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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.

Network36.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
36.0.0.0
Broadcast address
36.127.255.255
First usable
36.0.0.1
Last usable
36.127.255.254
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 24000000 · Integer 603979776 to 612368383
Reverse DNS zones
0.36.in-addr.arpa
1.36.in-addr.arpa
2.36.in-addr.arpa
3.36.in-addr.arpa
4.36.in-addr.arpa
5.36.in-addr.arpa
6.36.in-addr.arpa
7.36.in-addr.arpa
8.36.in-addr.arpa
9.36.in-addr.arpa
10.36.in-addr.arpa
11.36.in-addr.arpa
12.36.in-addr.arpa
13.36.in-addr.arpa
14.36.in-addr.arpa
15.36.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
Address00100100.00000000.00000000.0000000036.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00100100.00000000.00000000.0000000036.0.0.0
Broadcast00100100.01111111.11111111.1111111136.127.255.255
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)

36.0.0.0/9 makes 4,096 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
136.0.0.0/2136.0.0.1 to 36.0.7.25436.0.7.2552,046
236.0.8.0/2136.0.8.1 to 36.0.15.25436.0.15.2552,046
336.0.16.0/2136.0.16.1 to 36.0.23.25436.0.23.2552,046
436.0.24.0/2136.0.24.1 to 36.0.31.25436.0.31.2552,046
536.0.32.0/2136.0.32.1 to 36.0.39.25436.0.39.2552,046
636.0.40.0/2136.0.40.1 to 36.0.47.25436.0.47.2552,046
736.0.48.0/2136.0.48.1 to 36.0.55.25436.0.55.2552,046
836.0.56.0/2136.0.56.1 to 36.0.63.25436.0.63.2552,046
936.0.64.0/2136.0.64.1 to 36.0.71.25436.0.71.2552,046
1036.0.72.0/2136.0.72.1 to 36.0.79.25436.0.79.2552,046
1136.0.80.0/2136.0.80.1 to 36.0.87.25436.0.87.2552,046
1236.0.88.0/2136.0.88.1 to 36.0.95.25436.0.95.2552,046
1336.0.96.0/2136.0.96.1 to 36.0.103.25436.0.103.2552,046
1436.0.104.0/2136.0.104.1 to 36.0.111.25436.0.111.2552,046
1536.0.112.0/2136.0.112.1 to 36.0.119.25436.0.119.2552,046
1636.0.120.0/2136.0.120.1 to 36.0.127.25436.0.127.2552,046
1736.0.128.0/2136.0.128.1 to 36.0.135.25436.0.135.2552,046
1836.0.136.0/2136.0.136.1 to 36.0.143.25436.0.143.2552,046
1936.0.144.0/2136.0.144.1 to 36.0.151.25436.0.151.2552,046
2036.0.152.0/2136.0.152.1 to 36.0.159.25436.0.159.2552,046
2136.0.160.0/2136.0.160.1 to 36.0.167.25436.0.167.2552,046
2236.0.168.0/2136.0.168.1 to 36.0.175.25436.0.175.2552,046
2336.0.176.0/2136.0.176.1 to 36.0.183.25436.0.183.2552,046
2436.0.184.0/2136.0.184.1 to 36.0.191.25436.0.191.2552,046
2536.0.192.0/2136.0.192.1 to 36.0.199.25436.0.199.2552,046
2636.0.200.0/2136.0.200.1 to 36.0.207.25436.0.207.2552,046
2736.0.208.0/2136.0.208.1 to 36.0.215.25436.0.215.2552,046
2836.0.216.0/2136.0.216.1 to 36.0.223.25436.0.223.2552,046
2936.0.224.0/2136.0.224.1 to 36.0.231.25436.0.231.2552,046
3036.0.232.0/2136.0.232.1 to 36.0.239.25436.0.239.2552,046
3136.0.240.0/2136.0.240.1 to 36.0.247.25436.0.247.2552,046
3236.0.248.0/2136.0.248.1 to 36.0.255.25436.0.255.2552,046
3336.1.0.0/2136.1.0.1 to 36.1.7.25436.1.7.2552,046
3436.1.8.0/2136.1.8.1 to 36.1.15.25436.1.15.2552,046
3536.1.16.0/2136.1.16.1 to 36.1.23.25436.1.23.2552,046
3636.1.24.0/2136.1.24.1 to 36.1.31.25436.1.31.2552,046
3736.1.32.0/2136.1.32.1 to 36.1.39.25436.1.39.2552,046
3836.1.40.0/2136.1.40.1 to 36.1.47.25436.1.47.2552,046
3936.1.48.0/2136.1.48.1 to 36.1.55.25436.1.55.2552,046
4036.1.56.0/2136.1.56.1 to 36.1.63.25436.1.63.2552,046
4136.1.64.0/2136.1.64.1 to 36.1.71.25436.1.71.2552,046
4236.1.72.0/2136.1.72.1 to 36.1.79.25436.1.79.2552,046
4336.1.80.0/2136.1.80.1 to 36.1.87.25436.1.87.2552,046
4436.1.88.0/2136.1.88.1 to 36.1.95.25436.1.95.2552,046
4536.1.96.0/2136.1.96.1 to 36.1.103.25436.1.103.2552,046
4636.1.104.0/2136.1.104.1 to 36.1.111.25436.1.111.2552,046
4736.1.112.0/2136.1.112.1 to 36.1.119.25436.1.119.2552,046
4836.1.120.0/2136.1.120.1 to 36.1.127.25436.1.127.2552,046
4936.1.128.0/2136.1.128.1 to 36.1.135.25436.1.135.2552,046
5036.1.136.0/2136.1.136.1 to 36.1.143.25436.1.143.2552,046
5136.1.144.0/2136.1.144.1 to 36.1.151.25436.1.151.2552,046
5236.1.152.0/2136.1.152.1 to 36.1.159.25436.1.159.2552,046
5336.1.160.0/2136.1.160.1 to 36.1.167.25436.1.167.2552,046
5436.1.168.0/2136.1.168.1 to 36.1.175.25436.1.175.2552,046
5536.1.176.0/2136.1.176.1 to 36.1.183.25436.1.183.2552,046
5636.1.184.0/2136.1.184.1 to 36.1.191.25436.1.191.2552,046
5736.1.192.0/2136.1.192.1 to 36.1.199.25436.1.199.2552,046
5836.1.200.0/2136.1.200.1 to 36.1.207.25436.1.207.2552,046
5936.1.208.0/2136.1.208.1 to 36.1.215.25436.1.215.2552,046
6036.1.216.0/2136.1.216.1 to 36.1.223.25436.1.223.2552,046
6136.1.224.0/2136.1.224.1 to 36.1.231.25436.1.231.2552,046
6236.1.232.0/2136.1.232.1 to 36.1.239.25436.1.239.2552,046
6336.1.240.0/2136.1.240.1 to 36.1.247.25436.1.247.2552,046
6436.1.248.0/2136.1.248.1 to 36.1.255.25436.1.255.2552,046
6536.2.0.0/2136.2.0.1 to 36.2.7.25436.2.7.2552,046
6636.2.8.0/2136.2.8.1 to 36.2.15.25436.2.15.2552,046
6736.2.16.0/2136.2.16.1 to 36.2.23.25436.2.23.2552,046
6836.2.24.0/2136.2.24.1 to 36.2.31.25436.2.31.2552,046
6936.2.32.0/2136.2.32.1 to 36.2.39.25436.2.39.2552,046
7036.2.40.0/2136.2.40.1 to 36.2.47.25436.2.47.2552,046
7136.2.48.0/2136.2.48.1 to 36.2.55.25436.2.55.2552,046
7236.2.56.0/2136.2.56.1 to 36.2.63.25436.2.63.2552,046
7336.2.64.0/2136.2.64.1 to 36.2.71.25436.2.71.2552,046
7436.2.72.0/2136.2.72.1 to 36.2.79.25436.2.79.2552,046
7536.2.80.0/2136.2.80.1 to 36.2.87.25436.2.87.2552,046
7636.2.88.0/2136.2.88.1 to 36.2.95.25436.2.95.2552,046
7736.2.96.0/2136.2.96.1 to 36.2.103.25436.2.103.2552,046
7836.2.104.0/2136.2.104.1 to 36.2.111.25436.2.111.2552,046
7936.2.112.0/2136.2.112.1 to 36.2.119.25436.2.119.2552,046
8036.2.120.0/2136.2.120.1 to 36.2.127.25436.2.127.2552,046
8136.2.128.0/2136.2.128.1 to 36.2.135.25436.2.135.2552,046
8236.2.136.0/2136.2.136.1 to 36.2.143.25436.2.143.2552,046
8336.2.144.0/2136.2.144.1 to 36.2.151.25436.2.151.2552,046
8436.2.152.0/2136.2.152.1 to 36.2.159.25436.2.159.2552,046
8536.2.160.0/2136.2.160.1 to 36.2.167.25436.2.167.2552,046
8636.2.168.0/2136.2.168.1 to 36.2.175.25436.2.175.2552,046
8736.2.176.0/2136.2.176.1 to 36.2.183.25436.2.183.2552,046
8836.2.184.0/2136.2.184.1 to 36.2.191.25436.2.191.2552,046
8936.2.192.0/2136.2.192.1 to 36.2.199.25436.2.199.2552,046
9036.2.200.0/2136.2.200.1 to 36.2.207.25436.2.207.2552,046
9136.2.208.0/2136.2.208.1 to 36.2.215.25436.2.215.2552,046
9236.2.216.0/2136.2.216.1 to 36.2.223.25436.2.223.2552,046
9336.2.224.0/2136.2.224.1 to 36.2.231.25436.2.231.2552,046
9436.2.232.0/2136.2.232.1 to 36.2.239.25436.2.239.2552,046
9536.2.240.0/2136.2.240.1 to 36.2.247.25436.2.247.2552,046
9636.2.248.0/2136.2.248.1 to 36.2.255.25436.2.255.2552,046
9736.3.0.0/2136.3.0.1 to 36.3.7.25436.3.7.2552,046
9836.3.8.0/2136.3.8.1 to 36.3.15.25436.3.15.2552,046
9936.3.16.0/2136.3.16.1 to 36.3.23.25436.3.23.2552,046
10036.3.24.0/2136.3.24.1 to 36.3.31.25436.3.31.2552,046
10136.3.32.0/2136.3.32.1 to 36.3.39.25436.3.39.2552,046
10236.3.40.0/2136.3.40.1 to 36.3.47.25436.3.47.2552,046
10336.3.48.0/2136.3.48.1 to 36.3.55.25436.3.55.2552,046
10436.3.56.0/2136.3.56.1 to 36.3.63.25436.3.63.2552,046
10536.3.64.0/2136.3.64.1 to 36.3.71.25436.3.71.2552,046
10636.3.72.0/2136.3.72.1 to 36.3.79.25436.3.79.2552,046
10736.3.80.0/2136.3.80.1 to 36.3.87.25436.3.87.2552,046
10836.3.88.0/2136.3.88.1 to 36.3.95.25436.3.95.2552,046
10936.3.96.0/2136.3.96.1 to 36.3.103.25436.3.103.2552,046
11036.3.104.0/2136.3.104.1 to 36.3.111.25436.3.111.2552,046
11136.3.112.0/2136.3.112.1 to 36.3.119.25436.3.119.2552,046
11236.3.120.0/2136.3.120.1 to 36.3.127.25436.3.127.2552,046
11336.3.128.0/2136.3.128.1 to 36.3.135.25436.3.135.2552,046
11436.3.136.0/2136.3.136.1 to 36.3.143.25436.3.143.2552,046
11536.3.144.0/2136.3.144.1 to 36.3.151.25436.3.151.2552,046
11636.3.152.0/2136.3.152.1 to 36.3.159.25436.3.159.2552,046
11736.3.160.0/2136.3.160.1 to 36.3.167.25436.3.167.2552,046
11836.3.168.0/2136.3.168.1 to 36.3.175.25436.3.175.2552,046
11936.3.176.0/2136.3.176.1 to 36.3.183.25436.3.183.2552,046
12036.3.184.0/2136.3.184.1 to 36.3.191.25436.3.191.2552,046
12136.3.192.0/2136.3.192.1 to 36.3.199.25436.3.199.2552,046
12236.3.200.0/2136.3.200.1 to 36.3.207.25436.3.207.2552,046
12336.3.208.0/2136.3.208.1 to 36.3.215.25436.3.215.2552,046
12436.3.216.0/2136.3.216.1 to 36.3.223.25436.3.223.2552,046
12536.3.224.0/2136.3.224.1 to 36.3.231.25436.3.231.2552,046
12636.3.232.0/2136.3.232.1 to 36.3.239.25436.3.239.2552,046
12736.3.240.0/2136.3.240.1 to 36.3.247.25436.3.247.2552,046
12836.3.248.0/2136.3.248.1 to 36.3.255.25436.3.255.2552,046
12936.4.0.0/2136.4.0.1 to 36.4.7.25436.4.7.2552,046
13036.4.8.0/2136.4.8.1 to 36.4.15.25436.4.15.2552,046
13136.4.16.0/2136.4.16.1 to 36.4.23.25436.4.23.2552,046
13236.4.24.0/2136.4.24.1 to 36.4.31.25436.4.31.2552,046
13336.4.32.0/2136.4.32.1 to 36.4.39.25436.4.39.2552,046
13436.4.40.0/2136.4.40.1 to 36.4.47.25436.4.47.2552,046
13536.4.48.0/2136.4.48.1 to 36.4.55.25436.4.55.2552,046
13636.4.56.0/2136.4.56.1 to 36.4.63.25436.4.63.2552,046
13736.4.64.0/2136.4.64.1 to 36.4.71.25436.4.71.2552,046
13836.4.72.0/2136.4.72.1 to 36.4.79.25436.4.79.2552,046
13936.4.80.0/2136.4.80.1 to 36.4.87.25436.4.87.2552,046
14036.4.88.0/2136.4.88.1 to 36.4.95.25436.4.95.2552,046
14136.4.96.0/2136.4.96.1 to 36.4.103.25436.4.103.2552,046
14236.4.104.0/2136.4.104.1 to 36.4.111.25436.4.111.2552,046
14336.4.112.0/2136.4.112.1 to 36.4.119.25436.4.119.2552,046
14436.4.120.0/2136.4.120.1 to 36.4.127.25436.4.127.2552,046
14536.4.128.0/2136.4.128.1 to 36.4.135.25436.4.135.2552,046
14636.4.136.0/2136.4.136.1 to 36.4.143.25436.4.143.2552,046
14736.4.144.0/2136.4.144.1 to 36.4.151.25436.4.151.2552,046
14836.4.152.0/2136.4.152.1 to 36.4.159.25436.4.159.2552,046
14936.4.160.0/2136.4.160.1 to 36.4.167.25436.4.167.2552,046
15036.4.168.0/2136.4.168.1 to 36.4.175.25436.4.175.2552,046
15136.4.176.0/2136.4.176.1 to 36.4.183.25436.4.183.2552,046
15236.4.184.0/2136.4.184.1 to 36.4.191.25436.4.191.2552,046
15336.4.192.0/2136.4.192.1 to 36.4.199.25436.4.199.2552,046
15436.4.200.0/2136.4.200.1 to 36.4.207.25436.4.207.2552,046
15536.4.208.0/2136.4.208.1 to 36.4.215.25436.4.215.2552,046
15636.4.216.0/2136.4.216.1 to 36.4.223.25436.4.223.2552,046
15736.4.224.0/2136.4.224.1 to 36.4.231.25436.4.231.2552,046
15836.4.232.0/2136.4.232.1 to 36.4.239.25436.4.239.2552,046
15936.4.240.0/2136.4.240.1 to 36.4.247.25436.4.247.2552,046
16036.4.248.0/2136.4.248.1 to 36.4.255.25436.4.255.2552,046
16136.5.0.0/2136.5.0.1 to 36.5.7.25436.5.7.2552,046
16236.5.8.0/2136.5.8.1 to 36.5.15.25436.5.15.2552,046
16336.5.16.0/2136.5.16.1 to 36.5.23.25436.5.23.2552,046
16436.5.24.0/2136.5.24.1 to 36.5.31.25436.5.31.2552,046
16536.5.32.0/2136.5.32.1 to 36.5.39.25436.5.39.2552,046
16636.5.40.0/2136.5.40.1 to 36.5.47.25436.5.47.2552,046
16736.5.48.0/2136.5.48.1 to 36.5.55.25436.5.55.2552,046
16836.5.56.0/2136.5.56.1 to 36.5.63.25436.5.63.2552,046
16936.5.64.0/2136.5.64.1 to 36.5.71.25436.5.71.2552,046
17036.5.72.0/2136.5.72.1 to 36.5.79.25436.5.79.2552,046
17136.5.80.0/2136.5.80.1 to 36.5.87.25436.5.87.2552,046
17236.5.88.0/2136.5.88.1 to 36.5.95.25436.5.95.2552,046
17336.5.96.0/2136.5.96.1 to 36.5.103.25436.5.103.2552,046
17436.5.104.0/2136.5.104.1 to 36.5.111.25436.5.111.2552,046
17536.5.112.0/2136.5.112.1 to 36.5.119.25436.5.119.2552,046
17636.5.120.0/2136.5.120.1 to 36.5.127.25436.5.127.2552,046
17736.5.128.0/2136.5.128.1 to 36.5.135.25436.5.135.2552,046
17836.5.136.0/2136.5.136.1 to 36.5.143.25436.5.143.2552,046
17936.5.144.0/2136.5.144.1 to 36.5.151.25436.5.151.2552,046
18036.5.152.0/2136.5.152.1 to 36.5.159.25436.5.159.2552,046
18136.5.160.0/2136.5.160.1 to 36.5.167.25436.5.167.2552,046
18236.5.168.0/2136.5.168.1 to 36.5.175.25436.5.175.2552,046
18336.5.176.0/2136.5.176.1 to 36.5.183.25436.5.183.2552,046
18436.5.184.0/2136.5.184.1 to 36.5.191.25436.5.191.2552,046
18536.5.192.0/2136.5.192.1 to 36.5.199.25436.5.199.2552,046
18636.5.200.0/2136.5.200.1 to 36.5.207.25436.5.207.2552,046
18736.5.208.0/2136.5.208.1 to 36.5.215.25436.5.215.2552,046
18836.5.216.0/2136.5.216.1 to 36.5.223.25436.5.223.2552,046
18936.5.224.0/2136.5.224.1 to 36.5.231.25436.5.231.2552,046
19036.5.232.0/2136.5.232.1 to 36.5.239.25436.5.239.2552,046
19136.5.240.0/2136.5.240.1 to 36.5.247.25436.5.247.2552,046
19236.5.248.0/2136.5.248.1 to 36.5.255.25436.5.255.2552,046
19336.6.0.0/2136.6.0.1 to 36.6.7.25436.6.7.2552,046
19436.6.8.0/2136.6.8.1 to 36.6.15.25436.6.15.2552,046
19536.6.16.0/2136.6.16.1 to 36.6.23.25436.6.23.2552,046
19636.6.24.0/2136.6.24.1 to 36.6.31.25436.6.31.2552,046
19736.6.32.0/2136.6.32.1 to 36.6.39.25436.6.39.2552,046
19836.6.40.0/2136.6.40.1 to 36.6.47.25436.6.47.2552,046
19936.6.48.0/2136.6.48.1 to 36.6.55.25436.6.55.2552,046
20036.6.56.0/2136.6.56.1 to 36.6.63.25436.6.63.2552,046
20136.6.64.0/2136.6.64.1 to 36.6.71.25436.6.71.2552,046
20236.6.72.0/2136.6.72.1 to 36.6.79.25436.6.79.2552,046
20336.6.80.0/2136.6.80.1 to 36.6.87.25436.6.87.2552,046
20436.6.88.0/2136.6.88.1 to 36.6.95.25436.6.95.2552,046
20536.6.96.0/2136.6.96.1 to 36.6.103.25436.6.103.2552,046
20636.6.104.0/2136.6.104.1 to 36.6.111.25436.6.111.2552,046
20736.6.112.0/2136.6.112.1 to 36.6.119.25436.6.119.2552,046
20836.6.120.0/2136.6.120.1 to 36.6.127.25436.6.127.2552,046
20936.6.128.0/2136.6.128.1 to 36.6.135.25436.6.135.2552,046
21036.6.136.0/2136.6.136.1 to 36.6.143.25436.6.143.2552,046
21136.6.144.0/2136.6.144.1 to 36.6.151.25436.6.151.2552,046
21236.6.152.0/2136.6.152.1 to 36.6.159.25436.6.159.2552,046
21336.6.160.0/2136.6.160.1 to 36.6.167.25436.6.167.2552,046
21436.6.168.0/2136.6.168.1 to 36.6.175.25436.6.175.2552,046
21536.6.176.0/2136.6.176.1 to 36.6.183.25436.6.183.2552,046
21636.6.184.0/2136.6.184.1 to 36.6.191.25436.6.191.2552,046
21736.6.192.0/2136.6.192.1 to 36.6.199.25436.6.199.2552,046
21836.6.200.0/2136.6.200.1 to 36.6.207.25436.6.207.2552,046
21936.6.208.0/2136.6.208.1 to 36.6.215.25436.6.215.2552,046
22036.6.216.0/2136.6.216.1 to 36.6.223.25436.6.223.2552,046
22136.6.224.0/2136.6.224.1 to 36.6.231.25436.6.231.2552,046
22236.6.232.0/2136.6.232.1 to 36.6.239.25436.6.239.2552,046
22336.6.240.0/2136.6.240.1 to 36.6.247.25436.6.247.2552,046
22436.6.248.0/2136.6.248.1 to 36.6.255.25436.6.255.2552,046
22536.7.0.0/2136.7.0.1 to 36.7.7.25436.7.7.2552,046
22636.7.8.0/2136.7.8.1 to 36.7.15.25436.7.15.2552,046
22736.7.16.0/2136.7.16.1 to 36.7.23.25436.7.23.2552,046
22836.7.24.0/2136.7.24.1 to 36.7.31.25436.7.31.2552,046
22936.7.32.0/2136.7.32.1 to 36.7.39.25436.7.39.2552,046
23036.7.40.0/2136.7.40.1 to 36.7.47.25436.7.47.2552,046
23136.7.48.0/2136.7.48.1 to 36.7.55.25436.7.55.2552,046
23236.7.56.0/2136.7.56.1 to 36.7.63.25436.7.63.2552,046
23336.7.64.0/2136.7.64.1 to 36.7.71.25436.7.71.2552,046
23436.7.72.0/2136.7.72.1 to 36.7.79.25436.7.79.2552,046
23536.7.80.0/2136.7.80.1 to 36.7.87.25436.7.87.2552,046
23636.7.88.0/2136.7.88.1 to 36.7.95.25436.7.95.2552,046
23736.7.96.0/2136.7.96.1 to 36.7.103.25436.7.103.2552,046
23836.7.104.0/2136.7.104.1 to 36.7.111.25436.7.111.2552,046
23936.7.112.0/2136.7.112.1 to 36.7.119.25436.7.119.2552,046
24036.7.120.0/2136.7.120.1 to 36.7.127.25436.7.127.2552,046
24136.7.128.0/2136.7.128.1 to 36.7.135.25436.7.135.2552,046
24236.7.136.0/2136.7.136.1 to 36.7.143.25436.7.143.2552,046
24336.7.144.0/2136.7.144.1 to 36.7.151.25436.7.151.2552,046
24436.7.152.0/2136.7.152.1 to 36.7.159.25436.7.159.2552,046
24536.7.160.0/2136.7.160.1 to 36.7.167.25436.7.167.2552,046
24636.7.168.0/2136.7.168.1 to 36.7.175.25436.7.175.2552,046
24736.7.176.0/2136.7.176.1 to 36.7.183.25436.7.183.2552,046
24836.7.184.0/2136.7.184.1 to 36.7.191.25436.7.191.2552,046
24936.7.192.0/2136.7.192.1 to 36.7.199.25436.7.199.2552,046
25036.7.200.0/2136.7.200.1 to 36.7.207.25436.7.207.2552,046
25136.7.208.0/2136.7.208.1 to 36.7.215.25436.7.215.2552,046
25236.7.216.0/2136.7.216.1 to 36.7.223.25436.7.223.2552,046
25336.7.224.0/2136.7.224.1 to 36.7.231.25436.7.231.2552,046
25436.7.232.0/2136.7.232.1 to 36.7.239.25436.7.239.2552,046
25536.7.240.0/2136.7.240.1 to 36.7.247.25436.7.247.2552,046
25636.7.248.0/2136.7.248.1 to 36.7.255.25436.7.255.2552,046

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.