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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.

Network18.192.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
18.192.0.0
Broadcast address
18.255.255.255
First usable
18.192.0.1
Last usable
18.255.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
A (default /8)
As numbers
Hex 12C00000 · Integer 314572800 to 318767103
Reverse DNS zones
192.18.in-addr.arpa
193.18.in-addr.arpa
194.18.in-addr.arpa
195.18.in-addr.arpa
196.18.in-addr.arpa
197.18.in-addr.arpa
198.18.in-addr.arpa
199.18.in-addr.arpa
200.18.in-addr.arpa
201.18.in-addr.arpa
202.18.in-addr.arpa
203.18.in-addr.arpa
204.18.in-addr.arpa
205.18.in-addr.arpa
206.18.in-addr.arpa
207.18.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010010.11000000.00000000.0000000018.192.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00010010.11000000.00000000.0000000018.192.0.0
Broadcast00010010.11111111.11111111.1111111118.255.255.255
Split into smaller subnets/21
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

18.192.0.0/10 makes 2,048 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
118.192.0.0/2118.192.0.1 to 18.192.7.25418.192.7.2552,046
218.192.8.0/2118.192.8.1 to 18.192.15.25418.192.15.2552,046
318.192.16.0/2118.192.16.1 to 18.192.23.25418.192.23.2552,046
418.192.24.0/2118.192.24.1 to 18.192.31.25418.192.31.2552,046
518.192.32.0/2118.192.32.1 to 18.192.39.25418.192.39.2552,046
618.192.40.0/2118.192.40.1 to 18.192.47.25418.192.47.2552,046
718.192.48.0/2118.192.48.1 to 18.192.55.25418.192.55.2552,046
818.192.56.0/2118.192.56.1 to 18.192.63.25418.192.63.2552,046
918.192.64.0/2118.192.64.1 to 18.192.71.25418.192.71.2552,046
1018.192.72.0/2118.192.72.1 to 18.192.79.25418.192.79.2552,046
1118.192.80.0/2118.192.80.1 to 18.192.87.25418.192.87.2552,046
1218.192.88.0/2118.192.88.1 to 18.192.95.25418.192.95.2552,046
1318.192.96.0/2118.192.96.1 to 18.192.103.25418.192.103.2552,046
1418.192.104.0/2118.192.104.1 to 18.192.111.25418.192.111.2552,046
1518.192.112.0/2118.192.112.1 to 18.192.119.25418.192.119.2552,046
1618.192.120.0/2118.192.120.1 to 18.192.127.25418.192.127.2552,046
1718.192.128.0/2118.192.128.1 to 18.192.135.25418.192.135.2552,046
1818.192.136.0/2118.192.136.1 to 18.192.143.25418.192.143.2552,046
1918.192.144.0/2118.192.144.1 to 18.192.151.25418.192.151.2552,046
2018.192.152.0/2118.192.152.1 to 18.192.159.25418.192.159.2552,046
2118.192.160.0/2118.192.160.1 to 18.192.167.25418.192.167.2552,046
2218.192.168.0/2118.192.168.1 to 18.192.175.25418.192.175.2552,046
2318.192.176.0/2118.192.176.1 to 18.192.183.25418.192.183.2552,046
2418.192.184.0/2118.192.184.1 to 18.192.191.25418.192.191.2552,046
2518.192.192.0/2118.192.192.1 to 18.192.199.25418.192.199.2552,046
2618.192.200.0/2118.192.200.1 to 18.192.207.25418.192.207.2552,046
2718.192.208.0/2118.192.208.1 to 18.192.215.25418.192.215.2552,046
2818.192.216.0/2118.192.216.1 to 18.192.223.25418.192.223.2552,046
2918.192.224.0/2118.192.224.1 to 18.192.231.25418.192.231.2552,046
3018.192.232.0/2118.192.232.1 to 18.192.239.25418.192.239.2552,046
3118.192.240.0/2118.192.240.1 to 18.192.247.25418.192.247.2552,046
3218.192.248.0/2118.192.248.1 to 18.192.255.25418.192.255.2552,046
3318.193.0.0/2118.193.0.1 to 18.193.7.25418.193.7.2552,046
3418.193.8.0/2118.193.8.1 to 18.193.15.25418.193.15.2552,046
3518.193.16.0/2118.193.16.1 to 18.193.23.25418.193.23.2552,046
3618.193.24.0/2118.193.24.1 to 18.193.31.25418.193.31.2552,046
3718.193.32.0/2118.193.32.1 to 18.193.39.25418.193.39.2552,046
3818.193.40.0/2118.193.40.1 to 18.193.47.25418.193.47.2552,046
3918.193.48.0/2118.193.48.1 to 18.193.55.25418.193.55.2552,046
4018.193.56.0/2118.193.56.1 to 18.193.63.25418.193.63.2552,046
4118.193.64.0/2118.193.64.1 to 18.193.71.25418.193.71.2552,046
4218.193.72.0/2118.193.72.1 to 18.193.79.25418.193.79.2552,046
4318.193.80.0/2118.193.80.1 to 18.193.87.25418.193.87.2552,046
4418.193.88.0/2118.193.88.1 to 18.193.95.25418.193.95.2552,046
4518.193.96.0/2118.193.96.1 to 18.193.103.25418.193.103.2552,046
4618.193.104.0/2118.193.104.1 to 18.193.111.25418.193.111.2552,046
4718.193.112.0/2118.193.112.1 to 18.193.119.25418.193.119.2552,046
4818.193.120.0/2118.193.120.1 to 18.193.127.25418.193.127.2552,046
4918.193.128.0/2118.193.128.1 to 18.193.135.25418.193.135.2552,046
5018.193.136.0/2118.193.136.1 to 18.193.143.25418.193.143.2552,046
5118.193.144.0/2118.193.144.1 to 18.193.151.25418.193.151.2552,046
5218.193.152.0/2118.193.152.1 to 18.193.159.25418.193.159.2552,046
5318.193.160.0/2118.193.160.1 to 18.193.167.25418.193.167.2552,046
5418.193.168.0/2118.193.168.1 to 18.193.175.25418.193.175.2552,046
5518.193.176.0/2118.193.176.1 to 18.193.183.25418.193.183.2552,046
5618.193.184.0/2118.193.184.1 to 18.193.191.25418.193.191.2552,046
5718.193.192.0/2118.193.192.1 to 18.193.199.25418.193.199.2552,046
5818.193.200.0/2118.193.200.1 to 18.193.207.25418.193.207.2552,046
5918.193.208.0/2118.193.208.1 to 18.193.215.25418.193.215.2552,046
6018.193.216.0/2118.193.216.1 to 18.193.223.25418.193.223.2552,046
6118.193.224.0/2118.193.224.1 to 18.193.231.25418.193.231.2552,046
6218.193.232.0/2118.193.232.1 to 18.193.239.25418.193.239.2552,046
6318.193.240.0/2118.193.240.1 to 18.193.247.25418.193.247.2552,046
6418.193.248.0/2118.193.248.1 to 18.193.255.25418.193.255.2552,046
6518.194.0.0/2118.194.0.1 to 18.194.7.25418.194.7.2552,046
6618.194.8.0/2118.194.8.1 to 18.194.15.25418.194.15.2552,046
6718.194.16.0/2118.194.16.1 to 18.194.23.25418.194.23.2552,046
6818.194.24.0/2118.194.24.1 to 18.194.31.25418.194.31.2552,046
6918.194.32.0/2118.194.32.1 to 18.194.39.25418.194.39.2552,046
7018.194.40.0/2118.194.40.1 to 18.194.47.25418.194.47.2552,046
7118.194.48.0/2118.194.48.1 to 18.194.55.25418.194.55.2552,046
7218.194.56.0/2118.194.56.1 to 18.194.63.25418.194.63.2552,046
7318.194.64.0/2118.194.64.1 to 18.194.71.25418.194.71.2552,046
7418.194.72.0/2118.194.72.1 to 18.194.79.25418.194.79.2552,046
7518.194.80.0/2118.194.80.1 to 18.194.87.25418.194.87.2552,046
7618.194.88.0/2118.194.88.1 to 18.194.95.25418.194.95.2552,046
7718.194.96.0/2118.194.96.1 to 18.194.103.25418.194.103.2552,046
7818.194.104.0/2118.194.104.1 to 18.194.111.25418.194.111.2552,046
7918.194.112.0/2118.194.112.1 to 18.194.119.25418.194.119.2552,046
8018.194.120.0/2118.194.120.1 to 18.194.127.25418.194.127.2552,046
8118.194.128.0/2118.194.128.1 to 18.194.135.25418.194.135.2552,046
8218.194.136.0/2118.194.136.1 to 18.194.143.25418.194.143.2552,046
8318.194.144.0/2118.194.144.1 to 18.194.151.25418.194.151.2552,046
8418.194.152.0/2118.194.152.1 to 18.194.159.25418.194.159.2552,046
8518.194.160.0/2118.194.160.1 to 18.194.167.25418.194.167.2552,046
8618.194.168.0/2118.194.168.1 to 18.194.175.25418.194.175.2552,046
8718.194.176.0/2118.194.176.1 to 18.194.183.25418.194.183.2552,046
8818.194.184.0/2118.194.184.1 to 18.194.191.25418.194.191.2552,046
8918.194.192.0/2118.194.192.1 to 18.194.199.25418.194.199.2552,046
9018.194.200.0/2118.194.200.1 to 18.194.207.25418.194.207.2552,046
9118.194.208.0/2118.194.208.1 to 18.194.215.25418.194.215.2552,046
9218.194.216.0/2118.194.216.1 to 18.194.223.25418.194.223.2552,046
9318.194.224.0/2118.194.224.1 to 18.194.231.25418.194.231.2552,046
9418.194.232.0/2118.194.232.1 to 18.194.239.25418.194.239.2552,046
9518.194.240.0/2118.194.240.1 to 18.194.247.25418.194.247.2552,046
9618.194.248.0/2118.194.248.1 to 18.194.255.25418.194.255.2552,046
9718.195.0.0/2118.195.0.1 to 18.195.7.25418.195.7.2552,046
9818.195.8.0/2118.195.8.1 to 18.195.15.25418.195.15.2552,046
9918.195.16.0/2118.195.16.1 to 18.195.23.25418.195.23.2552,046
10018.195.24.0/2118.195.24.1 to 18.195.31.25418.195.31.2552,046
10118.195.32.0/2118.195.32.1 to 18.195.39.25418.195.39.2552,046
10218.195.40.0/2118.195.40.1 to 18.195.47.25418.195.47.2552,046
10318.195.48.0/2118.195.48.1 to 18.195.55.25418.195.55.2552,046
10418.195.56.0/2118.195.56.1 to 18.195.63.25418.195.63.2552,046
10518.195.64.0/2118.195.64.1 to 18.195.71.25418.195.71.2552,046
10618.195.72.0/2118.195.72.1 to 18.195.79.25418.195.79.2552,046
10718.195.80.0/2118.195.80.1 to 18.195.87.25418.195.87.2552,046
10818.195.88.0/2118.195.88.1 to 18.195.95.25418.195.95.2552,046
10918.195.96.0/2118.195.96.1 to 18.195.103.25418.195.103.2552,046
11018.195.104.0/2118.195.104.1 to 18.195.111.25418.195.111.2552,046
11118.195.112.0/2118.195.112.1 to 18.195.119.25418.195.119.2552,046
11218.195.120.0/2118.195.120.1 to 18.195.127.25418.195.127.2552,046
11318.195.128.0/2118.195.128.1 to 18.195.135.25418.195.135.2552,046
11418.195.136.0/2118.195.136.1 to 18.195.143.25418.195.143.2552,046
11518.195.144.0/2118.195.144.1 to 18.195.151.25418.195.151.2552,046
11618.195.152.0/2118.195.152.1 to 18.195.159.25418.195.159.2552,046
11718.195.160.0/2118.195.160.1 to 18.195.167.25418.195.167.2552,046
11818.195.168.0/2118.195.168.1 to 18.195.175.25418.195.175.2552,046
11918.195.176.0/2118.195.176.1 to 18.195.183.25418.195.183.2552,046
12018.195.184.0/2118.195.184.1 to 18.195.191.25418.195.191.2552,046
12118.195.192.0/2118.195.192.1 to 18.195.199.25418.195.199.2552,046
12218.195.200.0/2118.195.200.1 to 18.195.207.25418.195.207.2552,046
12318.195.208.0/2118.195.208.1 to 18.195.215.25418.195.215.2552,046
12418.195.216.0/2118.195.216.1 to 18.195.223.25418.195.223.2552,046
12518.195.224.0/2118.195.224.1 to 18.195.231.25418.195.231.2552,046
12618.195.232.0/2118.195.232.1 to 18.195.239.25418.195.239.2552,046
12718.195.240.0/2118.195.240.1 to 18.195.247.25418.195.247.2552,046
12818.195.248.0/2118.195.248.1 to 18.195.255.25418.195.255.2552,046
12918.196.0.0/2118.196.0.1 to 18.196.7.25418.196.7.2552,046
13018.196.8.0/2118.196.8.1 to 18.196.15.25418.196.15.2552,046
13118.196.16.0/2118.196.16.1 to 18.196.23.25418.196.23.2552,046
13218.196.24.0/2118.196.24.1 to 18.196.31.25418.196.31.2552,046
13318.196.32.0/2118.196.32.1 to 18.196.39.25418.196.39.2552,046
13418.196.40.0/2118.196.40.1 to 18.196.47.25418.196.47.2552,046
13518.196.48.0/2118.196.48.1 to 18.196.55.25418.196.55.2552,046
13618.196.56.0/2118.196.56.1 to 18.196.63.25418.196.63.2552,046
13718.196.64.0/2118.196.64.1 to 18.196.71.25418.196.71.2552,046
13818.196.72.0/2118.196.72.1 to 18.196.79.25418.196.79.2552,046
13918.196.80.0/2118.196.80.1 to 18.196.87.25418.196.87.2552,046
14018.196.88.0/2118.196.88.1 to 18.196.95.25418.196.95.2552,046
14118.196.96.0/2118.196.96.1 to 18.196.103.25418.196.103.2552,046
14218.196.104.0/2118.196.104.1 to 18.196.111.25418.196.111.2552,046
14318.196.112.0/2118.196.112.1 to 18.196.119.25418.196.119.2552,046
14418.196.120.0/2118.196.120.1 to 18.196.127.25418.196.127.2552,046
14518.196.128.0/2118.196.128.1 to 18.196.135.25418.196.135.2552,046
14618.196.136.0/2118.196.136.1 to 18.196.143.25418.196.143.2552,046
14718.196.144.0/2118.196.144.1 to 18.196.151.25418.196.151.2552,046
14818.196.152.0/2118.196.152.1 to 18.196.159.25418.196.159.2552,046
14918.196.160.0/2118.196.160.1 to 18.196.167.25418.196.167.2552,046
15018.196.168.0/2118.196.168.1 to 18.196.175.25418.196.175.2552,046
15118.196.176.0/2118.196.176.1 to 18.196.183.25418.196.183.2552,046
15218.196.184.0/2118.196.184.1 to 18.196.191.25418.196.191.2552,046
15318.196.192.0/2118.196.192.1 to 18.196.199.25418.196.199.2552,046
15418.196.200.0/2118.196.200.1 to 18.196.207.25418.196.207.2552,046
15518.196.208.0/2118.196.208.1 to 18.196.215.25418.196.215.2552,046
15618.196.216.0/2118.196.216.1 to 18.196.223.25418.196.223.2552,046
15718.196.224.0/2118.196.224.1 to 18.196.231.25418.196.231.2552,046
15818.196.232.0/2118.196.232.1 to 18.196.239.25418.196.239.2552,046
15918.196.240.0/2118.196.240.1 to 18.196.247.25418.196.247.2552,046
16018.196.248.0/2118.196.248.1 to 18.196.255.25418.196.255.2552,046
16118.197.0.0/2118.197.0.1 to 18.197.7.25418.197.7.2552,046
16218.197.8.0/2118.197.8.1 to 18.197.15.25418.197.15.2552,046
16318.197.16.0/2118.197.16.1 to 18.197.23.25418.197.23.2552,046
16418.197.24.0/2118.197.24.1 to 18.197.31.25418.197.31.2552,046
16518.197.32.0/2118.197.32.1 to 18.197.39.25418.197.39.2552,046
16618.197.40.0/2118.197.40.1 to 18.197.47.25418.197.47.2552,046
16718.197.48.0/2118.197.48.1 to 18.197.55.25418.197.55.2552,046
16818.197.56.0/2118.197.56.1 to 18.197.63.25418.197.63.2552,046
16918.197.64.0/2118.197.64.1 to 18.197.71.25418.197.71.2552,046
17018.197.72.0/2118.197.72.1 to 18.197.79.25418.197.79.2552,046
17118.197.80.0/2118.197.80.1 to 18.197.87.25418.197.87.2552,046
17218.197.88.0/2118.197.88.1 to 18.197.95.25418.197.95.2552,046
17318.197.96.0/2118.197.96.1 to 18.197.103.25418.197.103.2552,046
17418.197.104.0/2118.197.104.1 to 18.197.111.25418.197.111.2552,046
17518.197.112.0/2118.197.112.1 to 18.197.119.25418.197.119.2552,046
17618.197.120.0/2118.197.120.1 to 18.197.127.25418.197.127.2552,046
17718.197.128.0/2118.197.128.1 to 18.197.135.25418.197.135.2552,046
17818.197.136.0/2118.197.136.1 to 18.197.143.25418.197.143.2552,046
17918.197.144.0/2118.197.144.1 to 18.197.151.25418.197.151.2552,046
18018.197.152.0/2118.197.152.1 to 18.197.159.25418.197.159.2552,046
18118.197.160.0/2118.197.160.1 to 18.197.167.25418.197.167.2552,046
18218.197.168.0/2118.197.168.1 to 18.197.175.25418.197.175.2552,046
18318.197.176.0/2118.197.176.1 to 18.197.183.25418.197.183.2552,046
18418.197.184.0/2118.197.184.1 to 18.197.191.25418.197.191.2552,046
18518.197.192.0/2118.197.192.1 to 18.197.199.25418.197.199.2552,046
18618.197.200.0/2118.197.200.1 to 18.197.207.25418.197.207.2552,046
18718.197.208.0/2118.197.208.1 to 18.197.215.25418.197.215.2552,046
18818.197.216.0/2118.197.216.1 to 18.197.223.25418.197.223.2552,046
18918.197.224.0/2118.197.224.1 to 18.197.231.25418.197.231.2552,046
19018.197.232.0/2118.197.232.1 to 18.197.239.25418.197.239.2552,046
19118.197.240.0/2118.197.240.1 to 18.197.247.25418.197.247.2552,046
19218.197.248.0/2118.197.248.1 to 18.197.255.25418.197.255.2552,046
19318.198.0.0/2118.198.0.1 to 18.198.7.25418.198.7.2552,046
19418.198.8.0/2118.198.8.1 to 18.198.15.25418.198.15.2552,046
19518.198.16.0/2118.198.16.1 to 18.198.23.25418.198.23.2552,046
19618.198.24.0/2118.198.24.1 to 18.198.31.25418.198.31.2552,046
19718.198.32.0/2118.198.32.1 to 18.198.39.25418.198.39.2552,046
19818.198.40.0/2118.198.40.1 to 18.198.47.25418.198.47.2552,046
19918.198.48.0/2118.198.48.1 to 18.198.55.25418.198.55.2552,046
20018.198.56.0/2118.198.56.1 to 18.198.63.25418.198.63.2552,046
20118.198.64.0/2118.198.64.1 to 18.198.71.25418.198.71.2552,046
20218.198.72.0/2118.198.72.1 to 18.198.79.25418.198.79.2552,046
20318.198.80.0/2118.198.80.1 to 18.198.87.25418.198.87.2552,046
20418.198.88.0/2118.198.88.1 to 18.198.95.25418.198.95.2552,046
20518.198.96.0/2118.198.96.1 to 18.198.103.25418.198.103.2552,046
20618.198.104.0/2118.198.104.1 to 18.198.111.25418.198.111.2552,046
20718.198.112.0/2118.198.112.1 to 18.198.119.25418.198.119.2552,046
20818.198.120.0/2118.198.120.1 to 18.198.127.25418.198.127.2552,046
20918.198.128.0/2118.198.128.1 to 18.198.135.25418.198.135.2552,046
21018.198.136.0/2118.198.136.1 to 18.198.143.25418.198.143.2552,046
21118.198.144.0/2118.198.144.1 to 18.198.151.25418.198.151.2552,046
21218.198.152.0/2118.198.152.1 to 18.198.159.25418.198.159.2552,046
21318.198.160.0/2118.198.160.1 to 18.198.167.25418.198.167.2552,046
21418.198.168.0/2118.198.168.1 to 18.198.175.25418.198.175.2552,046
21518.198.176.0/2118.198.176.1 to 18.198.183.25418.198.183.2552,046
21618.198.184.0/2118.198.184.1 to 18.198.191.25418.198.191.2552,046
21718.198.192.0/2118.198.192.1 to 18.198.199.25418.198.199.2552,046
21818.198.200.0/2118.198.200.1 to 18.198.207.25418.198.207.2552,046
21918.198.208.0/2118.198.208.1 to 18.198.215.25418.198.215.2552,046
22018.198.216.0/2118.198.216.1 to 18.198.223.25418.198.223.2552,046
22118.198.224.0/2118.198.224.1 to 18.198.231.25418.198.231.2552,046
22218.198.232.0/2118.198.232.1 to 18.198.239.25418.198.239.2552,046
22318.198.240.0/2118.198.240.1 to 18.198.247.25418.198.247.2552,046
22418.198.248.0/2118.198.248.1 to 18.198.255.25418.198.255.2552,046
22518.199.0.0/2118.199.0.1 to 18.199.7.25418.199.7.2552,046
22618.199.8.0/2118.199.8.1 to 18.199.15.25418.199.15.2552,046
22718.199.16.0/2118.199.16.1 to 18.199.23.25418.199.23.2552,046
22818.199.24.0/2118.199.24.1 to 18.199.31.25418.199.31.2552,046
22918.199.32.0/2118.199.32.1 to 18.199.39.25418.199.39.2552,046
23018.199.40.0/2118.199.40.1 to 18.199.47.25418.199.47.2552,046
23118.199.48.0/2118.199.48.1 to 18.199.55.25418.199.55.2552,046
23218.199.56.0/2118.199.56.1 to 18.199.63.25418.199.63.2552,046
23318.199.64.0/2118.199.64.1 to 18.199.71.25418.199.71.2552,046
23418.199.72.0/2118.199.72.1 to 18.199.79.25418.199.79.2552,046
23518.199.80.0/2118.199.80.1 to 18.199.87.25418.199.87.2552,046
23618.199.88.0/2118.199.88.1 to 18.199.95.25418.199.95.2552,046
23718.199.96.0/2118.199.96.1 to 18.199.103.25418.199.103.2552,046
23818.199.104.0/2118.199.104.1 to 18.199.111.25418.199.111.2552,046
23918.199.112.0/2118.199.112.1 to 18.199.119.25418.199.119.2552,046
24018.199.120.0/2118.199.120.1 to 18.199.127.25418.199.127.2552,046
24118.199.128.0/2118.199.128.1 to 18.199.135.25418.199.135.2552,046
24218.199.136.0/2118.199.136.1 to 18.199.143.25418.199.143.2552,046
24318.199.144.0/2118.199.144.1 to 18.199.151.25418.199.151.2552,046
24418.199.152.0/2118.199.152.1 to 18.199.159.25418.199.159.2552,046
24518.199.160.0/2118.199.160.1 to 18.199.167.25418.199.167.2552,046
24618.199.168.0/2118.199.168.1 to 18.199.175.25418.199.175.2552,046
24718.199.176.0/2118.199.176.1 to 18.199.183.25418.199.183.2552,046
24818.199.184.0/2118.199.184.1 to 18.199.191.25418.199.191.2552,046
24918.199.192.0/2118.199.192.1 to 18.199.199.25418.199.199.2552,046
25018.199.200.0/2118.199.200.1 to 18.199.207.25418.199.207.2552,046
25118.199.208.0/2118.199.208.1 to 18.199.215.25418.199.215.2552,046
25218.199.216.0/2118.199.216.1 to 18.199.223.25418.199.223.2552,046
25318.199.224.0/2118.199.224.1 to 18.199.231.25418.199.231.2552,046
25418.199.232.0/2118.199.232.1 to 18.199.239.25418.199.239.2552,046
25518.199.240.0/2118.199.240.1 to 18.199.247.25418.199.247.2552,046
25618.199.248.0/2118.199.248.1 to 18.199.255.25418.199.255.2552,046

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.