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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.

Network66.2.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
66.2.0.0
Broadcast address
66.3.255.255
First usable
66.2.0.1
Last usable
66.3.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
A (default /8)
As numbers
Hex 42020000 · Integer 1107427328 to 1107558399
Reverse DNS zones
2.66.in-addr.arpa
3.66.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000010.00000010.00000000.0000000066.2.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network01000010.00000010.00000000.0000000066.2.0.0
Broadcast01000010.00000011.11111111.1111111166.3.255.255
Split into smaller subnets/24
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

66.2.0.0/15 makes 512 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
166.2.0.0/2466.2.0.1 to 66.2.0.25466.2.0.255254
266.2.1.0/2466.2.1.1 to 66.2.1.25466.2.1.255254
366.2.2.0/2466.2.2.1 to 66.2.2.25466.2.2.255254
466.2.3.0/2466.2.3.1 to 66.2.3.25466.2.3.255254
566.2.4.0/2466.2.4.1 to 66.2.4.25466.2.4.255254
666.2.5.0/2466.2.5.1 to 66.2.5.25466.2.5.255254
766.2.6.0/2466.2.6.1 to 66.2.6.25466.2.6.255254
866.2.7.0/2466.2.7.1 to 66.2.7.25466.2.7.255254
966.2.8.0/2466.2.8.1 to 66.2.8.25466.2.8.255254
1066.2.9.0/2466.2.9.1 to 66.2.9.25466.2.9.255254
1166.2.10.0/2466.2.10.1 to 66.2.10.25466.2.10.255254
1266.2.11.0/2466.2.11.1 to 66.2.11.25466.2.11.255254
1366.2.12.0/2466.2.12.1 to 66.2.12.25466.2.12.255254
1466.2.13.0/2466.2.13.1 to 66.2.13.25466.2.13.255254
1566.2.14.0/2466.2.14.1 to 66.2.14.25466.2.14.255254
1666.2.15.0/2466.2.15.1 to 66.2.15.25466.2.15.255254
1766.2.16.0/2466.2.16.1 to 66.2.16.25466.2.16.255254
1866.2.17.0/2466.2.17.1 to 66.2.17.25466.2.17.255254
1966.2.18.0/2466.2.18.1 to 66.2.18.25466.2.18.255254
2066.2.19.0/2466.2.19.1 to 66.2.19.25466.2.19.255254
2166.2.20.0/2466.2.20.1 to 66.2.20.25466.2.20.255254
2266.2.21.0/2466.2.21.1 to 66.2.21.25466.2.21.255254
2366.2.22.0/2466.2.22.1 to 66.2.22.25466.2.22.255254
2466.2.23.0/2466.2.23.1 to 66.2.23.25466.2.23.255254
2566.2.24.0/2466.2.24.1 to 66.2.24.25466.2.24.255254
2666.2.25.0/2466.2.25.1 to 66.2.25.25466.2.25.255254
2766.2.26.0/2466.2.26.1 to 66.2.26.25466.2.26.255254
2866.2.27.0/2466.2.27.1 to 66.2.27.25466.2.27.255254
2966.2.28.0/2466.2.28.1 to 66.2.28.25466.2.28.255254
3066.2.29.0/2466.2.29.1 to 66.2.29.25466.2.29.255254
3166.2.30.0/2466.2.30.1 to 66.2.30.25466.2.30.255254
3266.2.31.0/2466.2.31.1 to 66.2.31.25466.2.31.255254
3366.2.32.0/2466.2.32.1 to 66.2.32.25466.2.32.255254
3466.2.33.0/2466.2.33.1 to 66.2.33.25466.2.33.255254
3566.2.34.0/2466.2.34.1 to 66.2.34.25466.2.34.255254
3666.2.35.0/2466.2.35.1 to 66.2.35.25466.2.35.255254
3766.2.36.0/2466.2.36.1 to 66.2.36.25466.2.36.255254
3866.2.37.0/2466.2.37.1 to 66.2.37.25466.2.37.255254
3966.2.38.0/2466.2.38.1 to 66.2.38.25466.2.38.255254
4066.2.39.0/2466.2.39.1 to 66.2.39.25466.2.39.255254
4166.2.40.0/2466.2.40.1 to 66.2.40.25466.2.40.255254
4266.2.41.0/2466.2.41.1 to 66.2.41.25466.2.41.255254
4366.2.42.0/2466.2.42.1 to 66.2.42.25466.2.42.255254
4466.2.43.0/2466.2.43.1 to 66.2.43.25466.2.43.255254
4566.2.44.0/2466.2.44.1 to 66.2.44.25466.2.44.255254
4666.2.45.0/2466.2.45.1 to 66.2.45.25466.2.45.255254
4766.2.46.0/2466.2.46.1 to 66.2.46.25466.2.46.255254
4866.2.47.0/2466.2.47.1 to 66.2.47.25466.2.47.255254
4966.2.48.0/2466.2.48.1 to 66.2.48.25466.2.48.255254
5066.2.49.0/2466.2.49.1 to 66.2.49.25466.2.49.255254
5166.2.50.0/2466.2.50.1 to 66.2.50.25466.2.50.255254
5266.2.51.0/2466.2.51.1 to 66.2.51.25466.2.51.255254
5366.2.52.0/2466.2.52.1 to 66.2.52.25466.2.52.255254
5466.2.53.0/2466.2.53.1 to 66.2.53.25466.2.53.255254
5566.2.54.0/2466.2.54.1 to 66.2.54.25466.2.54.255254
5666.2.55.0/2466.2.55.1 to 66.2.55.25466.2.55.255254
5766.2.56.0/2466.2.56.1 to 66.2.56.25466.2.56.255254
5866.2.57.0/2466.2.57.1 to 66.2.57.25466.2.57.255254
5966.2.58.0/2466.2.58.1 to 66.2.58.25466.2.58.255254
6066.2.59.0/2466.2.59.1 to 66.2.59.25466.2.59.255254
6166.2.60.0/2466.2.60.1 to 66.2.60.25466.2.60.255254
6266.2.61.0/2466.2.61.1 to 66.2.61.25466.2.61.255254
6366.2.62.0/2466.2.62.1 to 66.2.62.25466.2.62.255254
6466.2.63.0/2466.2.63.1 to 66.2.63.25466.2.63.255254
6566.2.64.0/2466.2.64.1 to 66.2.64.25466.2.64.255254
6666.2.65.0/2466.2.65.1 to 66.2.65.25466.2.65.255254
6766.2.66.0/2466.2.66.1 to 66.2.66.25466.2.66.255254
6866.2.67.0/2466.2.67.1 to 66.2.67.25466.2.67.255254
6966.2.68.0/2466.2.68.1 to 66.2.68.25466.2.68.255254
7066.2.69.0/2466.2.69.1 to 66.2.69.25466.2.69.255254
7166.2.70.0/2466.2.70.1 to 66.2.70.25466.2.70.255254
7266.2.71.0/2466.2.71.1 to 66.2.71.25466.2.71.255254
7366.2.72.0/2466.2.72.1 to 66.2.72.25466.2.72.255254
7466.2.73.0/2466.2.73.1 to 66.2.73.25466.2.73.255254
7566.2.74.0/2466.2.74.1 to 66.2.74.25466.2.74.255254
7666.2.75.0/2466.2.75.1 to 66.2.75.25466.2.75.255254
7766.2.76.0/2466.2.76.1 to 66.2.76.25466.2.76.255254
7866.2.77.0/2466.2.77.1 to 66.2.77.25466.2.77.255254
7966.2.78.0/2466.2.78.1 to 66.2.78.25466.2.78.255254
8066.2.79.0/2466.2.79.1 to 66.2.79.25466.2.79.255254
8166.2.80.0/2466.2.80.1 to 66.2.80.25466.2.80.255254
8266.2.81.0/2466.2.81.1 to 66.2.81.25466.2.81.255254
8366.2.82.0/2466.2.82.1 to 66.2.82.25466.2.82.255254
8466.2.83.0/2466.2.83.1 to 66.2.83.25466.2.83.255254
8566.2.84.0/2466.2.84.1 to 66.2.84.25466.2.84.255254
8666.2.85.0/2466.2.85.1 to 66.2.85.25466.2.85.255254
8766.2.86.0/2466.2.86.1 to 66.2.86.25466.2.86.255254
8866.2.87.0/2466.2.87.1 to 66.2.87.25466.2.87.255254
8966.2.88.0/2466.2.88.1 to 66.2.88.25466.2.88.255254
9066.2.89.0/2466.2.89.1 to 66.2.89.25466.2.89.255254
9166.2.90.0/2466.2.90.1 to 66.2.90.25466.2.90.255254
9266.2.91.0/2466.2.91.1 to 66.2.91.25466.2.91.255254
9366.2.92.0/2466.2.92.1 to 66.2.92.25466.2.92.255254
9466.2.93.0/2466.2.93.1 to 66.2.93.25466.2.93.255254
9566.2.94.0/2466.2.94.1 to 66.2.94.25466.2.94.255254
9666.2.95.0/2466.2.95.1 to 66.2.95.25466.2.95.255254
9766.2.96.0/2466.2.96.1 to 66.2.96.25466.2.96.255254
9866.2.97.0/2466.2.97.1 to 66.2.97.25466.2.97.255254
9966.2.98.0/2466.2.98.1 to 66.2.98.25466.2.98.255254
10066.2.99.0/2466.2.99.1 to 66.2.99.25466.2.99.255254
10166.2.100.0/2466.2.100.1 to 66.2.100.25466.2.100.255254
10266.2.101.0/2466.2.101.1 to 66.2.101.25466.2.101.255254
10366.2.102.0/2466.2.102.1 to 66.2.102.25466.2.102.255254
10466.2.103.0/2466.2.103.1 to 66.2.103.25466.2.103.255254
10566.2.104.0/2466.2.104.1 to 66.2.104.25466.2.104.255254
10666.2.105.0/2466.2.105.1 to 66.2.105.25466.2.105.255254
10766.2.106.0/2466.2.106.1 to 66.2.106.25466.2.106.255254
10866.2.107.0/2466.2.107.1 to 66.2.107.25466.2.107.255254
10966.2.108.0/2466.2.108.1 to 66.2.108.25466.2.108.255254
11066.2.109.0/2466.2.109.1 to 66.2.109.25466.2.109.255254
11166.2.110.0/2466.2.110.1 to 66.2.110.25466.2.110.255254
11266.2.111.0/2466.2.111.1 to 66.2.111.25466.2.111.255254
11366.2.112.0/2466.2.112.1 to 66.2.112.25466.2.112.255254
11466.2.113.0/2466.2.113.1 to 66.2.113.25466.2.113.255254
11566.2.114.0/2466.2.114.1 to 66.2.114.25466.2.114.255254
11666.2.115.0/2466.2.115.1 to 66.2.115.25466.2.115.255254
11766.2.116.0/2466.2.116.1 to 66.2.116.25466.2.116.255254
11866.2.117.0/2466.2.117.1 to 66.2.117.25466.2.117.255254
11966.2.118.0/2466.2.118.1 to 66.2.118.25466.2.118.255254
12066.2.119.0/2466.2.119.1 to 66.2.119.25466.2.119.255254
12166.2.120.0/2466.2.120.1 to 66.2.120.25466.2.120.255254
12266.2.121.0/2466.2.121.1 to 66.2.121.25466.2.121.255254
12366.2.122.0/2466.2.122.1 to 66.2.122.25466.2.122.255254
12466.2.123.0/2466.2.123.1 to 66.2.123.25466.2.123.255254
12566.2.124.0/2466.2.124.1 to 66.2.124.25466.2.124.255254
12666.2.125.0/2466.2.125.1 to 66.2.125.25466.2.125.255254
12766.2.126.0/2466.2.126.1 to 66.2.126.25466.2.126.255254
12866.2.127.0/2466.2.127.1 to 66.2.127.25466.2.127.255254
12966.2.128.0/2466.2.128.1 to 66.2.128.25466.2.128.255254
13066.2.129.0/2466.2.129.1 to 66.2.129.25466.2.129.255254
13166.2.130.0/2466.2.130.1 to 66.2.130.25466.2.130.255254
13266.2.131.0/2466.2.131.1 to 66.2.131.25466.2.131.255254
13366.2.132.0/2466.2.132.1 to 66.2.132.25466.2.132.255254
13466.2.133.0/2466.2.133.1 to 66.2.133.25466.2.133.255254
13566.2.134.0/2466.2.134.1 to 66.2.134.25466.2.134.255254
13666.2.135.0/2466.2.135.1 to 66.2.135.25466.2.135.255254
13766.2.136.0/2466.2.136.1 to 66.2.136.25466.2.136.255254
13866.2.137.0/2466.2.137.1 to 66.2.137.25466.2.137.255254
13966.2.138.0/2466.2.138.1 to 66.2.138.25466.2.138.255254
14066.2.139.0/2466.2.139.1 to 66.2.139.25466.2.139.255254
14166.2.140.0/2466.2.140.1 to 66.2.140.25466.2.140.255254
14266.2.141.0/2466.2.141.1 to 66.2.141.25466.2.141.255254
14366.2.142.0/2466.2.142.1 to 66.2.142.25466.2.142.255254
14466.2.143.0/2466.2.143.1 to 66.2.143.25466.2.143.255254
14566.2.144.0/2466.2.144.1 to 66.2.144.25466.2.144.255254
14666.2.145.0/2466.2.145.1 to 66.2.145.25466.2.145.255254
14766.2.146.0/2466.2.146.1 to 66.2.146.25466.2.146.255254
14866.2.147.0/2466.2.147.1 to 66.2.147.25466.2.147.255254
14966.2.148.0/2466.2.148.1 to 66.2.148.25466.2.148.255254
15066.2.149.0/2466.2.149.1 to 66.2.149.25466.2.149.255254
15166.2.150.0/2466.2.150.1 to 66.2.150.25466.2.150.255254
15266.2.151.0/2466.2.151.1 to 66.2.151.25466.2.151.255254
15366.2.152.0/2466.2.152.1 to 66.2.152.25466.2.152.255254
15466.2.153.0/2466.2.153.1 to 66.2.153.25466.2.153.255254
15566.2.154.0/2466.2.154.1 to 66.2.154.25466.2.154.255254
15666.2.155.0/2466.2.155.1 to 66.2.155.25466.2.155.255254
15766.2.156.0/2466.2.156.1 to 66.2.156.25466.2.156.255254
15866.2.157.0/2466.2.157.1 to 66.2.157.25466.2.157.255254
15966.2.158.0/2466.2.158.1 to 66.2.158.25466.2.158.255254
16066.2.159.0/2466.2.159.1 to 66.2.159.25466.2.159.255254
16166.2.160.0/2466.2.160.1 to 66.2.160.25466.2.160.255254
16266.2.161.0/2466.2.161.1 to 66.2.161.25466.2.161.255254
16366.2.162.0/2466.2.162.1 to 66.2.162.25466.2.162.255254
16466.2.163.0/2466.2.163.1 to 66.2.163.25466.2.163.255254
16566.2.164.0/2466.2.164.1 to 66.2.164.25466.2.164.255254
16666.2.165.0/2466.2.165.1 to 66.2.165.25466.2.165.255254
16766.2.166.0/2466.2.166.1 to 66.2.166.25466.2.166.255254
16866.2.167.0/2466.2.167.1 to 66.2.167.25466.2.167.255254
16966.2.168.0/2466.2.168.1 to 66.2.168.25466.2.168.255254
17066.2.169.0/2466.2.169.1 to 66.2.169.25466.2.169.255254
17166.2.170.0/2466.2.170.1 to 66.2.170.25466.2.170.255254
17266.2.171.0/2466.2.171.1 to 66.2.171.25466.2.171.255254
17366.2.172.0/2466.2.172.1 to 66.2.172.25466.2.172.255254
17466.2.173.0/2466.2.173.1 to 66.2.173.25466.2.173.255254
17566.2.174.0/2466.2.174.1 to 66.2.174.25466.2.174.255254
17666.2.175.0/2466.2.175.1 to 66.2.175.25466.2.175.255254
17766.2.176.0/2466.2.176.1 to 66.2.176.25466.2.176.255254
17866.2.177.0/2466.2.177.1 to 66.2.177.25466.2.177.255254
17966.2.178.0/2466.2.178.1 to 66.2.178.25466.2.178.255254
18066.2.179.0/2466.2.179.1 to 66.2.179.25466.2.179.255254
18166.2.180.0/2466.2.180.1 to 66.2.180.25466.2.180.255254
18266.2.181.0/2466.2.181.1 to 66.2.181.25466.2.181.255254
18366.2.182.0/2466.2.182.1 to 66.2.182.25466.2.182.255254
18466.2.183.0/2466.2.183.1 to 66.2.183.25466.2.183.255254
18566.2.184.0/2466.2.184.1 to 66.2.184.25466.2.184.255254
18666.2.185.0/2466.2.185.1 to 66.2.185.25466.2.185.255254
18766.2.186.0/2466.2.186.1 to 66.2.186.25466.2.186.255254
18866.2.187.0/2466.2.187.1 to 66.2.187.25466.2.187.255254
18966.2.188.0/2466.2.188.1 to 66.2.188.25466.2.188.255254
19066.2.189.0/2466.2.189.1 to 66.2.189.25466.2.189.255254
19166.2.190.0/2466.2.190.1 to 66.2.190.25466.2.190.255254
19266.2.191.0/2466.2.191.1 to 66.2.191.25466.2.191.255254
19366.2.192.0/2466.2.192.1 to 66.2.192.25466.2.192.255254
19466.2.193.0/2466.2.193.1 to 66.2.193.25466.2.193.255254
19566.2.194.0/2466.2.194.1 to 66.2.194.25466.2.194.255254
19666.2.195.0/2466.2.195.1 to 66.2.195.25466.2.195.255254
19766.2.196.0/2466.2.196.1 to 66.2.196.25466.2.196.255254
19866.2.197.0/2466.2.197.1 to 66.2.197.25466.2.197.255254
19966.2.198.0/2466.2.198.1 to 66.2.198.25466.2.198.255254
20066.2.199.0/2466.2.199.1 to 66.2.199.25466.2.199.255254
20166.2.200.0/2466.2.200.1 to 66.2.200.25466.2.200.255254
20266.2.201.0/2466.2.201.1 to 66.2.201.25466.2.201.255254
20366.2.202.0/2466.2.202.1 to 66.2.202.25466.2.202.255254
20466.2.203.0/2466.2.203.1 to 66.2.203.25466.2.203.255254
20566.2.204.0/2466.2.204.1 to 66.2.204.25466.2.204.255254
20666.2.205.0/2466.2.205.1 to 66.2.205.25466.2.205.255254
20766.2.206.0/2466.2.206.1 to 66.2.206.25466.2.206.255254
20866.2.207.0/2466.2.207.1 to 66.2.207.25466.2.207.255254
20966.2.208.0/2466.2.208.1 to 66.2.208.25466.2.208.255254
21066.2.209.0/2466.2.209.1 to 66.2.209.25466.2.209.255254
21166.2.210.0/2466.2.210.1 to 66.2.210.25466.2.210.255254
21266.2.211.0/2466.2.211.1 to 66.2.211.25466.2.211.255254
21366.2.212.0/2466.2.212.1 to 66.2.212.25466.2.212.255254
21466.2.213.0/2466.2.213.1 to 66.2.213.25466.2.213.255254
21566.2.214.0/2466.2.214.1 to 66.2.214.25466.2.214.255254
21666.2.215.0/2466.2.215.1 to 66.2.215.25466.2.215.255254
21766.2.216.0/2466.2.216.1 to 66.2.216.25466.2.216.255254
21866.2.217.0/2466.2.217.1 to 66.2.217.25466.2.217.255254
21966.2.218.0/2466.2.218.1 to 66.2.218.25466.2.218.255254
22066.2.219.0/2466.2.219.1 to 66.2.219.25466.2.219.255254
22166.2.220.0/2466.2.220.1 to 66.2.220.25466.2.220.255254
22266.2.221.0/2466.2.221.1 to 66.2.221.25466.2.221.255254
22366.2.222.0/2466.2.222.1 to 66.2.222.25466.2.222.255254
22466.2.223.0/2466.2.223.1 to 66.2.223.25466.2.223.255254
22566.2.224.0/2466.2.224.1 to 66.2.224.25466.2.224.255254
22666.2.225.0/2466.2.225.1 to 66.2.225.25466.2.225.255254
22766.2.226.0/2466.2.226.1 to 66.2.226.25466.2.226.255254
22866.2.227.0/2466.2.227.1 to 66.2.227.25466.2.227.255254
22966.2.228.0/2466.2.228.1 to 66.2.228.25466.2.228.255254
23066.2.229.0/2466.2.229.1 to 66.2.229.25466.2.229.255254
23166.2.230.0/2466.2.230.1 to 66.2.230.25466.2.230.255254
23266.2.231.0/2466.2.231.1 to 66.2.231.25466.2.231.255254
23366.2.232.0/2466.2.232.1 to 66.2.232.25466.2.232.255254
23466.2.233.0/2466.2.233.1 to 66.2.233.25466.2.233.255254
23566.2.234.0/2466.2.234.1 to 66.2.234.25466.2.234.255254
23666.2.235.0/2466.2.235.1 to 66.2.235.25466.2.235.255254
23766.2.236.0/2466.2.236.1 to 66.2.236.25466.2.236.255254
23866.2.237.0/2466.2.237.1 to 66.2.237.25466.2.237.255254
23966.2.238.0/2466.2.238.1 to 66.2.238.25466.2.238.255254
24066.2.239.0/2466.2.239.1 to 66.2.239.25466.2.239.255254
24166.2.240.0/2466.2.240.1 to 66.2.240.25466.2.240.255254
24266.2.241.0/2466.2.241.1 to 66.2.241.25466.2.241.255254
24366.2.242.0/2466.2.242.1 to 66.2.242.25466.2.242.255254
24466.2.243.0/2466.2.243.1 to 66.2.243.25466.2.243.255254
24566.2.244.0/2466.2.244.1 to 66.2.244.25466.2.244.255254
24666.2.245.0/2466.2.245.1 to 66.2.245.25466.2.245.255254
24766.2.246.0/2466.2.246.1 to 66.2.246.25466.2.246.255254
24866.2.247.0/2466.2.247.1 to 66.2.247.25466.2.247.255254
24966.2.248.0/2466.2.248.1 to 66.2.248.25466.2.248.255254
25066.2.249.0/2466.2.249.1 to 66.2.249.25466.2.249.255254
25166.2.250.0/2466.2.250.1 to 66.2.250.25466.2.250.255254
25266.2.251.0/2466.2.251.1 to 66.2.251.25466.2.251.255254
25366.2.252.0/2466.2.252.1 to 66.2.252.25466.2.252.255254
25466.2.253.0/2466.2.253.1 to 66.2.253.25466.2.253.255254
25566.2.254.0/2466.2.254.1 to 66.2.254.25466.2.254.255254
25666.2.255.0/2466.2.255.1 to 66.2.255.25466.2.255.255254

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.