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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.

Network20.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
20.0.0.0
Broadcast address
20.255.255.255
First usable
20.0.0.1
Last usable
20.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 14000000 · Integer 335544320 to 352321535
Reverse DNS zone
20.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010100..00000000.00000000.0000000020.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00010100..00000000.00000000.0000000020.0.0.0
Broadcast00010100..11111111.11111111.1111111120.255.255.255
Split into smaller subnets/16
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

20.0.0.0/8 makes 256 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
120.0.0.0/1620.0.0.1 to 20.0.255.25420.0.255.25565,534
220.1.0.0/1620.1.0.1 to 20.1.255.25420.1.255.25565,534
320.2.0.0/1620.2.0.1 to 20.2.255.25420.2.255.25565,534
420.3.0.0/1620.3.0.1 to 20.3.255.25420.3.255.25565,534
520.4.0.0/1620.4.0.1 to 20.4.255.25420.4.255.25565,534
620.5.0.0/1620.5.0.1 to 20.5.255.25420.5.255.25565,534
720.6.0.0/1620.6.0.1 to 20.6.255.25420.6.255.25565,534
820.7.0.0/1620.7.0.1 to 20.7.255.25420.7.255.25565,534
920.8.0.0/1620.8.0.1 to 20.8.255.25420.8.255.25565,534
1020.9.0.0/1620.9.0.1 to 20.9.255.25420.9.255.25565,534
1120.10.0.0/1620.10.0.1 to 20.10.255.25420.10.255.25565,534
1220.11.0.0/1620.11.0.1 to 20.11.255.25420.11.255.25565,534
1320.12.0.0/1620.12.0.1 to 20.12.255.25420.12.255.25565,534
1420.13.0.0/1620.13.0.1 to 20.13.255.25420.13.255.25565,534
1520.14.0.0/1620.14.0.1 to 20.14.255.25420.14.255.25565,534
1620.15.0.0/1620.15.0.1 to 20.15.255.25420.15.255.25565,534
1720.16.0.0/1620.16.0.1 to 20.16.255.25420.16.255.25565,534
1820.17.0.0/1620.17.0.1 to 20.17.255.25420.17.255.25565,534
1920.18.0.0/1620.18.0.1 to 20.18.255.25420.18.255.25565,534
2020.19.0.0/1620.19.0.1 to 20.19.255.25420.19.255.25565,534
2120.20.0.0/1620.20.0.1 to 20.20.255.25420.20.255.25565,534
2220.21.0.0/1620.21.0.1 to 20.21.255.25420.21.255.25565,534
2320.22.0.0/1620.22.0.1 to 20.22.255.25420.22.255.25565,534
2420.23.0.0/1620.23.0.1 to 20.23.255.25420.23.255.25565,534
2520.24.0.0/1620.24.0.1 to 20.24.255.25420.24.255.25565,534
2620.25.0.0/1620.25.0.1 to 20.25.255.25420.25.255.25565,534
2720.26.0.0/1620.26.0.1 to 20.26.255.25420.26.255.25565,534
2820.27.0.0/1620.27.0.1 to 20.27.255.25420.27.255.25565,534
2920.28.0.0/1620.28.0.1 to 20.28.255.25420.28.255.25565,534
3020.29.0.0/1620.29.0.1 to 20.29.255.25420.29.255.25565,534
3120.30.0.0/1620.30.0.1 to 20.30.255.25420.30.255.25565,534
3220.31.0.0/1620.31.0.1 to 20.31.255.25420.31.255.25565,534
3320.32.0.0/1620.32.0.1 to 20.32.255.25420.32.255.25565,534
3420.33.0.0/1620.33.0.1 to 20.33.255.25420.33.255.25565,534
3520.34.0.0/1620.34.0.1 to 20.34.255.25420.34.255.25565,534
3620.35.0.0/1620.35.0.1 to 20.35.255.25420.35.255.25565,534
3720.36.0.0/1620.36.0.1 to 20.36.255.25420.36.255.25565,534
3820.37.0.0/1620.37.0.1 to 20.37.255.25420.37.255.25565,534
3920.38.0.0/1620.38.0.1 to 20.38.255.25420.38.255.25565,534
4020.39.0.0/1620.39.0.1 to 20.39.255.25420.39.255.25565,534
4120.40.0.0/1620.40.0.1 to 20.40.255.25420.40.255.25565,534
4220.41.0.0/1620.41.0.1 to 20.41.255.25420.41.255.25565,534
4320.42.0.0/1620.42.0.1 to 20.42.255.25420.42.255.25565,534
4420.43.0.0/1620.43.0.1 to 20.43.255.25420.43.255.25565,534
4520.44.0.0/1620.44.0.1 to 20.44.255.25420.44.255.25565,534
4620.45.0.0/1620.45.0.1 to 20.45.255.25420.45.255.25565,534
4720.46.0.0/1620.46.0.1 to 20.46.255.25420.46.255.25565,534
4820.47.0.0/1620.47.0.1 to 20.47.255.25420.47.255.25565,534
4920.48.0.0/1620.48.0.1 to 20.48.255.25420.48.255.25565,534
5020.49.0.0/1620.49.0.1 to 20.49.255.25420.49.255.25565,534
5120.50.0.0/1620.50.0.1 to 20.50.255.25420.50.255.25565,534
5220.51.0.0/1620.51.0.1 to 20.51.255.25420.51.255.25565,534
5320.52.0.0/1620.52.0.1 to 20.52.255.25420.52.255.25565,534
5420.53.0.0/1620.53.0.1 to 20.53.255.25420.53.255.25565,534
5520.54.0.0/1620.54.0.1 to 20.54.255.25420.54.255.25565,534
5620.55.0.0/1620.55.0.1 to 20.55.255.25420.55.255.25565,534
5720.56.0.0/1620.56.0.1 to 20.56.255.25420.56.255.25565,534
5820.57.0.0/1620.57.0.1 to 20.57.255.25420.57.255.25565,534
5920.58.0.0/1620.58.0.1 to 20.58.255.25420.58.255.25565,534
6020.59.0.0/1620.59.0.1 to 20.59.255.25420.59.255.25565,534
6120.60.0.0/1620.60.0.1 to 20.60.255.25420.60.255.25565,534
6220.61.0.0/1620.61.0.1 to 20.61.255.25420.61.255.25565,534
6320.62.0.0/1620.62.0.1 to 20.62.255.25420.62.255.25565,534
6420.63.0.0/1620.63.0.1 to 20.63.255.25420.63.255.25565,534
6520.64.0.0/1620.64.0.1 to 20.64.255.25420.64.255.25565,534
6620.65.0.0/1620.65.0.1 to 20.65.255.25420.65.255.25565,534
6720.66.0.0/1620.66.0.1 to 20.66.255.25420.66.255.25565,534
6820.67.0.0/1620.67.0.1 to 20.67.255.25420.67.255.25565,534
6920.68.0.0/1620.68.0.1 to 20.68.255.25420.68.255.25565,534
7020.69.0.0/1620.69.0.1 to 20.69.255.25420.69.255.25565,534
7120.70.0.0/1620.70.0.1 to 20.70.255.25420.70.255.25565,534
7220.71.0.0/1620.71.0.1 to 20.71.255.25420.71.255.25565,534
7320.72.0.0/1620.72.0.1 to 20.72.255.25420.72.255.25565,534
7420.73.0.0/1620.73.0.1 to 20.73.255.25420.73.255.25565,534
7520.74.0.0/1620.74.0.1 to 20.74.255.25420.74.255.25565,534
7620.75.0.0/1620.75.0.1 to 20.75.255.25420.75.255.25565,534
7720.76.0.0/1620.76.0.1 to 20.76.255.25420.76.255.25565,534
7820.77.0.0/1620.77.0.1 to 20.77.255.25420.77.255.25565,534
7920.78.0.0/1620.78.0.1 to 20.78.255.25420.78.255.25565,534
8020.79.0.0/1620.79.0.1 to 20.79.255.25420.79.255.25565,534
8120.80.0.0/1620.80.0.1 to 20.80.255.25420.80.255.25565,534
8220.81.0.0/1620.81.0.1 to 20.81.255.25420.81.255.25565,534
8320.82.0.0/1620.82.0.1 to 20.82.255.25420.82.255.25565,534
8420.83.0.0/1620.83.0.1 to 20.83.255.25420.83.255.25565,534
8520.84.0.0/1620.84.0.1 to 20.84.255.25420.84.255.25565,534
8620.85.0.0/1620.85.0.1 to 20.85.255.25420.85.255.25565,534
8720.86.0.0/1620.86.0.1 to 20.86.255.25420.86.255.25565,534
8820.87.0.0/1620.87.0.1 to 20.87.255.25420.87.255.25565,534
8920.88.0.0/1620.88.0.1 to 20.88.255.25420.88.255.25565,534
9020.89.0.0/1620.89.0.1 to 20.89.255.25420.89.255.25565,534
9120.90.0.0/1620.90.0.1 to 20.90.255.25420.90.255.25565,534
9220.91.0.0/1620.91.0.1 to 20.91.255.25420.91.255.25565,534
9320.92.0.0/1620.92.0.1 to 20.92.255.25420.92.255.25565,534
9420.93.0.0/1620.93.0.1 to 20.93.255.25420.93.255.25565,534
9520.94.0.0/1620.94.0.1 to 20.94.255.25420.94.255.25565,534
9620.95.0.0/1620.95.0.1 to 20.95.255.25420.95.255.25565,534
9720.96.0.0/1620.96.0.1 to 20.96.255.25420.96.255.25565,534
9820.97.0.0/1620.97.0.1 to 20.97.255.25420.97.255.25565,534
9920.98.0.0/1620.98.0.1 to 20.98.255.25420.98.255.25565,534
10020.99.0.0/1620.99.0.1 to 20.99.255.25420.99.255.25565,534
10120.100.0.0/1620.100.0.1 to 20.100.255.25420.100.255.25565,534
10220.101.0.0/1620.101.0.1 to 20.101.255.25420.101.255.25565,534
10320.102.0.0/1620.102.0.1 to 20.102.255.25420.102.255.25565,534
10420.103.0.0/1620.103.0.1 to 20.103.255.25420.103.255.25565,534
10520.104.0.0/1620.104.0.1 to 20.104.255.25420.104.255.25565,534
10620.105.0.0/1620.105.0.1 to 20.105.255.25420.105.255.25565,534
10720.106.0.0/1620.106.0.1 to 20.106.255.25420.106.255.25565,534
10820.107.0.0/1620.107.0.1 to 20.107.255.25420.107.255.25565,534
10920.108.0.0/1620.108.0.1 to 20.108.255.25420.108.255.25565,534
11020.109.0.0/1620.109.0.1 to 20.109.255.25420.109.255.25565,534
11120.110.0.0/1620.110.0.1 to 20.110.255.25420.110.255.25565,534
11220.111.0.0/1620.111.0.1 to 20.111.255.25420.111.255.25565,534
11320.112.0.0/1620.112.0.1 to 20.112.255.25420.112.255.25565,534
11420.113.0.0/1620.113.0.1 to 20.113.255.25420.113.255.25565,534
11520.114.0.0/1620.114.0.1 to 20.114.255.25420.114.255.25565,534
11620.115.0.0/1620.115.0.1 to 20.115.255.25420.115.255.25565,534
11720.116.0.0/1620.116.0.1 to 20.116.255.25420.116.255.25565,534
11820.117.0.0/1620.117.0.1 to 20.117.255.25420.117.255.25565,534
11920.118.0.0/1620.118.0.1 to 20.118.255.25420.118.255.25565,534
12020.119.0.0/1620.119.0.1 to 20.119.255.25420.119.255.25565,534
12120.120.0.0/1620.120.0.1 to 20.120.255.25420.120.255.25565,534
12220.121.0.0/1620.121.0.1 to 20.121.255.25420.121.255.25565,534
12320.122.0.0/1620.122.0.1 to 20.122.255.25420.122.255.25565,534
12420.123.0.0/1620.123.0.1 to 20.123.255.25420.123.255.25565,534
12520.124.0.0/1620.124.0.1 to 20.124.255.25420.124.255.25565,534
12620.125.0.0/1620.125.0.1 to 20.125.255.25420.125.255.25565,534
12720.126.0.0/1620.126.0.1 to 20.126.255.25420.126.255.25565,534
12820.127.0.0/1620.127.0.1 to 20.127.255.25420.127.255.25565,534
12920.128.0.0/1620.128.0.1 to 20.128.255.25420.128.255.25565,534
13020.129.0.0/1620.129.0.1 to 20.129.255.25420.129.255.25565,534
13120.130.0.0/1620.130.0.1 to 20.130.255.25420.130.255.25565,534
13220.131.0.0/1620.131.0.1 to 20.131.255.25420.131.255.25565,534
13320.132.0.0/1620.132.0.1 to 20.132.255.25420.132.255.25565,534
13420.133.0.0/1620.133.0.1 to 20.133.255.25420.133.255.25565,534
13520.134.0.0/1620.134.0.1 to 20.134.255.25420.134.255.25565,534
13620.135.0.0/1620.135.0.1 to 20.135.255.25420.135.255.25565,534
13720.136.0.0/1620.136.0.1 to 20.136.255.25420.136.255.25565,534
13820.137.0.0/1620.137.0.1 to 20.137.255.25420.137.255.25565,534
13920.138.0.0/1620.138.0.1 to 20.138.255.25420.138.255.25565,534
14020.139.0.0/1620.139.0.1 to 20.139.255.25420.139.255.25565,534
14120.140.0.0/1620.140.0.1 to 20.140.255.25420.140.255.25565,534
14220.141.0.0/1620.141.0.1 to 20.141.255.25420.141.255.25565,534
14320.142.0.0/1620.142.0.1 to 20.142.255.25420.142.255.25565,534
14420.143.0.0/1620.143.0.1 to 20.143.255.25420.143.255.25565,534
14520.144.0.0/1620.144.0.1 to 20.144.255.25420.144.255.25565,534
14620.145.0.0/1620.145.0.1 to 20.145.255.25420.145.255.25565,534
14720.146.0.0/1620.146.0.1 to 20.146.255.25420.146.255.25565,534
14820.147.0.0/1620.147.0.1 to 20.147.255.25420.147.255.25565,534
14920.148.0.0/1620.148.0.1 to 20.148.255.25420.148.255.25565,534
15020.149.0.0/1620.149.0.1 to 20.149.255.25420.149.255.25565,534
15120.150.0.0/1620.150.0.1 to 20.150.255.25420.150.255.25565,534
15220.151.0.0/1620.151.0.1 to 20.151.255.25420.151.255.25565,534
15320.152.0.0/1620.152.0.1 to 20.152.255.25420.152.255.25565,534
15420.153.0.0/1620.153.0.1 to 20.153.255.25420.153.255.25565,534
15520.154.0.0/1620.154.0.1 to 20.154.255.25420.154.255.25565,534
15620.155.0.0/1620.155.0.1 to 20.155.255.25420.155.255.25565,534
15720.156.0.0/1620.156.0.1 to 20.156.255.25420.156.255.25565,534
15820.157.0.0/1620.157.0.1 to 20.157.255.25420.157.255.25565,534
15920.158.0.0/1620.158.0.1 to 20.158.255.25420.158.255.25565,534
16020.159.0.0/1620.159.0.1 to 20.159.255.25420.159.255.25565,534
16120.160.0.0/1620.160.0.1 to 20.160.255.25420.160.255.25565,534
16220.161.0.0/1620.161.0.1 to 20.161.255.25420.161.255.25565,534
16320.162.0.0/1620.162.0.1 to 20.162.255.25420.162.255.25565,534
16420.163.0.0/1620.163.0.1 to 20.163.255.25420.163.255.25565,534
16520.164.0.0/1620.164.0.1 to 20.164.255.25420.164.255.25565,534
16620.165.0.0/1620.165.0.1 to 20.165.255.25420.165.255.25565,534
16720.166.0.0/1620.166.0.1 to 20.166.255.25420.166.255.25565,534
16820.167.0.0/1620.167.0.1 to 20.167.255.25420.167.255.25565,534
16920.168.0.0/1620.168.0.1 to 20.168.255.25420.168.255.25565,534
17020.169.0.0/1620.169.0.1 to 20.169.255.25420.169.255.25565,534
17120.170.0.0/1620.170.0.1 to 20.170.255.25420.170.255.25565,534
17220.171.0.0/1620.171.0.1 to 20.171.255.25420.171.255.25565,534
17320.172.0.0/1620.172.0.1 to 20.172.255.25420.172.255.25565,534
17420.173.0.0/1620.173.0.1 to 20.173.255.25420.173.255.25565,534
17520.174.0.0/1620.174.0.1 to 20.174.255.25420.174.255.25565,534
17620.175.0.0/1620.175.0.1 to 20.175.255.25420.175.255.25565,534
17720.176.0.0/1620.176.0.1 to 20.176.255.25420.176.255.25565,534
17820.177.0.0/1620.177.0.1 to 20.177.255.25420.177.255.25565,534
17920.178.0.0/1620.178.0.1 to 20.178.255.25420.178.255.25565,534
18020.179.0.0/1620.179.0.1 to 20.179.255.25420.179.255.25565,534
18120.180.0.0/1620.180.0.1 to 20.180.255.25420.180.255.25565,534
18220.181.0.0/1620.181.0.1 to 20.181.255.25420.181.255.25565,534
18320.182.0.0/1620.182.0.1 to 20.182.255.25420.182.255.25565,534
18420.183.0.0/1620.183.0.1 to 20.183.255.25420.183.255.25565,534
18520.184.0.0/1620.184.0.1 to 20.184.255.25420.184.255.25565,534
18620.185.0.0/1620.185.0.1 to 20.185.255.25420.185.255.25565,534
18720.186.0.0/1620.186.0.1 to 20.186.255.25420.186.255.25565,534
18820.187.0.0/1620.187.0.1 to 20.187.255.25420.187.255.25565,534
18920.188.0.0/1620.188.0.1 to 20.188.255.25420.188.255.25565,534
19020.189.0.0/1620.189.0.1 to 20.189.255.25420.189.255.25565,534
19120.190.0.0/1620.190.0.1 to 20.190.255.25420.190.255.25565,534
19220.191.0.0/1620.191.0.1 to 20.191.255.25420.191.255.25565,534
19320.192.0.0/1620.192.0.1 to 20.192.255.25420.192.255.25565,534
19420.193.0.0/1620.193.0.1 to 20.193.255.25420.193.255.25565,534
19520.194.0.0/1620.194.0.1 to 20.194.255.25420.194.255.25565,534
19620.195.0.0/1620.195.0.1 to 20.195.255.25420.195.255.25565,534
19720.196.0.0/1620.196.0.1 to 20.196.255.25420.196.255.25565,534
19820.197.0.0/1620.197.0.1 to 20.197.255.25420.197.255.25565,534
19920.198.0.0/1620.198.0.1 to 20.198.255.25420.198.255.25565,534
20020.199.0.0/1620.199.0.1 to 20.199.255.25420.199.255.25565,534
20120.200.0.0/1620.200.0.1 to 20.200.255.25420.200.255.25565,534
20220.201.0.0/1620.201.0.1 to 20.201.255.25420.201.255.25565,534
20320.202.0.0/1620.202.0.1 to 20.202.255.25420.202.255.25565,534
20420.203.0.0/1620.203.0.1 to 20.203.255.25420.203.255.25565,534
20520.204.0.0/1620.204.0.1 to 20.204.255.25420.204.255.25565,534
20620.205.0.0/1620.205.0.1 to 20.205.255.25420.205.255.25565,534
20720.206.0.0/1620.206.0.1 to 20.206.255.25420.206.255.25565,534
20820.207.0.0/1620.207.0.1 to 20.207.255.25420.207.255.25565,534
20920.208.0.0/1620.208.0.1 to 20.208.255.25420.208.255.25565,534
21020.209.0.0/1620.209.0.1 to 20.209.255.25420.209.255.25565,534
21120.210.0.0/1620.210.0.1 to 20.210.255.25420.210.255.25565,534
21220.211.0.0/1620.211.0.1 to 20.211.255.25420.211.255.25565,534
21320.212.0.0/1620.212.0.1 to 20.212.255.25420.212.255.25565,534
21420.213.0.0/1620.213.0.1 to 20.213.255.25420.213.255.25565,534
21520.214.0.0/1620.214.0.1 to 20.214.255.25420.214.255.25565,534
21620.215.0.0/1620.215.0.1 to 20.215.255.25420.215.255.25565,534
21720.216.0.0/1620.216.0.1 to 20.216.255.25420.216.255.25565,534
21820.217.0.0/1620.217.0.1 to 20.217.255.25420.217.255.25565,534
21920.218.0.0/1620.218.0.1 to 20.218.255.25420.218.255.25565,534
22020.219.0.0/1620.219.0.1 to 20.219.255.25420.219.255.25565,534
22120.220.0.0/1620.220.0.1 to 20.220.255.25420.220.255.25565,534
22220.221.0.0/1620.221.0.1 to 20.221.255.25420.221.255.25565,534
22320.222.0.0/1620.222.0.1 to 20.222.255.25420.222.255.25565,534
22420.223.0.0/1620.223.0.1 to 20.223.255.25420.223.255.25565,534
22520.224.0.0/1620.224.0.1 to 20.224.255.25420.224.255.25565,534
22620.225.0.0/1620.225.0.1 to 20.225.255.25420.225.255.25565,534
22720.226.0.0/1620.226.0.1 to 20.226.255.25420.226.255.25565,534
22820.227.0.0/1620.227.0.1 to 20.227.255.25420.227.255.25565,534
22920.228.0.0/1620.228.0.1 to 20.228.255.25420.228.255.25565,534
23020.229.0.0/1620.229.0.1 to 20.229.255.25420.229.255.25565,534
23120.230.0.0/1620.230.0.1 to 20.230.255.25420.230.255.25565,534
23220.231.0.0/1620.231.0.1 to 20.231.255.25420.231.255.25565,534
23320.232.0.0/1620.232.0.1 to 20.232.255.25420.232.255.25565,534
23420.233.0.0/1620.233.0.1 to 20.233.255.25420.233.255.25565,534
23520.234.0.0/1620.234.0.1 to 20.234.255.25420.234.255.25565,534
23620.235.0.0/1620.235.0.1 to 20.235.255.25420.235.255.25565,534
23720.236.0.0/1620.236.0.1 to 20.236.255.25420.236.255.25565,534
23820.237.0.0/1620.237.0.1 to 20.237.255.25420.237.255.25565,534
23920.238.0.0/1620.238.0.1 to 20.238.255.25420.238.255.25565,534
24020.239.0.0/1620.239.0.1 to 20.239.255.25420.239.255.25565,534
24120.240.0.0/1620.240.0.1 to 20.240.255.25420.240.255.25565,534
24220.241.0.0/1620.241.0.1 to 20.241.255.25420.241.255.25565,534
24320.242.0.0/1620.242.0.1 to 20.242.255.25420.242.255.25565,534
24420.243.0.0/1620.243.0.1 to 20.243.255.25420.243.255.25565,534
24520.244.0.0/1620.244.0.1 to 20.244.255.25420.244.255.25565,534
24620.245.0.0/1620.245.0.1 to 20.245.255.25420.245.255.25565,534
24720.246.0.0/1620.246.0.1 to 20.246.255.25420.246.255.25565,534
24820.247.0.0/1620.247.0.1 to 20.247.255.25420.247.255.25565,534
24920.248.0.0/1620.248.0.1 to 20.248.255.25420.248.255.25565,534
25020.249.0.0/1620.249.0.1 to 20.249.255.25420.249.255.25565,534
25120.250.0.0/1620.250.0.1 to 20.250.255.25420.250.255.25565,534
25220.251.0.0/1620.251.0.1 to 20.251.255.25420.251.255.25565,534
25320.252.0.0/1620.252.0.1 to 20.252.255.25420.252.255.25565,534
25420.253.0.0/1620.253.0.1 to 20.253.255.25420.253.255.25565,534
25520.254.0.0/1620.254.0.1 to 20.254.255.25420.254.255.25565,534
25620.255.0.0/1620.255.0.1 to 20.255.255.25420.255.255.25565,534

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.