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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.

Network81.166.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
81.166.0.0
Broadcast address
81.167.255.255
First usable
81.166.0.1
Last usable
81.167.255.254
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 51A60000 · Integer 1369833472 to 1369964543
Reverse DNS zones
166.81.in-addr.arpa
167.81.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
Address01010001.10100110.00000000.0000000081.166.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network01010001.10100110.00000000.0000000081.166.0.0
Broadcast01010001.10100111.11111111.1111111181.167.255.255
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)

81.166.0.0/15 makes 4,096 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
181.166.0.0/2781.166.0.1 to 81.166.0.3081.166.0.3130
281.166.0.32/2781.166.0.33 to 81.166.0.6281.166.0.6330
381.166.0.64/2781.166.0.65 to 81.166.0.9481.166.0.9530
481.166.0.96/2781.166.0.97 to 81.166.0.12681.166.0.12730
581.166.0.128/2781.166.0.129 to 81.166.0.15881.166.0.15930
681.166.0.160/2781.166.0.161 to 81.166.0.19081.166.0.19130
781.166.0.192/2781.166.0.193 to 81.166.0.22281.166.0.22330
881.166.0.224/2781.166.0.225 to 81.166.0.25481.166.0.25530
981.166.1.0/2781.166.1.1 to 81.166.1.3081.166.1.3130
1081.166.1.32/2781.166.1.33 to 81.166.1.6281.166.1.6330
1181.166.1.64/2781.166.1.65 to 81.166.1.9481.166.1.9530
1281.166.1.96/2781.166.1.97 to 81.166.1.12681.166.1.12730
1381.166.1.128/2781.166.1.129 to 81.166.1.15881.166.1.15930
1481.166.1.160/2781.166.1.161 to 81.166.1.19081.166.1.19130
1581.166.1.192/2781.166.1.193 to 81.166.1.22281.166.1.22330
1681.166.1.224/2781.166.1.225 to 81.166.1.25481.166.1.25530
1781.166.2.0/2781.166.2.1 to 81.166.2.3081.166.2.3130
1881.166.2.32/2781.166.2.33 to 81.166.2.6281.166.2.6330
1981.166.2.64/2781.166.2.65 to 81.166.2.9481.166.2.9530
2081.166.2.96/2781.166.2.97 to 81.166.2.12681.166.2.12730
2181.166.2.128/2781.166.2.129 to 81.166.2.15881.166.2.15930
2281.166.2.160/2781.166.2.161 to 81.166.2.19081.166.2.19130
2381.166.2.192/2781.166.2.193 to 81.166.2.22281.166.2.22330
2481.166.2.224/2781.166.2.225 to 81.166.2.25481.166.2.25530
2581.166.3.0/2781.166.3.1 to 81.166.3.3081.166.3.3130
2681.166.3.32/2781.166.3.33 to 81.166.3.6281.166.3.6330
2781.166.3.64/2781.166.3.65 to 81.166.3.9481.166.3.9530
2881.166.3.96/2781.166.3.97 to 81.166.3.12681.166.3.12730
2981.166.3.128/2781.166.3.129 to 81.166.3.15881.166.3.15930
3081.166.3.160/2781.166.3.161 to 81.166.3.19081.166.3.19130
3181.166.3.192/2781.166.3.193 to 81.166.3.22281.166.3.22330
3281.166.3.224/2781.166.3.225 to 81.166.3.25481.166.3.25530
3381.166.4.0/2781.166.4.1 to 81.166.4.3081.166.4.3130
3481.166.4.32/2781.166.4.33 to 81.166.4.6281.166.4.6330
3581.166.4.64/2781.166.4.65 to 81.166.4.9481.166.4.9530
3681.166.4.96/2781.166.4.97 to 81.166.4.12681.166.4.12730
3781.166.4.128/2781.166.4.129 to 81.166.4.15881.166.4.15930
3881.166.4.160/2781.166.4.161 to 81.166.4.19081.166.4.19130
3981.166.4.192/2781.166.4.193 to 81.166.4.22281.166.4.22330
4081.166.4.224/2781.166.4.225 to 81.166.4.25481.166.4.25530
4181.166.5.0/2781.166.5.1 to 81.166.5.3081.166.5.3130
4281.166.5.32/2781.166.5.33 to 81.166.5.6281.166.5.6330
4381.166.5.64/2781.166.5.65 to 81.166.5.9481.166.5.9530
4481.166.5.96/2781.166.5.97 to 81.166.5.12681.166.5.12730
4581.166.5.128/2781.166.5.129 to 81.166.5.15881.166.5.15930
4681.166.5.160/2781.166.5.161 to 81.166.5.19081.166.5.19130
4781.166.5.192/2781.166.5.193 to 81.166.5.22281.166.5.22330
4881.166.5.224/2781.166.5.225 to 81.166.5.25481.166.5.25530
4981.166.6.0/2781.166.6.1 to 81.166.6.3081.166.6.3130
5081.166.6.32/2781.166.6.33 to 81.166.6.6281.166.6.6330
5181.166.6.64/2781.166.6.65 to 81.166.6.9481.166.6.9530
5281.166.6.96/2781.166.6.97 to 81.166.6.12681.166.6.12730
5381.166.6.128/2781.166.6.129 to 81.166.6.15881.166.6.15930
5481.166.6.160/2781.166.6.161 to 81.166.6.19081.166.6.19130
5581.166.6.192/2781.166.6.193 to 81.166.6.22281.166.6.22330
5681.166.6.224/2781.166.6.225 to 81.166.6.25481.166.6.25530
5781.166.7.0/2781.166.7.1 to 81.166.7.3081.166.7.3130
5881.166.7.32/2781.166.7.33 to 81.166.7.6281.166.7.6330
5981.166.7.64/2781.166.7.65 to 81.166.7.9481.166.7.9530
6081.166.7.96/2781.166.7.97 to 81.166.7.12681.166.7.12730
6181.166.7.128/2781.166.7.129 to 81.166.7.15881.166.7.15930
6281.166.7.160/2781.166.7.161 to 81.166.7.19081.166.7.19130
6381.166.7.192/2781.166.7.193 to 81.166.7.22281.166.7.22330
6481.166.7.224/2781.166.7.225 to 81.166.7.25481.166.7.25530
6581.166.8.0/2781.166.8.1 to 81.166.8.3081.166.8.3130
6681.166.8.32/2781.166.8.33 to 81.166.8.6281.166.8.6330
6781.166.8.64/2781.166.8.65 to 81.166.8.9481.166.8.9530
6881.166.8.96/2781.166.8.97 to 81.166.8.12681.166.8.12730
6981.166.8.128/2781.166.8.129 to 81.166.8.15881.166.8.15930
7081.166.8.160/2781.166.8.161 to 81.166.8.19081.166.8.19130
7181.166.8.192/2781.166.8.193 to 81.166.8.22281.166.8.22330
7281.166.8.224/2781.166.8.225 to 81.166.8.25481.166.8.25530
7381.166.9.0/2781.166.9.1 to 81.166.9.3081.166.9.3130
7481.166.9.32/2781.166.9.33 to 81.166.9.6281.166.9.6330
7581.166.9.64/2781.166.9.65 to 81.166.9.9481.166.9.9530
7681.166.9.96/2781.166.9.97 to 81.166.9.12681.166.9.12730
7781.166.9.128/2781.166.9.129 to 81.166.9.15881.166.9.15930
7881.166.9.160/2781.166.9.161 to 81.166.9.19081.166.9.19130
7981.166.9.192/2781.166.9.193 to 81.166.9.22281.166.9.22330
8081.166.9.224/2781.166.9.225 to 81.166.9.25481.166.9.25530
8181.166.10.0/2781.166.10.1 to 81.166.10.3081.166.10.3130
8281.166.10.32/2781.166.10.33 to 81.166.10.6281.166.10.6330
8381.166.10.64/2781.166.10.65 to 81.166.10.9481.166.10.9530
8481.166.10.96/2781.166.10.97 to 81.166.10.12681.166.10.12730
8581.166.10.128/2781.166.10.129 to 81.166.10.15881.166.10.15930
8681.166.10.160/2781.166.10.161 to 81.166.10.19081.166.10.19130
8781.166.10.192/2781.166.10.193 to 81.166.10.22281.166.10.22330
8881.166.10.224/2781.166.10.225 to 81.166.10.25481.166.10.25530
8981.166.11.0/2781.166.11.1 to 81.166.11.3081.166.11.3130
9081.166.11.32/2781.166.11.33 to 81.166.11.6281.166.11.6330
9181.166.11.64/2781.166.11.65 to 81.166.11.9481.166.11.9530
9281.166.11.96/2781.166.11.97 to 81.166.11.12681.166.11.12730
9381.166.11.128/2781.166.11.129 to 81.166.11.15881.166.11.15930
9481.166.11.160/2781.166.11.161 to 81.166.11.19081.166.11.19130
9581.166.11.192/2781.166.11.193 to 81.166.11.22281.166.11.22330
9681.166.11.224/2781.166.11.225 to 81.166.11.25481.166.11.25530
9781.166.12.0/2781.166.12.1 to 81.166.12.3081.166.12.3130
9881.166.12.32/2781.166.12.33 to 81.166.12.6281.166.12.6330
9981.166.12.64/2781.166.12.65 to 81.166.12.9481.166.12.9530
10081.166.12.96/2781.166.12.97 to 81.166.12.12681.166.12.12730
10181.166.12.128/2781.166.12.129 to 81.166.12.15881.166.12.15930
10281.166.12.160/2781.166.12.161 to 81.166.12.19081.166.12.19130
10381.166.12.192/2781.166.12.193 to 81.166.12.22281.166.12.22330
10481.166.12.224/2781.166.12.225 to 81.166.12.25481.166.12.25530
10581.166.13.0/2781.166.13.1 to 81.166.13.3081.166.13.3130
10681.166.13.32/2781.166.13.33 to 81.166.13.6281.166.13.6330
10781.166.13.64/2781.166.13.65 to 81.166.13.9481.166.13.9530
10881.166.13.96/2781.166.13.97 to 81.166.13.12681.166.13.12730
10981.166.13.128/2781.166.13.129 to 81.166.13.15881.166.13.15930
11081.166.13.160/2781.166.13.161 to 81.166.13.19081.166.13.19130
11181.166.13.192/2781.166.13.193 to 81.166.13.22281.166.13.22330
11281.166.13.224/2781.166.13.225 to 81.166.13.25481.166.13.25530
11381.166.14.0/2781.166.14.1 to 81.166.14.3081.166.14.3130
11481.166.14.32/2781.166.14.33 to 81.166.14.6281.166.14.6330
11581.166.14.64/2781.166.14.65 to 81.166.14.9481.166.14.9530
11681.166.14.96/2781.166.14.97 to 81.166.14.12681.166.14.12730
11781.166.14.128/2781.166.14.129 to 81.166.14.15881.166.14.15930
11881.166.14.160/2781.166.14.161 to 81.166.14.19081.166.14.19130
11981.166.14.192/2781.166.14.193 to 81.166.14.22281.166.14.22330
12081.166.14.224/2781.166.14.225 to 81.166.14.25481.166.14.25530
12181.166.15.0/2781.166.15.1 to 81.166.15.3081.166.15.3130
12281.166.15.32/2781.166.15.33 to 81.166.15.6281.166.15.6330
12381.166.15.64/2781.166.15.65 to 81.166.15.9481.166.15.9530
12481.166.15.96/2781.166.15.97 to 81.166.15.12681.166.15.12730
12581.166.15.128/2781.166.15.129 to 81.166.15.15881.166.15.15930
12681.166.15.160/2781.166.15.161 to 81.166.15.19081.166.15.19130
12781.166.15.192/2781.166.15.193 to 81.166.15.22281.166.15.22330
12881.166.15.224/2781.166.15.225 to 81.166.15.25481.166.15.25530
12981.166.16.0/2781.166.16.1 to 81.166.16.3081.166.16.3130
13081.166.16.32/2781.166.16.33 to 81.166.16.6281.166.16.6330
13181.166.16.64/2781.166.16.65 to 81.166.16.9481.166.16.9530
13281.166.16.96/2781.166.16.97 to 81.166.16.12681.166.16.12730
13381.166.16.128/2781.166.16.129 to 81.166.16.15881.166.16.15930
13481.166.16.160/2781.166.16.161 to 81.166.16.19081.166.16.19130
13581.166.16.192/2781.166.16.193 to 81.166.16.22281.166.16.22330
13681.166.16.224/2781.166.16.225 to 81.166.16.25481.166.16.25530
13781.166.17.0/2781.166.17.1 to 81.166.17.3081.166.17.3130
13881.166.17.32/2781.166.17.33 to 81.166.17.6281.166.17.6330
13981.166.17.64/2781.166.17.65 to 81.166.17.9481.166.17.9530
14081.166.17.96/2781.166.17.97 to 81.166.17.12681.166.17.12730
14181.166.17.128/2781.166.17.129 to 81.166.17.15881.166.17.15930
14281.166.17.160/2781.166.17.161 to 81.166.17.19081.166.17.19130
14381.166.17.192/2781.166.17.193 to 81.166.17.22281.166.17.22330
14481.166.17.224/2781.166.17.225 to 81.166.17.25481.166.17.25530
14581.166.18.0/2781.166.18.1 to 81.166.18.3081.166.18.3130
14681.166.18.32/2781.166.18.33 to 81.166.18.6281.166.18.6330
14781.166.18.64/2781.166.18.65 to 81.166.18.9481.166.18.9530
14881.166.18.96/2781.166.18.97 to 81.166.18.12681.166.18.12730
14981.166.18.128/2781.166.18.129 to 81.166.18.15881.166.18.15930
15081.166.18.160/2781.166.18.161 to 81.166.18.19081.166.18.19130
15181.166.18.192/2781.166.18.193 to 81.166.18.22281.166.18.22330
15281.166.18.224/2781.166.18.225 to 81.166.18.25481.166.18.25530
15381.166.19.0/2781.166.19.1 to 81.166.19.3081.166.19.3130
15481.166.19.32/2781.166.19.33 to 81.166.19.6281.166.19.6330
15581.166.19.64/2781.166.19.65 to 81.166.19.9481.166.19.9530
15681.166.19.96/2781.166.19.97 to 81.166.19.12681.166.19.12730
15781.166.19.128/2781.166.19.129 to 81.166.19.15881.166.19.15930
15881.166.19.160/2781.166.19.161 to 81.166.19.19081.166.19.19130
15981.166.19.192/2781.166.19.193 to 81.166.19.22281.166.19.22330
16081.166.19.224/2781.166.19.225 to 81.166.19.25481.166.19.25530
16181.166.20.0/2781.166.20.1 to 81.166.20.3081.166.20.3130
16281.166.20.32/2781.166.20.33 to 81.166.20.6281.166.20.6330
16381.166.20.64/2781.166.20.65 to 81.166.20.9481.166.20.9530
16481.166.20.96/2781.166.20.97 to 81.166.20.12681.166.20.12730
16581.166.20.128/2781.166.20.129 to 81.166.20.15881.166.20.15930
16681.166.20.160/2781.166.20.161 to 81.166.20.19081.166.20.19130
16781.166.20.192/2781.166.20.193 to 81.166.20.22281.166.20.22330
16881.166.20.224/2781.166.20.225 to 81.166.20.25481.166.20.25530
16981.166.21.0/2781.166.21.1 to 81.166.21.3081.166.21.3130
17081.166.21.32/2781.166.21.33 to 81.166.21.6281.166.21.6330
17181.166.21.64/2781.166.21.65 to 81.166.21.9481.166.21.9530
17281.166.21.96/2781.166.21.97 to 81.166.21.12681.166.21.12730
17381.166.21.128/2781.166.21.129 to 81.166.21.15881.166.21.15930
17481.166.21.160/2781.166.21.161 to 81.166.21.19081.166.21.19130
17581.166.21.192/2781.166.21.193 to 81.166.21.22281.166.21.22330
17681.166.21.224/2781.166.21.225 to 81.166.21.25481.166.21.25530
17781.166.22.0/2781.166.22.1 to 81.166.22.3081.166.22.3130
17881.166.22.32/2781.166.22.33 to 81.166.22.6281.166.22.6330
17981.166.22.64/2781.166.22.65 to 81.166.22.9481.166.22.9530
18081.166.22.96/2781.166.22.97 to 81.166.22.12681.166.22.12730
18181.166.22.128/2781.166.22.129 to 81.166.22.15881.166.22.15930
18281.166.22.160/2781.166.22.161 to 81.166.22.19081.166.22.19130
18381.166.22.192/2781.166.22.193 to 81.166.22.22281.166.22.22330
18481.166.22.224/2781.166.22.225 to 81.166.22.25481.166.22.25530
18581.166.23.0/2781.166.23.1 to 81.166.23.3081.166.23.3130
18681.166.23.32/2781.166.23.33 to 81.166.23.6281.166.23.6330
18781.166.23.64/2781.166.23.65 to 81.166.23.9481.166.23.9530
18881.166.23.96/2781.166.23.97 to 81.166.23.12681.166.23.12730
18981.166.23.128/2781.166.23.129 to 81.166.23.15881.166.23.15930
19081.166.23.160/2781.166.23.161 to 81.166.23.19081.166.23.19130
19181.166.23.192/2781.166.23.193 to 81.166.23.22281.166.23.22330
19281.166.23.224/2781.166.23.225 to 81.166.23.25481.166.23.25530
19381.166.24.0/2781.166.24.1 to 81.166.24.3081.166.24.3130
19481.166.24.32/2781.166.24.33 to 81.166.24.6281.166.24.6330
19581.166.24.64/2781.166.24.65 to 81.166.24.9481.166.24.9530
19681.166.24.96/2781.166.24.97 to 81.166.24.12681.166.24.12730
19781.166.24.128/2781.166.24.129 to 81.166.24.15881.166.24.15930
19881.166.24.160/2781.166.24.161 to 81.166.24.19081.166.24.19130
19981.166.24.192/2781.166.24.193 to 81.166.24.22281.166.24.22330
20081.166.24.224/2781.166.24.225 to 81.166.24.25481.166.24.25530
20181.166.25.0/2781.166.25.1 to 81.166.25.3081.166.25.3130
20281.166.25.32/2781.166.25.33 to 81.166.25.6281.166.25.6330
20381.166.25.64/2781.166.25.65 to 81.166.25.9481.166.25.9530
20481.166.25.96/2781.166.25.97 to 81.166.25.12681.166.25.12730
20581.166.25.128/2781.166.25.129 to 81.166.25.15881.166.25.15930
20681.166.25.160/2781.166.25.161 to 81.166.25.19081.166.25.19130
20781.166.25.192/2781.166.25.193 to 81.166.25.22281.166.25.22330
20881.166.25.224/2781.166.25.225 to 81.166.25.25481.166.25.25530
20981.166.26.0/2781.166.26.1 to 81.166.26.3081.166.26.3130
21081.166.26.32/2781.166.26.33 to 81.166.26.6281.166.26.6330
21181.166.26.64/2781.166.26.65 to 81.166.26.9481.166.26.9530
21281.166.26.96/2781.166.26.97 to 81.166.26.12681.166.26.12730
21381.166.26.128/2781.166.26.129 to 81.166.26.15881.166.26.15930
21481.166.26.160/2781.166.26.161 to 81.166.26.19081.166.26.19130
21581.166.26.192/2781.166.26.193 to 81.166.26.22281.166.26.22330
21681.166.26.224/2781.166.26.225 to 81.166.26.25481.166.26.25530
21781.166.27.0/2781.166.27.1 to 81.166.27.3081.166.27.3130
21881.166.27.32/2781.166.27.33 to 81.166.27.6281.166.27.6330
21981.166.27.64/2781.166.27.65 to 81.166.27.9481.166.27.9530
22081.166.27.96/2781.166.27.97 to 81.166.27.12681.166.27.12730
22181.166.27.128/2781.166.27.129 to 81.166.27.15881.166.27.15930
22281.166.27.160/2781.166.27.161 to 81.166.27.19081.166.27.19130
22381.166.27.192/2781.166.27.193 to 81.166.27.22281.166.27.22330
22481.166.27.224/2781.166.27.225 to 81.166.27.25481.166.27.25530
22581.166.28.0/2781.166.28.1 to 81.166.28.3081.166.28.3130
22681.166.28.32/2781.166.28.33 to 81.166.28.6281.166.28.6330
22781.166.28.64/2781.166.28.65 to 81.166.28.9481.166.28.9530
22881.166.28.96/2781.166.28.97 to 81.166.28.12681.166.28.12730
22981.166.28.128/2781.166.28.129 to 81.166.28.15881.166.28.15930
23081.166.28.160/2781.166.28.161 to 81.166.28.19081.166.28.19130
23181.166.28.192/2781.166.28.193 to 81.166.28.22281.166.28.22330
23281.166.28.224/2781.166.28.225 to 81.166.28.25481.166.28.25530
23381.166.29.0/2781.166.29.1 to 81.166.29.3081.166.29.3130
23481.166.29.32/2781.166.29.33 to 81.166.29.6281.166.29.6330
23581.166.29.64/2781.166.29.65 to 81.166.29.9481.166.29.9530
23681.166.29.96/2781.166.29.97 to 81.166.29.12681.166.29.12730
23781.166.29.128/2781.166.29.129 to 81.166.29.15881.166.29.15930
23881.166.29.160/2781.166.29.161 to 81.166.29.19081.166.29.19130
23981.166.29.192/2781.166.29.193 to 81.166.29.22281.166.29.22330
24081.166.29.224/2781.166.29.225 to 81.166.29.25481.166.29.25530
24181.166.30.0/2781.166.30.1 to 81.166.30.3081.166.30.3130
24281.166.30.32/2781.166.30.33 to 81.166.30.6281.166.30.6330
24381.166.30.64/2781.166.30.65 to 81.166.30.9481.166.30.9530
24481.166.30.96/2781.166.30.97 to 81.166.30.12681.166.30.12730
24581.166.30.128/2781.166.30.129 to 81.166.30.15881.166.30.15930
24681.166.30.160/2781.166.30.161 to 81.166.30.19081.166.30.19130
24781.166.30.192/2781.166.30.193 to 81.166.30.22281.166.30.22330
24881.166.30.224/2781.166.30.225 to 81.166.30.25481.166.30.25530
24981.166.31.0/2781.166.31.1 to 81.166.31.3081.166.31.3130
25081.166.31.32/2781.166.31.33 to 81.166.31.6281.166.31.6330
25181.166.31.64/2781.166.31.65 to 81.166.31.9481.166.31.9530
25281.166.31.96/2781.166.31.97 to 81.166.31.12681.166.31.12730
25381.166.31.128/2781.166.31.129 to 81.166.31.15881.166.31.15930
25481.166.31.160/2781.166.31.161 to 81.166.31.19081.166.31.19130
25581.166.31.192/2781.166.31.193 to 81.166.31.22281.166.31.22330
25681.166.31.224/2781.166.31.225 to 81.166.31.25481.166.31.25530

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.