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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.

Network43.80.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
43.80.0.0
Broadcast address
43.95.255.255
First usable
43.80.0.1
Last usable
43.95.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
A (default /8)
As numbers
Hex 2B500000 · Integer 726663168 to 727711743
Reverse DNS zones
80.43.in-addr.arpa
81.43.in-addr.arpa
82.43.in-addr.arpa
83.43.in-addr.arpa
84.43.in-addr.arpa
85.43.in-addr.arpa
86.43.in-addr.arpa
87.43.in-addr.arpa
88.43.in-addr.arpa
89.43.in-addr.arpa
90.43.in-addr.arpa
91.43.in-addr.arpa
92.43.in-addr.arpa
93.43.in-addr.arpa
94.43.in-addr.arpa
95.43.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00101011.01010000.00000000.0000000043.80.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network00101011.01010000.00000000.0000000043.80.0.0
Broadcast00101011.01011111.11111111.1111111143.95.255.255
Split into smaller subnets/23
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

43.80.0.0/12 makes 2,048 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
143.80.0.0/2343.80.0.1 to 43.80.1.25443.80.1.255510
243.80.2.0/2343.80.2.1 to 43.80.3.25443.80.3.255510
343.80.4.0/2343.80.4.1 to 43.80.5.25443.80.5.255510
443.80.6.0/2343.80.6.1 to 43.80.7.25443.80.7.255510
543.80.8.0/2343.80.8.1 to 43.80.9.25443.80.9.255510
643.80.10.0/2343.80.10.1 to 43.80.11.25443.80.11.255510
743.80.12.0/2343.80.12.1 to 43.80.13.25443.80.13.255510
843.80.14.0/2343.80.14.1 to 43.80.15.25443.80.15.255510
943.80.16.0/2343.80.16.1 to 43.80.17.25443.80.17.255510
1043.80.18.0/2343.80.18.1 to 43.80.19.25443.80.19.255510
1143.80.20.0/2343.80.20.1 to 43.80.21.25443.80.21.255510
1243.80.22.0/2343.80.22.1 to 43.80.23.25443.80.23.255510
1343.80.24.0/2343.80.24.1 to 43.80.25.25443.80.25.255510
1443.80.26.0/2343.80.26.1 to 43.80.27.25443.80.27.255510
1543.80.28.0/2343.80.28.1 to 43.80.29.25443.80.29.255510
1643.80.30.0/2343.80.30.1 to 43.80.31.25443.80.31.255510
1743.80.32.0/2343.80.32.1 to 43.80.33.25443.80.33.255510
1843.80.34.0/2343.80.34.1 to 43.80.35.25443.80.35.255510
1943.80.36.0/2343.80.36.1 to 43.80.37.25443.80.37.255510
2043.80.38.0/2343.80.38.1 to 43.80.39.25443.80.39.255510
2143.80.40.0/2343.80.40.1 to 43.80.41.25443.80.41.255510
2243.80.42.0/2343.80.42.1 to 43.80.43.25443.80.43.255510
2343.80.44.0/2343.80.44.1 to 43.80.45.25443.80.45.255510
2443.80.46.0/2343.80.46.1 to 43.80.47.25443.80.47.255510
2543.80.48.0/2343.80.48.1 to 43.80.49.25443.80.49.255510
2643.80.50.0/2343.80.50.1 to 43.80.51.25443.80.51.255510
2743.80.52.0/2343.80.52.1 to 43.80.53.25443.80.53.255510
2843.80.54.0/2343.80.54.1 to 43.80.55.25443.80.55.255510
2943.80.56.0/2343.80.56.1 to 43.80.57.25443.80.57.255510
3043.80.58.0/2343.80.58.1 to 43.80.59.25443.80.59.255510
3143.80.60.0/2343.80.60.1 to 43.80.61.25443.80.61.255510
3243.80.62.0/2343.80.62.1 to 43.80.63.25443.80.63.255510
3343.80.64.0/2343.80.64.1 to 43.80.65.25443.80.65.255510
3443.80.66.0/2343.80.66.1 to 43.80.67.25443.80.67.255510
3543.80.68.0/2343.80.68.1 to 43.80.69.25443.80.69.255510
3643.80.70.0/2343.80.70.1 to 43.80.71.25443.80.71.255510
3743.80.72.0/2343.80.72.1 to 43.80.73.25443.80.73.255510
3843.80.74.0/2343.80.74.1 to 43.80.75.25443.80.75.255510
3943.80.76.0/2343.80.76.1 to 43.80.77.25443.80.77.255510
4043.80.78.0/2343.80.78.1 to 43.80.79.25443.80.79.255510
4143.80.80.0/2343.80.80.1 to 43.80.81.25443.80.81.255510
4243.80.82.0/2343.80.82.1 to 43.80.83.25443.80.83.255510
4343.80.84.0/2343.80.84.1 to 43.80.85.25443.80.85.255510
4443.80.86.0/2343.80.86.1 to 43.80.87.25443.80.87.255510
4543.80.88.0/2343.80.88.1 to 43.80.89.25443.80.89.255510
4643.80.90.0/2343.80.90.1 to 43.80.91.25443.80.91.255510
4743.80.92.0/2343.80.92.1 to 43.80.93.25443.80.93.255510
4843.80.94.0/2343.80.94.1 to 43.80.95.25443.80.95.255510
4943.80.96.0/2343.80.96.1 to 43.80.97.25443.80.97.255510
5043.80.98.0/2343.80.98.1 to 43.80.99.25443.80.99.255510
5143.80.100.0/2343.80.100.1 to 43.80.101.25443.80.101.255510
5243.80.102.0/2343.80.102.1 to 43.80.103.25443.80.103.255510
5343.80.104.0/2343.80.104.1 to 43.80.105.25443.80.105.255510
5443.80.106.0/2343.80.106.1 to 43.80.107.25443.80.107.255510
5543.80.108.0/2343.80.108.1 to 43.80.109.25443.80.109.255510
5643.80.110.0/2343.80.110.1 to 43.80.111.25443.80.111.255510
5743.80.112.0/2343.80.112.1 to 43.80.113.25443.80.113.255510
5843.80.114.0/2343.80.114.1 to 43.80.115.25443.80.115.255510
5943.80.116.0/2343.80.116.1 to 43.80.117.25443.80.117.255510
6043.80.118.0/2343.80.118.1 to 43.80.119.25443.80.119.255510
6143.80.120.0/2343.80.120.1 to 43.80.121.25443.80.121.255510
6243.80.122.0/2343.80.122.1 to 43.80.123.25443.80.123.255510
6343.80.124.0/2343.80.124.1 to 43.80.125.25443.80.125.255510
6443.80.126.0/2343.80.126.1 to 43.80.127.25443.80.127.255510
6543.80.128.0/2343.80.128.1 to 43.80.129.25443.80.129.255510
6643.80.130.0/2343.80.130.1 to 43.80.131.25443.80.131.255510
6743.80.132.0/2343.80.132.1 to 43.80.133.25443.80.133.255510
6843.80.134.0/2343.80.134.1 to 43.80.135.25443.80.135.255510
6943.80.136.0/2343.80.136.1 to 43.80.137.25443.80.137.255510
7043.80.138.0/2343.80.138.1 to 43.80.139.25443.80.139.255510
7143.80.140.0/2343.80.140.1 to 43.80.141.25443.80.141.255510
7243.80.142.0/2343.80.142.1 to 43.80.143.25443.80.143.255510
7343.80.144.0/2343.80.144.1 to 43.80.145.25443.80.145.255510
7443.80.146.0/2343.80.146.1 to 43.80.147.25443.80.147.255510
7543.80.148.0/2343.80.148.1 to 43.80.149.25443.80.149.255510
7643.80.150.0/2343.80.150.1 to 43.80.151.25443.80.151.255510
7743.80.152.0/2343.80.152.1 to 43.80.153.25443.80.153.255510
7843.80.154.0/2343.80.154.1 to 43.80.155.25443.80.155.255510
7943.80.156.0/2343.80.156.1 to 43.80.157.25443.80.157.255510
8043.80.158.0/2343.80.158.1 to 43.80.159.25443.80.159.255510
8143.80.160.0/2343.80.160.1 to 43.80.161.25443.80.161.255510
8243.80.162.0/2343.80.162.1 to 43.80.163.25443.80.163.255510
8343.80.164.0/2343.80.164.1 to 43.80.165.25443.80.165.255510
8443.80.166.0/2343.80.166.1 to 43.80.167.25443.80.167.255510
8543.80.168.0/2343.80.168.1 to 43.80.169.25443.80.169.255510
8643.80.170.0/2343.80.170.1 to 43.80.171.25443.80.171.255510
8743.80.172.0/2343.80.172.1 to 43.80.173.25443.80.173.255510
8843.80.174.0/2343.80.174.1 to 43.80.175.25443.80.175.255510
8943.80.176.0/2343.80.176.1 to 43.80.177.25443.80.177.255510
9043.80.178.0/2343.80.178.1 to 43.80.179.25443.80.179.255510
9143.80.180.0/2343.80.180.1 to 43.80.181.25443.80.181.255510
9243.80.182.0/2343.80.182.1 to 43.80.183.25443.80.183.255510
9343.80.184.0/2343.80.184.1 to 43.80.185.25443.80.185.255510
9443.80.186.0/2343.80.186.1 to 43.80.187.25443.80.187.255510
9543.80.188.0/2343.80.188.1 to 43.80.189.25443.80.189.255510
9643.80.190.0/2343.80.190.1 to 43.80.191.25443.80.191.255510
9743.80.192.0/2343.80.192.1 to 43.80.193.25443.80.193.255510
9843.80.194.0/2343.80.194.1 to 43.80.195.25443.80.195.255510
9943.80.196.0/2343.80.196.1 to 43.80.197.25443.80.197.255510
10043.80.198.0/2343.80.198.1 to 43.80.199.25443.80.199.255510
10143.80.200.0/2343.80.200.1 to 43.80.201.25443.80.201.255510
10243.80.202.0/2343.80.202.1 to 43.80.203.25443.80.203.255510
10343.80.204.0/2343.80.204.1 to 43.80.205.25443.80.205.255510
10443.80.206.0/2343.80.206.1 to 43.80.207.25443.80.207.255510
10543.80.208.0/2343.80.208.1 to 43.80.209.25443.80.209.255510
10643.80.210.0/2343.80.210.1 to 43.80.211.25443.80.211.255510
10743.80.212.0/2343.80.212.1 to 43.80.213.25443.80.213.255510
10843.80.214.0/2343.80.214.1 to 43.80.215.25443.80.215.255510
10943.80.216.0/2343.80.216.1 to 43.80.217.25443.80.217.255510
11043.80.218.0/2343.80.218.1 to 43.80.219.25443.80.219.255510
11143.80.220.0/2343.80.220.1 to 43.80.221.25443.80.221.255510
11243.80.222.0/2343.80.222.1 to 43.80.223.25443.80.223.255510
11343.80.224.0/2343.80.224.1 to 43.80.225.25443.80.225.255510
11443.80.226.0/2343.80.226.1 to 43.80.227.25443.80.227.255510
11543.80.228.0/2343.80.228.1 to 43.80.229.25443.80.229.255510
11643.80.230.0/2343.80.230.1 to 43.80.231.25443.80.231.255510
11743.80.232.0/2343.80.232.1 to 43.80.233.25443.80.233.255510
11843.80.234.0/2343.80.234.1 to 43.80.235.25443.80.235.255510
11943.80.236.0/2343.80.236.1 to 43.80.237.25443.80.237.255510
12043.80.238.0/2343.80.238.1 to 43.80.239.25443.80.239.255510
12143.80.240.0/2343.80.240.1 to 43.80.241.25443.80.241.255510
12243.80.242.0/2343.80.242.1 to 43.80.243.25443.80.243.255510
12343.80.244.0/2343.80.244.1 to 43.80.245.25443.80.245.255510
12443.80.246.0/2343.80.246.1 to 43.80.247.25443.80.247.255510
12543.80.248.0/2343.80.248.1 to 43.80.249.25443.80.249.255510
12643.80.250.0/2343.80.250.1 to 43.80.251.25443.80.251.255510
12743.80.252.0/2343.80.252.1 to 43.80.253.25443.80.253.255510
12843.80.254.0/2343.80.254.1 to 43.80.255.25443.80.255.255510
12943.81.0.0/2343.81.0.1 to 43.81.1.25443.81.1.255510
13043.81.2.0/2343.81.2.1 to 43.81.3.25443.81.3.255510
13143.81.4.0/2343.81.4.1 to 43.81.5.25443.81.5.255510
13243.81.6.0/2343.81.6.1 to 43.81.7.25443.81.7.255510
13343.81.8.0/2343.81.8.1 to 43.81.9.25443.81.9.255510
13443.81.10.0/2343.81.10.1 to 43.81.11.25443.81.11.255510
13543.81.12.0/2343.81.12.1 to 43.81.13.25443.81.13.255510
13643.81.14.0/2343.81.14.1 to 43.81.15.25443.81.15.255510
13743.81.16.0/2343.81.16.1 to 43.81.17.25443.81.17.255510
13843.81.18.0/2343.81.18.1 to 43.81.19.25443.81.19.255510
13943.81.20.0/2343.81.20.1 to 43.81.21.25443.81.21.255510
14043.81.22.0/2343.81.22.1 to 43.81.23.25443.81.23.255510
14143.81.24.0/2343.81.24.1 to 43.81.25.25443.81.25.255510
14243.81.26.0/2343.81.26.1 to 43.81.27.25443.81.27.255510
14343.81.28.0/2343.81.28.1 to 43.81.29.25443.81.29.255510
14443.81.30.0/2343.81.30.1 to 43.81.31.25443.81.31.255510
14543.81.32.0/2343.81.32.1 to 43.81.33.25443.81.33.255510
14643.81.34.0/2343.81.34.1 to 43.81.35.25443.81.35.255510
14743.81.36.0/2343.81.36.1 to 43.81.37.25443.81.37.255510
14843.81.38.0/2343.81.38.1 to 43.81.39.25443.81.39.255510
14943.81.40.0/2343.81.40.1 to 43.81.41.25443.81.41.255510
15043.81.42.0/2343.81.42.1 to 43.81.43.25443.81.43.255510
15143.81.44.0/2343.81.44.1 to 43.81.45.25443.81.45.255510
15243.81.46.0/2343.81.46.1 to 43.81.47.25443.81.47.255510
15343.81.48.0/2343.81.48.1 to 43.81.49.25443.81.49.255510
15443.81.50.0/2343.81.50.1 to 43.81.51.25443.81.51.255510
15543.81.52.0/2343.81.52.1 to 43.81.53.25443.81.53.255510
15643.81.54.0/2343.81.54.1 to 43.81.55.25443.81.55.255510
15743.81.56.0/2343.81.56.1 to 43.81.57.25443.81.57.255510
15843.81.58.0/2343.81.58.1 to 43.81.59.25443.81.59.255510
15943.81.60.0/2343.81.60.1 to 43.81.61.25443.81.61.255510
16043.81.62.0/2343.81.62.1 to 43.81.63.25443.81.63.255510
16143.81.64.0/2343.81.64.1 to 43.81.65.25443.81.65.255510
16243.81.66.0/2343.81.66.1 to 43.81.67.25443.81.67.255510
16343.81.68.0/2343.81.68.1 to 43.81.69.25443.81.69.255510
16443.81.70.0/2343.81.70.1 to 43.81.71.25443.81.71.255510
16543.81.72.0/2343.81.72.1 to 43.81.73.25443.81.73.255510
16643.81.74.0/2343.81.74.1 to 43.81.75.25443.81.75.255510
16743.81.76.0/2343.81.76.1 to 43.81.77.25443.81.77.255510
16843.81.78.0/2343.81.78.1 to 43.81.79.25443.81.79.255510
16943.81.80.0/2343.81.80.1 to 43.81.81.25443.81.81.255510
17043.81.82.0/2343.81.82.1 to 43.81.83.25443.81.83.255510
17143.81.84.0/2343.81.84.1 to 43.81.85.25443.81.85.255510
17243.81.86.0/2343.81.86.1 to 43.81.87.25443.81.87.255510
17343.81.88.0/2343.81.88.1 to 43.81.89.25443.81.89.255510
17443.81.90.0/2343.81.90.1 to 43.81.91.25443.81.91.255510
17543.81.92.0/2343.81.92.1 to 43.81.93.25443.81.93.255510
17643.81.94.0/2343.81.94.1 to 43.81.95.25443.81.95.255510
17743.81.96.0/2343.81.96.1 to 43.81.97.25443.81.97.255510
17843.81.98.0/2343.81.98.1 to 43.81.99.25443.81.99.255510
17943.81.100.0/2343.81.100.1 to 43.81.101.25443.81.101.255510
18043.81.102.0/2343.81.102.1 to 43.81.103.25443.81.103.255510
18143.81.104.0/2343.81.104.1 to 43.81.105.25443.81.105.255510
18243.81.106.0/2343.81.106.1 to 43.81.107.25443.81.107.255510
18343.81.108.0/2343.81.108.1 to 43.81.109.25443.81.109.255510
18443.81.110.0/2343.81.110.1 to 43.81.111.25443.81.111.255510
18543.81.112.0/2343.81.112.1 to 43.81.113.25443.81.113.255510
18643.81.114.0/2343.81.114.1 to 43.81.115.25443.81.115.255510
18743.81.116.0/2343.81.116.1 to 43.81.117.25443.81.117.255510
18843.81.118.0/2343.81.118.1 to 43.81.119.25443.81.119.255510
18943.81.120.0/2343.81.120.1 to 43.81.121.25443.81.121.255510
19043.81.122.0/2343.81.122.1 to 43.81.123.25443.81.123.255510
19143.81.124.0/2343.81.124.1 to 43.81.125.25443.81.125.255510
19243.81.126.0/2343.81.126.1 to 43.81.127.25443.81.127.255510
19343.81.128.0/2343.81.128.1 to 43.81.129.25443.81.129.255510
19443.81.130.0/2343.81.130.1 to 43.81.131.25443.81.131.255510
19543.81.132.0/2343.81.132.1 to 43.81.133.25443.81.133.255510
19643.81.134.0/2343.81.134.1 to 43.81.135.25443.81.135.255510
19743.81.136.0/2343.81.136.1 to 43.81.137.25443.81.137.255510
19843.81.138.0/2343.81.138.1 to 43.81.139.25443.81.139.255510
19943.81.140.0/2343.81.140.1 to 43.81.141.25443.81.141.255510
20043.81.142.0/2343.81.142.1 to 43.81.143.25443.81.143.255510
20143.81.144.0/2343.81.144.1 to 43.81.145.25443.81.145.255510
20243.81.146.0/2343.81.146.1 to 43.81.147.25443.81.147.255510
20343.81.148.0/2343.81.148.1 to 43.81.149.25443.81.149.255510
20443.81.150.0/2343.81.150.1 to 43.81.151.25443.81.151.255510
20543.81.152.0/2343.81.152.1 to 43.81.153.25443.81.153.255510
20643.81.154.0/2343.81.154.1 to 43.81.155.25443.81.155.255510
20743.81.156.0/2343.81.156.1 to 43.81.157.25443.81.157.255510
20843.81.158.0/2343.81.158.1 to 43.81.159.25443.81.159.255510
20943.81.160.0/2343.81.160.1 to 43.81.161.25443.81.161.255510
21043.81.162.0/2343.81.162.1 to 43.81.163.25443.81.163.255510
21143.81.164.0/2343.81.164.1 to 43.81.165.25443.81.165.255510
21243.81.166.0/2343.81.166.1 to 43.81.167.25443.81.167.255510
21343.81.168.0/2343.81.168.1 to 43.81.169.25443.81.169.255510
21443.81.170.0/2343.81.170.1 to 43.81.171.25443.81.171.255510
21543.81.172.0/2343.81.172.1 to 43.81.173.25443.81.173.255510
21643.81.174.0/2343.81.174.1 to 43.81.175.25443.81.175.255510
21743.81.176.0/2343.81.176.1 to 43.81.177.25443.81.177.255510
21843.81.178.0/2343.81.178.1 to 43.81.179.25443.81.179.255510
21943.81.180.0/2343.81.180.1 to 43.81.181.25443.81.181.255510
22043.81.182.0/2343.81.182.1 to 43.81.183.25443.81.183.255510
22143.81.184.0/2343.81.184.1 to 43.81.185.25443.81.185.255510
22243.81.186.0/2343.81.186.1 to 43.81.187.25443.81.187.255510
22343.81.188.0/2343.81.188.1 to 43.81.189.25443.81.189.255510
22443.81.190.0/2343.81.190.1 to 43.81.191.25443.81.191.255510
22543.81.192.0/2343.81.192.1 to 43.81.193.25443.81.193.255510
22643.81.194.0/2343.81.194.1 to 43.81.195.25443.81.195.255510
22743.81.196.0/2343.81.196.1 to 43.81.197.25443.81.197.255510
22843.81.198.0/2343.81.198.1 to 43.81.199.25443.81.199.255510
22943.81.200.0/2343.81.200.1 to 43.81.201.25443.81.201.255510
23043.81.202.0/2343.81.202.1 to 43.81.203.25443.81.203.255510
23143.81.204.0/2343.81.204.1 to 43.81.205.25443.81.205.255510
23243.81.206.0/2343.81.206.1 to 43.81.207.25443.81.207.255510
23343.81.208.0/2343.81.208.1 to 43.81.209.25443.81.209.255510
23443.81.210.0/2343.81.210.1 to 43.81.211.25443.81.211.255510
23543.81.212.0/2343.81.212.1 to 43.81.213.25443.81.213.255510
23643.81.214.0/2343.81.214.1 to 43.81.215.25443.81.215.255510
23743.81.216.0/2343.81.216.1 to 43.81.217.25443.81.217.255510
23843.81.218.0/2343.81.218.1 to 43.81.219.25443.81.219.255510
23943.81.220.0/2343.81.220.1 to 43.81.221.25443.81.221.255510
24043.81.222.0/2343.81.222.1 to 43.81.223.25443.81.223.255510
24143.81.224.0/2343.81.224.1 to 43.81.225.25443.81.225.255510
24243.81.226.0/2343.81.226.1 to 43.81.227.25443.81.227.255510
24343.81.228.0/2343.81.228.1 to 43.81.229.25443.81.229.255510
24443.81.230.0/2343.81.230.1 to 43.81.231.25443.81.231.255510
24543.81.232.0/2343.81.232.1 to 43.81.233.25443.81.233.255510
24643.81.234.0/2343.81.234.1 to 43.81.235.25443.81.235.255510
24743.81.236.0/2343.81.236.1 to 43.81.237.25443.81.237.255510
24843.81.238.0/2343.81.238.1 to 43.81.239.25443.81.239.255510
24943.81.240.0/2343.81.240.1 to 43.81.241.25443.81.241.255510
25043.81.242.0/2343.81.242.1 to 43.81.243.25443.81.243.255510
25143.81.244.0/2343.81.244.1 to 43.81.245.25443.81.245.255510
25243.81.246.0/2343.81.246.1 to 43.81.247.25443.81.247.255510
25343.81.248.0/2343.81.248.1 to 43.81.249.25443.81.249.255510
25443.81.250.0/2343.81.250.1 to 43.81.251.25443.81.251.255510
25543.81.252.0/2343.81.252.1 to 43.81.253.25443.81.253.255510
25643.81.254.0/2343.81.254.1 to 43.81.255.25443.81.255.255510

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.