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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.

Network6.0.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
6.0.0.0
Broadcast address
6.15.255.255
First usable
6.0.0.1
Last usable
6.15.255.254
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 06000000 · Integer 100663296 to 101711871
Reverse DNS zones
0.6.in-addr.arpa
1.6.in-addr.arpa
2.6.in-addr.arpa
3.6.in-addr.arpa
4.6.in-addr.arpa
5.6.in-addr.arpa
6.6.in-addr.arpa
7.6.in-addr.arpa
8.6.in-addr.arpa
9.6.in-addr.arpa
10.6.in-addr.arpa
11.6.in-addr.arpa
12.6.in-addr.arpa
13.6.in-addr.arpa
14.6.in-addr.arpa
15.6.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
Address00000110.00000000.00000000.000000006.0.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network00000110.00000000.00000000.000000006.0.0.0
Broadcast00000110.00001111.11111111.111111116.15.255.255
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)

6.0.0.0/12 makes 4,096 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
16.0.0.0/246.0.0.1 to 6.0.0.2546.0.0.255254
26.0.1.0/246.0.1.1 to 6.0.1.2546.0.1.255254
36.0.2.0/246.0.2.1 to 6.0.2.2546.0.2.255254
46.0.3.0/246.0.3.1 to 6.0.3.2546.0.3.255254
56.0.4.0/246.0.4.1 to 6.0.4.2546.0.4.255254
66.0.5.0/246.0.5.1 to 6.0.5.2546.0.5.255254
76.0.6.0/246.0.6.1 to 6.0.6.2546.0.6.255254
86.0.7.0/246.0.7.1 to 6.0.7.2546.0.7.255254
96.0.8.0/246.0.8.1 to 6.0.8.2546.0.8.255254
106.0.9.0/246.0.9.1 to 6.0.9.2546.0.9.255254
116.0.10.0/246.0.10.1 to 6.0.10.2546.0.10.255254
126.0.11.0/246.0.11.1 to 6.0.11.2546.0.11.255254
136.0.12.0/246.0.12.1 to 6.0.12.2546.0.12.255254
146.0.13.0/246.0.13.1 to 6.0.13.2546.0.13.255254
156.0.14.0/246.0.14.1 to 6.0.14.2546.0.14.255254
166.0.15.0/246.0.15.1 to 6.0.15.2546.0.15.255254
176.0.16.0/246.0.16.1 to 6.0.16.2546.0.16.255254
186.0.17.0/246.0.17.1 to 6.0.17.2546.0.17.255254
196.0.18.0/246.0.18.1 to 6.0.18.2546.0.18.255254
206.0.19.0/246.0.19.1 to 6.0.19.2546.0.19.255254
216.0.20.0/246.0.20.1 to 6.0.20.2546.0.20.255254
226.0.21.0/246.0.21.1 to 6.0.21.2546.0.21.255254
236.0.22.0/246.0.22.1 to 6.0.22.2546.0.22.255254
246.0.23.0/246.0.23.1 to 6.0.23.2546.0.23.255254
256.0.24.0/246.0.24.1 to 6.0.24.2546.0.24.255254
266.0.25.0/246.0.25.1 to 6.0.25.2546.0.25.255254
276.0.26.0/246.0.26.1 to 6.0.26.2546.0.26.255254
286.0.27.0/246.0.27.1 to 6.0.27.2546.0.27.255254
296.0.28.0/246.0.28.1 to 6.0.28.2546.0.28.255254
306.0.29.0/246.0.29.1 to 6.0.29.2546.0.29.255254
316.0.30.0/246.0.30.1 to 6.0.30.2546.0.30.255254
326.0.31.0/246.0.31.1 to 6.0.31.2546.0.31.255254
336.0.32.0/246.0.32.1 to 6.0.32.2546.0.32.255254
346.0.33.0/246.0.33.1 to 6.0.33.2546.0.33.255254
356.0.34.0/246.0.34.1 to 6.0.34.2546.0.34.255254
366.0.35.0/246.0.35.1 to 6.0.35.2546.0.35.255254
376.0.36.0/246.0.36.1 to 6.0.36.2546.0.36.255254
386.0.37.0/246.0.37.1 to 6.0.37.2546.0.37.255254
396.0.38.0/246.0.38.1 to 6.0.38.2546.0.38.255254
406.0.39.0/246.0.39.1 to 6.0.39.2546.0.39.255254
416.0.40.0/246.0.40.1 to 6.0.40.2546.0.40.255254
426.0.41.0/246.0.41.1 to 6.0.41.2546.0.41.255254
436.0.42.0/246.0.42.1 to 6.0.42.2546.0.42.255254
446.0.43.0/246.0.43.1 to 6.0.43.2546.0.43.255254
456.0.44.0/246.0.44.1 to 6.0.44.2546.0.44.255254
466.0.45.0/246.0.45.1 to 6.0.45.2546.0.45.255254
476.0.46.0/246.0.46.1 to 6.0.46.2546.0.46.255254
486.0.47.0/246.0.47.1 to 6.0.47.2546.0.47.255254
496.0.48.0/246.0.48.1 to 6.0.48.2546.0.48.255254
506.0.49.0/246.0.49.1 to 6.0.49.2546.0.49.255254
516.0.50.0/246.0.50.1 to 6.0.50.2546.0.50.255254
526.0.51.0/246.0.51.1 to 6.0.51.2546.0.51.255254
536.0.52.0/246.0.52.1 to 6.0.52.2546.0.52.255254
546.0.53.0/246.0.53.1 to 6.0.53.2546.0.53.255254
556.0.54.0/246.0.54.1 to 6.0.54.2546.0.54.255254
566.0.55.0/246.0.55.1 to 6.0.55.2546.0.55.255254
576.0.56.0/246.0.56.1 to 6.0.56.2546.0.56.255254
586.0.57.0/246.0.57.1 to 6.0.57.2546.0.57.255254
596.0.58.0/246.0.58.1 to 6.0.58.2546.0.58.255254
606.0.59.0/246.0.59.1 to 6.0.59.2546.0.59.255254
616.0.60.0/246.0.60.1 to 6.0.60.2546.0.60.255254
626.0.61.0/246.0.61.1 to 6.0.61.2546.0.61.255254
636.0.62.0/246.0.62.1 to 6.0.62.2546.0.62.255254
646.0.63.0/246.0.63.1 to 6.0.63.2546.0.63.255254
656.0.64.0/246.0.64.1 to 6.0.64.2546.0.64.255254
666.0.65.0/246.0.65.1 to 6.0.65.2546.0.65.255254
676.0.66.0/246.0.66.1 to 6.0.66.2546.0.66.255254
686.0.67.0/246.0.67.1 to 6.0.67.2546.0.67.255254
696.0.68.0/246.0.68.1 to 6.0.68.2546.0.68.255254
706.0.69.0/246.0.69.1 to 6.0.69.2546.0.69.255254
716.0.70.0/246.0.70.1 to 6.0.70.2546.0.70.255254
726.0.71.0/246.0.71.1 to 6.0.71.2546.0.71.255254
736.0.72.0/246.0.72.1 to 6.0.72.2546.0.72.255254
746.0.73.0/246.0.73.1 to 6.0.73.2546.0.73.255254
756.0.74.0/246.0.74.1 to 6.0.74.2546.0.74.255254
766.0.75.0/246.0.75.1 to 6.0.75.2546.0.75.255254
776.0.76.0/246.0.76.1 to 6.0.76.2546.0.76.255254
786.0.77.0/246.0.77.1 to 6.0.77.2546.0.77.255254
796.0.78.0/246.0.78.1 to 6.0.78.2546.0.78.255254
806.0.79.0/246.0.79.1 to 6.0.79.2546.0.79.255254
816.0.80.0/246.0.80.1 to 6.0.80.2546.0.80.255254
826.0.81.0/246.0.81.1 to 6.0.81.2546.0.81.255254
836.0.82.0/246.0.82.1 to 6.0.82.2546.0.82.255254
846.0.83.0/246.0.83.1 to 6.0.83.2546.0.83.255254
856.0.84.0/246.0.84.1 to 6.0.84.2546.0.84.255254
866.0.85.0/246.0.85.1 to 6.0.85.2546.0.85.255254
876.0.86.0/246.0.86.1 to 6.0.86.2546.0.86.255254
886.0.87.0/246.0.87.1 to 6.0.87.2546.0.87.255254
896.0.88.0/246.0.88.1 to 6.0.88.2546.0.88.255254
906.0.89.0/246.0.89.1 to 6.0.89.2546.0.89.255254
916.0.90.0/246.0.90.1 to 6.0.90.2546.0.90.255254
926.0.91.0/246.0.91.1 to 6.0.91.2546.0.91.255254
936.0.92.0/246.0.92.1 to 6.0.92.2546.0.92.255254
946.0.93.0/246.0.93.1 to 6.0.93.2546.0.93.255254
956.0.94.0/246.0.94.1 to 6.0.94.2546.0.94.255254
966.0.95.0/246.0.95.1 to 6.0.95.2546.0.95.255254
976.0.96.0/246.0.96.1 to 6.0.96.2546.0.96.255254
986.0.97.0/246.0.97.1 to 6.0.97.2546.0.97.255254
996.0.98.0/246.0.98.1 to 6.0.98.2546.0.98.255254
1006.0.99.0/246.0.99.1 to 6.0.99.2546.0.99.255254
1016.0.100.0/246.0.100.1 to 6.0.100.2546.0.100.255254
1026.0.101.0/246.0.101.1 to 6.0.101.2546.0.101.255254
1036.0.102.0/246.0.102.1 to 6.0.102.2546.0.102.255254
1046.0.103.0/246.0.103.1 to 6.0.103.2546.0.103.255254
1056.0.104.0/246.0.104.1 to 6.0.104.2546.0.104.255254
1066.0.105.0/246.0.105.1 to 6.0.105.2546.0.105.255254
1076.0.106.0/246.0.106.1 to 6.0.106.2546.0.106.255254
1086.0.107.0/246.0.107.1 to 6.0.107.2546.0.107.255254
1096.0.108.0/246.0.108.1 to 6.0.108.2546.0.108.255254
1106.0.109.0/246.0.109.1 to 6.0.109.2546.0.109.255254
1116.0.110.0/246.0.110.1 to 6.0.110.2546.0.110.255254
1126.0.111.0/246.0.111.1 to 6.0.111.2546.0.111.255254
1136.0.112.0/246.0.112.1 to 6.0.112.2546.0.112.255254
1146.0.113.0/246.0.113.1 to 6.0.113.2546.0.113.255254
1156.0.114.0/246.0.114.1 to 6.0.114.2546.0.114.255254
1166.0.115.0/246.0.115.1 to 6.0.115.2546.0.115.255254
1176.0.116.0/246.0.116.1 to 6.0.116.2546.0.116.255254
1186.0.117.0/246.0.117.1 to 6.0.117.2546.0.117.255254
1196.0.118.0/246.0.118.1 to 6.0.118.2546.0.118.255254
1206.0.119.0/246.0.119.1 to 6.0.119.2546.0.119.255254
1216.0.120.0/246.0.120.1 to 6.0.120.2546.0.120.255254
1226.0.121.0/246.0.121.1 to 6.0.121.2546.0.121.255254
1236.0.122.0/246.0.122.1 to 6.0.122.2546.0.122.255254
1246.0.123.0/246.0.123.1 to 6.0.123.2546.0.123.255254
1256.0.124.0/246.0.124.1 to 6.0.124.2546.0.124.255254
1266.0.125.0/246.0.125.1 to 6.0.125.2546.0.125.255254
1276.0.126.0/246.0.126.1 to 6.0.126.2546.0.126.255254
1286.0.127.0/246.0.127.1 to 6.0.127.2546.0.127.255254
1296.0.128.0/246.0.128.1 to 6.0.128.2546.0.128.255254
1306.0.129.0/246.0.129.1 to 6.0.129.2546.0.129.255254
1316.0.130.0/246.0.130.1 to 6.0.130.2546.0.130.255254
1326.0.131.0/246.0.131.1 to 6.0.131.2546.0.131.255254
1336.0.132.0/246.0.132.1 to 6.0.132.2546.0.132.255254
1346.0.133.0/246.0.133.1 to 6.0.133.2546.0.133.255254
1356.0.134.0/246.0.134.1 to 6.0.134.2546.0.134.255254
1366.0.135.0/246.0.135.1 to 6.0.135.2546.0.135.255254
1376.0.136.0/246.0.136.1 to 6.0.136.2546.0.136.255254
1386.0.137.0/246.0.137.1 to 6.0.137.2546.0.137.255254
1396.0.138.0/246.0.138.1 to 6.0.138.2546.0.138.255254
1406.0.139.0/246.0.139.1 to 6.0.139.2546.0.139.255254
1416.0.140.0/246.0.140.1 to 6.0.140.2546.0.140.255254
1426.0.141.0/246.0.141.1 to 6.0.141.2546.0.141.255254
1436.0.142.0/246.0.142.1 to 6.0.142.2546.0.142.255254
1446.0.143.0/246.0.143.1 to 6.0.143.2546.0.143.255254
1456.0.144.0/246.0.144.1 to 6.0.144.2546.0.144.255254
1466.0.145.0/246.0.145.1 to 6.0.145.2546.0.145.255254
1476.0.146.0/246.0.146.1 to 6.0.146.2546.0.146.255254
1486.0.147.0/246.0.147.1 to 6.0.147.2546.0.147.255254
1496.0.148.0/246.0.148.1 to 6.0.148.2546.0.148.255254
1506.0.149.0/246.0.149.1 to 6.0.149.2546.0.149.255254
1516.0.150.0/246.0.150.1 to 6.0.150.2546.0.150.255254
1526.0.151.0/246.0.151.1 to 6.0.151.2546.0.151.255254
1536.0.152.0/246.0.152.1 to 6.0.152.2546.0.152.255254
1546.0.153.0/246.0.153.1 to 6.0.153.2546.0.153.255254
1556.0.154.0/246.0.154.1 to 6.0.154.2546.0.154.255254
1566.0.155.0/246.0.155.1 to 6.0.155.2546.0.155.255254
1576.0.156.0/246.0.156.1 to 6.0.156.2546.0.156.255254
1586.0.157.0/246.0.157.1 to 6.0.157.2546.0.157.255254
1596.0.158.0/246.0.158.1 to 6.0.158.2546.0.158.255254
1606.0.159.0/246.0.159.1 to 6.0.159.2546.0.159.255254
1616.0.160.0/246.0.160.1 to 6.0.160.2546.0.160.255254
1626.0.161.0/246.0.161.1 to 6.0.161.2546.0.161.255254
1636.0.162.0/246.0.162.1 to 6.0.162.2546.0.162.255254
1646.0.163.0/246.0.163.1 to 6.0.163.2546.0.163.255254
1656.0.164.0/246.0.164.1 to 6.0.164.2546.0.164.255254
1666.0.165.0/246.0.165.1 to 6.0.165.2546.0.165.255254
1676.0.166.0/246.0.166.1 to 6.0.166.2546.0.166.255254
1686.0.167.0/246.0.167.1 to 6.0.167.2546.0.167.255254
1696.0.168.0/246.0.168.1 to 6.0.168.2546.0.168.255254
1706.0.169.0/246.0.169.1 to 6.0.169.2546.0.169.255254
1716.0.170.0/246.0.170.1 to 6.0.170.2546.0.170.255254
1726.0.171.0/246.0.171.1 to 6.0.171.2546.0.171.255254
1736.0.172.0/246.0.172.1 to 6.0.172.2546.0.172.255254
1746.0.173.0/246.0.173.1 to 6.0.173.2546.0.173.255254
1756.0.174.0/246.0.174.1 to 6.0.174.2546.0.174.255254
1766.0.175.0/246.0.175.1 to 6.0.175.2546.0.175.255254
1776.0.176.0/246.0.176.1 to 6.0.176.2546.0.176.255254
1786.0.177.0/246.0.177.1 to 6.0.177.2546.0.177.255254
1796.0.178.0/246.0.178.1 to 6.0.178.2546.0.178.255254
1806.0.179.0/246.0.179.1 to 6.0.179.2546.0.179.255254
1816.0.180.0/246.0.180.1 to 6.0.180.2546.0.180.255254
1826.0.181.0/246.0.181.1 to 6.0.181.2546.0.181.255254
1836.0.182.0/246.0.182.1 to 6.0.182.2546.0.182.255254
1846.0.183.0/246.0.183.1 to 6.0.183.2546.0.183.255254
1856.0.184.0/246.0.184.1 to 6.0.184.2546.0.184.255254
1866.0.185.0/246.0.185.1 to 6.0.185.2546.0.185.255254
1876.0.186.0/246.0.186.1 to 6.0.186.2546.0.186.255254
1886.0.187.0/246.0.187.1 to 6.0.187.2546.0.187.255254
1896.0.188.0/246.0.188.1 to 6.0.188.2546.0.188.255254
1906.0.189.0/246.0.189.1 to 6.0.189.2546.0.189.255254
1916.0.190.0/246.0.190.1 to 6.0.190.2546.0.190.255254
1926.0.191.0/246.0.191.1 to 6.0.191.2546.0.191.255254
1936.0.192.0/246.0.192.1 to 6.0.192.2546.0.192.255254
1946.0.193.0/246.0.193.1 to 6.0.193.2546.0.193.255254
1956.0.194.0/246.0.194.1 to 6.0.194.2546.0.194.255254
1966.0.195.0/246.0.195.1 to 6.0.195.2546.0.195.255254
1976.0.196.0/246.0.196.1 to 6.0.196.2546.0.196.255254
1986.0.197.0/246.0.197.1 to 6.0.197.2546.0.197.255254
1996.0.198.0/246.0.198.1 to 6.0.198.2546.0.198.255254
2006.0.199.0/246.0.199.1 to 6.0.199.2546.0.199.255254
2016.0.200.0/246.0.200.1 to 6.0.200.2546.0.200.255254
2026.0.201.0/246.0.201.1 to 6.0.201.2546.0.201.255254
2036.0.202.0/246.0.202.1 to 6.0.202.2546.0.202.255254
2046.0.203.0/246.0.203.1 to 6.0.203.2546.0.203.255254
2056.0.204.0/246.0.204.1 to 6.0.204.2546.0.204.255254
2066.0.205.0/246.0.205.1 to 6.0.205.2546.0.205.255254
2076.0.206.0/246.0.206.1 to 6.0.206.2546.0.206.255254
2086.0.207.0/246.0.207.1 to 6.0.207.2546.0.207.255254
2096.0.208.0/246.0.208.1 to 6.0.208.2546.0.208.255254
2106.0.209.0/246.0.209.1 to 6.0.209.2546.0.209.255254
2116.0.210.0/246.0.210.1 to 6.0.210.2546.0.210.255254
2126.0.211.0/246.0.211.1 to 6.0.211.2546.0.211.255254
2136.0.212.0/246.0.212.1 to 6.0.212.2546.0.212.255254
2146.0.213.0/246.0.213.1 to 6.0.213.2546.0.213.255254
2156.0.214.0/246.0.214.1 to 6.0.214.2546.0.214.255254
2166.0.215.0/246.0.215.1 to 6.0.215.2546.0.215.255254
2176.0.216.0/246.0.216.1 to 6.0.216.2546.0.216.255254
2186.0.217.0/246.0.217.1 to 6.0.217.2546.0.217.255254
2196.0.218.0/246.0.218.1 to 6.0.218.2546.0.218.255254
2206.0.219.0/246.0.219.1 to 6.0.219.2546.0.219.255254
2216.0.220.0/246.0.220.1 to 6.0.220.2546.0.220.255254
2226.0.221.0/246.0.221.1 to 6.0.221.2546.0.221.255254
2236.0.222.0/246.0.222.1 to 6.0.222.2546.0.222.255254
2246.0.223.0/246.0.223.1 to 6.0.223.2546.0.223.255254
2256.0.224.0/246.0.224.1 to 6.0.224.2546.0.224.255254
2266.0.225.0/246.0.225.1 to 6.0.225.2546.0.225.255254
2276.0.226.0/246.0.226.1 to 6.0.226.2546.0.226.255254
2286.0.227.0/246.0.227.1 to 6.0.227.2546.0.227.255254
2296.0.228.0/246.0.228.1 to 6.0.228.2546.0.228.255254
2306.0.229.0/246.0.229.1 to 6.0.229.2546.0.229.255254
2316.0.230.0/246.0.230.1 to 6.0.230.2546.0.230.255254
2326.0.231.0/246.0.231.1 to 6.0.231.2546.0.231.255254
2336.0.232.0/246.0.232.1 to 6.0.232.2546.0.232.255254
2346.0.233.0/246.0.233.1 to 6.0.233.2546.0.233.255254
2356.0.234.0/246.0.234.1 to 6.0.234.2546.0.234.255254
2366.0.235.0/246.0.235.1 to 6.0.235.2546.0.235.255254
2376.0.236.0/246.0.236.1 to 6.0.236.2546.0.236.255254
2386.0.237.0/246.0.237.1 to 6.0.237.2546.0.237.255254
2396.0.238.0/246.0.238.1 to 6.0.238.2546.0.238.255254
2406.0.239.0/246.0.239.1 to 6.0.239.2546.0.239.255254
2416.0.240.0/246.0.240.1 to 6.0.240.2546.0.240.255254
2426.0.241.0/246.0.241.1 to 6.0.241.2546.0.241.255254
2436.0.242.0/246.0.242.1 to 6.0.242.2546.0.242.255254
2446.0.243.0/246.0.243.1 to 6.0.243.2546.0.243.255254
2456.0.244.0/246.0.244.1 to 6.0.244.2546.0.244.255254
2466.0.245.0/246.0.245.1 to 6.0.245.2546.0.245.255254
2476.0.246.0/246.0.246.1 to 6.0.246.2546.0.246.255254
2486.0.247.0/246.0.247.1 to 6.0.247.2546.0.247.255254
2496.0.248.0/246.0.248.1 to 6.0.248.2546.0.248.255254
2506.0.249.0/246.0.249.1 to 6.0.249.2546.0.249.255254
2516.0.250.0/246.0.250.1 to 6.0.250.2546.0.250.255254
2526.0.251.0/246.0.251.1 to 6.0.251.2546.0.251.255254
2536.0.252.0/246.0.252.1 to 6.0.252.2546.0.252.255254
2546.0.253.0/246.0.253.1 to 6.0.253.2546.0.253.255254
2556.0.254.0/246.0.254.1 to 6.0.254.2546.0.254.255254
2566.0.255.0/246.0.255.1 to 6.0.255.2546.0.255.255254

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.