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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.

Network18.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
18.0.0.0
Broadcast address
19.255.255.255
First usable
18.0.0.1
Last usable
19.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
A (default /8)
As numbers
Hex 12000000 · Integer 301989888 to 335544319
Reverse DNS zones
18.in-addr.arpa
19.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010010.00000000.00000000.0000000018.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network00010010.00000000.00000000.0000000018.0.0.0
Broadcast00010011.11111111.11111111.1111111119.255.255.255
Split into smaller subnets/16
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

18.0.0.0/7 makes 512 subnets of /16; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
118.0.0.0/1618.0.0.1 to 18.0.255.25418.0.255.25565,534
218.1.0.0/1618.1.0.1 to 18.1.255.25418.1.255.25565,534
318.2.0.0/1618.2.0.1 to 18.2.255.25418.2.255.25565,534
418.3.0.0/1618.3.0.1 to 18.3.255.25418.3.255.25565,534
518.4.0.0/1618.4.0.1 to 18.4.255.25418.4.255.25565,534
618.5.0.0/1618.5.0.1 to 18.5.255.25418.5.255.25565,534
718.6.0.0/1618.6.0.1 to 18.6.255.25418.6.255.25565,534
818.7.0.0/1618.7.0.1 to 18.7.255.25418.7.255.25565,534
918.8.0.0/1618.8.0.1 to 18.8.255.25418.8.255.25565,534
1018.9.0.0/1618.9.0.1 to 18.9.255.25418.9.255.25565,534
1118.10.0.0/1618.10.0.1 to 18.10.255.25418.10.255.25565,534
1218.11.0.0/1618.11.0.1 to 18.11.255.25418.11.255.25565,534
1318.12.0.0/1618.12.0.1 to 18.12.255.25418.12.255.25565,534
1418.13.0.0/1618.13.0.1 to 18.13.255.25418.13.255.25565,534
1518.14.0.0/1618.14.0.1 to 18.14.255.25418.14.255.25565,534
1618.15.0.0/1618.15.0.1 to 18.15.255.25418.15.255.25565,534
1718.16.0.0/1618.16.0.1 to 18.16.255.25418.16.255.25565,534
1818.17.0.0/1618.17.0.1 to 18.17.255.25418.17.255.25565,534
1918.18.0.0/1618.18.0.1 to 18.18.255.25418.18.255.25565,534
2018.19.0.0/1618.19.0.1 to 18.19.255.25418.19.255.25565,534
2118.20.0.0/1618.20.0.1 to 18.20.255.25418.20.255.25565,534
2218.21.0.0/1618.21.0.1 to 18.21.255.25418.21.255.25565,534
2318.22.0.0/1618.22.0.1 to 18.22.255.25418.22.255.25565,534
2418.23.0.0/1618.23.0.1 to 18.23.255.25418.23.255.25565,534
2518.24.0.0/1618.24.0.1 to 18.24.255.25418.24.255.25565,534
2618.25.0.0/1618.25.0.1 to 18.25.255.25418.25.255.25565,534
2718.26.0.0/1618.26.0.1 to 18.26.255.25418.26.255.25565,534
2818.27.0.0/1618.27.0.1 to 18.27.255.25418.27.255.25565,534
2918.28.0.0/1618.28.0.1 to 18.28.255.25418.28.255.25565,534
3018.29.0.0/1618.29.0.1 to 18.29.255.25418.29.255.25565,534
3118.30.0.0/1618.30.0.1 to 18.30.255.25418.30.255.25565,534
3218.31.0.0/1618.31.0.1 to 18.31.255.25418.31.255.25565,534
3318.32.0.0/1618.32.0.1 to 18.32.255.25418.32.255.25565,534
3418.33.0.0/1618.33.0.1 to 18.33.255.25418.33.255.25565,534
3518.34.0.0/1618.34.0.1 to 18.34.255.25418.34.255.25565,534
3618.35.0.0/1618.35.0.1 to 18.35.255.25418.35.255.25565,534
3718.36.0.0/1618.36.0.1 to 18.36.255.25418.36.255.25565,534
3818.37.0.0/1618.37.0.1 to 18.37.255.25418.37.255.25565,534
3918.38.0.0/1618.38.0.1 to 18.38.255.25418.38.255.25565,534
4018.39.0.0/1618.39.0.1 to 18.39.255.25418.39.255.25565,534
4118.40.0.0/1618.40.0.1 to 18.40.255.25418.40.255.25565,534
4218.41.0.0/1618.41.0.1 to 18.41.255.25418.41.255.25565,534
4318.42.0.0/1618.42.0.1 to 18.42.255.25418.42.255.25565,534
4418.43.0.0/1618.43.0.1 to 18.43.255.25418.43.255.25565,534
4518.44.0.0/1618.44.0.1 to 18.44.255.25418.44.255.25565,534
4618.45.0.0/1618.45.0.1 to 18.45.255.25418.45.255.25565,534
4718.46.0.0/1618.46.0.1 to 18.46.255.25418.46.255.25565,534
4818.47.0.0/1618.47.0.1 to 18.47.255.25418.47.255.25565,534
4918.48.0.0/1618.48.0.1 to 18.48.255.25418.48.255.25565,534
5018.49.0.0/1618.49.0.1 to 18.49.255.25418.49.255.25565,534
5118.50.0.0/1618.50.0.1 to 18.50.255.25418.50.255.25565,534
5218.51.0.0/1618.51.0.1 to 18.51.255.25418.51.255.25565,534
5318.52.0.0/1618.52.0.1 to 18.52.255.25418.52.255.25565,534
5418.53.0.0/1618.53.0.1 to 18.53.255.25418.53.255.25565,534
5518.54.0.0/1618.54.0.1 to 18.54.255.25418.54.255.25565,534
5618.55.0.0/1618.55.0.1 to 18.55.255.25418.55.255.25565,534
5718.56.0.0/1618.56.0.1 to 18.56.255.25418.56.255.25565,534
5818.57.0.0/1618.57.0.1 to 18.57.255.25418.57.255.25565,534
5918.58.0.0/1618.58.0.1 to 18.58.255.25418.58.255.25565,534
6018.59.0.0/1618.59.0.1 to 18.59.255.25418.59.255.25565,534
6118.60.0.0/1618.60.0.1 to 18.60.255.25418.60.255.25565,534
6218.61.0.0/1618.61.0.1 to 18.61.255.25418.61.255.25565,534
6318.62.0.0/1618.62.0.1 to 18.62.255.25418.62.255.25565,534
6418.63.0.0/1618.63.0.1 to 18.63.255.25418.63.255.25565,534
6518.64.0.0/1618.64.0.1 to 18.64.255.25418.64.255.25565,534
6618.65.0.0/1618.65.0.1 to 18.65.255.25418.65.255.25565,534
6718.66.0.0/1618.66.0.1 to 18.66.255.25418.66.255.25565,534
6818.67.0.0/1618.67.0.1 to 18.67.255.25418.67.255.25565,534
6918.68.0.0/1618.68.0.1 to 18.68.255.25418.68.255.25565,534
7018.69.0.0/1618.69.0.1 to 18.69.255.25418.69.255.25565,534
7118.70.0.0/1618.70.0.1 to 18.70.255.25418.70.255.25565,534
7218.71.0.0/1618.71.0.1 to 18.71.255.25418.71.255.25565,534
7318.72.0.0/1618.72.0.1 to 18.72.255.25418.72.255.25565,534
7418.73.0.0/1618.73.0.1 to 18.73.255.25418.73.255.25565,534
7518.74.0.0/1618.74.0.1 to 18.74.255.25418.74.255.25565,534
7618.75.0.0/1618.75.0.1 to 18.75.255.25418.75.255.25565,534
7718.76.0.0/1618.76.0.1 to 18.76.255.25418.76.255.25565,534
7818.77.0.0/1618.77.0.1 to 18.77.255.25418.77.255.25565,534
7918.78.0.0/1618.78.0.1 to 18.78.255.25418.78.255.25565,534
8018.79.0.0/1618.79.0.1 to 18.79.255.25418.79.255.25565,534
8118.80.0.0/1618.80.0.1 to 18.80.255.25418.80.255.25565,534
8218.81.0.0/1618.81.0.1 to 18.81.255.25418.81.255.25565,534
8318.82.0.0/1618.82.0.1 to 18.82.255.25418.82.255.25565,534
8418.83.0.0/1618.83.0.1 to 18.83.255.25418.83.255.25565,534
8518.84.0.0/1618.84.0.1 to 18.84.255.25418.84.255.25565,534
8618.85.0.0/1618.85.0.1 to 18.85.255.25418.85.255.25565,534
8718.86.0.0/1618.86.0.1 to 18.86.255.25418.86.255.25565,534
8818.87.0.0/1618.87.0.1 to 18.87.255.25418.87.255.25565,534
8918.88.0.0/1618.88.0.1 to 18.88.255.25418.88.255.25565,534
9018.89.0.0/1618.89.0.1 to 18.89.255.25418.89.255.25565,534
9118.90.0.0/1618.90.0.1 to 18.90.255.25418.90.255.25565,534
9218.91.0.0/1618.91.0.1 to 18.91.255.25418.91.255.25565,534
9318.92.0.0/1618.92.0.1 to 18.92.255.25418.92.255.25565,534
9418.93.0.0/1618.93.0.1 to 18.93.255.25418.93.255.25565,534
9518.94.0.0/1618.94.0.1 to 18.94.255.25418.94.255.25565,534
9618.95.0.0/1618.95.0.1 to 18.95.255.25418.95.255.25565,534
9718.96.0.0/1618.96.0.1 to 18.96.255.25418.96.255.25565,534
9818.97.0.0/1618.97.0.1 to 18.97.255.25418.97.255.25565,534
9918.98.0.0/1618.98.0.1 to 18.98.255.25418.98.255.25565,534
10018.99.0.0/1618.99.0.1 to 18.99.255.25418.99.255.25565,534
10118.100.0.0/1618.100.0.1 to 18.100.255.25418.100.255.25565,534
10218.101.0.0/1618.101.0.1 to 18.101.255.25418.101.255.25565,534
10318.102.0.0/1618.102.0.1 to 18.102.255.25418.102.255.25565,534
10418.103.0.0/1618.103.0.1 to 18.103.255.25418.103.255.25565,534
10518.104.0.0/1618.104.0.1 to 18.104.255.25418.104.255.25565,534
10618.105.0.0/1618.105.0.1 to 18.105.255.25418.105.255.25565,534
10718.106.0.0/1618.106.0.1 to 18.106.255.25418.106.255.25565,534
10818.107.0.0/1618.107.0.1 to 18.107.255.25418.107.255.25565,534
10918.108.0.0/1618.108.0.1 to 18.108.255.25418.108.255.25565,534
11018.109.0.0/1618.109.0.1 to 18.109.255.25418.109.255.25565,534
11118.110.0.0/1618.110.0.1 to 18.110.255.25418.110.255.25565,534
11218.111.0.0/1618.111.0.1 to 18.111.255.25418.111.255.25565,534
11318.112.0.0/1618.112.0.1 to 18.112.255.25418.112.255.25565,534
11418.113.0.0/1618.113.0.1 to 18.113.255.25418.113.255.25565,534
11518.114.0.0/1618.114.0.1 to 18.114.255.25418.114.255.25565,534
11618.115.0.0/1618.115.0.1 to 18.115.255.25418.115.255.25565,534
11718.116.0.0/1618.116.0.1 to 18.116.255.25418.116.255.25565,534
11818.117.0.0/1618.117.0.1 to 18.117.255.25418.117.255.25565,534
11918.118.0.0/1618.118.0.1 to 18.118.255.25418.118.255.25565,534
12018.119.0.0/1618.119.0.1 to 18.119.255.25418.119.255.25565,534
12118.120.0.0/1618.120.0.1 to 18.120.255.25418.120.255.25565,534
12218.121.0.0/1618.121.0.1 to 18.121.255.25418.121.255.25565,534
12318.122.0.0/1618.122.0.1 to 18.122.255.25418.122.255.25565,534
12418.123.0.0/1618.123.0.1 to 18.123.255.25418.123.255.25565,534
12518.124.0.0/1618.124.0.1 to 18.124.255.25418.124.255.25565,534
12618.125.0.0/1618.125.0.1 to 18.125.255.25418.125.255.25565,534
12718.126.0.0/1618.126.0.1 to 18.126.255.25418.126.255.25565,534
12818.127.0.0/1618.127.0.1 to 18.127.255.25418.127.255.25565,534
12918.128.0.0/1618.128.0.1 to 18.128.255.25418.128.255.25565,534
13018.129.0.0/1618.129.0.1 to 18.129.255.25418.129.255.25565,534
13118.130.0.0/1618.130.0.1 to 18.130.255.25418.130.255.25565,534
13218.131.0.0/1618.131.0.1 to 18.131.255.25418.131.255.25565,534
13318.132.0.0/1618.132.0.1 to 18.132.255.25418.132.255.25565,534
13418.133.0.0/1618.133.0.1 to 18.133.255.25418.133.255.25565,534
13518.134.0.0/1618.134.0.1 to 18.134.255.25418.134.255.25565,534
13618.135.0.0/1618.135.0.1 to 18.135.255.25418.135.255.25565,534
13718.136.0.0/1618.136.0.1 to 18.136.255.25418.136.255.25565,534
13818.137.0.0/1618.137.0.1 to 18.137.255.25418.137.255.25565,534
13918.138.0.0/1618.138.0.1 to 18.138.255.25418.138.255.25565,534
14018.139.0.0/1618.139.0.1 to 18.139.255.25418.139.255.25565,534
14118.140.0.0/1618.140.0.1 to 18.140.255.25418.140.255.25565,534
14218.141.0.0/1618.141.0.1 to 18.141.255.25418.141.255.25565,534
14318.142.0.0/1618.142.0.1 to 18.142.255.25418.142.255.25565,534
14418.143.0.0/1618.143.0.1 to 18.143.255.25418.143.255.25565,534
14518.144.0.0/1618.144.0.1 to 18.144.255.25418.144.255.25565,534
14618.145.0.0/1618.145.0.1 to 18.145.255.25418.145.255.25565,534
14718.146.0.0/1618.146.0.1 to 18.146.255.25418.146.255.25565,534
14818.147.0.0/1618.147.0.1 to 18.147.255.25418.147.255.25565,534
14918.148.0.0/1618.148.0.1 to 18.148.255.25418.148.255.25565,534
15018.149.0.0/1618.149.0.1 to 18.149.255.25418.149.255.25565,534
15118.150.0.0/1618.150.0.1 to 18.150.255.25418.150.255.25565,534
15218.151.0.0/1618.151.0.1 to 18.151.255.25418.151.255.25565,534
15318.152.0.0/1618.152.0.1 to 18.152.255.25418.152.255.25565,534
15418.153.0.0/1618.153.0.1 to 18.153.255.25418.153.255.25565,534
15518.154.0.0/1618.154.0.1 to 18.154.255.25418.154.255.25565,534
15618.155.0.0/1618.155.0.1 to 18.155.255.25418.155.255.25565,534
15718.156.0.0/1618.156.0.1 to 18.156.255.25418.156.255.25565,534
15818.157.0.0/1618.157.0.1 to 18.157.255.25418.157.255.25565,534
15918.158.0.0/1618.158.0.1 to 18.158.255.25418.158.255.25565,534
16018.159.0.0/1618.159.0.1 to 18.159.255.25418.159.255.25565,534
16118.160.0.0/1618.160.0.1 to 18.160.255.25418.160.255.25565,534
16218.161.0.0/1618.161.0.1 to 18.161.255.25418.161.255.25565,534
16318.162.0.0/1618.162.0.1 to 18.162.255.25418.162.255.25565,534
16418.163.0.0/1618.163.0.1 to 18.163.255.25418.163.255.25565,534
16518.164.0.0/1618.164.0.1 to 18.164.255.25418.164.255.25565,534
16618.165.0.0/1618.165.0.1 to 18.165.255.25418.165.255.25565,534
16718.166.0.0/1618.166.0.1 to 18.166.255.25418.166.255.25565,534
16818.167.0.0/1618.167.0.1 to 18.167.255.25418.167.255.25565,534
16918.168.0.0/1618.168.0.1 to 18.168.255.25418.168.255.25565,534
17018.169.0.0/1618.169.0.1 to 18.169.255.25418.169.255.25565,534
17118.170.0.0/1618.170.0.1 to 18.170.255.25418.170.255.25565,534
17218.171.0.0/1618.171.0.1 to 18.171.255.25418.171.255.25565,534
17318.172.0.0/1618.172.0.1 to 18.172.255.25418.172.255.25565,534
17418.173.0.0/1618.173.0.1 to 18.173.255.25418.173.255.25565,534
17518.174.0.0/1618.174.0.1 to 18.174.255.25418.174.255.25565,534
17618.175.0.0/1618.175.0.1 to 18.175.255.25418.175.255.25565,534
17718.176.0.0/1618.176.0.1 to 18.176.255.25418.176.255.25565,534
17818.177.0.0/1618.177.0.1 to 18.177.255.25418.177.255.25565,534
17918.178.0.0/1618.178.0.1 to 18.178.255.25418.178.255.25565,534
18018.179.0.0/1618.179.0.1 to 18.179.255.25418.179.255.25565,534
18118.180.0.0/1618.180.0.1 to 18.180.255.25418.180.255.25565,534
18218.181.0.0/1618.181.0.1 to 18.181.255.25418.181.255.25565,534
18318.182.0.0/1618.182.0.1 to 18.182.255.25418.182.255.25565,534
18418.183.0.0/1618.183.0.1 to 18.183.255.25418.183.255.25565,534
18518.184.0.0/1618.184.0.1 to 18.184.255.25418.184.255.25565,534
18618.185.0.0/1618.185.0.1 to 18.185.255.25418.185.255.25565,534
18718.186.0.0/1618.186.0.1 to 18.186.255.25418.186.255.25565,534
18818.187.0.0/1618.187.0.1 to 18.187.255.25418.187.255.25565,534
18918.188.0.0/1618.188.0.1 to 18.188.255.25418.188.255.25565,534
19018.189.0.0/1618.189.0.1 to 18.189.255.25418.189.255.25565,534
19118.190.0.0/1618.190.0.1 to 18.190.255.25418.190.255.25565,534
19218.191.0.0/1618.191.0.1 to 18.191.255.25418.191.255.25565,534
19318.192.0.0/1618.192.0.1 to 18.192.255.25418.192.255.25565,534
19418.193.0.0/1618.193.0.1 to 18.193.255.25418.193.255.25565,534
19518.194.0.0/1618.194.0.1 to 18.194.255.25418.194.255.25565,534
19618.195.0.0/1618.195.0.1 to 18.195.255.25418.195.255.25565,534
19718.196.0.0/1618.196.0.1 to 18.196.255.25418.196.255.25565,534
19818.197.0.0/1618.197.0.1 to 18.197.255.25418.197.255.25565,534
19918.198.0.0/1618.198.0.1 to 18.198.255.25418.198.255.25565,534
20018.199.0.0/1618.199.0.1 to 18.199.255.25418.199.255.25565,534
20118.200.0.0/1618.200.0.1 to 18.200.255.25418.200.255.25565,534
20218.201.0.0/1618.201.0.1 to 18.201.255.25418.201.255.25565,534
20318.202.0.0/1618.202.0.1 to 18.202.255.25418.202.255.25565,534
20418.203.0.0/1618.203.0.1 to 18.203.255.25418.203.255.25565,534
20518.204.0.0/1618.204.0.1 to 18.204.255.25418.204.255.25565,534
20618.205.0.0/1618.205.0.1 to 18.205.255.25418.205.255.25565,534
20718.206.0.0/1618.206.0.1 to 18.206.255.25418.206.255.25565,534
20818.207.0.0/1618.207.0.1 to 18.207.255.25418.207.255.25565,534
20918.208.0.0/1618.208.0.1 to 18.208.255.25418.208.255.25565,534
21018.209.0.0/1618.209.0.1 to 18.209.255.25418.209.255.25565,534
21118.210.0.0/1618.210.0.1 to 18.210.255.25418.210.255.25565,534
21218.211.0.0/1618.211.0.1 to 18.211.255.25418.211.255.25565,534
21318.212.0.0/1618.212.0.1 to 18.212.255.25418.212.255.25565,534
21418.213.0.0/1618.213.0.1 to 18.213.255.25418.213.255.25565,534
21518.214.0.0/1618.214.0.1 to 18.214.255.25418.214.255.25565,534
21618.215.0.0/1618.215.0.1 to 18.215.255.25418.215.255.25565,534
21718.216.0.0/1618.216.0.1 to 18.216.255.25418.216.255.25565,534
21818.217.0.0/1618.217.0.1 to 18.217.255.25418.217.255.25565,534
21918.218.0.0/1618.218.0.1 to 18.218.255.25418.218.255.25565,534
22018.219.0.0/1618.219.0.1 to 18.219.255.25418.219.255.25565,534
22118.220.0.0/1618.220.0.1 to 18.220.255.25418.220.255.25565,534
22218.221.0.0/1618.221.0.1 to 18.221.255.25418.221.255.25565,534
22318.222.0.0/1618.222.0.1 to 18.222.255.25418.222.255.25565,534
22418.223.0.0/1618.223.0.1 to 18.223.255.25418.223.255.25565,534
22518.224.0.0/1618.224.0.1 to 18.224.255.25418.224.255.25565,534
22618.225.0.0/1618.225.0.1 to 18.225.255.25418.225.255.25565,534
22718.226.0.0/1618.226.0.1 to 18.226.255.25418.226.255.25565,534
22818.227.0.0/1618.227.0.1 to 18.227.255.25418.227.255.25565,534
22918.228.0.0/1618.228.0.1 to 18.228.255.25418.228.255.25565,534
23018.229.0.0/1618.229.0.1 to 18.229.255.25418.229.255.25565,534
23118.230.0.0/1618.230.0.1 to 18.230.255.25418.230.255.25565,534
23218.231.0.0/1618.231.0.1 to 18.231.255.25418.231.255.25565,534
23318.232.0.0/1618.232.0.1 to 18.232.255.25418.232.255.25565,534
23418.233.0.0/1618.233.0.1 to 18.233.255.25418.233.255.25565,534
23518.234.0.0/1618.234.0.1 to 18.234.255.25418.234.255.25565,534
23618.235.0.0/1618.235.0.1 to 18.235.255.25418.235.255.25565,534
23718.236.0.0/1618.236.0.1 to 18.236.255.25418.236.255.25565,534
23818.237.0.0/1618.237.0.1 to 18.237.255.25418.237.255.25565,534
23918.238.0.0/1618.238.0.1 to 18.238.255.25418.238.255.25565,534
24018.239.0.0/1618.239.0.1 to 18.239.255.25418.239.255.25565,534
24118.240.0.0/1618.240.0.1 to 18.240.255.25418.240.255.25565,534
24218.241.0.0/1618.241.0.1 to 18.241.255.25418.241.255.25565,534
24318.242.0.0/1618.242.0.1 to 18.242.255.25418.242.255.25565,534
24418.243.0.0/1618.243.0.1 to 18.243.255.25418.243.255.25565,534
24518.244.0.0/1618.244.0.1 to 18.244.255.25418.244.255.25565,534
24618.245.0.0/1618.245.0.1 to 18.245.255.25418.245.255.25565,534
24718.246.0.0/1618.246.0.1 to 18.246.255.25418.246.255.25565,534
24818.247.0.0/1618.247.0.1 to 18.247.255.25418.247.255.25565,534
24918.248.0.0/1618.248.0.1 to 18.248.255.25418.248.255.25565,534
25018.249.0.0/1618.249.0.1 to 18.249.255.25418.249.255.25565,534
25118.250.0.0/1618.250.0.1 to 18.250.255.25418.250.255.25565,534
25218.251.0.0/1618.251.0.1 to 18.251.255.25418.251.255.25565,534
25318.252.0.0/1618.252.0.1 to 18.252.255.25418.252.255.25565,534
25418.253.0.0/1618.253.0.1 to 18.253.255.25418.253.255.25565,534
25518.254.0.0/1618.254.0.1 to 18.254.255.25418.254.255.25565,534
25618.255.0.0/1618.255.0.1 to 18.255.255.25418.255.255.25565,534

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.