31.15817.166.31.15930
25417.166.31.160/2717.166.31.161 to 17.166.31.19017.166.31.19130
25517.166.31.192/2717.166.31.193 to 17.166.31.22217.166.31.22330
25617.166.31.224/2717.166.31.225 to 17.166.31.25417.166.31.25530

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.