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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.

Network12.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
12.0.0.0
Broadcast address
12.255.255.255
First usable
12.0.0.1
Last usable
12.255.255.254
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 0C000000 · Integer 201326592 to 218103807
Reverse DNS zone
12.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001100..00000000.00000000.0000000012.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00001100..00000000.00000000.0000000012.0.0.0
Broadcast00001100..11111111.11111111.1111111112.255.255.255
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)

12.0.0.0/8 makes 256 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
112.0.0.0/1612.0.0.1 to 12.0.255.25412.0.255.25565,534
212.1.0.0/1612.1.0.1 to 12.1.255.25412.1.255.25565,534
312.2.0.0/1612.2.0.1 to 12.2.255.25412.2.255.25565,534
412.3.0.0/1612.3.0.1 to 12.3.255.25412.3.255.25565,534
512.4.0.0/1612.4.0.1 to 12.4.255.25412.4.255.25565,534
612.5.0.0/1612.5.0.1 to 12.5.255.25412.5.255.25565,534
712.6.0.0/1612.6.0.1 to 12.6.255.25412.6.255.25565,534
812.7.0.0/1612.7.0.1 to 12.7.255.25412.7.255.25565,534
912.8.0.0/1612.8.0.1 to 12.8.255.25412.8.255.25565,534
1012.9.0.0/1612.9.0.1 to 12.9.255.25412.9.255.25565,534
1112.10.0.0/1612.10.0.1 to 12.10.255.25412.10.255.25565,534
1212.11.0.0/1612.11.0.1 to 12.11.255.25412.11.255.25565,534
1312.12.0.0/1612.12.0.1 to 12.12.255.25412.12.255.25565,534
1412.13.0.0/1612.13.0.1 to 12.13.255.25412.13.255.25565,534
1512.14.0.0/1612.14.0.1 to 12.14.255.25412.14.255.25565,534
1612.15.0.0/1612.15.0.1 to 12.15.255.25412.15.255.25565,534
1712.16.0.0/1612.16.0.1 to 12.16.255.25412.16.255.25565,534
1812.17.0.0/1612.17.0.1 to 12.17.255.25412.17.255.25565,534
1912.18.0.0/1612.18.0.1 to 12.18.255.25412.18.255.25565,534
2012.19.0.0/1612.19.0.1 to 12.19.255.25412.19.255.25565,534
2112.20.0.0/1612.20.0.1 to 12.20.255.25412.20.255.25565,534
2212.21.0.0/1612.21.0.1 to 12.21.255.25412.21.255.25565,534
2312.22.0.0/1612.22.0.1 to 12.22.255.25412.22.255.25565,534
2412.23.0.0/1612.23.0.1 to 12.23.255.25412.23.255.25565,534
2512.24.0.0/1612.24.0.1 to 12.24.255.25412.24.255.25565,534
2612.25.0.0/1612.25.0.1 to 12.25.255.25412.25.255.25565,534
2712.26.0.0/1612.26.0.1 to 12.26.255.25412.26.255.25565,534
2812.27.0.0/1612.27.0.1 to 12.27.255.25412.27.255.25565,534
2912.28.0.0/1612.28.0.1 to 12.28.255.25412.28.255.25565,534
3012.29.0.0/1612.29.0.1 to 12.29.255.25412.29.255.25565,534
3112.30.0.0/1612.30.0.1 to 12.30.255.25412.30.255.25565,534
3212.31.0.0/1612.31.0.1 to 12.31.255.25412.31.255.25565,534
3312.32.0.0/1612.32.0.1 to 12.32.255.25412.32.255.25565,534
3412.33.0.0/1612.33.0.1 to 12.33.255.25412.33.255.25565,534
3512.34.0.0/1612.34.0.1 to 12.34.255.25412.34.255.25565,534
3612.35.0.0/1612.35.0.1 to 12.35.255.25412.35.255.25565,534
3712.36.0.0/1612.36.0.1 to 12.36.255.25412.36.255.25565,534
3812.37.0.0/1612.37.0.1 to 12.37.255.25412.37.255.25565,534
3912.38.0.0/1612.38.0.1 to 12.38.255.25412.38.255.25565,534
4012.39.0.0/1612.39.0.1 to 12.39.255.25412.39.255.25565,534
4112.40.0.0/1612.40.0.1 to 12.40.255.25412.40.255.25565,534
4212.41.0.0/1612.41.0.1 to 12.41.255.25412.41.255.25565,534
4312.42.0.0/1612.42.0.1 to 12.42.255.25412.42.255.25565,534
4412.43.0.0/1612.43.0.1 to 12.43.255.25412.43.255.25565,534
4512.44.0.0/1612.44.0.1 to 12.44.255.25412.44.255.25565,534
4612.45.0.0/1612.45.0.1 to 12.45.255.25412.45.255.25565,534
4712.46.0.0/1612.46.0.1 to 12.46.255.25412.46.255.25565,534
4812.47.0.0/1612.47.0.1 to 12.47.255.25412.47.255.25565,534
4912.48.0.0/1612.48.0.1 to 12.48.255.25412.48.255.25565,534
5012.49.0.0/1612.49.0.1 to 12.49.255.25412.49.255.25565,534
5112.50.0.0/1612.50.0.1 to 12.50.255.25412.50.255.25565,534
5212.51.0.0/1612.51.0.1 to 12.51.255.25412.51.255.25565,534
5312.52.0.0/1612.52.0.1 to 12.52.255.25412.52.255.25565,534
5412.53.0.0/1612.53.0.1 to 12.53.255.25412.53.255.25565,534
5512.54.0.0/1612.54.0.1 to 12.54.255.25412.54.255.25565,534
5612.55.0.0/1612.55.0.1 to 12.55.255.25412.55.255.25565,534
5712.56.0.0/1612.56.0.1 to 12.56.255.25412.56.255.25565,534
5812.57.0.0/1612.57.0.1 to 12.57.255.25412.57.255.25565,534
5912.58.0.0/1612.58.0.1 to 12.58.255.25412.58.255.25565,534
6012.59.0.0/1612.59.0.1 to 12.59.255.25412.59.255.25565,534
6112.60.0.0/1612.60.0.1 to 12.60.255.25412.60.255.25565,534
6212.61.0.0/1612.61.0.1 to 12.61.255.25412.61.255.25565,534
6312.62.0.0/1612.62.0.1 to 12.62.255.25412.62.255.25565,534
6412.63.0.0/1612.63.0.1 to 12.63.255.25412.63.255.25565,534
6512.64.0.0/1612.64.0.1 to 12.64.255.25412.64.255.25565,534
6612.65.0.0/1612.65.0.1 to 12.65.255.25412.65.255.25565,534
6712.66.0.0/1612.66.0.1 to 12.66.255.25412.66.255.25565,534
6812.67.0.0/1612.67.0.1 to 12.67.255.25412.67.255.25565,534
6912.68.0.0/1612.68.0.1 to 12.68.255.25412.68.255.25565,534
7012.69.0.0/1612.69.0.1 to 12.69.255.25412.69.255.25565,534
7112.70.0.0/1612.70.0.1 to 12.70.255.25412.70.255.25565,534
7212.71.0.0/1612.71.0.1 to 12.71.255.25412.71.255.25565,534
7312.72.0.0/1612.72.0.1 to 12.72.255.25412.72.255.25565,534
7412.73.0.0/1612.73.0.1 to 12.73.255.25412.73.255.25565,534
7512.74.0.0/1612.74.0.1 to 12.74.255.25412.74.255.25565,534
7612.75.0.0/1612.75.0.1 to 12.75.255.25412.75.255.25565,534
7712.76.0.0/1612.76.0.1 to 12.76.255.25412.76.255.25565,534
7812.77.0.0/1612.77.0.1 to 12.77.255.25412.77.255.25565,534
7912.78.0.0/1612.78.0.1 to 12.78.255.25412.78.255.25565,534
8012.79.0.0/1612.79.0.1 to 12.79.255.25412.79.255.25565,534
8112.80.0.0/1612.80.0.1 to 12.80.255.25412.80.255.25565,534
8212.81.0.0/1612.81.0.1 to 12.81.255.25412.81.255.25565,534
8312.82.0.0/1612.82.0.1 to 12.82.255.25412.82.255.25565,534
8412.83.0.0/1612.83.0.1 to 12.83.255.25412.83.255.25565,534
8512.84.0.0/1612.84.0.1 to 12.84.255.25412.84.255.25565,534
8612.85.0.0/1612.85.0.1 to 12.85.255.25412.85.255.25565,534
8712.86.0.0/1612.86.0.1 to 12.86.255.25412.86.255.25565,534
8812.87.0.0/1612.87.0.1 to 12.87.255.25412.87.255.25565,534
8912.88.0.0/1612.88.0.1 to 12.88.255.25412.88.255.25565,534
9012.89.0.0/1612.89.0.1 to 12.89.255.25412.89.255.25565,534
9112.90.0.0/1612.90.0.1 to 12.90.255.25412.90.255.25565,534
9212.91.0.0/1612.91.0.1 to 12.91.255.25412.91.255.25565,534
9312.92.0.0/1612.92.0.1 to 12.92.255.25412.92.255.25565,534
9412.93.0.0/1612.93.0.1 to 12.93.255.25412.93.255.25565,534
9512.94.0.0/1612.94.0.1 to 12.94.255.25412.94.255.25565,534
9612.95.0.0/1612.95.0.1 to 12.95.255.25412.95.255.25565,534
9712.96.0.0/1612.96.0.1 to 12.96.255.25412.96.255.25565,534
9812.97.0.0/1612.97.0.1 to 12.97.255.25412.97.255.25565,534
9912.98.0.0/1612.98.0.1 to 12.98.255.25412.98.255.25565,534
10012.99.0.0/1612.99.0.1 to 12.99.255.25412.99.255.25565,534
10112.100.0.0/1612.100.0.1 to 12.100.255.25412.100.255.25565,534
10212.101.0.0/1612.101.0.1 to 12.101.255.25412.101.255.25565,534
10312.102.0.0/1612.102.0.1 to 12.102.255.25412.102.255.25565,534
10412.103.0.0/1612.103.0.1 to 12.103.255.25412.103.255.25565,534
10512.104.0.0/1612.104.0.1 to 12.104.255.25412.104.255.25565,534
10612.105.0.0/1612.105.0.1 to 12.105.255.25412.105.255.25565,534
10712.106.0.0/1612.106.0.1 to 12.106.255.25412.106.255.25565,534
10812.107.0.0/1612.107.0.1 to 12.107.255.25412.107.255.25565,534
10912.108.0.0/1612.108.0.1 to 12.108.255.25412.108.255.25565,534
11012.109.0.0/1612.109.0.1 to 12.109.255.25412.109.255.25565,534
11112.110.0.0/1612.110.0.1 to 12.110.255.25412.110.255.25565,534
11212.111.0.0/1612.111.0.1 to 12.111.255.25412.111.255.25565,534
11312.112.0.0/1612.112.0.1 to 12.112.255.25412.112.255.25565,534
11412.113.0.0/1612.113.0.1 to 12.113.255.25412.113.255.25565,534
11512.114.0.0/1612.114.0.1 to 12.114.255.25412.114.255.25565,534
11612.115.0.0/1612.115.0.1 to 12.115.255.25412.115.255.25565,534
11712.116.0.0/1612.116.0.1 to 12.116.255.25412.116.255.25565,534
11812.117.0.0/1612.117.0.1 to 12.117.255.25412.117.255.25565,534
11912.118.0.0/1612.118.0.1 to 12.118.255.25412.118.255.25565,534
12012.119.0.0/1612.119.0.1 to 12.119.255.25412.119.255.25565,534
12112.120.0.0/1612.120.0.1 to 12.120.255.25412.120.255.25565,534
12212.121.0.0/1612.121.0.1 to 12.121.255.25412.121.255.25565,534
12312.122.0.0/1612.122.0.1 to 12.122.255.25412.122.255.25565,534
12412.123.0.0/1612.123.0.1 to 12.123.255.25412.123.255.25565,534
12512.124.0.0/1612.124.0.1 to 12.124.255.25412.124.255.25565,534
12612.125.0.0/1612.125.0.1 to 12.125.255.25412.125.255.25565,534
12712.126.0.0/1612.126.0.1 to 12.126.255.25412.126.255.25565,534
12812.127.0.0/1612.127.0.1 to 12.127.255.25412.127.255.25565,534
12912.128.0.0/1612.128.0.1 to 12.128.255.25412.128.255.25565,534
13012.129.0.0/1612.129.0.1 to 12.129.255.25412.129.255.25565,534
13112.130.0.0/1612.130.0.1 to 12.130.255.25412.130.255.25565,534
13212.131.0.0/1612.131.0.1 to 12.131.255.25412.131.255.25565,534
13312.132.0.0/1612.132.0.1 to 12.132.255.25412.132.255.25565,534
13412.133.0.0/1612.133.0.1 to 12.133.255.25412.133.255.25565,534
13512.134.0.0/1612.134.0.1 to 12.134.255.25412.134.255.25565,534
13612.135.0.0/1612.135.0.1 to 12.135.255.25412.135.255.25565,534
13712.136.0.0/1612.136.0.1 to 12.136.255.25412.136.255.25565,534
13812.137.0.0/1612.137.0.1 to 12.137.255.25412.137.255.25565,534
13912.138.0.0/1612.138.0.1 to 12.138.255.25412.138.255.25565,534
14012.139.0.0/1612.139.0.1 to 12.139.255.25412.139.255.25565,534
14112.140.0.0/1612.140.0.1 to 12.140.255.25412.140.255.25565,534
14212.141.0.0/1612.141.0.1 to 12.141.255.25412.141.255.25565,534
14312.142.0.0/1612.142.0.1 to 12.142.255.25412.142.255.25565,534
14412.143.0.0/1612.143.0.1 to 12.143.255.25412.143.255.25565,534
14512.144.0.0/1612.144.0.1 to 12.144.255.25412.144.255.25565,534
14612.145.0.0/1612.145.0.1 to 12.145.255.25412.145.255.25565,534
14712.146.0.0/1612.146.0.1 to 12.146.255.25412.146.255.25565,534
14812.147.0.0/1612.147.0.1 to 12.147.255.25412.147.255.25565,534
14912.148.0.0/1612.148.0.1 to 12.148.255.25412.148.255.25565,534
15012.149.0.0/1612.149.0.1 to 12.149.255.25412.149.255.25565,534
15112.150.0.0/1612.150.0.1 to 12.150.255.25412.150.255.25565,534
15212.151.0.0/1612.151.0.1 to 12.151.255.25412.151.255.25565,534
15312.152.0.0/1612.152.0.1 to 12.152.255.25412.152.255.25565,534
15412.153.0.0/1612.153.0.1 to 12.153.255.25412.153.255.25565,534
15512.154.0.0/1612.154.0.1 to 12.154.255.25412.154.255.25565,534
15612.155.0.0/1612.155.0.1 to 12.155.255.25412.155.255.25565,534
15712.156.0.0/1612.156.0.1 to 12.156.255.25412.156.255.25565,534
15812.157.0.0/1612.157.0.1 to 12.157.255.25412.157.255.25565,534
15912.158.0.0/1612.158.0.1 to 12.158.255.25412.158.255.25565,534
16012.159.0.0/1612.159.0.1 to 12.159.255.25412.159.255.25565,534
16112.160.0.0/1612.160.0.1 to 12.160.255.25412.160.255.25565,534
16212.161.0.0/1612.161.0.1 to 12.161.255.25412.161.255.25565,534
16312.162.0.0/1612.162.0.1 to 12.162.255.25412.162.255.25565,534
16412.163.0.0/1612.163.0.1 to 12.163.255.25412.163.255.25565,534
16512.164.0.0/1612.164.0.1 to 12.164.255.25412.164.255.25565,534
16612.165.0.0/1612.165.0.1 to 12.165.255.25412.165.255.25565,534
16712.166.0.0/1612.166.0.1 to 12.166.255.25412.166.255.25565,534
16812.167.0.0/1612.167.0.1 to 12.167.255.25412.167.255.25565,534
16912.168.0.0/1612.168.0.1 to 12.168.255.25412.168.255.25565,534
17012.169.0.0/1612.169.0.1 to 12.169.255.25412.169.255.25565,534
17112.170.0.0/1612.170.0.1 to 12.170.255.25412.170.255.25565,534
17212.171.0.0/1612.171.0.1 to 12.171.255.25412.171.255.25565,534
17312.172.0.0/1612.172.0.1 to 12.172.255.25412.172.255.25565,534
17412.173.0.0/1612.173.0.1 to 12.173.255.25412.173.255.25565,534
17512.174.0.0/1612.174.0.1 to 12.174.255.25412.174.255.25565,534
17612.175.0.0/1612.175.0.1 to 12.175.255.25412.175.255.25565,534
17712.176.0.0/1612.176.0.1 to 12.176.255.25412.176.255.25565,534
17812.177.0.0/1612.177.0.1 to 12.177.255.25412.177.255.25565,534
17912.178.0.0/1612.178.0.1 to 12.178.255.25412.178.255.25565,534
18012.179.0.0/1612.179.0.1 to 12.179.255.25412.179.255.25565,534
18112.180.0.0/1612.180.0.1 to 12.180.255.25412.180.255.25565,534
18212.181.0.0/1612.181.0.1 to 12.181.255.25412.181.255.25565,534
18312.182.0.0/1612.182.0.1 to 12.182.255.25412.182.255.25565,534
18412.183.0.0/1612.183.0.1 to 12.183.255.25412.183.255.25565,534
18512.184.0.0/1612.184.0.1 to 12.184.255.25412.184.255.25565,534
18612.185.0.0/1612.185.0.1 to 12.185.255.25412.185.255.25565,534
18712.186.0.0/1612.186.0.1 to 12.186.255.25412.186.255.25565,534
18812.187.0.0/1612.187.0.1 to 12.187.255.25412.187.255.25565,534
18912.188.0.0/1612.188.0.1 to 12.188.255.25412.188.255.25565,534
19012.189.0.0/1612.189.0.1 to 12.189.255.25412.189.255.25565,534
19112.190.0.0/1612.190.0.1 to 12.190.255.25412.190.255.25565,534
19212.191.0.0/1612.191.0.1 to 12.191.255.25412.191.255.25565,534
19312.192.0.0/1612.192.0.1 to 12.192.255.25412.192.255.25565,534
19412.193.0.0/1612.193.0.1 to 12.193.255.25412.193.255.25565,534
19512.194.0.0/1612.194.0.1 to 12.194.255.25412.194.255.25565,534
19612.195.0.0/1612.195.0.1 to 12.195.255.25412.195.255.25565,534
19712.196.0.0/1612.196.0.1 to 12.196.255.25412.196.255.25565,534
19812.197.0.0/1612.197.0.1 to 12.197.255.25412.197.255.25565,534
19912.198.0.0/1612.198.0.1 to 12.198.255.25412.198.255.25565,534
20012.199.0.0/1612.199.0.1 to 12.199.255.25412.199.255.25565,534
20112.200.0.0/1612.200.0.1 to 12.200.255.25412.200.255.25565,534
20212.201.0.0/1612.201.0.1 to 12.201.255.25412.201.255.25565,534
20312.202.0.0/1612.202.0.1 to 12.202.255.25412.202.255.25565,534
20412.203.0.0/1612.203.0.1 to 12.203.255.25412.203.255.25565,534
20512.204.0.0/1612.204.0.1 to 12.204.255.25412.204.255.25565,534
20612.205.0.0/1612.205.0.1 to 12.205.255.25412.205.255.25565,534
20712.206.0.0/1612.206.0.1 to 12.206.255.25412.206.255.25565,534
20812.207.0.0/1612.207.0.1 to 12.207.255.25412.207.255.25565,534
20912.208.0.0/1612.208.0.1 to 12.208.255.25412.208.255.25565,534
21012.209.0.0/1612.209.0.1 to 12.209.255.25412.209.255.25565,534
21112.210.0.0/1612.210.0.1 to 12.210.255.25412.210.255.25565,534
21212.211.0.0/1612.211.0.1 to 12.211.255.25412.211.255.25565,534
21312.212.0.0/1612.212.0.1 to 12.212.255.25412.212.255.25565,534
21412.213.0.0/1612.213.0.1 to 12.213.255.25412.213.255.25565,534
21512.214.0.0/1612.214.0.1 to 12.214.255.25412.214.255.25565,534
21612.215.0.0/1612.215.0.1 to 12.215.255.25412.215.255.25565,534
21712.216.0.0/1612.216.0.1 to 12.216.255.25412.216.255.25565,534
21812.217.0.0/1612.217.0.1 to 12.217.255.25412.217.255.25565,534
21912.218.0.0/1612.218.0.1 to 12.218.255.25412.218.255.25565,534
22012.219.0.0/1612.219.0.1 to 12.219.255.25412.219.255.25565,534
22112.220.0.0/1612.220.0.1 to 12.220.255.25412.220.255.25565,534
22212.221.0.0/1612.221.0.1 to 12.221.255.25412.221.255.25565,534
22312.222.0.0/1612.222.0.1 to 12.222.255.25412.222.255.25565,534
22412.223.0.0/1612.223.0.1 to 12.223.255.25412.223.255.25565,534
22512.224.0.0/1612.224.0.1 to 12.224.255.25412.224.255.25565,534
22612.225.0.0/1612.225.0.1 to 12.225.255.25412.225.255.25565,534
22712.226.0.0/1612.226.0.1 to 12.226.255.25412.226.255.25565,534
22812.227.0.0/1612.227.0.1 to 12.227.255.25412.227.255.25565,534
22912.228.0.0/1612.228.0.1 to 12.228.255.25412.228.255.25565,534
23012.229.0.0/1612.229.0.1 to 12.229.255.25412.229.255.25565,534
23112.230.0.0/1612.230.0.1 to 12.230.255.25412.230.255.25565,534
23212.231.0.0/1612.231.0.1 to 12.231.255.25412.231.255.25565,534
23312.232.0.0/1612.232.0.1 to 12.232.255.25412.232.255.25565,534
23412.233.0.0/1612.233.0.1 to 12.233.255.25412.233.255.25565,534
23512.234.0.0/1612.234.0.1 to 12.234.255.25412.234.255.25565,534
23612.235.0.0/1612.235.0.1 to 12.235.255.25412.235.255.25565,534
23712.236.0.0/1612.236.0.1 to 12.236.255.25412.236.255.25565,534
23812.237.0.0/1612.237.0.1 to 12.237.255.25412.237.255.25565,534
23912.238.0.0/1612.238.0.1 to 12.238.255.25412.238.255.25565,534
24012.239.0.0/1612.239.0.1 to 12.239.255.25412.239.255.25565,534
24112.240.0.0/1612.240.0.1 to 12.240.255.25412.240.255.25565,534
24212.241.0.0/1612.241.0.1 to 12.241.255.25412.241.255.25565,534
24312.242.0.0/1612.242.0.1 to 12.242.255.25412.242.255.25565,534
24412.243.0.0/1612.243.0.1 to 12.243.255.25412.243.255.25565,534
24512.244.0.0/1612.244.0.1 to 12.244.255.25412.244.255.25565,534
24612.245.0.0/1612.245.0.1 to 12.245.255.25412.245.255.25565,534
24712.246.0.0/1612.246.0.1 to 12.246.255.25412.246.255.25565,534
24812.247.0.0/1612.247.0.1 to 12.247.255.25412.247.255.25565,534
24912.248.0.0/1612.248.0.1 to 12.248.255.25412.248.255.25565,534
25012.249.0.0/1612.249.0.1 to 12.249.255.25412.249.255.25565,534
25112.250.0.0/1612.250.0.1 to 12.250.255.25412.250.255.25565,534
25212.251.0.0/1612.251.0.1 to 12.251.255.25412.251.255.25565,534
25312.252.0.0/1612.252.0.1 to 12.252.255.25412.252.255.25565,534
25412.253.0.0/1612.253.0.1 to 12.253.255.25412.253.255.25565,534
25512.254.0.0/1612.254.0.1 to 12.254.255.25412.254.255.25565,534
25612.255.0.0/1612.255.0.1 to 12.255.255.25412.255.255.25565,534

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.