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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.

Network6.80.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
6.80.0.0
Broadcast address
6.95.255.255
First usable
6.80.0.1
Last usable
6.95.255.254
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 06500000 · Integer 105906176 to 106954751
Reverse DNS zones
80.6.in-addr.arpa
81.6.in-addr.arpa
82.6.in-addr.arpa
83.6.in-addr.arpa
84.6.in-addr.arpa
85.6.in-addr.arpa
86.6.in-addr.arpa
87.6.in-addr.arpa
88.6.in-addr.arpa
89.6.in-addr.arpa
90.6.in-addr.arpa
91.6.in-addr.arpa
92.6.in-addr.arpa
93.6.in-addr.arpa
94.6.in-addr.arpa
95.6.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
Address00000110.01010000.00000000.000000006.80.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network00000110.01010000.00000000.000000006.80.0.0
Broadcast00000110.01011111.11111111.111111116.95.255.255
Split into smaller subnets/21
/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)

6.80.0.0/12 makes 512 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
16.80.0.0/216.80.0.1 to 6.80.7.2546.80.7.2552,046
26.80.8.0/216.80.8.1 to 6.80.15.2546.80.15.2552,046
36.80.16.0/216.80.16.1 to 6.80.23.2546.80.23.2552,046
46.80.24.0/216.80.24.1 to 6.80.31.2546.80.31.2552,046
56.80.32.0/216.80.32.1 to 6.80.39.2546.80.39.2552,046
66.80.40.0/216.80.40.1 to 6.80.47.2546.80.47.2552,046
76.80.48.0/216.80.48.1 to 6.80.55.2546.80.55.2552,046
86.80.56.0/216.80.56.1 to 6.80.63.2546.80.63.2552,046
96.80.64.0/216.80.64.1 to 6.80.71.2546.80.71.2552,046
106.80.72.0/216.80.72.1 to 6.80.79.2546.80.79.2552,046
116.80.80.0/216.80.80.1 to 6.80.87.2546.80.87.2552,046
126.80.88.0/216.80.88.1 to 6.80.95.2546.80.95.2552,046
136.80.96.0/216.80.96.1 to 6.80.103.2546.80.103.2552,046
146.80.104.0/216.80.104.1 to 6.80.111.2546.80.111.2552,046
156.80.112.0/216.80.112.1 to 6.80.119.2546.80.119.2552,046
166.80.120.0/216.80.120.1 to 6.80.127.2546.80.127.2552,046
176.80.128.0/216.80.128.1 to 6.80.135.2546.80.135.2552,046
186.80.136.0/216.80.136.1 to 6.80.143.2546.80.143.2552,046
196.80.144.0/216.80.144.1 to 6.80.151.2546.80.151.2552,046
206.80.152.0/216.80.152.1 to 6.80.159.2546.80.159.2552,046
216.80.160.0/216.80.160.1 to 6.80.167.2546.80.167.2552,046
226.80.168.0/216.80.168.1 to 6.80.175.2546.80.175.2552,046
236.80.176.0/216.80.176.1 to 6.80.183.2546.80.183.2552,046
246.80.184.0/216.80.184.1 to 6.80.191.2546.80.191.2552,046
256.80.192.0/216.80.192.1 to 6.80.199.2546.80.199.2552,046
266.80.200.0/216.80.200.1 to 6.80.207.2546.80.207.2552,046
276.80.208.0/216.80.208.1 to 6.80.215.2546.80.215.2552,046
286.80.216.0/216.80.216.1 to 6.80.223.2546.80.223.2552,046
296.80.224.0/216.80.224.1 to 6.80.231.2546.80.231.2552,046
306.80.232.0/216.80.232.1 to 6.80.239.2546.80.239.2552,046
316.80.240.0/216.80.240.1 to 6.80.247.2546.80.247.2552,046
326.80.248.0/216.80.248.1 to 6.80.255.2546.80.255.2552,046
336.81.0.0/216.81.0.1 to 6.81.7.2546.81.7.2552,046
346.81.8.0/216.81.8.1 to 6.81.15.2546.81.15.2552,046
356.81.16.0/216.81.16.1 to 6.81.23.2546.81.23.2552,046
366.81.24.0/216.81.24.1 to 6.81.31.2546.81.31.2552,046
376.81.32.0/216.81.32.1 to 6.81.39.2546.81.39.2552,046
386.81.40.0/216.81.40.1 to 6.81.47.2546.81.47.2552,046
396.81.48.0/216.81.48.1 to 6.81.55.2546.81.55.2552,046
406.81.56.0/216.81.56.1 to 6.81.63.2546.81.63.2552,046
416.81.64.0/216.81.64.1 to 6.81.71.2546.81.71.2552,046
426.81.72.0/216.81.72.1 to 6.81.79.2546.81.79.2552,046
436.81.80.0/216.81.80.1 to 6.81.87.2546.81.87.2552,046
446.81.88.0/216.81.88.1 to 6.81.95.2546.81.95.2552,046
456.81.96.0/216.81.96.1 to 6.81.103.2546.81.103.2552,046
466.81.104.0/216.81.104.1 to 6.81.111.2546.81.111.2552,046
476.81.112.0/216.81.112.1 to 6.81.119.2546.81.119.2552,046
486.81.120.0/216.81.120.1 to 6.81.127.2546.81.127.2552,046
496.81.128.0/216.81.128.1 to 6.81.135.2546.81.135.2552,046
506.81.136.0/216.81.136.1 to 6.81.143.2546.81.143.2552,046
516.81.144.0/216.81.144.1 to 6.81.151.2546.81.151.2552,046
526.81.152.0/216.81.152.1 to 6.81.159.2546.81.159.2552,046
536.81.160.0/216.81.160.1 to 6.81.167.2546.81.167.2552,046
546.81.168.0/216.81.168.1 to 6.81.175.2546.81.175.2552,046
556.81.176.0/216.81.176.1 to 6.81.183.2546.81.183.2552,046
566.81.184.0/216.81.184.1 to 6.81.191.2546.81.191.2552,046
576.81.192.0/216.81.192.1 to 6.81.199.2546.81.199.2552,046
586.81.200.0/216.81.200.1 to 6.81.207.2546.81.207.2552,046
596.81.208.0/216.81.208.1 to 6.81.215.2546.81.215.2552,046
606.81.216.0/216.81.216.1 to 6.81.223.2546.81.223.2552,046
616.81.224.0/216.81.224.1 to 6.81.231.2546.81.231.2552,046
626.81.232.0/216.81.232.1 to 6.81.239.2546.81.239.2552,046
636.81.240.0/216.81.240.1 to 6.81.247.2546.81.247.2552,046
646.81.248.0/216.81.248.1 to 6.81.255.2546.81.255.2552,046
656.82.0.0/216.82.0.1 to 6.82.7.2546.82.7.2552,046
666.82.8.0/216.82.8.1 to 6.82.15.2546.82.15.2552,046
676.82.16.0/216.82.16.1 to 6.82.23.2546.82.23.2552,046
686.82.24.0/216.82.24.1 to 6.82.31.2546.82.31.2552,046
696.82.32.0/216.82.32.1 to 6.82.39.2546.82.39.2552,046
706.82.40.0/216.82.40.1 to 6.82.47.2546.82.47.2552,046
716.82.48.0/216.82.48.1 to 6.82.55.2546.82.55.2552,046
726.82.56.0/216.82.56.1 to 6.82.63.2546.82.63.2552,046
736.82.64.0/216.82.64.1 to 6.82.71.2546.82.71.2552,046
746.82.72.0/216.82.72.1 to 6.82.79.2546.82.79.2552,046
756.82.80.0/216.82.80.1 to 6.82.87.2546.82.87.2552,046
766.82.88.0/216.82.88.1 to 6.82.95.2546.82.95.2552,046
776.82.96.0/216.82.96.1 to 6.82.103.2546.82.103.2552,046
786.82.104.0/216.82.104.1 to 6.82.111.2546.82.111.2552,046
796.82.112.0/216.82.112.1 to 6.82.119.2546.82.119.2552,046
806.82.120.0/216.82.120.1 to 6.82.127.2546.82.127.2552,046
816.82.128.0/216.82.128.1 to 6.82.135.2546.82.135.2552,046
826.82.136.0/216.82.136.1 to 6.82.143.2546.82.143.2552,046
836.82.144.0/216.82.144.1 to 6.82.151.2546.82.151.2552,046
846.82.152.0/216.82.152.1 to 6.82.159.2546.82.159.2552,046
856.82.160.0/216.82.160.1 to 6.82.167.2546.82.167.2552,046
866.82.168.0/216.82.168.1 to 6.82.175.2546.82.175.2552,046
876.82.176.0/216.82.176.1 to 6.82.183.2546.82.183.2552,046
886.82.184.0/216.82.184.1 to 6.82.191.2546.82.191.2552,046
896.82.192.0/216.82.192.1 to 6.82.199.2546.82.199.2552,046
906.82.200.0/216.82.200.1 to 6.82.207.2546.82.207.2552,046
916.82.208.0/216.82.208.1 to 6.82.215.2546.82.215.2552,046
926.82.216.0/216.82.216.1 to 6.82.223.2546.82.223.2552,046
936.82.224.0/216.82.224.1 to 6.82.231.2546.82.231.2552,046
946.82.232.0/216.82.232.1 to 6.82.239.2546.82.239.2552,046
956.82.240.0/216.82.240.1 to 6.82.247.2546.82.247.2552,046
966.82.248.0/216.82.248.1 to 6.82.255.2546.82.255.2552,046
976.83.0.0/216.83.0.1 to 6.83.7.2546.83.7.2552,046
986.83.8.0/216.83.8.1 to 6.83.15.2546.83.15.2552,046
996.83.16.0/216.83.16.1 to 6.83.23.2546.83.23.2552,046
1006.83.24.0/216.83.24.1 to 6.83.31.2546.83.31.2552,046
1016.83.32.0/216.83.32.1 to 6.83.39.2546.83.39.2552,046
1026.83.40.0/216.83.40.1 to 6.83.47.2546.83.47.2552,046
1036.83.48.0/216.83.48.1 to 6.83.55.2546.83.55.2552,046
1046.83.56.0/216.83.56.1 to 6.83.63.2546.83.63.2552,046
1056.83.64.0/216.83.64.1 to 6.83.71.2546.83.71.2552,046
1066.83.72.0/216.83.72.1 to 6.83.79.2546.83.79.2552,046
1076.83.80.0/216.83.80.1 to 6.83.87.2546.83.87.2552,046
1086.83.88.0/216.83.88.1 to 6.83.95.2546.83.95.2552,046
1096.83.96.0/216.83.96.1 to 6.83.103.2546.83.103.2552,046
1106.83.104.0/216.83.104.1 to 6.83.111.2546.83.111.2552,046
1116.83.112.0/216.83.112.1 to 6.83.119.2546.83.119.2552,046
1126.83.120.0/216.83.120.1 to 6.83.127.2546.83.127.2552,046
1136.83.128.0/216.83.128.1 to 6.83.135.2546.83.135.2552,046
1146.83.136.0/216.83.136.1 to 6.83.143.2546.83.143.2552,046
1156.83.144.0/216.83.144.1 to 6.83.151.2546.83.151.2552,046
1166.83.152.0/216.83.152.1 to 6.83.159.2546.83.159.2552,046
1176.83.160.0/216.83.160.1 to 6.83.167.2546.83.167.2552,046
1186.83.168.0/216.83.168.1 to 6.83.175.2546.83.175.2552,046
1196.83.176.0/216.83.176.1 to 6.83.183.2546.83.183.2552,046
1206.83.184.0/216.83.184.1 to 6.83.191.2546.83.191.2552,046
1216.83.192.0/216.83.192.1 to 6.83.199.2546.83.199.2552,046
1226.83.200.0/216.83.200.1 to 6.83.207.2546.83.207.2552,046
1236.83.208.0/216.83.208.1 to 6.83.215.2546.83.215.2552,046
1246.83.216.0/216.83.216.1 to 6.83.223.2546.83.223.2552,046
1256.83.224.0/216.83.224.1 to 6.83.231.2546.83.231.2552,046
1266.83.232.0/216.83.232.1 to 6.83.239.2546.83.239.2552,046
1276.83.240.0/216.83.240.1 to 6.83.247.2546.83.247.2552,046
1286.83.248.0/216.83.248.1 to 6.83.255.2546.83.255.2552,046
1296.84.0.0/216.84.0.1 to 6.84.7.2546.84.7.2552,046
1306.84.8.0/216.84.8.1 to 6.84.15.2546.84.15.2552,046
1316.84.16.0/216.84.16.1 to 6.84.23.2546.84.23.2552,046
1326.84.24.0/216.84.24.1 to 6.84.31.2546.84.31.2552,046
1336.84.32.0/216.84.32.1 to 6.84.39.2546.84.39.2552,046
1346.84.40.0/216.84.40.1 to 6.84.47.2546.84.47.2552,046
1356.84.48.0/216.84.48.1 to 6.84.55.2546.84.55.2552,046
1366.84.56.0/216.84.56.1 to 6.84.63.2546.84.63.2552,046
1376.84.64.0/216.84.64.1 to 6.84.71.2546.84.71.2552,046
1386.84.72.0/216.84.72.1 to 6.84.79.2546.84.79.2552,046
1396.84.80.0/216.84.80.1 to 6.84.87.2546.84.87.2552,046
1406.84.88.0/216.84.88.1 to 6.84.95.2546.84.95.2552,046
1416.84.96.0/216.84.96.1 to 6.84.103.2546.84.103.2552,046
1426.84.104.0/216.84.104.1 to 6.84.111.2546.84.111.2552,046
1436.84.112.0/216.84.112.1 to 6.84.119.2546.84.119.2552,046
1446.84.120.0/216.84.120.1 to 6.84.127.2546.84.127.2552,046
1456.84.128.0/216.84.128.1 to 6.84.135.2546.84.135.2552,046
1466.84.136.0/216.84.136.1 to 6.84.143.2546.84.143.2552,046
1476.84.144.0/216.84.144.1 to 6.84.151.2546.84.151.2552,046
1486.84.152.0/216.84.152.1 to 6.84.159.2546.84.159.2552,046
1496.84.160.0/216.84.160.1 to 6.84.167.2546.84.167.2552,046
1506.84.168.0/216.84.168.1 to 6.84.175.2546.84.175.2552,046
1516.84.176.0/216.84.176.1 to 6.84.183.2546.84.183.2552,046
1526.84.184.0/216.84.184.1 to 6.84.191.2546.84.191.2552,046
1536.84.192.0/216.84.192.1 to 6.84.199.2546.84.199.2552,046
1546.84.200.0/216.84.200.1 to 6.84.207.2546.84.207.2552,046
1556.84.208.0/216.84.208.1 to 6.84.215.2546.84.215.2552,046
1566.84.216.0/216.84.216.1 to 6.84.223.2546.84.223.2552,046
1576.84.224.0/216.84.224.1 to 6.84.231.2546.84.231.2552,046
1586.84.232.0/216.84.232.1 to 6.84.239.2546.84.239.2552,046
1596.84.240.0/216.84.240.1 to 6.84.247.2546.84.247.2552,046
1606.84.248.0/216.84.248.1 to 6.84.255.2546.84.255.2552,046
1616.85.0.0/216.85.0.1 to 6.85.7.2546.85.7.2552,046
1626.85.8.0/216.85.8.1 to 6.85.15.2546.85.15.2552,046
1636.85.16.0/216.85.16.1 to 6.85.23.2546.85.23.2552,046
1646.85.24.0/216.85.24.1 to 6.85.31.2546.85.31.2552,046
1656.85.32.0/216.85.32.1 to 6.85.39.2546.85.39.2552,046
1666.85.40.0/216.85.40.1 to 6.85.47.2546.85.47.2552,046
1676.85.48.0/216.85.48.1 to 6.85.55.2546.85.55.2552,046
1686.85.56.0/216.85.56.1 to 6.85.63.2546.85.63.2552,046
1696.85.64.0/216.85.64.1 to 6.85.71.2546.85.71.2552,046
1706.85.72.0/216.85.72.1 to 6.85.79.2546.85.79.2552,046
1716.85.80.0/216.85.80.1 to 6.85.87.2546.85.87.2552,046
1726.85.88.0/216.85.88.1 to 6.85.95.2546.85.95.2552,046
1736.85.96.0/216.85.96.1 to 6.85.103.2546.85.103.2552,046
1746.85.104.0/216.85.104.1 to 6.85.111.2546.85.111.2552,046
1756.85.112.0/216.85.112.1 to 6.85.119.2546.85.119.2552,046
1766.85.120.0/216.85.120.1 to 6.85.127.2546.85.127.2552,046
1776.85.128.0/216.85.128.1 to 6.85.135.2546.85.135.2552,046
1786.85.136.0/216.85.136.1 to 6.85.143.2546.85.143.2552,046
1796.85.144.0/216.85.144.1 to 6.85.151.2546.85.151.2552,046
1806.85.152.0/216.85.152.1 to 6.85.159.2546.85.159.2552,046
1816.85.160.0/216.85.160.1 to 6.85.167.2546.85.167.2552,046
1826.85.168.0/216.85.168.1 to 6.85.175.2546.85.175.2552,046
1836.85.176.0/216.85.176.1 to 6.85.183.2546.85.183.2552,046
1846.85.184.0/216.85.184.1 to 6.85.191.2546.85.191.2552,046
1856.85.192.0/216.85.192.1 to 6.85.199.2546.85.199.2552,046
1866.85.200.0/216.85.200.1 to 6.85.207.2546.85.207.2552,046
1876.85.208.0/216.85.208.1 to 6.85.215.2546.85.215.2552,046
1886.85.216.0/216.85.216.1 to 6.85.223.2546.85.223.2552,046
1896.85.224.0/216.85.224.1 to 6.85.231.2546.85.231.2552,046
1906.85.232.0/216.85.232.1 to 6.85.239.2546.85.239.2552,046
1916.85.240.0/216.85.240.1 to 6.85.247.2546.85.247.2552,046
1926.85.248.0/216.85.248.1 to 6.85.255.2546.85.255.2552,046
1936.86.0.0/216.86.0.1 to 6.86.7.2546.86.7.2552,046
1946.86.8.0/216.86.8.1 to 6.86.15.2546.86.15.2552,046
1956.86.16.0/216.86.16.1 to 6.86.23.2546.86.23.2552,046
1966.86.24.0/216.86.24.1 to 6.86.31.2546.86.31.2552,046
1976.86.32.0/216.86.32.1 to 6.86.39.2546.86.39.2552,046
1986.86.40.0/216.86.40.1 to 6.86.47.2546.86.47.2552,046
1996.86.48.0/216.86.48.1 to 6.86.55.2546.86.55.2552,046
2006.86.56.0/216.86.56.1 to 6.86.63.2546.86.63.2552,046
2016.86.64.0/216.86.64.1 to 6.86.71.2546.86.71.2552,046
2026.86.72.0/216.86.72.1 to 6.86.79.2546.86.79.2552,046
2036.86.80.0/216.86.80.1 to 6.86.87.2546.86.87.2552,046
2046.86.88.0/216.86.88.1 to 6.86.95.2546.86.95.2552,046
2056.86.96.0/216.86.96.1 to 6.86.103.2546.86.103.2552,046
2066.86.104.0/216.86.104.1 to 6.86.111.2546.86.111.2552,046
2076.86.112.0/216.86.112.1 to 6.86.119.2546.86.119.2552,046
2086.86.120.0/216.86.120.1 to 6.86.127.2546.86.127.2552,046
2096.86.128.0/216.86.128.1 to 6.86.135.2546.86.135.2552,046
2106.86.136.0/216.86.136.1 to 6.86.143.2546.86.143.2552,046
2116.86.144.0/216.86.144.1 to 6.86.151.2546.86.151.2552,046
2126.86.152.0/216.86.152.1 to 6.86.159.2546.86.159.2552,046
2136.86.160.0/216.86.160.1 to 6.86.167.2546.86.167.2552,046
2146.86.168.0/216.86.168.1 to 6.86.175.2546.86.175.2552,046
2156.86.176.0/216.86.176.1 to 6.86.183.2546.86.183.2552,046
2166.86.184.0/216.86.184.1 to 6.86.191.2546.86.191.2552,046
2176.86.192.0/216.86.192.1 to 6.86.199.2546.86.199.2552,046
2186.86.200.0/216.86.200.1 to 6.86.207.2546.86.207.2552,046
2196.86.208.0/216.86.208.1 to 6.86.215.2546.86.215.2552,046
2206.86.216.0/216.86.216.1 to 6.86.223.2546.86.223.2552,046
2216.86.224.0/216.86.224.1 to 6.86.231.2546.86.231.2552,046
2226.86.232.0/216.86.232.1 to 6.86.239.2546.86.239.2552,046
2236.86.240.0/216.86.240.1 to 6.86.247.2546.86.247.2552,046
2246.86.248.0/216.86.248.1 to 6.86.255.2546.86.255.2552,046
2256.87.0.0/216.87.0.1 to 6.87.7.2546.87.7.2552,046
2266.87.8.0/216.87.8.1 to 6.87.15.2546.87.15.2552,046
2276.87.16.0/216.87.16.1 to 6.87.23.2546.87.23.2552,046
2286.87.24.0/216.87.24.1 to 6.87.31.2546.87.31.2552,046
2296.87.32.0/216.87.32.1 to 6.87.39.2546.87.39.2552,046
2306.87.40.0/216.87.40.1 to 6.87.47.2546.87.47.2552,046
2316.87.48.0/216.87.48.1 to 6.87.55.2546.87.55.2552,046
2326.87.56.0/216.87.56.1 to 6.87.63.2546.87.63.2552,046
2336.87.64.0/216.87.64.1 to 6.87.71.2546.87.71.2552,046
2346.87.72.0/216.87.72.1 to 6.87.79.2546.87.79.2552,046
2356.87.80.0/216.87.80.1 to 6.87.87.2546.87.87.2552,046
2366.87.88.0/216.87.88.1 to 6.87.95.2546.87.95.2552,046
2376.87.96.0/216.87.96.1 to 6.87.103.2546.87.103.2552,046
2386.87.104.0/216.87.104.1 to 6.87.111.2546.87.111.2552,046
2396.87.112.0/216.87.112.1 to 6.87.119.2546.87.119.2552,046
2406.87.120.0/216.87.120.1 to 6.87.127.2546.87.127.2552,046
2416.87.128.0/216.87.128.1 to 6.87.135.2546.87.135.2552,046
2426.87.136.0/216.87.136.1 to 6.87.143.2546.87.143.2552,046
2436.87.144.0/216.87.144.1 to 6.87.151.2546.87.151.2552,046
2446.87.152.0/216.87.152.1 to 6.87.159.2546.87.159.2552,046
2456.87.160.0/216.87.160.1 to 6.87.167.2546.87.167.2552,046
2466.87.168.0/216.87.168.1 to 6.87.175.2546.87.175.2552,046
2476.87.176.0/216.87.176.1 to 6.87.183.2546.87.183.2552,046
2486.87.184.0/216.87.184.1 to 6.87.191.2546.87.191.2552,046
2496.87.192.0/216.87.192.1 to 6.87.199.2546.87.199.2552,046
2506.87.200.0/216.87.200.1 to 6.87.207.2546.87.207.2552,046
2516.87.208.0/216.87.208.1 to 6.87.215.2546.87.215.2552,046
2526.87.216.0/216.87.216.1 to 6.87.223.2546.87.223.2552,046
2536.87.224.0/216.87.224.1 to 6.87.231.2546.87.231.2552,046
2546.87.232.0/216.87.232.1 to 6.87.239.2546.87.239.2552,046
2556.87.240.0/216.87.240.1 to 6.87.247.2546.87.247.2552,046
2566.87.248.0/216.87.248.1 to 6.87.255.2546.87.255.2552,046

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.