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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.

Network18.30.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
18.30.0.0
Broadcast address
18.30.255.255
First usable
18.30.0.1
Last usable
18.30.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
A (default /8)
As numbers
Hex 121E0000 · Integer 303955968 to 304021503
Reverse DNS zone
30.18.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010010.00011110..00000000.0000000018.30.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network00010010.00011110..00000000.0000000018.30.0.0
Broadcast00010010.00011110..11111111.1111111118.30.255.255
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

18.30.0.0/16 makes 256 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
118.30.0.0/2418.30.0.1 to 18.30.0.25418.30.0.255254
218.30.1.0/2418.30.1.1 to 18.30.1.25418.30.1.255254
318.30.2.0/2418.30.2.1 to 18.30.2.25418.30.2.255254
418.30.3.0/2418.30.3.1 to 18.30.3.25418.30.3.255254
518.30.4.0/2418.30.4.1 to 18.30.4.25418.30.4.255254
618.30.5.0/2418.30.5.1 to 18.30.5.25418.30.5.255254
718.30.6.0/2418.30.6.1 to 18.30.6.25418.30.6.255254
818.30.7.0/2418.30.7.1 to 18.30.7.25418.30.7.255254
918.30.8.0/2418.30.8.1 to 18.30.8.25418.30.8.255254
1018.30.9.0/2418.30.9.1 to 18.30.9.25418.30.9.255254
1118.30.10.0/2418.30.10.1 to 18.30.10.25418.30.10.255254
1218.30.11.0/2418.30.11.1 to 18.30.11.25418.30.11.255254
1318.30.12.0/2418.30.12.1 to 18.30.12.25418.30.12.255254
1418.30.13.0/2418.30.13.1 to 18.30.13.25418.30.13.255254
1518.30.14.0/2418.30.14.1 to 18.30.14.25418.30.14.255254
1618.30.15.0/2418.30.15.1 to 18.30.15.25418.30.15.255254
1718.30.16.0/2418.30.16.1 to 18.30.16.25418.30.16.255254
1818.30.17.0/2418.30.17.1 to 18.30.17.25418.30.17.255254
1918.30.18.0/2418.30.18.1 to 18.30.18.25418.30.18.255254
2018.30.19.0/2418.30.19.1 to 18.30.19.25418.30.19.255254
2118.30.20.0/2418.30.20.1 to 18.30.20.25418.30.20.255254
2218.30.21.0/2418.30.21.1 to 18.30.21.25418.30.21.255254
2318.30.22.0/2418.30.22.1 to 18.30.22.25418.30.22.255254
2418.30.23.0/2418.30.23.1 to 18.30.23.25418.30.23.255254
2518.30.24.0/2418.30.24.1 to 18.30.24.25418.30.24.255254
2618.30.25.0/2418.30.25.1 to 18.30.25.25418.30.25.255254
2718.30.26.0/2418.30.26.1 to 18.30.26.25418.30.26.255254
2818.30.27.0/2418.30.27.1 to 18.30.27.25418.30.27.255254
2918.30.28.0/2418.30.28.1 to 18.30.28.25418.30.28.255254
3018.30.29.0/2418.30.29.1 to 18.30.29.25418.30.29.255254
3118.30.30.0/2418.30.30.1 to 18.30.30.25418.30.30.255254
3218.30.31.0/2418.30.31.1 to 18.30.31.25418.30.31.255254
3318.30.32.0/2418.30.32.1 to 18.30.32.25418.30.32.255254
3418.30.33.0/2418.30.33.1 to 18.30.33.25418.30.33.255254
3518.30.34.0/2418.30.34.1 to 18.30.34.25418.30.34.255254
3618.30.35.0/2418.30.35.1 to 18.30.35.25418.30.35.255254
3718.30.36.0/2418.30.36.1 to 18.30.36.25418.30.36.255254
3818.30.37.0/2418.30.37.1 to 18.30.37.25418.30.37.255254
3918.30.38.0/2418.30.38.1 to 18.30.38.25418.30.38.255254
4018.30.39.0/2418.30.39.1 to 18.30.39.25418.30.39.255254
4118.30.40.0/2418.30.40.1 to 18.30.40.25418.30.40.255254
4218.30.41.0/2418.30.41.1 to 18.30.41.25418.30.41.255254
4318.30.42.0/2418.30.42.1 to 18.30.42.25418.30.42.255254
4418.30.43.0/2418.30.43.1 to 18.30.43.25418.30.43.255254
4518.30.44.0/2418.30.44.1 to 18.30.44.25418.30.44.255254
4618.30.45.0/2418.30.45.1 to 18.30.45.25418.30.45.255254
4718.30.46.0/2418.30.46.1 to 18.30.46.25418.30.46.255254
4818.30.47.0/2418.30.47.1 to 18.30.47.25418.30.47.255254
4918.30.48.0/2418.30.48.1 to 18.30.48.25418.30.48.255254
5018.30.49.0/2418.30.49.1 to 18.30.49.25418.30.49.255254
5118.30.50.0/2418.30.50.1 to 18.30.50.25418.30.50.255254
5218.30.51.0/2418.30.51.1 to 18.30.51.25418.30.51.255254
5318.30.52.0/2418.30.52.1 to 18.30.52.25418.30.52.255254
5418.30.53.0/2418.30.53.1 to 18.30.53.25418.30.53.255254
5518.30.54.0/2418.30.54.1 to 18.30.54.25418.30.54.255254
5618.30.55.0/2418.30.55.1 to 18.30.55.25418.30.55.255254
5718.30.56.0/2418.30.56.1 to 18.30.56.25418.30.56.255254
5818.30.57.0/2418.30.57.1 to 18.30.57.25418.30.57.255254
5918.30.58.0/2418.30.58.1 to 18.30.58.25418.30.58.255254
6018.30.59.0/2418.30.59.1 to 18.30.59.25418.30.59.255254
6118.30.60.0/2418.30.60.1 to 18.30.60.25418.30.60.255254
6218.30.61.0/2418.30.61.1 to 18.30.61.25418.30.61.255254
6318.30.62.0/2418.30.62.1 to 18.30.62.25418.30.62.255254
6418.30.63.0/2418.30.63.1 to 18.30.63.25418.30.63.255254
6518.30.64.0/2418.30.64.1 to 18.30.64.25418.30.64.255254
6618.30.65.0/2418.30.65.1 to 18.30.65.25418.30.65.255254
6718.30.66.0/2418.30.66.1 to 18.30.66.25418.30.66.255254
6818.30.67.0/2418.30.67.1 to 18.30.67.25418.30.67.255254
6918.30.68.0/2418.30.68.1 to 18.30.68.25418.30.68.255254
7018.30.69.0/2418.30.69.1 to 18.30.69.25418.30.69.255254
7118.30.70.0/2418.30.70.1 to 18.30.70.25418.30.70.255254
7218.30.71.0/2418.30.71.1 to 18.30.71.25418.30.71.255254
7318.30.72.0/2418.30.72.1 to 18.30.72.25418.30.72.255254
7418.30.73.0/2418.30.73.1 to 18.30.73.25418.30.73.255254
7518.30.74.0/2418.30.74.1 to 18.30.74.25418.30.74.255254
7618.30.75.0/2418.30.75.1 to 18.30.75.25418.30.75.255254
7718.30.76.0/2418.30.76.1 to 18.30.76.25418.30.76.255254
7818.30.77.0/2418.30.77.1 to 18.30.77.25418.30.77.255254
7918.30.78.0/2418.30.78.1 to 18.30.78.25418.30.78.255254
8018.30.79.0/2418.30.79.1 to 18.30.79.25418.30.79.255254
8118.30.80.0/2418.30.80.1 to 18.30.80.25418.30.80.255254
8218.30.81.0/2418.30.81.1 to 18.30.81.25418.30.81.255254
8318.30.82.0/2418.30.82.1 to 18.30.82.25418.30.82.255254
8418.30.83.0/2418.30.83.1 to 18.30.83.25418.30.83.255254
8518.30.84.0/2418.30.84.1 to 18.30.84.25418.30.84.255254
8618.30.85.0/2418.30.85.1 to 18.30.85.25418.30.85.255254
8718.30.86.0/2418.30.86.1 to 18.30.86.25418.30.86.255254
8818.30.87.0/2418.30.87.1 to 18.30.87.25418.30.87.255254
8918.30.88.0/2418.30.88.1 to 18.30.88.25418.30.88.255254
9018.30.89.0/2418.30.89.1 to 18.30.89.25418.30.89.255254
9118.30.90.0/2418.30.90.1 to 18.30.90.25418.30.90.255254
9218.30.91.0/2418.30.91.1 to 18.30.91.25418.30.91.255254
9318.30.92.0/2418.30.92.1 to 18.30.92.25418.30.92.255254
9418.30.93.0/2418.30.93.1 to 18.30.93.25418.30.93.255254
9518.30.94.0/2418.30.94.1 to 18.30.94.25418.30.94.255254
9618.30.95.0/2418.30.95.1 to 18.30.95.25418.30.95.255254
9718.30.96.0/2418.30.96.1 to 18.30.96.25418.30.96.255254
9818.30.97.0/2418.30.97.1 to 18.30.97.25418.30.97.255254
9918.30.98.0/2418.30.98.1 to 18.30.98.25418.30.98.255254
10018.30.99.0/2418.30.99.1 to 18.30.99.25418.30.99.255254
10118.30.100.0/2418.30.100.1 to 18.30.100.25418.30.100.255254
10218.30.101.0/2418.30.101.1 to 18.30.101.25418.30.101.255254
10318.30.102.0/2418.30.102.1 to 18.30.102.25418.30.102.255254
10418.30.103.0/2418.30.103.1 to 18.30.103.25418.30.103.255254
10518.30.104.0/2418.30.104.1 to 18.30.104.25418.30.104.255254
10618.30.105.0/2418.30.105.1 to 18.30.105.25418.30.105.255254
10718.30.106.0/2418.30.106.1 to 18.30.106.25418.30.106.255254
10818.30.107.0/2418.30.107.1 to 18.30.107.25418.30.107.255254
10918.30.108.0/2418.30.108.1 to 18.30.108.25418.30.108.255254
11018.30.109.0/2418.30.109.1 to 18.30.109.25418.30.109.255254
11118.30.110.0/2418.30.110.1 to 18.30.110.25418.30.110.255254
11218.30.111.0/2418.30.111.1 to 18.30.111.25418.30.111.255254
11318.30.112.0/2418.30.112.1 to 18.30.112.25418.30.112.255254
11418.30.113.0/2418.30.113.1 to 18.30.113.25418.30.113.255254
11518.30.114.0/2418.30.114.1 to 18.30.114.25418.30.114.255254
11618.30.115.0/2418.30.115.1 to 18.30.115.25418.30.115.255254
11718.30.116.0/2418.30.116.1 to 18.30.116.25418.30.116.255254
11818.30.117.0/2418.30.117.1 to 18.30.117.25418.30.117.255254
11918.30.118.0/2418.30.118.1 to 18.30.118.25418.30.118.255254
12018.30.119.0/2418.30.119.1 to 18.30.119.25418.30.119.255254
12118.30.120.0/2418.30.120.1 to 18.30.120.25418.30.120.255254
12218.30.121.0/2418.30.121.1 to 18.30.121.25418.30.121.255254
12318.30.122.0/2418.30.122.1 to 18.30.122.25418.30.122.255254
12418.30.123.0/2418.30.123.1 to 18.30.123.25418.30.123.255254
12518.30.124.0/2418.30.124.1 to 18.30.124.25418.30.124.255254
12618.30.125.0/2418.30.125.1 to 18.30.125.25418.30.125.255254
12718.30.126.0/2418.30.126.1 to 18.30.126.25418.30.126.255254
12818.30.127.0/2418.30.127.1 to 18.30.127.25418.30.127.255254
12918.30.128.0/2418.30.128.1 to 18.30.128.25418.30.128.255254
13018.30.129.0/2418.30.129.1 to 18.30.129.25418.30.129.255254
13118.30.130.0/2418.30.130.1 to 18.30.130.25418.30.130.255254
13218.30.131.0/2418.30.131.1 to 18.30.131.25418.30.131.255254
13318.30.132.0/2418.30.132.1 to 18.30.132.25418.30.132.255254
13418.30.133.0/2418.30.133.1 to 18.30.133.25418.30.133.255254
13518.30.134.0/2418.30.134.1 to 18.30.134.25418.30.134.255254
13618.30.135.0/2418.30.135.1 to 18.30.135.25418.30.135.255254
13718.30.136.0/2418.30.136.1 to 18.30.136.25418.30.136.255254
13818.30.137.0/2418.30.137.1 to 18.30.137.25418.30.137.255254
13918.30.138.0/2418.30.138.1 to 18.30.138.25418.30.138.255254
14018.30.139.0/2418.30.139.1 to 18.30.139.25418.30.139.255254
14118.30.140.0/2418.30.140.1 to 18.30.140.25418.30.140.255254
14218.30.141.0/2418.30.141.1 to 18.30.141.25418.30.141.255254
14318.30.142.0/2418.30.142.1 to 18.30.142.25418.30.142.255254
14418.30.143.0/2418.30.143.1 to 18.30.143.25418.30.143.255254
14518.30.144.0/2418.30.144.1 to 18.30.144.25418.30.144.255254
14618.30.145.0/2418.30.145.1 to 18.30.145.25418.30.145.255254
14718.30.146.0/2418.30.146.1 to 18.30.146.25418.30.146.255254
14818.30.147.0/2418.30.147.1 to 18.30.147.25418.30.147.255254
14918.30.148.0/2418.30.148.1 to 18.30.148.25418.30.148.255254
15018.30.149.0/2418.30.149.1 to 18.30.149.25418.30.149.255254
15118.30.150.0/2418.30.150.1 to 18.30.150.25418.30.150.255254
15218.30.151.0/2418.30.151.1 to 18.30.151.25418.30.151.255254
15318.30.152.0/2418.30.152.1 to 18.30.152.25418.30.152.255254
15418.30.153.0/2418.30.153.1 to 18.30.153.25418.30.153.255254
15518.30.154.0/2418.30.154.1 to 18.30.154.25418.30.154.255254
15618.30.155.0/2418.30.155.1 to 18.30.155.25418.30.155.255254
15718.30.156.0/2418.30.156.1 to 18.30.156.25418.30.156.255254
15818.30.157.0/2418.30.157.1 to 18.30.157.25418.30.157.255254
15918.30.158.0/2418.30.158.1 to 18.30.158.25418.30.158.255254
16018.30.159.0/2418.30.159.1 to 18.30.159.25418.30.159.255254
16118.30.160.0/2418.30.160.1 to 18.30.160.25418.30.160.255254
16218.30.161.0/2418.30.161.1 to 18.30.161.25418.30.161.255254
16318.30.162.0/2418.30.162.1 to 18.30.162.25418.30.162.255254
16418.30.163.0/2418.30.163.1 to 18.30.163.25418.30.163.255254
16518.30.164.0/2418.30.164.1 to 18.30.164.25418.30.164.255254
16618.30.165.0/2418.30.165.1 to 18.30.165.25418.30.165.255254
16718.30.166.0/2418.30.166.1 to 18.30.166.25418.30.166.255254
16818.30.167.0/2418.30.167.1 to 18.30.167.25418.30.167.255254
16918.30.168.0/2418.30.168.1 to 18.30.168.25418.30.168.255254
17018.30.169.0/2418.30.169.1 to 18.30.169.25418.30.169.255254
17118.30.170.0/2418.30.170.1 to 18.30.170.25418.30.170.255254
17218.30.171.0/2418.30.171.1 to 18.30.171.25418.30.171.255254
17318.30.172.0/2418.30.172.1 to 18.30.172.25418.30.172.255254
17418.30.173.0/2418.30.173.1 to 18.30.173.25418.30.173.255254
17518.30.174.0/2418.30.174.1 to 18.30.174.25418.30.174.255254
17618.30.175.0/2418.30.175.1 to 18.30.175.25418.30.175.255254
17718.30.176.0/2418.30.176.1 to 18.30.176.25418.30.176.255254
17818.30.177.0/2418.30.177.1 to 18.30.177.25418.30.177.255254
17918.30.178.0/2418.30.178.1 to 18.30.178.25418.30.178.255254
18018.30.179.0/2418.30.179.1 to 18.30.179.25418.30.179.255254
18118.30.180.0/2418.30.180.1 to 18.30.180.25418.30.180.255254
18218.30.181.0/2418.30.181.1 to 18.30.181.25418.30.181.255254
18318.30.182.0/2418.30.182.1 to 18.30.182.25418.30.182.255254
18418.30.183.0/2418.30.183.1 to 18.30.183.25418.30.183.255254
18518.30.184.0/2418.30.184.1 to 18.30.184.25418.30.184.255254
18618.30.185.0/2418.30.185.1 to 18.30.185.25418.30.185.255254
18718.30.186.0/2418.30.186.1 to 18.30.186.25418.30.186.255254
18818.30.187.0/2418.30.187.1 to 18.30.187.25418.30.187.255254
18918.30.188.0/2418.30.188.1 to 18.30.188.25418.30.188.255254
19018.30.189.0/2418.30.189.1 to 18.30.189.25418.30.189.255254
19118.30.190.0/2418.30.190.1 to 18.30.190.25418.30.190.255254
19218.30.191.0/2418.30.191.1 to 18.30.191.25418.30.191.255254
19318.30.192.0/2418.30.192.1 to 18.30.192.25418.30.192.255254
19418.30.193.0/2418.30.193.1 to 18.30.193.25418.30.193.255254
19518.30.194.0/2418.30.194.1 to 18.30.194.25418.30.194.255254
19618.30.195.0/2418.30.195.1 to 18.30.195.25418.30.195.255254
19718.30.196.0/2418.30.196.1 to 18.30.196.25418.30.196.255254
19818.30.197.0/2418.30.197.1 to 18.30.197.25418.30.197.255254
19918.30.198.0/2418.30.198.1 to 18.30.198.25418.30.198.255254
20018.30.199.0/2418.30.199.1 to 18.30.199.25418.30.199.255254
20118.30.200.0/2418.30.200.1 to 18.30.200.25418.30.200.255254
20218.30.201.0/2418.30.201.1 to 18.30.201.25418.30.201.255254
20318.30.202.0/2418.30.202.1 to 18.30.202.25418.30.202.255254
20418.30.203.0/2418.30.203.1 to 18.30.203.25418.30.203.255254
20518.30.204.0/2418.30.204.1 to 18.30.204.25418.30.204.255254
20618.30.205.0/2418.30.205.1 to 18.30.205.25418.30.205.255254
20718.30.206.0/2418.30.206.1 to 18.30.206.25418.30.206.255254
20818.30.207.0/2418.30.207.1 to 18.30.207.25418.30.207.255254
20918.30.208.0/2418.30.208.1 to 18.30.208.25418.30.208.255254
21018.30.209.0/2418.30.209.1 to 18.30.209.25418.30.209.255254
21118.30.210.0/2418.30.210.1 to 18.30.210.25418.30.210.255254
21218.30.211.0/2418.30.211.1 to 18.30.211.25418.30.211.255254
21318.30.212.0/2418.30.212.1 to 18.30.212.25418.30.212.255254
21418.30.213.0/2418.30.213.1 to 18.30.213.25418.30.213.255254
21518.30.214.0/2418.30.214.1 to 18.30.214.25418.30.214.255254
21618.30.215.0/2418.30.215.1 to 18.30.215.25418.30.215.255254
21718.30.216.0/2418.30.216.1 to 18.30.216.25418.30.216.255254
21818.30.217.0/2418.30.217.1 to 18.30.217.25418.30.217.255254
21918.30.218.0/2418.30.218.1 to 18.30.218.25418.30.218.255254
22018.30.219.0/2418.30.219.1 to 18.30.219.25418.30.219.255254
22118.30.220.0/2418.30.220.1 to 18.30.220.25418.30.220.255254
22218.30.221.0/2418.30.221.1 to 18.30.221.25418.30.221.255254
22318.30.222.0/2418.30.222.1 to 18.30.222.25418.30.222.255254
22418.30.223.0/2418.30.223.1 to 18.30.223.25418.30.223.255254
22518.30.224.0/2418.30.224.1 to 18.30.224.25418.30.224.255254
22618.30.225.0/2418.30.225.1 to 18.30.225.25418.30.225.255254
22718.30.226.0/2418.30.226.1 to 18.30.226.25418.30.226.255254
22818.30.227.0/2418.30.227.1 to 18.30.227.25418.30.227.255254
22918.30.228.0/2418.30.228.1 to 18.30.228.25418.30.228.255254
23018.30.229.0/2418.30.229.1 to 18.30.229.25418.30.229.255254
23118.30.230.0/2418.30.230.1 to 18.30.230.25418.30.230.255254
23218.30.231.0/2418.30.231.1 to 18.30.231.25418.30.231.255254
23318.30.232.0/2418.30.232.1 to 18.30.232.25418.30.232.255254
23418.30.233.0/2418.30.233.1 to 18.30.233.25418.30.233.255254
23518.30.234.0/2418.30.234.1 to 18.30.234.25418.30.234.255254
23618.30.235.0/2418.30.235.1 to 18.30.235.25418.30.235.255254
23718.30.236.0/2418.30.236.1 to 18.30.236.25418.30.236.255254
23818.30.237.0/2418.30.237.1 to 18.30.237.25418.30.237.255254
23918.30.238.0/2418.30.238.1 to 18.30.238.25418.30.238.255254
24018.30.239.0/2418.30.239.1 to 18.30.239.25418.30.239.255254
24118.30.240.0/2418.30.240.1 to 18.30.240.25418.30.240.255254
24218.30.241.0/2418.30.241.1 to 18.30.241.25418.30.241.255254
24318.30.242.0/2418.30.242.1 to 18.30.242.25418.30.242.255254
24418.30.243.0/2418.30.243.1 to 18.30.243.25418.30.243.255254
24518.30.244.0/2418.30.244.1 to 18.30.244.25418.30.244.255254
24618.30.245.0/2418.30.245.1 to 18.30.245.25418.30.245.255254
24718.30.246.0/2418.30.246.1 to 18.30.246.25418.30.246.255254
24818.30.247.0/2418.30.247.1 to 18.30.247.25418.30.247.255254
24918.30.248.0/2418.30.248.1 to 18.30.248.25418.30.248.255254
25018.30.249.0/2418.30.249.1 to 18.30.249.25418.30.249.255254
25118.30.250.0/2418.30.250.1 to 18.30.250.25418.30.250.255254
25218.30.251.0/2418.30.251.1 to 18.30.251.25418.30.251.255254
25318.30.252.0/2418.30.252.1 to 18.30.252.25418.30.252.255254
25418.30.253.0/2418.30.253.1 to 18.30.253.25418.30.253.255254
25518.30.254.0/2418.30.254.1 to 18.30.254.25418.30.254.255254
25618.30.255.0/2418.30.255.1 to 18.30.255.25418.30.255.255254

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.