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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.

Network29.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
29.128.0.0
Broadcast address
29.255.255.255
First usable
29.128.0.1
Last usable
29.255.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 1D800000 · Integer 494927872 to 503316479
Reverse DNS zones
128.29.in-addr.arpa
129.29.in-addr.arpa
130.29.in-addr.arpa
131.29.in-addr.arpa
132.29.in-addr.arpa
133.29.in-addr.arpa
134.29.in-addr.arpa
135.29.in-addr.arpa
136.29.in-addr.arpa
137.29.in-addr.arpa
138.29.in-addr.arpa
139.29.in-addr.arpa
140.29.in-addr.arpa
141.29.in-addr.arpa
142.29.in-addr.arpa
143.29.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011101.10000000.00000000.0000000029.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00011101.10000000.00000000.0000000029.128.0.0
Broadcast00011101.11111111.11111111.1111111129.255.255.255
Split into smaller subnets/21
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

29.128.0.0/9 makes 4,096 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
129.128.0.0/2129.128.0.1 to 29.128.7.25429.128.7.2552,046
229.128.8.0/2129.128.8.1 to 29.128.15.25429.128.15.2552,046
329.128.16.0/2129.128.16.1 to 29.128.23.25429.128.23.2552,046
429.128.24.0/2129.128.24.1 to 29.128.31.25429.128.31.2552,046
529.128.32.0/2129.128.32.1 to 29.128.39.25429.128.39.2552,046
629.128.40.0/2129.128.40.1 to 29.128.47.25429.128.47.2552,046
729.128.48.0/2129.128.48.1 to 29.128.55.25429.128.55.2552,046
829.128.56.0/2129.128.56.1 to 29.128.63.25429.128.63.2552,046
929.128.64.0/2129.128.64.1 to 29.128.71.25429.128.71.2552,046
1029.128.72.0/2129.128.72.1 to 29.128.79.25429.128.79.2552,046
1129.128.80.0/2129.128.80.1 to 29.128.87.25429.128.87.2552,046
1229.128.88.0/2129.128.88.1 to 29.128.95.25429.128.95.2552,046
1329.128.96.0/2129.128.96.1 to 29.128.103.25429.128.103.2552,046
1429.128.104.0/2129.128.104.1 to 29.128.111.25429.128.111.2552,046
1529.128.112.0/2129.128.112.1 to 29.128.119.25429.128.119.2552,046
1629.128.120.0/2129.128.120.1 to 29.128.127.25429.128.127.2552,046
1729.128.128.0/2129.128.128.1 to 29.128.135.25429.128.135.2552,046
1829.128.136.0/2129.128.136.1 to 29.128.143.25429.128.143.2552,046
1929.128.144.0/2129.128.144.1 to 29.128.151.25429.128.151.2552,046
2029.128.152.0/2129.128.152.1 to 29.128.159.25429.128.159.2552,046
2129.128.160.0/2129.128.160.1 to 29.128.167.25429.128.167.2552,046
2229.128.168.0/2129.128.168.1 to 29.128.175.25429.128.175.2552,046
2329.128.176.0/2129.128.176.1 to 29.128.183.25429.128.183.2552,046
2429.128.184.0/2129.128.184.1 to 29.128.191.25429.128.191.2552,046
2529.128.192.0/2129.128.192.1 to 29.128.199.25429.128.199.2552,046
2629.128.200.0/2129.128.200.1 to 29.128.207.25429.128.207.2552,046
2729.128.208.0/2129.128.208.1 to 29.128.215.25429.128.215.2552,046
2829.128.216.0/2129.128.216.1 to 29.128.223.25429.128.223.2552,046
2929.128.224.0/2129.128.224.1 to 29.128.231.25429.128.231.2552,046
3029.128.232.0/2129.128.232.1 to 29.128.239.25429.128.239.2552,046
3129.128.240.0/2129.128.240.1 to 29.128.247.25429.128.247.2552,046
3229.128.248.0/2129.128.248.1 to 29.128.255.25429.128.255.2552,046
3329.129.0.0/2129.129.0.1 to 29.129.7.25429.129.7.2552,046
3429.129.8.0/2129.129.8.1 to 29.129.15.25429.129.15.2552,046
3529.129.16.0/2129.129.16.1 to 29.129.23.25429.129.23.2552,046
3629.129.24.0/2129.129.24.1 to 29.129.31.25429.129.31.2552,046
3729.129.32.0/2129.129.32.1 to 29.129.39.25429.129.39.2552,046
3829.129.40.0/2129.129.40.1 to 29.129.47.25429.129.47.2552,046
3929.129.48.0/2129.129.48.1 to 29.129.55.25429.129.55.2552,046
4029.129.56.0/2129.129.56.1 to 29.129.63.25429.129.63.2552,046
4129.129.64.0/2129.129.64.1 to 29.129.71.25429.129.71.2552,046
4229.129.72.0/2129.129.72.1 to 29.129.79.25429.129.79.2552,046
4329.129.80.0/2129.129.80.1 to 29.129.87.25429.129.87.2552,046
4429.129.88.0/2129.129.88.1 to 29.129.95.25429.129.95.2552,046
4529.129.96.0/2129.129.96.1 to 29.129.103.25429.129.103.2552,046
4629.129.104.0/2129.129.104.1 to 29.129.111.25429.129.111.2552,046
4729.129.112.0/2129.129.112.1 to 29.129.119.25429.129.119.2552,046
4829.129.120.0/2129.129.120.1 to 29.129.127.25429.129.127.2552,046
4929.129.128.0/2129.129.128.1 to 29.129.135.25429.129.135.2552,046
5029.129.136.0/2129.129.136.1 to 29.129.143.25429.129.143.2552,046
5129.129.144.0/2129.129.144.1 to 29.129.151.25429.129.151.2552,046
5229.129.152.0/2129.129.152.1 to 29.129.159.25429.129.159.2552,046
5329.129.160.0/2129.129.160.1 to 29.129.167.25429.129.167.2552,046
5429.129.168.0/2129.129.168.1 to 29.129.175.25429.129.175.2552,046
5529.129.176.0/2129.129.176.1 to 29.129.183.25429.129.183.2552,046
5629.129.184.0/2129.129.184.1 to 29.129.191.25429.129.191.2552,046
5729.129.192.0/2129.129.192.1 to 29.129.199.25429.129.199.2552,046
5829.129.200.0/2129.129.200.1 to 29.129.207.25429.129.207.2552,046
5929.129.208.0/2129.129.208.1 to 29.129.215.25429.129.215.2552,046
6029.129.216.0/2129.129.216.1 to 29.129.223.25429.129.223.2552,046
6129.129.224.0/2129.129.224.1 to 29.129.231.25429.129.231.2552,046
6229.129.232.0/2129.129.232.1 to 29.129.239.25429.129.239.2552,046
6329.129.240.0/2129.129.240.1 to 29.129.247.25429.129.247.2552,046
6429.129.248.0/2129.129.248.1 to 29.129.255.25429.129.255.2552,046
6529.130.0.0/2129.130.0.1 to 29.130.7.25429.130.7.2552,046
6629.130.8.0/2129.130.8.1 to 29.130.15.25429.130.15.2552,046
6729.130.16.0/2129.130.16.1 to 29.130.23.25429.130.23.2552,046
6829.130.24.0/2129.130.24.1 to 29.130.31.25429.130.31.2552,046
6929.130.32.0/2129.130.32.1 to 29.130.39.25429.130.39.2552,046
7029.130.40.0/2129.130.40.1 to 29.130.47.25429.130.47.2552,046
7129.130.48.0/2129.130.48.1 to 29.130.55.25429.130.55.2552,046
7229.130.56.0/2129.130.56.1 to 29.130.63.25429.130.63.2552,046
7329.130.64.0/2129.130.64.1 to 29.130.71.25429.130.71.2552,046
7429.130.72.0/2129.130.72.1 to 29.130.79.25429.130.79.2552,046
7529.130.80.0/2129.130.80.1 to 29.130.87.25429.130.87.2552,046
7629.130.88.0/2129.130.88.1 to 29.130.95.25429.130.95.2552,046
7729.130.96.0/2129.130.96.1 to 29.130.103.25429.130.103.2552,046
7829.130.104.0/2129.130.104.1 to 29.130.111.25429.130.111.2552,046
7929.130.112.0/2129.130.112.1 to 29.130.119.25429.130.119.2552,046
8029.130.120.0/2129.130.120.1 to 29.130.127.25429.130.127.2552,046
8129.130.128.0/2129.130.128.1 to 29.130.135.25429.130.135.2552,046
8229.130.136.0/2129.130.136.1 to 29.130.143.25429.130.143.2552,046
8329.130.144.0/2129.130.144.1 to 29.130.151.25429.130.151.2552,046
8429.130.152.0/2129.130.152.1 to 29.130.159.25429.130.159.2552,046
8529.130.160.0/2129.130.160.1 to 29.130.167.25429.130.167.2552,046
8629.130.168.0/2129.130.168.1 to 29.130.175.25429.130.175.2552,046
8729.130.176.0/2129.130.176.1 to 29.130.183.25429.130.183.2552,046
8829.130.184.0/2129.130.184.1 to 29.130.191.25429.130.191.2552,046
8929.130.192.0/2129.130.192.1 to 29.130.199.25429.130.199.2552,046
9029.130.200.0/2129.130.200.1 to 29.130.207.25429.130.207.2552,046
9129.130.208.0/2129.130.208.1 to 29.130.215.25429.130.215.2552,046
9229.130.216.0/2129.130.216.1 to 29.130.223.25429.130.223.2552,046
9329.130.224.0/2129.130.224.1 to 29.130.231.25429.130.231.2552,046
9429.130.232.0/2129.130.232.1 to 29.130.239.25429.130.239.2552,046
9529.130.240.0/2129.130.240.1 to 29.130.247.25429.130.247.2552,046
9629.130.248.0/2129.130.248.1 to 29.130.255.25429.130.255.2552,046
9729.131.0.0/2129.131.0.1 to 29.131.7.25429.131.7.2552,046
9829.131.8.0/2129.131.8.1 to 29.131.15.25429.131.15.2552,046
9929.131.16.0/2129.131.16.1 to 29.131.23.25429.131.23.2552,046
10029.131.24.0/2129.131.24.1 to 29.131.31.25429.131.31.2552,046
10129.131.32.0/2129.131.32.1 to 29.131.39.25429.131.39.2552,046
10229.131.40.0/2129.131.40.1 to 29.131.47.25429.131.47.2552,046
10329.131.48.0/2129.131.48.1 to 29.131.55.25429.131.55.2552,046
10429.131.56.0/2129.131.56.1 to 29.131.63.25429.131.63.2552,046
10529.131.64.0/2129.131.64.1 to 29.131.71.25429.131.71.2552,046
10629.131.72.0/2129.131.72.1 to 29.131.79.25429.131.79.2552,046
10729.131.80.0/2129.131.80.1 to 29.131.87.25429.131.87.2552,046
10829.131.88.0/2129.131.88.1 to 29.131.95.25429.131.95.2552,046
10929.131.96.0/2129.131.96.1 to 29.131.103.25429.131.103.2552,046
11029.131.104.0/2129.131.104.1 to 29.131.111.25429.131.111.2552,046
11129.131.112.0/2129.131.112.1 to 29.131.119.25429.131.119.2552,046
11229.131.120.0/2129.131.120.1 to 29.131.127.25429.131.127.2552,046
11329.131.128.0/2129.131.128.1 to 29.131.135.25429.131.135.2552,046
11429.131.136.0/2129.131.136.1 to 29.131.143.25429.131.143.2552,046
11529.131.144.0/2129.131.144.1 to 29.131.151.25429.131.151.2552,046
11629.131.152.0/2129.131.152.1 to 29.131.159.25429.131.159.2552,046
11729.131.160.0/2129.131.160.1 to 29.131.167.25429.131.167.2552,046
11829.131.168.0/2129.131.168.1 to 29.131.175.25429.131.175.2552,046
11929.131.176.0/2129.131.176.1 to 29.131.183.25429.131.183.2552,046
12029.131.184.0/2129.131.184.1 to 29.131.191.25429.131.191.2552,046
12129.131.192.0/2129.131.192.1 to 29.131.199.25429.131.199.2552,046
12229.131.200.0/2129.131.200.1 to 29.131.207.25429.131.207.2552,046
12329.131.208.0/2129.131.208.1 to 29.131.215.25429.131.215.2552,046
12429.131.216.0/2129.131.216.1 to 29.131.223.25429.131.223.2552,046
12529.131.224.0/2129.131.224.1 to 29.131.231.25429.131.231.2552,046
12629.131.232.0/2129.131.232.1 to 29.131.239.25429.131.239.2552,046
12729.131.240.0/2129.131.240.1 to 29.131.247.25429.131.247.2552,046
12829.131.248.0/2129.131.248.1 to 29.131.255.25429.131.255.2552,046
12929.132.0.0/2129.132.0.1 to 29.132.7.25429.132.7.2552,046
13029.132.8.0/2129.132.8.1 to 29.132.15.25429.132.15.2552,046
13129.132.16.0/2129.132.16.1 to 29.132.23.25429.132.23.2552,046
13229.132.24.0/2129.132.24.1 to 29.132.31.25429.132.31.2552,046
13329.132.32.0/2129.132.32.1 to 29.132.39.25429.132.39.2552,046
13429.132.40.0/2129.132.40.1 to 29.132.47.25429.132.47.2552,046
13529.132.48.0/2129.132.48.1 to 29.132.55.25429.132.55.2552,046
13629.132.56.0/2129.132.56.1 to 29.132.63.25429.132.63.2552,046
13729.132.64.0/2129.132.64.1 to 29.132.71.25429.132.71.2552,046
13829.132.72.0/2129.132.72.1 to 29.132.79.25429.132.79.2552,046
13929.132.80.0/2129.132.80.1 to 29.132.87.25429.132.87.2552,046
14029.132.88.0/2129.132.88.1 to 29.132.95.25429.132.95.2552,046
14129.132.96.0/2129.132.96.1 to 29.132.103.25429.132.103.2552,046
14229.132.104.0/2129.132.104.1 to 29.132.111.25429.132.111.2552,046
14329.132.112.0/2129.132.112.1 to 29.132.119.25429.132.119.2552,046
14429.132.120.0/2129.132.120.1 to 29.132.127.25429.132.127.2552,046
14529.132.128.0/2129.132.128.1 to 29.132.135.25429.132.135.2552,046
14629.132.136.0/2129.132.136.1 to 29.132.143.25429.132.143.2552,046
14729.132.144.0/2129.132.144.1 to 29.132.151.25429.132.151.2552,046
14829.132.152.0/2129.132.152.1 to 29.132.159.25429.132.159.2552,046
14929.132.160.0/2129.132.160.1 to 29.132.167.25429.132.167.2552,046
15029.132.168.0/2129.132.168.1 to 29.132.175.25429.132.175.2552,046
15129.132.176.0/2129.132.176.1 to 29.132.183.25429.132.183.2552,046
15229.132.184.0/2129.132.184.1 to 29.132.191.25429.132.191.2552,046
15329.132.192.0/2129.132.192.1 to 29.132.199.25429.132.199.2552,046
15429.132.200.0/2129.132.200.1 to 29.132.207.25429.132.207.2552,046
15529.132.208.0/2129.132.208.1 to 29.132.215.25429.132.215.2552,046
15629.132.216.0/2129.132.216.1 to 29.132.223.25429.132.223.2552,046
15729.132.224.0/2129.132.224.1 to 29.132.231.25429.132.231.2552,046
15829.132.232.0/2129.132.232.1 to 29.132.239.25429.132.239.2552,046
15929.132.240.0/2129.132.240.1 to 29.132.247.25429.132.247.2552,046
16029.132.248.0/2129.132.248.1 to 29.132.255.25429.132.255.2552,046
16129.133.0.0/2129.133.0.1 to 29.133.7.25429.133.7.2552,046
16229.133.8.0/2129.133.8.1 to 29.133.15.25429.133.15.2552,046
16329.133.16.0/2129.133.16.1 to 29.133.23.25429.133.23.2552,046
16429.133.24.0/2129.133.24.1 to 29.133.31.25429.133.31.2552,046
16529.133.32.0/2129.133.32.1 to 29.133.39.25429.133.39.2552,046
16629.133.40.0/2129.133.40.1 to 29.133.47.25429.133.47.2552,046
16729.133.48.0/2129.133.48.1 to 29.133.55.25429.133.55.2552,046
16829.133.56.0/2129.133.56.1 to 29.133.63.25429.133.63.2552,046
16929.133.64.0/2129.133.64.1 to 29.133.71.25429.133.71.2552,046
17029.133.72.0/2129.133.72.1 to 29.133.79.25429.133.79.2552,046
17129.133.80.0/2129.133.80.1 to 29.133.87.25429.133.87.2552,046
17229.133.88.0/2129.133.88.1 to 29.133.95.25429.133.95.2552,046
17329.133.96.0/2129.133.96.1 to 29.133.103.25429.133.103.2552,046
17429.133.104.0/2129.133.104.1 to 29.133.111.25429.133.111.2552,046
17529.133.112.0/2129.133.112.1 to 29.133.119.25429.133.119.2552,046
17629.133.120.0/2129.133.120.1 to 29.133.127.25429.133.127.2552,046
17729.133.128.0/2129.133.128.1 to 29.133.135.25429.133.135.2552,046
17829.133.136.0/2129.133.136.1 to 29.133.143.25429.133.143.2552,046
17929.133.144.0/2129.133.144.1 to 29.133.151.25429.133.151.2552,046
18029.133.152.0/2129.133.152.1 to 29.133.159.25429.133.159.2552,046
18129.133.160.0/2129.133.160.1 to 29.133.167.25429.133.167.2552,046
18229.133.168.0/2129.133.168.1 to 29.133.175.25429.133.175.2552,046
18329.133.176.0/2129.133.176.1 to 29.133.183.25429.133.183.2552,046
18429.133.184.0/2129.133.184.1 to 29.133.191.25429.133.191.2552,046
18529.133.192.0/2129.133.192.1 to 29.133.199.25429.133.199.2552,046
18629.133.200.0/2129.133.200.1 to 29.133.207.25429.133.207.2552,046
18729.133.208.0/2129.133.208.1 to 29.133.215.25429.133.215.2552,046
18829.133.216.0/2129.133.216.1 to 29.133.223.25429.133.223.2552,046
18929.133.224.0/2129.133.224.1 to 29.133.231.25429.133.231.2552,046
19029.133.232.0/2129.133.232.1 to 29.133.239.25429.133.239.2552,046
19129.133.240.0/2129.133.240.1 to 29.133.247.25429.133.247.2552,046
19229.133.248.0/2129.133.248.1 to 29.133.255.25429.133.255.2552,046
19329.134.0.0/2129.134.0.1 to 29.134.7.25429.134.7.2552,046
19429.134.8.0/2129.134.8.1 to 29.134.15.25429.134.15.2552,046
19529.134.16.0/2129.134.16.1 to 29.134.23.25429.134.23.2552,046
19629.134.24.0/2129.134.24.1 to 29.134.31.25429.134.31.2552,046
19729.134.32.0/2129.134.32.1 to 29.134.39.25429.134.39.2552,046
19829.134.40.0/2129.134.40.1 to 29.134.47.25429.134.47.2552,046
19929.134.48.0/2129.134.48.1 to 29.134.55.25429.134.55.2552,046
20029.134.56.0/2129.134.56.1 to 29.134.63.25429.134.63.2552,046
20129.134.64.0/2129.134.64.1 to 29.134.71.25429.134.71.2552,046
20229.134.72.0/2129.134.72.1 to 29.134.79.25429.134.79.2552,046
20329.134.80.0/2129.134.80.1 to 29.134.87.25429.134.87.2552,046
20429.134.88.0/2129.134.88.1 to 29.134.95.25429.134.95.2552,046
20529.134.96.0/2129.134.96.1 to 29.134.103.25429.134.103.2552,046
20629.134.104.0/2129.134.104.1 to 29.134.111.25429.134.111.2552,046
20729.134.112.0/2129.134.112.1 to 29.134.119.25429.134.119.2552,046
20829.134.120.0/2129.134.120.1 to 29.134.127.25429.134.127.2552,046
20929.134.128.0/2129.134.128.1 to 29.134.135.25429.134.135.2552,046
21029.134.136.0/2129.134.136.1 to 29.134.143.25429.134.143.2552,046
21129.134.144.0/2129.134.144.1 to 29.134.151.25429.134.151.2552,046
21229.134.152.0/2129.134.152.1 to 29.134.159.25429.134.159.2552,046
21329.134.160.0/2129.134.160.1 to 29.134.167.25429.134.167.2552,046
21429.134.168.0/2129.134.168.1 to 29.134.175.25429.134.175.2552,046
21529.134.176.0/2129.134.176.1 to 29.134.183.25429.134.183.2552,046
21629.134.184.0/2129.134.184.1 to 29.134.191.25429.134.191.2552,046
21729.134.192.0/2129.134.192.1 to 29.134.199.25429.134.199.2552,046
21829.134.200.0/2129.134.200.1 to 29.134.207.25429.134.207.2552,046
21929.134.208.0/2129.134.208.1 to 29.134.215.25429.134.215.2552,046
22029.134.216.0/2129.134.216.1 to 29.134.223.25429.134.223.2552,046
22129.134.224.0/2129.134.224.1 to 29.134.231.25429.134.231.2552,046
22229.134.232.0/2129.134.232.1 to 29.134.239.25429.134.239.2552,046
22329.134.240.0/2129.134.240.1 to 29.134.247.25429.134.247.2552,046
22429.134.248.0/2129.134.248.1 to 29.134.255.25429.134.255.2552,046
22529.135.0.0/2129.135.0.1 to 29.135.7.25429.135.7.2552,046
22629.135.8.0/2129.135.8.1 to 29.135.15.25429.135.15.2552,046
22729.135.16.0/2129.135.16.1 to 29.135.23.25429.135.23.2552,046
22829.135.24.0/2129.135.24.1 to 29.135.31.25429.135.31.2552,046
22929.135.32.0/2129.135.32.1 to 29.135.39.25429.135.39.2552,046
23029.135.40.0/2129.135.40.1 to 29.135.47.25429.135.47.2552,046
23129.135.48.0/2129.135.48.1 to 29.135.55.25429.135.55.2552,046
23229.135.56.0/2129.135.56.1 to 29.135.63.25429.135.63.2552,046
23329.135.64.0/2129.135.64.1 to 29.135.71.25429.135.71.2552,046
23429.135.72.0/2129.135.72.1 to 29.135.79.25429.135.79.2552,046
23529.135.80.0/2129.135.80.1 to 29.135.87.25429.135.87.2552,046
23629.135.88.0/2129.135.88.1 to 29.135.95.25429.135.95.2552,046
23729.135.96.0/2129.135.96.1 to 29.135.103.25429.135.103.2552,046
23829.135.104.0/2129.135.104.1 to 29.135.111.25429.135.111.2552,046
23929.135.112.0/2129.135.112.1 to 29.135.119.25429.135.119.2552,046
24029.135.120.0/2129.135.120.1 to 29.135.127.25429.135.127.2552,046
24129.135.128.0/2129.135.128.1 to 29.135.135.25429.135.135.2552,046
24229.135.136.0/2129.135.136.1 to 29.135.143.25429.135.143.2552,046
24329.135.144.0/2129.135.144.1 to 29.135.151.25429.135.151.2552,046
24429.135.152.0/2129.135.152.1 to 29.135.159.25429.135.159.2552,046
24529.135.160.0/2129.135.160.1 to 29.135.167.25429.135.167.2552,046
24629.135.168.0/2129.135.168.1 to 29.135.175.25429.135.175.2552,046
24729.135.176.0/2129.135.176.1 to 29.135.183.25429.135.183.2552,046
24829.135.184.0/2129.135.184.1 to 29.135.191.25429.135.191.2552,046
24929.135.192.0/2129.135.192.1 to 29.135.199.25429.135.199.2552,046
25029.135.200.0/2129.135.200.1 to 29.135.207.25429.135.207.2552,046
25129.135.208.0/2129.135.208.1 to 29.135.215.25429.135.215.2552,046
25229.135.216.0/2129.135.216.1 to 29.135.223.25429.135.223.2552,046
25329.135.224.0/2129.135.224.1 to 29.135.231.25429.135.231.2552,046
25429.135.232.0/2129.135.232.1 to 29.135.239.25429.135.239.2552,046
25529.135.240.0/2129.135.240.1 to 29.135.247.25429.135.247.2552,046
25629.135.248.0/2129.135.248.1 to 29.135.255.25429.135.255.2552,046

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.