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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.

Network12.240.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
12.240.0.0
Broadcast address
12.255.255.255
First usable
12.240.0.1
Last usable
12.255.255.254
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 0CF00000 · Integer 217055232 to 218103807
Reverse DNS zones
240.12.in-addr.arpa
241.12.in-addr.arpa
242.12.in-addr.arpa
243.12.in-addr.arpa
244.12.in-addr.arpa
245.12.in-addr.arpa
246.12.in-addr.arpa
247.12.in-addr.arpa
248.12.in-addr.arpa
249.12.in-addr.arpa
250.12.in-addr.arpa
251.12.in-addr.arpa
252.12.in-addr.arpa
253.12.in-addr.arpa
254.12.in-addr.arpa
255.12.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
Address00001100.11110000.00000000.0000000012.240.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network00001100.11110000.00000000.0000000012.240.0.0
Broadcast00001100.11111111.11111111.1111111112.255.255.255
Split into smaller subnets/24
/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)

12.240.0.0/12 makes 4,096 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
112.240.0.0/2412.240.0.1 to 12.240.0.25412.240.0.255254
212.240.1.0/2412.240.1.1 to 12.240.1.25412.240.1.255254
312.240.2.0/2412.240.2.1 to 12.240.2.25412.240.2.255254
412.240.3.0/2412.240.3.1 to 12.240.3.25412.240.3.255254
512.240.4.0/2412.240.4.1 to 12.240.4.25412.240.4.255254
612.240.5.0/2412.240.5.1 to 12.240.5.25412.240.5.255254
712.240.6.0/2412.240.6.1 to 12.240.6.25412.240.6.255254
812.240.7.0/2412.240.7.1 to 12.240.7.25412.240.7.255254
912.240.8.0/2412.240.8.1 to 12.240.8.25412.240.8.255254
1012.240.9.0/2412.240.9.1 to 12.240.9.25412.240.9.255254
1112.240.10.0/2412.240.10.1 to 12.240.10.25412.240.10.255254
1212.240.11.0/2412.240.11.1 to 12.240.11.25412.240.11.255254
1312.240.12.0/2412.240.12.1 to 12.240.12.25412.240.12.255254
1412.240.13.0/2412.240.13.1 to 12.240.13.25412.240.13.255254
1512.240.14.0/2412.240.14.1 to 12.240.14.25412.240.14.255254
1612.240.15.0/2412.240.15.1 to 12.240.15.25412.240.15.255254
1712.240.16.0/2412.240.16.1 to 12.240.16.25412.240.16.255254
1812.240.17.0/2412.240.17.1 to 12.240.17.25412.240.17.255254
1912.240.18.0/2412.240.18.1 to 12.240.18.25412.240.18.255254
2012.240.19.0/2412.240.19.1 to 12.240.19.25412.240.19.255254
2112.240.20.0/2412.240.20.1 to 12.240.20.25412.240.20.255254
2212.240.21.0/2412.240.21.1 to 12.240.21.25412.240.21.255254
2312.240.22.0/2412.240.22.1 to 12.240.22.25412.240.22.255254
2412.240.23.0/2412.240.23.1 to 12.240.23.25412.240.23.255254
2512.240.24.0/2412.240.24.1 to 12.240.24.25412.240.24.255254
2612.240.25.0/2412.240.25.1 to 12.240.25.25412.240.25.255254
2712.240.26.0/2412.240.26.1 to 12.240.26.25412.240.26.255254
2812.240.27.0/2412.240.27.1 to 12.240.27.25412.240.27.255254
2912.240.28.0/2412.240.28.1 to 12.240.28.25412.240.28.255254
3012.240.29.0/2412.240.29.1 to 12.240.29.25412.240.29.255254
3112.240.30.0/2412.240.30.1 to 12.240.30.25412.240.30.255254
3212.240.31.0/2412.240.31.1 to 12.240.31.25412.240.31.255254
3312.240.32.0/2412.240.32.1 to 12.240.32.25412.240.32.255254
3412.240.33.0/2412.240.33.1 to 12.240.33.25412.240.33.255254
3512.240.34.0/2412.240.34.1 to 12.240.34.25412.240.34.255254
3612.240.35.0/2412.240.35.1 to 12.240.35.25412.240.35.255254
3712.240.36.0/2412.240.36.1 to 12.240.36.25412.240.36.255254
3812.240.37.0/2412.240.37.1 to 12.240.37.25412.240.37.255254
3912.240.38.0/2412.240.38.1 to 12.240.38.25412.240.38.255254
4012.240.39.0/2412.240.39.1 to 12.240.39.25412.240.39.255254
4112.240.40.0/2412.240.40.1 to 12.240.40.25412.240.40.255254
4212.240.41.0/2412.240.41.1 to 12.240.41.25412.240.41.255254
4312.240.42.0/2412.240.42.1 to 12.240.42.25412.240.42.255254
4412.240.43.0/2412.240.43.1 to 12.240.43.25412.240.43.255254
4512.240.44.0/2412.240.44.1 to 12.240.44.25412.240.44.255254
4612.240.45.0/2412.240.45.1 to 12.240.45.25412.240.45.255254
4712.240.46.0/2412.240.46.1 to 12.240.46.25412.240.46.255254
4812.240.47.0/2412.240.47.1 to 12.240.47.25412.240.47.255254
4912.240.48.0/2412.240.48.1 to 12.240.48.25412.240.48.255254
5012.240.49.0/2412.240.49.1 to 12.240.49.25412.240.49.255254
5112.240.50.0/2412.240.50.1 to 12.240.50.25412.240.50.255254
5212.240.51.0/2412.240.51.1 to 12.240.51.25412.240.51.255254
5312.240.52.0/2412.240.52.1 to 12.240.52.25412.240.52.255254
5412.240.53.0/2412.240.53.1 to 12.240.53.25412.240.53.255254
5512.240.54.0/2412.240.54.1 to 12.240.54.25412.240.54.255254
5612.240.55.0/2412.240.55.1 to 12.240.55.25412.240.55.255254
5712.240.56.0/2412.240.56.1 to 12.240.56.25412.240.56.255254
5812.240.57.0/2412.240.57.1 to 12.240.57.25412.240.57.255254
5912.240.58.0/2412.240.58.1 to 12.240.58.25412.240.58.255254
6012.240.59.0/2412.240.59.1 to 12.240.59.25412.240.59.255254
6112.240.60.0/2412.240.60.1 to 12.240.60.25412.240.60.255254
6212.240.61.0/2412.240.61.1 to 12.240.61.25412.240.61.255254
6312.240.62.0/2412.240.62.1 to 12.240.62.25412.240.62.255254
6412.240.63.0/2412.240.63.1 to 12.240.63.25412.240.63.255254
6512.240.64.0/2412.240.64.1 to 12.240.64.25412.240.64.255254
6612.240.65.0/2412.240.65.1 to 12.240.65.25412.240.65.255254
6712.240.66.0/2412.240.66.1 to 12.240.66.25412.240.66.255254
6812.240.67.0/2412.240.67.1 to 12.240.67.25412.240.67.255254
6912.240.68.0/2412.240.68.1 to 12.240.68.25412.240.68.255254
7012.240.69.0/2412.240.69.1 to 12.240.69.25412.240.69.255254
7112.240.70.0/2412.240.70.1 to 12.240.70.25412.240.70.255254
7212.240.71.0/2412.240.71.1 to 12.240.71.25412.240.71.255254
7312.240.72.0/2412.240.72.1 to 12.240.72.25412.240.72.255254
7412.240.73.0/2412.240.73.1 to 12.240.73.25412.240.73.255254
7512.240.74.0/2412.240.74.1 to 12.240.74.25412.240.74.255254
7612.240.75.0/2412.240.75.1 to 12.240.75.25412.240.75.255254
7712.240.76.0/2412.240.76.1 to 12.240.76.25412.240.76.255254
7812.240.77.0/2412.240.77.1 to 12.240.77.25412.240.77.255254
7912.240.78.0/2412.240.78.1 to 12.240.78.25412.240.78.255254
8012.240.79.0/2412.240.79.1 to 12.240.79.25412.240.79.255254
8112.240.80.0/2412.240.80.1 to 12.240.80.25412.240.80.255254
8212.240.81.0/2412.240.81.1 to 12.240.81.25412.240.81.255254
8312.240.82.0/2412.240.82.1 to 12.240.82.25412.240.82.255254
8412.240.83.0/2412.240.83.1 to 12.240.83.25412.240.83.255254
8512.240.84.0/2412.240.84.1 to 12.240.84.25412.240.84.255254
8612.240.85.0/2412.240.85.1 to 12.240.85.25412.240.85.255254
8712.240.86.0/2412.240.86.1 to 12.240.86.25412.240.86.255254
8812.240.87.0/2412.240.87.1 to 12.240.87.25412.240.87.255254
8912.240.88.0/2412.240.88.1 to 12.240.88.25412.240.88.255254
9012.240.89.0/2412.240.89.1 to 12.240.89.25412.240.89.255254
9112.240.90.0/2412.240.90.1 to 12.240.90.25412.240.90.255254
9212.240.91.0/2412.240.91.1 to 12.240.91.25412.240.91.255254
9312.240.92.0/2412.240.92.1 to 12.240.92.25412.240.92.255254
9412.240.93.0/2412.240.93.1 to 12.240.93.25412.240.93.255254
9512.240.94.0/2412.240.94.1 to 12.240.94.25412.240.94.255254
9612.240.95.0/2412.240.95.1 to 12.240.95.25412.240.95.255254
9712.240.96.0/2412.240.96.1 to 12.240.96.25412.240.96.255254
9812.240.97.0/2412.240.97.1 to 12.240.97.25412.240.97.255254
9912.240.98.0/2412.240.98.1 to 12.240.98.25412.240.98.255254
10012.240.99.0/2412.240.99.1 to 12.240.99.25412.240.99.255254
10112.240.100.0/2412.240.100.1 to 12.240.100.25412.240.100.255254
10212.240.101.0/2412.240.101.1 to 12.240.101.25412.240.101.255254
10312.240.102.0/2412.240.102.1 to 12.240.102.25412.240.102.255254
10412.240.103.0/2412.240.103.1 to 12.240.103.25412.240.103.255254
10512.240.104.0/2412.240.104.1 to 12.240.104.25412.240.104.255254
10612.240.105.0/2412.240.105.1 to 12.240.105.25412.240.105.255254
10712.240.106.0/2412.240.106.1 to 12.240.106.25412.240.106.255254
10812.240.107.0/2412.240.107.1 to 12.240.107.25412.240.107.255254
10912.240.108.0/2412.240.108.1 to 12.240.108.25412.240.108.255254
11012.240.109.0/2412.240.109.1 to 12.240.109.25412.240.109.255254
11112.240.110.0/2412.240.110.1 to 12.240.110.25412.240.110.255254
11212.240.111.0/2412.240.111.1 to 12.240.111.25412.240.111.255254
11312.240.112.0/2412.240.112.1 to 12.240.112.25412.240.112.255254
11412.240.113.0/2412.240.113.1 to 12.240.113.25412.240.113.255254
11512.240.114.0/2412.240.114.1 to 12.240.114.25412.240.114.255254
11612.240.115.0/2412.240.115.1 to 12.240.115.25412.240.115.255254
11712.240.116.0/2412.240.116.1 to 12.240.116.25412.240.116.255254
11812.240.117.0/2412.240.117.1 to 12.240.117.25412.240.117.255254
11912.240.118.0/2412.240.118.1 to 12.240.118.25412.240.118.255254
12012.240.119.0/2412.240.119.1 to 12.240.119.25412.240.119.255254
12112.240.120.0/2412.240.120.1 to 12.240.120.25412.240.120.255254
12212.240.121.0/2412.240.121.1 to 12.240.121.25412.240.121.255254
12312.240.122.0/2412.240.122.1 to 12.240.122.25412.240.122.255254
12412.240.123.0/2412.240.123.1 to 12.240.123.25412.240.123.255254
12512.240.124.0/2412.240.124.1 to 12.240.124.25412.240.124.255254
12612.240.125.0/2412.240.125.1 to 12.240.125.25412.240.125.255254
12712.240.126.0/2412.240.126.1 to 12.240.126.25412.240.126.255254
12812.240.127.0/2412.240.127.1 to 12.240.127.25412.240.127.255254
12912.240.128.0/2412.240.128.1 to 12.240.128.25412.240.128.255254
13012.240.129.0/2412.240.129.1 to 12.240.129.25412.240.129.255254
13112.240.130.0/2412.240.130.1 to 12.240.130.25412.240.130.255254
13212.240.131.0/2412.240.131.1 to 12.240.131.25412.240.131.255254
13312.240.132.0/2412.240.132.1 to 12.240.132.25412.240.132.255254
13412.240.133.0/2412.240.133.1 to 12.240.133.25412.240.133.255254
13512.240.134.0/2412.240.134.1 to 12.240.134.25412.240.134.255254
13612.240.135.0/2412.240.135.1 to 12.240.135.25412.240.135.255254
13712.240.136.0/2412.240.136.1 to 12.240.136.25412.240.136.255254
13812.240.137.0/2412.240.137.1 to 12.240.137.25412.240.137.255254
13912.240.138.0/2412.240.138.1 to 12.240.138.25412.240.138.255254
14012.240.139.0/2412.240.139.1 to 12.240.139.25412.240.139.255254
14112.240.140.0/2412.240.140.1 to 12.240.140.25412.240.140.255254
14212.240.141.0/2412.240.141.1 to 12.240.141.25412.240.141.255254
14312.240.142.0/2412.240.142.1 to 12.240.142.25412.240.142.255254
14412.240.143.0/2412.240.143.1 to 12.240.143.25412.240.143.255254
14512.240.144.0/2412.240.144.1 to 12.240.144.25412.240.144.255254
14612.240.145.0/2412.240.145.1 to 12.240.145.25412.240.145.255254
14712.240.146.0/2412.240.146.1 to 12.240.146.25412.240.146.255254
14812.240.147.0/2412.240.147.1 to 12.240.147.25412.240.147.255254
14912.240.148.0/2412.240.148.1 to 12.240.148.25412.240.148.255254
15012.240.149.0/2412.240.149.1 to 12.240.149.25412.240.149.255254
15112.240.150.0/2412.240.150.1 to 12.240.150.25412.240.150.255254
15212.240.151.0/2412.240.151.1 to 12.240.151.25412.240.151.255254
15312.240.152.0/2412.240.152.1 to 12.240.152.25412.240.152.255254
15412.240.153.0/2412.240.153.1 to 12.240.153.25412.240.153.255254
15512.240.154.0/2412.240.154.1 to 12.240.154.25412.240.154.255254
15612.240.155.0/2412.240.155.1 to 12.240.155.25412.240.155.255254
15712.240.156.0/2412.240.156.1 to 12.240.156.25412.240.156.255254
15812.240.157.0/2412.240.157.1 to 12.240.157.25412.240.157.255254
15912.240.158.0/2412.240.158.1 to 12.240.158.25412.240.158.255254
16012.240.159.0/2412.240.159.1 to 12.240.159.25412.240.159.255254
16112.240.160.0/2412.240.160.1 to 12.240.160.25412.240.160.255254
16212.240.161.0/2412.240.161.1 to 12.240.161.25412.240.161.255254
16312.240.162.0/2412.240.162.1 to 12.240.162.25412.240.162.255254
16412.240.163.0/2412.240.163.1 to 12.240.163.25412.240.163.255254
16512.240.164.0/2412.240.164.1 to 12.240.164.25412.240.164.255254
16612.240.165.0/2412.240.165.1 to 12.240.165.25412.240.165.255254
16712.240.166.0/2412.240.166.1 to 12.240.166.25412.240.166.255254
16812.240.167.0/2412.240.167.1 to 12.240.167.25412.240.167.255254
16912.240.168.0/2412.240.168.1 to 12.240.168.25412.240.168.255254
17012.240.169.0/2412.240.169.1 to 12.240.169.25412.240.169.255254
17112.240.170.0/2412.240.170.1 to 12.240.170.25412.240.170.255254
17212.240.171.0/2412.240.171.1 to 12.240.171.25412.240.171.255254
17312.240.172.0/2412.240.172.1 to 12.240.172.25412.240.172.255254
17412.240.173.0/2412.240.173.1 to 12.240.173.25412.240.173.255254
17512.240.174.0/2412.240.174.1 to 12.240.174.25412.240.174.255254
17612.240.175.0/2412.240.175.1 to 12.240.175.25412.240.175.255254
17712.240.176.0/2412.240.176.1 to 12.240.176.25412.240.176.255254
17812.240.177.0/2412.240.177.1 to 12.240.177.25412.240.177.255254
17912.240.178.0/2412.240.178.1 to 12.240.178.25412.240.178.255254
18012.240.179.0/2412.240.179.1 to 12.240.179.25412.240.179.255254
18112.240.180.0/2412.240.180.1 to 12.240.180.25412.240.180.255254
18212.240.181.0/2412.240.181.1 to 12.240.181.25412.240.181.255254
18312.240.182.0/2412.240.182.1 to 12.240.182.25412.240.182.255254
18412.240.183.0/2412.240.183.1 to 12.240.183.25412.240.183.255254
18512.240.184.0/2412.240.184.1 to 12.240.184.25412.240.184.255254
18612.240.185.0/2412.240.185.1 to 12.240.185.25412.240.185.255254
18712.240.186.0/2412.240.186.1 to 12.240.186.25412.240.186.255254
18812.240.187.0/2412.240.187.1 to 12.240.187.25412.240.187.255254
18912.240.188.0/2412.240.188.1 to 12.240.188.25412.240.188.255254
19012.240.189.0/2412.240.189.1 to 12.240.189.25412.240.189.255254
19112.240.190.0/2412.240.190.1 to 12.240.190.25412.240.190.255254
19212.240.191.0/2412.240.191.1 to 12.240.191.25412.240.191.255254
19312.240.192.0/2412.240.192.1 to 12.240.192.25412.240.192.255254
19412.240.193.0/2412.240.193.1 to 12.240.193.25412.240.193.255254
19512.240.194.0/2412.240.194.1 to 12.240.194.25412.240.194.255254
19612.240.195.0/2412.240.195.1 to 12.240.195.25412.240.195.255254
19712.240.196.0/2412.240.196.1 to 12.240.196.25412.240.196.255254
19812.240.197.0/2412.240.197.1 to 12.240.197.25412.240.197.255254
19912.240.198.0/2412.240.198.1 to 12.240.198.25412.240.198.255254
20012.240.199.0/2412.240.199.1 to 12.240.199.25412.240.199.255254
20112.240.200.0/2412.240.200.1 to 12.240.200.25412.240.200.255254
20212.240.201.0/2412.240.201.1 to 12.240.201.25412.240.201.255254
20312.240.202.0/2412.240.202.1 to 12.240.202.25412.240.202.255254
20412.240.203.0/2412.240.203.1 to 12.240.203.25412.240.203.255254
20512.240.204.0/2412.240.204.1 to 12.240.204.25412.240.204.255254
20612.240.205.0/2412.240.205.1 to 12.240.205.25412.240.205.255254
20712.240.206.0/2412.240.206.1 to 12.240.206.25412.240.206.255254
20812.240.207.0/2412.240.207.1 to 12.240.207.25412.240.207.255254
20912.240.208.0/2412.240.208.1 to 12.240.208.25412.240.208.255254
21012.240.209.0/2412.240.209.1 to 12.240.209.25412.240.209.255254
21112.240.210.0/2412.240.210.1 to 12.240.210.25412.240.210.255254
21212.240.211.0/2412.240.211.1 to 12.240.211.25412.240.211.255254
21312.240.212.0/2412.240.212.1 to 12.240.212.25412.240.212.255254
21412.240.213.0/2412.240.213.1 to 12.240.213.25412.240.213.255254
21512.240.214.0/2412.240.214.1 to 12.240.214.25412.240.214.255254
21612.240.215.0/2412.240.215.1 to 12.240.215.25412.240.215.255254
21712.240.216.0/2412.240.216.1 to 12.240.216.25412.240.216.255254
21812.240.217.0/2412.240.217.1 to 12.240.217.25412.240.217.255254
21912.240.218.0/2412.240.218.1 to 12.240.218.25412.240.218.255254
22012.240.219.0/2412.240.219.1 to 12.240.219.25412.240.219.255254
22112.240.220.0/2412.240.220.1 to 12.240.220.25412.240.220.255254
22212.240.221.0/2412.240.221.1 to 12.240.221.25412.240.221.255254
22312.240.222.0/2412.240.222.1 to 12.240.222.25412.240.222.255254
22412.240.223.0/2412.240.223.1 to 12.240.223.25412.240.223.255254
22512.240.224.0/2412.240.224.1 to 12.240.224.25412.240.224.255254
22612.240.225.0/2412.240.225.1 to 12.240.225.25412.240.225.255254
22712.240.226.0/2412.240.226.1 to 12.240.226.25412.240.226.255254
22812.240.227.0/2412.240.227.1 to 12.240.227.25412.240.227.255254
22912.240.228.0/2412.240.228.1 to 12.240.228.25412.240.228.255254
23012.240.229.0/2412.240.229.1 to 12.240.229.25412.240.229.255254
23112.240.230.0/2412.240.230.1 to 12.240.230.25412.240.230.255254
23212.240.231.0/2412.240.231.1 to 12.240.231.25412.240.231.255254
23312.240.232.0/2412.240.232.1 to 12.240.232.25412.240.232.255254
23412.240.233.0/2412.240.233.1 to 12.240.233.25412.240.233.255254
23512.240.234.0/2412.240.234.1 to 12.240.234.25412.240.234.255254
23612.240.235.0/2412.240.235.1 to 12.240.235.25412.240.235.255254
23712.240.236.0/2412.240.236.1 to 12.240.236.25412.240.236.255254
23812.240.237.0/2412.240.237.1 to 12.240.237.25412.240.237.255254
23912.240.238.0/2412.240.238.1 to 12.240.238.25412.240.238.255254
24012.240.239.0/2412.240.239.1 to 12.240.239.25412.240.239.255254
24112.240.240.0/2412.240.240.1 to 12.240.240.25412.240.240.255254
24212.240.241.0/2412.240.241.1 to 12.240.241.25412.240.241.255254
24312.240.242.0/2412.240.242.1 to 12.240.242.25412.240.242.255254
24412.240.243.0/2412.240.243.1 to 12.240.243.25412.240.243.255254
24512.240.244.0/2412.240.244.1 to 12.240.244.25412.240.244.255254
24612.240.245.0/2412.240.245.1 to 12.240.245.25412.240.245.255254
24712.240.246.0/2412.240.246.1 to 12.240.246.25412.240.246.255254
24812.240.247.0/2412.240.247.1 to 12.240.247.25412.240.247.255254
24912.240.248.0/2412.240.248.1 to 12.240.248.25412.240.248.255254
25012.240.249.0/2412.240.249.1 to 12.240.249.25412.240.249.255254
25112.240.250.0/2412.240.250.1 to 12.240.250.25412.240.250.255254
25212.240.251.0/2412.240.251.1 to 12.240.251.25412.240.251.255254
25312.240.252.0/2412.240.252.1 to 12.240.252.25412.240.252.255254
25412.240.253.0/2412.240.253.1 to 12.240.253.25412.240.253.255254
25512.240.254.0/2412.240.254.1 to 12.240.254.25412.240.254.255254
25612.240.255.0/2412.240.255.1 to 12.240.255.25412.240.255.255254

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.