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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.

Network10.16.128.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
10.16.128.0
Broadcast address
10.16.191.255
First usable
10.16.128.1
Last usable
10.16.191.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Private (RFC 1918) 10.0.0.0/8
Office and home networks; not routed on the internet
Old class
A (default /8)
As numbers
Hex 0A108000 · Integer 168853504 to 168869887
Reverse DNS zones
128.16.10.in-addr.arpa
129.16.10.in-addr.arpa
130.16.10.in-addr.arpa
131.16.10.in-addr.arpa
132.16.10.in-addr.arpa
133.16.10.in-addr.arpa
134.16.10.in-addr.arpa
135.16.10.in-addr.arpa
136.16.10.in-addr.arpa
137.16.10.in-addr.arpa
138.16.10.in-addr.arpa
139.16.10.in-addr.arpa
140.16.10.in-addr.arpa
141.16.10.in-addr.arpa
142.16.10.in-addr.arpa
143.16.10.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001010.00010000.10000000.0000000010.16.128.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00001010.00010000.10000000.0000000010.16.128.0
Broadcast00001010.00010000.10111111.1111111110.16.191.255
Split into smaller subnets/26
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

10.16.128.0/18 makes 256 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
110.16.128.0/2610.16.128.1 to 10.16.128.6210.16.128.6362
210.16.128.64/2610.16.128.65 to 10.16.128.12610.16.128.12762
310.16.128.128/2610.16.128.129 to 10.16.128.19010.16.128.19162
410.16.128.192/2610.16.128.193 to 10.16.128.25410.16.128.25562
510.16.129.0/2610.16.129.1 to 10.16.129.6210.16.129.6362
610.16.129.64/2610.16.129.65 to 10.16.129.12610.16.129.12762
710.16.129.128/2610.16.129.129 to 10.16.129.19010.16.129.19162
810.16.129.192/2610.16.129.193 to 10.16.129.25410.16.129.25562
910.16.130.0/2610.16.130.1 to 10.16.130.6210.16.130.6362
1010.16.130.64/2610.16.130.65 to 10.16.130.12610.16.130.12762
1110.16.130.128/2610.16.130.129 to 10.16.130.19010.16.130.19162
1210.16.130.192/2610.16.130.193 to 10.16.130.25410.16.130.25562
1310.16.131.0/2610.16.131.1 to 10.16.131.6210.16.131.6362
1410.16.131.64/2610.16.131.65 to 10.16.131.12610.16.131.12762
1510.16.131.128/2610.16.131.129 to 10.16.131.19010.16.131.19162
1610.16.131.192/2610.16.131.193 to 10.16.131.25410.16.131.25562
1710.16.132.0/2610.16.132.1 to 10.16.132.6210.16.132.6362
1810.16.132.64/2610.16.132.65 to 10.16.132.12610.16.132.12762
1910.16.132.128/2610.16.132.129 to 10.16.132.19010.16.132.19162
2010.16.132.192/2610.16.132.193 to 10.16.132.25410.16.132.25562
2110.16.133.0/2610.16.133.1 to 10.16.133.6210.16.133.6362
2210.16.133.64/2610.16.133.65 to 10.16.133.12610.16.133.12762
2310.16.133.128/2610.16.133.129 to 10.16.133.19010.16.133.19162
2410.16.133.192/2610.16.133.193 to 10.16.133.25410.16.133.25562
2510.16.134.0/2610.16.134.1 to 10.16.134.6210.16.134.6362
2610.16.134.64/2610.16.134.65 to 10.16.134.12610.16.134.12762
2710.16.134.128/2610.16.134.129 to 10.16.134.19010.16.134.19162
2810.16.134.192/2610.16.134.193 to 10.16.134.25410.16.134.25562
2910.16.135.0/2610.16.135.1 to 10.16.135.6210.16.135.6362
3010.16.135.64/2610.16.135.65 to 10.16.135.12610.16.135.12762
3110.16.135.128/2610.16.135.129 to 10.16.135.19010.16.135.19162
3210.16.135.192/2610.16.135.193 to 10.16.135.25410.16.135.25562
3310.16.136.0/2610.16.136.1 to 10.16.136.6210.16.136.6362
3410.16.136.64/2610.16.136.65 to 10.16.136.12610.16.136.12762
3510.16.136.128/2610.16.136.129 to 10.16.136.19010.16.136.19162
3610.16.136.192/2610.16.136.193 to 10.16.136.25410.16.136.25562
3710.16.137.0/2610.16.137.1 to 10.16.137.6210.16.137.6362
3810.16.137.64/2610.16.137.65 to 10.16.137.12610.16.137.12762
3910.16.137.128/2610.16.137.129 to 10.16.137.19010.16.137.19162
4010.16.137.192/2610.16.137.193 to 10.16.137.25410.16.137.25562
4110.16.138.0/2610.16.138.1 to 10.16.138.6210.16.138.6362
4210.16.138.64/2610.16.138.65 to 10.16.138.12610.16.138.12762
4310.16.138.128/2610.16.138.129 to 10.16.138.19010.16.138.19162
4410.16.138.192/2610.16.138.193 to 10.16.138.25410.16.138.25562
4510.16.139.0/2610.16.139.1 to 10.16.139.6210.16.139.6362
4610.16.139.64/2610.16.139.65 to 10.16.139.12610.16.139.12762
4710.16.139.128/2610.16.139.129 to 10.16.139.19010.16.139.19162
4810.16.139.192/2610.16.139.193 to 10.16.139.25410.16.139.25562
4910.16.140.0/2610.16.140.1 to 10.16.140.6210.16.140.6362
5010.16.140.64/2610.16.140.65 to 10.16.140.12610.16.140.12762
5110.16.140.128/2610.16.140.129 to 10.16.140.19010.16.140.19162
5210.16.140.192/2610.16.140.193 to 10.16.140.25410.16.140.25562
5310.16.141.0/2610.16.141.1 to 10.16.141.6210.16.141.6362
5410.16.141.64/2610.16.141.65 to 10.16.141.12610.16.141.12762
5510.16.141.128/2610.16.141.129 to 10.16.141.19010.16.141.19162
5610.16.141.192/2610.16.141.193 to 10.16.141.25410.16.141.25562
5710.16.142.0/2610.16.142.1 to 10.16.142.6210.16.142.6362
5810.16.142.64/2610.16.142.65 to 10.16.142.12610.16.142.12762
5910.16.142.128/2610.16.142.129 to 10.16.142.19010.16.142.19162
6010.16.142.192/2610.16.142.193 to 10.16.142.25410.16.142.25562
6110.16.143.0/2610.16.143.1 to 10.16.143.6210.16.143.6362
6210.16.143.64/2610.16.143.65 to 10.16.143.12610.16.143.12762
6310.16.143.128/2610.16.143.129 to 10.16.143.19010.16.143.19162
6410.16.143.192/2610.16.143.193 to 10.16.143.25410.16.143.25562
6510.16.144.0/2610.16.144.1 to 10.16.144.6210.16.144.6362
6610.16.144.64/2610.16.144.65 to 10.16.144.12610.16.144.12762
6710.16.144.128/2610.16.144.129 to 10.16.144.19010.16.144.19162
6810.16.144.192/2610.16.144.193 to 10.16.144.25410.16.144.25562
6910.16.145.0/2610.16.145.1 to 10.16.145.6210.16.145.6362
7010.16.145.64/2610.16.145.65 to 10.16.145.12610.16.145.12762
7110.16.145.128/2610.16.145.129 to 10.16.145.19010.16.145.19162
7210.16.145.192/2610.16.145.193 to 10.16.145.25410.16.145.25562
7310.16.146.0/2610.16.146.1 to 10.16.146.6210.16.146.6362
7410.16.146.64/2610.16.146.65 to 10.16.146.12610.16.146.12762
7510.16.146.128/2610.16.146.129 to 10.16.146.19010.16.146.19162
7610.16.146.192/2610.16.146.193 to 10.16.146.25410.16.146.25562
7710.16.147.0/2610.16.147.1 to 10.16.147.6210.16.147.6362
7810.16.147.64/2610.16.147.65 to 10.16.147.12610.16.147.12762
7910.16.147.128/2610.16.147.129 to 10.16.147.19010.16.147.19162
8010.16.147.192/2610.16.147.193 to 10.16.147.25410.16.147.25562
8110.16.148.0/2610.16.148.1 to 10.16.148.6210.16.148.6362
8210.16.148.64/2610.16.148.65 to 10.16.148.12610.16.148.12762
8310.16.148.128/2610.16.148.129 to 10.16.148.19010.16.148.19162
8410.16.148.192/2610.16.148.193 to 10.16.148.25410.16.148.25562
8510.16.149.0/2610.16.149.1 to 10.16.149.6210.16.149.6362
8610.16.149.64/2610.16.149.65 to 10.16.149.12610.16.149.12762
8710.16.149.128/2610.16.149.129 to 10.16.149.19010.16.149.19162
8810.16.149.192/2610.16.149.193 to 10.16.149.25410.16.149.25562
8910.16.150.0/2610.16.150.1 to 10.16.150.6210.16.150.6362
9010.16.150.64/2610.16.150.65 to 10.16.150.12610.16.150.12762
9110.16.150.128/2610.16.150.129 to 10.16.150.19010.16.150.19162
9210.16.150.192/2610.16.150.193 to 10.16.150.25410.16.150.25562
9310.16.151.0/2610.16.151.1 to 10.16.151.6210.16.151.6362
9410.16.151.64/2610.16.151.65 to 10.16.151.12610.16.151.12762
9510.16.151.128/2610.16.151.129 to 10.16.151.19010.16.151.19162
9610.16.151.192/2610.16.151.193 to 10.16.151.25410.16.151.25562
9710.16.152.0/2610.16.152.1 to 10.16.152.6210.16.152.6362
9810.16.152.64/2610.16.152.65 to 10.16.152.12610.16.152.12762
9910.16.152.128/2610.16.152.129 to 10.16.152.19010.16.152.19162
10010.16.152.192/2610.16.152.193 to 10.16.152.25410.16.152.25562
10110.16.153.0/2610.16.153.1 to 10.16.153.6210.16.153.6362
10210.16.153.64/2610.16.153.65 to 10.16.153.12610.16.153.12762
10310.16.153.128/2610.16.153.129 to 10.16.153.19010.16.153.19162
10410.16.153.192/2610.16.153.193 to 10.16.153.25410.16.153.25562
10510.16.154.0/2610.16.154.1 to 10.16.154.6210.16.154.6362
10610.16.154.64/2610.16.154.65 to 10.16.154.12610.16.154.12762
10710.16.154.128/2610.16.154.129 to 10.16.154.19010.16.154.19162
10810.16.154.192/2610.16.154.193 to 10.16.154.25410.16.154.25562
10910.16.155.0/2610.16.155.1 to 10.16.155.6210.16.155.6362
11010.16.155.64/2610.16.155.65 to 10.16.155.12610.16.155.12762
11110.16.155.128/2610.16.155.129 to 10.16.155.19010.16.155.19162
11210.16.155.192/2610.16.155.193 to 10.16.155.25410.16.155.25562
11310.16.156.0/2610.16.156.1 to 10.16.156.6210.16.156.6362
11410.16.156.64/2610.16.156.65 to 10.16.156.12610.16.156.12762
11510.16.156.128/2610.16.156.129 to 10.16.156.19010.16.156.19162
11610.16.156.192/2610.16.156.193 to 10.16.156.25410.16.156.25562
11710.16.157.0/2610.16.157.1 to 10.16.157.6210.16.157.6362
11810.16.157.64/2610.16.157.65 to 10.16.157.12610.16.157.12762
11910.16.157.128/2610.16.157.129 to 10.16.157.19010.16.157.19162
12010.16.157.192/2610.16.157.193 to 10.16.157.25410.16.157.25562
12110.16.158.0/2610.16.158.1 to 10.16.158.6210.16.158.6362
12210.16.158.64/2610.16.158.65 to 10.16.158.12610.16.158.12762
12310.16.158.128/2610.16.158.129 to 10.16.158.19010.16.158.19162
12410.16.158.192/2610.16.158.193 to 10.16.158.25410.16.158.25562
12510.16.159.0/2610.16.159.1 to 10.16.159.6210.16.159.6362
12610.16.159.64/2610.16.159.65 to 10.16.159.12610.16.159.12762
12710.16.159.128/2610.16.159.129 to 10.16.159.19010.16.159.19162
12810.16.159.192/2610.16.159.193 to 10.16.159.25410.16.159.25562
12910.16.160.0/2610.16.160.1 to 10.16.160.6210.16.160.6362
13010.16.160.64/2610.16.160.65 to 10.16.160.12610.16.160.12762
13110.16.160.128/2610.16.160.129 to 10.16.160.19010.16.160.19162
13210.16.160.192/2610.16.160.193 to 10.16.160.25410.16.160.25562
13310.16.161.0/2610.16.161.1 to 10.16.161.6210.16.161.6362
13410.16.161.64/2610.16.161.65 to 10.16.161.12610.16.161.12762
13510.16.161.128/2610.16.161.129 to 10.16.161.19010.16.161.19162
13610.16.161.192/2610.16.161.193 to 10.16.161.25410.16.161.25562
13710.16.162.0/2610.16.162.1 to 10.16.162.6210.16.162.6362
13810.16.162.64/2610.16.162.65 to 10.16.162.12610.16.162.12762
13910.16.162.128/2610.16.162.129 to 10.16.162.19010.16.162.19162
14010.16.162.192/2610.16.162.193 to 10.16.162.25410.16.162.25562
14110.16.163.0/2610.16.163.1 to 10.16.163.6210.16.163.6362
14210.16.163.64/2610.16.163.65 to 10.16.163.12610.16.163.12762
14310.16.163.128/2610.16.163.129 to 10.16.163.19010.16.163.19162
14410.16.163.192/2610.16.163.193 to 10.16.163.25410.16.163.25562
14510.16.164.0/2610.16.164.1 to 10.16.164.6210.16.164.6362
14610.16.164.64/2610.16.164.65 to 10.16.164.12610.16.164.12762
14710.16.164.128/2610.16.164.129 to 10.16.164.19010.16.164.19162
14810.16.164.192/2610.16.164.193 to 10.16.164.25410.16.164.25562
14910.16.165.0/2610.16.165.1 to 10.16.165.6210.16.165.6362
15010.16.165.64/2610.16.165.65 to 10.16.165.12610.16.165.12762
15110.16.165.128/2610.16.165.129 to 10.16.165.19010.16.165.19162
15210.16.165.192/2610.16.165.193 to 10.16.165.25410.16.165.25562
15310.16.166.0/2610.16.166.1 to 10.16.166.6210.16.166.6362
15410.16.166.64/2610.16.166.65 to 10.16.166.12610.16.166.12762
15510.16.166.128/2610.16.166.129 to 10.16.166.19010.16.166.19162
15610.16.166.192/2610.16.166.193 to 10.16.166.25410.16.166.25562
15710.16.167.0/2610.16.167.1 to 10.16.167.6210.16.167.6362
15810.16.167.64/2610.16.167.65 to 10.16.167.12610.16.167.12762
15910.16.167.128/2610.16.167.129 to 10.16.167.19010.16.167.19162
16010.16.167.192/2610.16.167.193 to 10.16.167.25410.16.167.25562
16110.16.168.0/2610.16.168.1 to 10.16.168.6210.16.168.6362
16210.16.168.64/2610.16.168.65 to 10.16.168.12610.16.168.12762
16310.16.168.128/2610.16.168.129 to 10.16.168.19010.16.168.19162
16410.16.168.192/2610.16.168.193 to 10.16.168.25410.16.168.25562
16510.16.169.0/2610.16.169.1 to 10.16.169.6210.16.169.6362
16610.16.169.64/2610.16.169.65 to 10.16.169.12610.16.169.12762
16710.16.169.128/2610.16.169.129 to 10.16.169.19010.16.169.19162
16810.16.169.192/2610.16.169.193 to 10.16.169.25410.16.169.25562
16910.16.170.0/2610.16.170.1 to 10.16.170.6210.16.170.6362
17010.16.170.64/2610.16.170.65 to 10.16.170.12610.16.170.12762
17110.16.170.128/2610.16.170.129 to 10.16.170.19010.16.170.19162
17210.16.170.192/2610.16.170.193 to 10.16.170.25410.16.170.25562
17310.16.171.0/2610.16.171.1 to 10.16.171.6210.16.171.6362
17410.16.171.64/2610.16.171.65 to 10.16.171.12610.16.171.12762
17510.16.171.128/2610.16.171.129 to 10.16.171.19010.16.171.19162
17610.16.171.192/2610.16.171.193 to 10.16.171.25410.16.171.25562
17710.16.172.0/2610.16.172.1 to 10.16.172.6210.16.172.6362
17810.16.172.64/2610.16.172.65 to 10.16.172.12610.16.172.12762
17910.16.172.128/2610.16.172.129 to 10.16.172.19010.16.172.19162
18010.16.172.192/2610.16.172.193 to 10.16.172.25410.16.172.25562
18110.16.173.0/2610.16.173.1 to 10.16.173.6210.16.173.6362
18210.16.173.64/2610.16.173.65 to 10.16.173.12610.16.173.12762
18310.16.173.128/2610.16.173.129 to 10.16.173.19010.16.173.19162
18410.16.173.192/2610.16.173.193 to 10.16.173.25410.16.173.25562
18510.16.174.0/2610.16.174.1 to 10.16.174.6210.16.174.6362
18610.16.174.64/2610.16.174.65 to 10.16.174.12610.16.174.12762
18710.16.174.128/2610.16.174.129 to 10.16.174.19010.16.174.19162
18810.16.174.192/2610.16.174.193 to 10.16.174.25410.16.174.25562
18910.16.175.0/2610.16.175.1 to 10.16.175.6210.16.175.6362
19010.16.175.64/2610.16.175.65 to 10.16.175.12610.16.175.12762
19110.16.175.128/2610.16.175.129 to 10.16.175.19010.16.175.19162
19210.16.175.192/2610.16.175.193 to 10.16.175.25410.16.175.25562
19310.16.176.0/2610.16.176.1 to 10.16.176.6210.16.176.6362
19410.16.176.64/2610.16.176.65 to 10.16.176.12610.16.176.12762
19510.16.176.128/2610.16.176.129 to 10.16.176.19010.16.176.19162
19610.16.176.192/2610.16.176.193 to 10.16.176.25410.16.176.25562
19710.16.177.0/2610.16.177.1 to 10.16.177.6210.16.177.6362
19810.16.177.64/2610.16.177.65 to 10.16.177.12610.16.177.12762
19910.16.177.128/2610.16.177.129 to 10.16.177.19010.16.177.19162
20010.16.177.192/2610.16.177.193 to 10.16.177.25410.16.177.25562
20110.16.178.0/2610.16.178.1 to 10.16.178.6210.16.178.6362
20210.16.178.64/2610.16.178.65 to 10.16.178.12610.16.178.12762
20310.16.178.128/2610.16.178.129 to 10.16.178.19010.16.178.19162
20410.16.178.192/2610.16.178.193 to 10.16.178.25410.16.178.25562
20510.16.179.0/2610.16.179.1 to 10.16.179.6210.16.179.6362
20610.16.179.64/2610.16.179.65 to 10.16.179.12610.16.179.12762
20710.16.179.128/2610.16.179.129 to 10.16.179.19010.16.179.19162
20810.16.179.192/2610.16.179.193 to 10.16.179.25410.16.179.25562
20910.16.180.0/2610.16.180.1 to 10.16.180.6210.16.180.6362
21010.16.180.64/2610.16.180.65 to 10.16.180.12610.16.180.12762
21110.16.180.128/2610.16.180.129 to 10.16.180.19010.16.180.19162
21210.16.180.192/2610.16.180.193 to 10.16.180.25410.16.180.25562
21310.16.181.0/2610.16.181.1 to 10.16.181.6210.16.181.6362
21410.16.181.64/2610.16.181.65 to 10.16.181.12610.16.181.12762
21510.16.181.128/2610.16.181.129 to 10.16.181.19010.16.181.19162
21610.16.181.192/2610.16.181.193 to 10.16.181.25410.16.181.25562
21710.16.182.0/2610.16.182.1 to 10.16.182.6210.16.182.6362
21810.16.182.64/2610.16.182.65 to 10.16.182.12610.16.182.12762
21910.16.182.128/2610.16.182.129 to 10.16.182.19010.16.182.19162
22010.16.182.192/2610.16.182.193 to 10.16.182.25410.16.182.25562
22110.16.183.0/2610.16.183.1 to 10.16.183.6210.16.183.6362
22210.16.183.64/2610.16.183.65 to 10.16.183.12610.16.183.12762
22310.16.183.128/2610.16.183.129 to 10.16.183.19010.16.183.19162
22410.16.183.192/2610.16.183.193 to 10.16.183.25410.16.183.25562
22510.16.184.0/2610.16.184.1 to 10.16.184.6210.16.184.6362
22610.16.184.64/2610.16.184.65 to 10.16.184.12610.16.184.12762
22710.16.184.128/2610.16.184.129 to 10.16.184.19010.16.184.19162
22810.16.184.192/2610.16.184.193 to 10.16.184.25410.16.184.25562
22910.16.185.0/2610.16.185.1 to 10.16.185.6210.16.185.6362
23010.16.185.64/2610.16.185.65 to 10.16.185.12610.16.185.12762
23110.16.185.128/2610.16.185.129 to 10.16.185.19010.16.185.19162
23210.16.185.192/2610.16.185.193 to 10.16.185.25410.16.185.25562
23310.16.186.0/2610.16.186.1 to 10.16.186.6210.16.186.6362
23410.16.186.64/2610.16.186.65 to 10.16.186.12610.16.186.12762
23510.16.186.128/2610.16.186.129 to 10.16.186.19010.16.186.19162
23610.16.186.192/2610.16.186.193 to 10.16.186.25410.16.186.25562
23710.16.187.0/2610.16.187.1 to 10.16.187.6210.16.187.6362
23810.16.187.64/2610.16.187.65 to 10.16.187.12610.16.187.12762
23910.16.187.128/2610.16.187.129 to 10.16.187.19010.16.187.19162
24010.16.187.192/2610.16.187.193 to 10.16.187.25410.16.187.25562
24110.16.188.0/2610.16.188.1 to 10.16.188.6210.16.188.6362
24210.16.188.64/2610.16.188.65 to 10.16.188.12610.16.188.12762
24310.16.188.128/2610.16.188.129 to 10.16.188.19010.16.188.19162
24410.16.188.192/2610.16.188.193 to 10.16.188.25410.16.188.25562
24510.16.189.0/2610.16.189.1 to 10.16.189.6210.16.189.6362
24610.16.189.64/2610.16.189.65 to 10.16.189.12610.16.189.12762
24710.16.189.128/2610.16.189.129 to 10.16.189.19010.16.189.19162
24810.16.189.192/2610.16.189.193 to 10.16.189.25410.16.189.25562
24910.16.190.0/2610.16.190.1 to 10.16.190.6210.16.190.6362
25010.16.190.64/2610.16.190.65 to 10.16.190.12610.16.190.12762
25110.16.190.128/2610.16.190.129 to 10.16.190.19010.16.190.19162
25210.16.190.192/2610.16.190.193 to 10.16.190.25410.16.190.25562
25310.16.191.0/2610.16.191.1 to 10.16.191.6210.16.191.6362
25410.16.191.64/2610.16.191.65 to 10.16.191.12610.16.191.12762
25510.16.191.128/2610.16.191.129 to 10.16.191.19010.16.191.19162
25610.16.191.192/2610.16.191.193 to 10.16.191.25410.16.191.25562

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.