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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.

Network4.0.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
4.0.0.0
Broadcast address
4.15.255.255
First usable
4.0.0.1
Last usable
4.15.255.254
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 04000000 · Integer 67108864 to 68157439
Reverse DNS zones
0.4.in-addr.arpa
1.4.in-addr.arpa
2.4.in-addr.arpa
3.4.in-addr.arpa
4.4.in-addr.arpa
5.4.in-addr.arpa
6.4.in-addr.arpa
7.4.in-addr.arpa
8.4.in-addr.arpa
9.4.in-addr.arpa
10.4.in-addr.arpa
11.4.in-addr.arpa
12.4.in-addr.arpa
13.4.in-addr.arpa
14.4.in-addr.arpa
15.4.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
Address00000100.00000000.00000000.000000004.0.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network00000100.00000000.00000000.000000004.0.0.0
Broadcast00000100.00001111.11111111.111111114.15.255.255
Split into smaller subnets/20
/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)

4.0.0.0/12 makes 256 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
14.0.0.0/204.0.0.1 to 4.0.15.2544.0.15.2554,094
24.0.16.0/204.0.16.1 to 4.0.31.2544.0.31.2554,094
34.0.32.0/204.0.32.1 to 4.0.47.2544.0.47.2554,094
44.0.48.0/204.0.48.1 to 4.0.63.2544.0.63.2554,094
54.0.64.0/204.0.64.1 to 4.0.79.2544.0.79.2554,094
64.0.80.0/204.0.80.1 to 4.0.95.2544.0.95.2554,094
74.0.96.0/204.0.96.1 to 4.0.111.2544.0.111.2554,094
84.0.112.0/204.0.112.1 to 4.0.127.2544.0.127.2554,094
94.0.128.0/204.0.128.1 to 4.0.143.2544.0.143.2554,094
104.0.144.0/204.0.144.1 to 4.0.159.2544.0.159.2554,094
114.0.160.0/204.0.160.1 to 4.0.175.2544.0.175.2554,094
124.0.176.0/204.0.176.1 to 4.0.191.2544.0.191.2554,094
134.0.192.0/204.0.192.1 to 4.0.207.2544.0.207.2554,094
144.0.208.0/204.0.208.1 to 4.0.223.2544.0.223.2554,094
154.0.224.0/204.0.224.1 to 4.0.239.2544.0.239.2554,094
164.0.240.0/204.0.240.1 to 4.0.255.2544.0.255.2554,094
174.1.0.0/204.1.0.1 to 4.1.15.2544.1.15.2554,094
184.1.16.0/204.1.16.1 to 4.1.31.2544.1.31.2554,094
194.1.32.0/204.1.32.1 to 4.1.47.2544.1.47.2554,094
204.1.48.0/204.1.48.1 to 4.1.63.2544.1.63.2554,094
214.1.64.0/204.1.64.1 to 4.1.79.2544.1.79.2554,094
224.1.80.0/204.1.80.1 to 4.1.95.2544.1.95.2554,094
234.1.96.0/204.1.96.1 to 4.1.111.2544.1.111.2554,094
244.1.112.0/204.1.112.1 to 4.1.127.2544.1.127.2554,094
254.1.128.0/204.1.128.1 to 4.1.143.2544.1.143.2554,094
264.1.144.0/204.1.144.1 to 4.1.159.2544.1.159.2554,094
274.1.160.0/204.1.160.1 to 4.1.175.2544.1.175.2554,094
284.1.176.0/204.1.176.1 to 4.1.191.2544.1.191.2554,094
294.1.192.0/204.1.192.1 to 4.1.207.2544.1.207.2554,094
304.1.208.0/204.1.208.1 to 4.1.223.2544.1.223.2554,094
314.1.224.0/204.1.224.1 to 4.1.239.2544.1.239.2554,094
324.1.240.0/204.1.240.1 to 4.1.255.2544.1.255.2554,094
334.2.0.0/204.2.0.1 to 4.2.15.2544.2.15.2554,094
344.2.16.0/204.2.16.1 to 4.2.31.2544.2.31.2554,094
354.2.32.0/204.2.32.1 to 4.2.47.2544.2.47.2554,094
364.2.48.0/204.2.48.1 to 4.2.63.2544.2.63.2554,094
374.2.64.0/204.2.64.1 to 4.2.79.2544.2.79.2554,094
384.2.80.0/204.2.80.1 to 4.2.95.2544.2.95.2554,094
394.2.96.0/204.2.96.1 to 4.2.111.2544.2.111.2554,094
404.2.112.0/204.2.112.1 to 4.2.127.2544.2.127.2554,094
414.2.128.0/204.2.128.1 to 4.2.143.2544.2.143.2554,094
424.2.144.0/204.2.144.1 to 4.2.159.2544.2.159.2554,094
434.2.160.0/204.2.160.1 to 4.2.175.2544.2.175.2554,094
444.2.176.0/204.2.176.1 to 4.2.191.2544.2.191.2554,094
454.2.192.0/204.2.192.1 to 4.2.207.2544.2.207.2554,094
464.2.208.0/204.2.208.1 to 4.2.223.2544.2.223.2554,094
474.2.224.0/204.2.224.1 to 4.2.239.2544.2.239.2554,094
484.2.240.0/204.2.240.1 to 4.2.255.2544.2.255.2554,094
494.3.0.0/204.3.0.1 to 4.3.15.2544.3.15.2554,094
504.3.16.0/204.3.16.1 to 4.3.31.2544.3.31.2554,094
514.3.32.0/204.3.32.1 to 4.3.47.2544.3.47.2554,094
524.3.48.0/204.3.48.1 to 4.3.63.2544.3.63.2554,094
534.3.64.0/204.3.64.1 to 4.3.79.2544.3.79.2554,094
544.3.80.0/204.3.80.1 to 4.3.95.2544.3.95.2554,094
554.3.96.0/204.3.96.1 to 4.3.111.2544.3.111.2554,094
564.3.112.0/204.3.112.1 to 4.3.127.2544.3.127.2554,094
574.3.128.0/204.3.128.1 to 4.3.143.2544.3.143.2554,094
584.3.144.0/204.3.144.1 to 4.3.159.2544.3.159.2554,094
594.3.160.0/204.3.160.1 to 4.3.175.2544.3.175.2554,094
604.3.176.0/204.3.176.1 to 4.3.191.2544.3.191.2554,094
614.3.192.0/204.3.192.1 to 4.3.207.2544.3.207.2554,094
624.3.208.0/204.3.208.1 to 4.3.223.2544.3.223.2554,094
634.3.224.0/204.3.224.1 to 4.3.239.2544.3.239.2554,094
644.3.240.0/204.3.240.1 to 4.3.255.2544.3.255.2554,094
654.4.0.0/204.4.0.1 to 4.4.15.2544.4.15.2554,094
664.4.16.0/204.4.16.1 to 4.4.31.2544.4.31.2554,094
674.4.32.0/204.4.32.1 to 4.4.47.2544.4.47.2554,094
684.4.48.0/204.4.48.1 to 4.4.63.2544.4.63.2554,094
694.4.64.0/204.4.64.1 to 4.4.79.2544.4.79.2554,094
704.4.80.0/204.4.80.1 to 4.4.95.2544.4.95.2554,094
714.4.96.0/204.4.96.1 to 4.4.111.2544.4.111.2554,094
724.4.112.0/204.4.112.1 to 4.4.127.2544.4.127.2554,094
734.4.128.0/204.4.128.1 to 4.4.143.2544.4.143.2554,094
744.4.144.0/204.4.144.1 to 4.4.159.2544.4.159.2554,094
754.4.160.0/204.4.160.1 to 4.4.175.2544.4.175.2554,094
764.4.176.0/204.4.176.1 to 4.4.191.2544.4.191.2554,094
774.4.192.0/204.4.192.1 to 4.4.207.2544.4.207.2554,094
784.4.208.0/204.4.208.1 to 4.4.223.2544.4.223.2554,094
794.4.224.0/204.4.224.1 to 4.4.239.2544.4.239.2554,094
804.4.240.0/204.4.240.1 to 4.4.255.2544.4.255.2554,094
814.5.0.0/204.5.0.1 to 4.5.15.2544.5.15.2554,094
824.5.16.0/204.5.16.1 to 4.5.31.2544.5.31.2554,094
834.5.32.0/204.5.32.1 to 4.5.47.2544.5.47.2554,094
844.5.48.0/204.5.48.1 to 4.5.63.2544.5.63.2554,094
854.5.64.0/204.5.64.1 to 4.5.79.2544.5.79.2554,094
864.5.80.0/204.5.80.1 to 4.5.95.2544.5.95.2554,094
874.5.96.0/204.5.96.1 to 4.5.111.2544.5.111.2554,094
884.5.112.0/204.5.112.1 to 4.5.127.2544.5.127.2554,094
894.5.128.0/204.5.128.1 to 4.5.143.2544.5.143.2554,094
904.5.144.0/204.5.144.1 to 4.5.159.2544.5.159.2554,094
914.5.160.0/204.5.160.1 to 4.5.175.2544.5.175.2554,094
924.5.176.0/204.5.176.1 to 4.5.191.2544.5.191.2554,094
934.5.192.0/204.5.192.1 to 4.5.207.2544.5.207.2554,094
944.5.208.0/204.5.208.1 to 4.5.223.2544.5.223.2554,094
954.5.224.0/204.5.224.1 to 4.5.239.2544.5.239.2554,094
964.5.240.0/204.5.240.1 to 4.5.255.2544.5.255.2554,094
974.6.0.0/204.6.0.1 to 4.6.15.2544.6.15.2554,094
984.6.16.0/204.6.16.1 to 4.6.31.2544.6.31.2554,094
994.6.32.0/204.6.32.1 to 4.6.47.2544.6.47.2554,094
1004.6.48.0/204.6.48.1 to 4.6.63.2544.6.63.2554,094
1014.6.64.0/204.6.64.1 to 4.6.79.2544.6.79.2554,094
1024.6.80.0/204.6.80.1 to 4.6.95.2544.6.95.2554,094
1034.6.96.0/204.6.96.1 to 4.6.111.2544.6.111.2554,094
1044.6.112.0/204.6.112.1 to 4.6.127.2544.6.127.2554,094
1054.6.128.0/204.6.128.1 to 4.6.143.2544.6.143.2554,094
1064.6.144.0/204.6.144.1 to 4.6.159.2544.6.159.2554,094
1074.6.160.0/204.6.160.1 to 4.6.175.2544.6.175.2554,094
1084.6.176.0/204.6.176.1 to 4.6.191.2544.6.191.2554,094
1094.6.192.0/204.6.192.1 to 4.6.207.2544.6.207.2554,094
1104.6.208.0/204.6.208.1 to 4.6.223.2544.6.223.2554,094
1114.6.224.0/204.6.224.1 to 4.6.239.2544.6.239.2554,094
1124.6.240.0/204.6.240.1 to 4.6.255.2544.6.255.2554,094
1134.7.0.0/204.7.0.1 to 4.7.15.2544.7.15.2554,094
1144.7.16.0/204.7.16.1 to 4.7.31.2544.7.31.2554,094
1154.7.32.0/204.7.32.1 to 4.7.47.2544.7.47.2554,094
1164.7.48.0/204.7.48.1 to 4.7.63.2544.7.63.2554,094
1174.7.64.0/204.7.64.1 to 4.7.79.2544.7.79.2554,094
1184.7.80.0/204.7.80.1 to 4.7.95.2544.7.95.2554,094
1194.7.96.0/204.7.96.1 to 4.7.111.2544.7.111.2554,094
1204.7.112.0/204.7.112.1 to 4.7.127.2544.7.127.2554,094
1214.7.128.0/204.7.128.1 to 4.7.143.2544.7.143.2554,094
1224.7.144.0/204.7.144.1 to 4.7.159.2544.7.159.2554,094
1234.7.160.0/204.7.160.1 to 4.7.175.2544.7.175.2554,094
1244.7.176.0/204.7.176.1 to 4.7.191.2544.7.191.2554,094
1254.7.192.0/204.7.192.1 to 4.7.207.2544.7.207.2554,094
1264.7.208.0/204.7.208.1 to 4.7.223.2544.7.223.2554,094
1274.7.224.0/204.7.224.1 to 4.7.239.2544.7.239.2554,094
1284.7.240.0/204.7.240.1 to 4.7.255.2544.7.255.2554,094
1294.8.0.0/204.8.0.1 to 4.8.15.2544.8.15.2554,094
1304.8.16.0/204.8.16.1 to 4.8.31.2544.8.31.2554,094
1314.8.32.0/204.8.32.1 to 4.8.47.2544.8.47.2554,094
1324.8.48.0/204.8.48.1 to 4.8.63.2544.8.63.2554,094
1334.8.64.0/204.8.64.1 to 4.8.79.2544.8.79.2554,094
1344.8.80.0/204.8.80.1 to 4.8.95.2544.8.95.2554,094
1354.8.96.0/204.8.96.1 to 4.8.111.2544.8.111.2554,094
1364.8.112.0/204.8.112.1 to 4.8.127.2544.8.127.2554,094
1374.8.128.0/204.8.128.1 to 4.8.143.2544.8.143.2554,094
1384.8.144.0/204.8.144.1 to 4.8.159.2544.8.159.2554,094
1394.8.160.0/204.8.160.1 to 4.8.175.2544.8.175.2554,094
1404.8.176.0/204.8.176.1 to 4.8.191.2544.8.191.2554,094
1414.8.192.0/204.8.192.1 to 4.8.207.2544.8.207.2554,094
1424.8.208.0/204.8.208.1 to 4.8.223.2544.8.223.2554,094
1434.8.224.0/204.8.224.1 to 4.8.239.2544.8.239.2554,094
1444.8.240.0/204.8.240.1 to 4.8.255.2544.8.255.2554,094
1454.9.0.0/204.9.0.1 to 4.9.15.2544.9.15.2554,094
1464.9.16.0/204.9.16.1 to 4.9.31.2544.9.31.2554,094
1474.9.32.0/204.9.32.1 to 4.9.47.2544.9.47.2554,094
1484.9.48.0/204.9.48.1 to 4.9.63.2544.9.63.2554,094
1494.9.64.0/204.9.64.1 to 4.9.79.2544.9.79.2554,094
1504.9.80.0/204.9.80.1 to 4.9.95.2544.9.95.2554,094
1514.9.96.0/204.9.96.1 to 4.9.111.2544.9.111.2554,094
1524.9.112.0/204.9.112.1 to 4.9.127.2544.9.127.2554,094
1534.9.128.0/204.9.128.1 to 4.9.143.2544.9.143.2554,094
1544.9.144.0/204.9.144.1 to 4.9.159.2544.9.159.2554,094
1554.9.160.0/204.9.160.1 to 4.9.175.2544.9.175.2554,094
1564.9.176.0/204.9.176.1 to 4.9.191.2544.9.191.2554,094
1574.9.192.0/204.9.192.1 to 4.9.207.2544.9.207.2554,094
1584.9.208.0/204.9.208.1 to 4.9.223.2544.9.223.2554,094
1594.9.224.0/204.9.224.1 to 4.9.239.2544.9.239.2554,094
1604.9.240.0/204.9.240.1 to 4.9.255.2544.9.255.2554,094
1614.10.0.0/204.10.0.1 to 4.10.15.2544.10.15.2554,094
1624.10.16.0/204.10.16.1 to 4.10.31.2544.10.31.2554,094
1634.10.32.0/204.10.32.1 to 4.10.47.2544.10.47.2554,094
1644.10.48.0/204.10.48.1 to 4.10.63.2544.10.63.2554,094
1654.10.64.0/204.10.64.1 to 4.10.79.2544.10.79.2554,094
1664.10.80.0/204.10.80.1 to 4.10.95.2544.10.95.2554,094
1674.10.96.0/204.10.96.1 to 4.10.111.2544.10.111.2554,094
1684.10.112.0/204.10.112.1 to 4.10.127.2544.10.127.2554,094
1694.10.128.0/204.10.128.1 to 4.10.143.2544.10.143.2554,094
1704.10.144.0/204.10.144.1 to 4.10.159.2544.10.159.2554,094
1714.10.160.0/204.10.160.1 to 4.10.175.2544.10.175.2554,094
1724.10.176.0/204.10.176.1 to 4.10.191.2544.10.191.2554,094
1734.10.192.0/204.10.192.1 to 4.10.207.2544.10.207.2554,094
1744.10.208.0/204.10.208.1 to 4.10.223.2544.10.223.2554,094
1754.10.224.0/204.10.224.1 to 4.10.239.2544.10.239.2554,094
1764.10.240.0/204.10.240.1 to 4.10.255.2544.10.255.2554,094
1774.11.0.0/204.11.0.1 to 4.11.15.2544.11.15.2554,094
1784.11.16.0/204.11.16.1 to 4.11.31.2544.11.31.2554,094
1794.11.32.0/204.11.32.1 to 4.11.47.2544.11.47.2554,094
1804.11.48.0/204.11.48.1 to 4.11.63.2544.11.63.2554,094
1814.11.64.0/204.11.64.1 to 4.11.79.2544.11.79.2554,094
1824.11.80.0/204.11.80.1 to 4.11.95.2544.11.95.2554,094
1834.11.96.0/204.11.96.1 to 4.11.111.2544.11.111.2554,094
1844.11.112.0/204.11.112.1 to 4.11.127.2544.11.127.2554,094
1854.11.128.0/204.11.128.1 to 4.11.143.2544.11.143.2554,094
1864.11.144.0/204.11.144.1 to 4.11.159.2544.11.159.2554,094
1874.11.160.0/204.11.160.1 to 4.11.175.2544.11.175.2554,094
1884.11.176.0/204.11.176.1 to 4.11.191.2544.11.191.2554,094
1894.11.192.0/204.11.192.1 to 4.11.207.2544.11.207.2554,094
1904.11.208.0/204.11.208.1 to 4.11.223.2544.11.223.2554,094
1914.11.224.0/204.11.224.1 to 4.11.239.2544.11.239.2554,094
1924.11.240.0/204.11.240.1 to 4.11.255.2544.11.255.2554,094
1934.12.0.0/204.12.0.1 to 4.12.15.2544.12.15.2554,094
1944.12.16.0/204.12.16.1 to 4.12.31.2544.12.31.2554,094
1954.12.32.0/204.12.32.1 to 4.12.47.2544.12.47.2554,094
1964.12.48.0/204.12.48.1 to 4.12.63.2544.12.63.2554,094
1974.12.64.0/204.12.64.1 to 4.12.79.2544.12.79.2554,094
1984.12.80.0/204.12.80.1 to 4.12.95.2544.12.95.2554,094
1994.12.96.0/204.12.96.1 to 4.12.111.2544.12.111.2554,094
2004.12.112.0/204.12.112.1 to 4.12.127.2544.12.127.2554,094
2014.12.128.0/204.12.128.1 to 4.12.143.2544.12.143.2554,094
2024.12.144.0/204.12.144.1 to 4.12.159.2544.12.159.2554,094
2034.12.160.0/204.12.160.1 to 4.12.175.2544.12.175.2554,094
2044.12.176.0/204.12.176.1 to 4.12.191.2544.12.191.2554,094
2054.12.192.0/204.12.192.1 to 4.12.207.2544.12.207.2554,094
2064.12.208.0/204.12.208.1 to 4.12.223.2544.12.223.2554,094
2074.12.224.0/204.12.224.1 to 4.12.239.2544.12.239.2554,094
2084.12.240.0/204.12.240.1 to 4.12.255.2544.12.255.2554,094
2094.13.0.0/204.13.0.1 to 4.13.15.2544.13.15.2554,094
2104.13.16.0/204.13.16.1 to 4.13.31.2544.13.31.2554,094
2114.13.32.0/204.13.32.1 to 4.13.47.2544.13.47.2554,094
2124.13.48.0/204.13.48.1 to 4.13.63.2544.13.63.2554,094
2134.13.64.0/204.13.64.1 to 4.13.79.2544.13.79.2554,094
2144.13.80.0/204.13.80.1 to 4.13.95.2544.13.95.2554,094
2154.13.96.0/204.13.96.1 to 4.13.111.2544.13.111.2554,094
2164.13.112.0/204.13.112.1 to 4.13.127.2544.13.127.2554,094
2174.13.128.0/204.13.128.1 to 4.13.143.2544.13.143.2554,094
2184.13.144.0/204.13.144.1 to 4.13.159.2544.13.159.2554,094
2194.13.160.0/204.13.160.1 to 4.13.175.2544.13.175.2554,094
2204.13.176.0/204.13.176.1 to 4.13.191.2544.13.191.2554,094
2214.13.192.0/204.13.192.1 to 4.13.207.2544.13.207.2554,094
2224.13.208.0/204.13.208.1 to 4.13.223.2544.13.223.2554,094
2234.13.224.0/204.13.224.1 to 4.13.239.2544.13.239.2554,094
2244.13.240.0/204.13.240.1 to 4.13.255.2544.13.255.2554,094
2254.14.0.0/204.14.0.1 to 4.14.15.2544.14.15.2554,094
2264.14.16.0/204.14.16.1 to 4.14.31.2544.14.31.2554,094
2274.14.32.0/204.14.32.1 to 4.14.47.2544.14.47.2554,094
2284.14.48.0/204.14.48.1 to 4.14.63.2544.14.63.2554,094
2294.14.64.0/204.14.64.1 to 4.14.79.2544.14.79.2554,094
2304.14.80.0/204.14.80.1 to 4.14.95.2544.14.95.2554,094
2314.14.96.0/204.14.96.1 to 4.14.111.2544.14.111.2554,094
2324.14.112.0/204.14.112.1 to 4.14.127.2544.14.127.2554,094
2334.14.128.0/204.14.128.1 to 4.14.143.2544.14.143.2554,094
2344.14.144.0/204.14.144.1 to 4.14.159.2544.14.159.2554,094
2354.14.160.0/204.14.160.1 to 4.14.175.2544.14.175.2554,094
2364.14.176.0/204.14.176.1 to 4.14.191.2544.14.191.2554,094
2374.14.192.0/204.14.192.1 to 4.14.207.2544.14.207.2554,094
2384.14.208.0/204.14.208.1 to 4.14.223.2544.14.223.2554,094
2394.14.224.0/204.14.224.1 to 4.14.239.2544.14.239.2554,094
2404.14.240.0/204.14.240.1 to 4.14.255.2544.14.255.2554,094
2414.15.0.0/204.15.0.1 to 4.15.15.2544.15.15.2554,094
2424.15.16.0/204.15.16.1 to 4.15.31.2544.15.31.2554,094
2434.15.32.0/204.15.32.1 to 4.15.47.2544.15.47.2554,094
2444.15.48.0/204.15.48.1 to 4.15.63.2544.15.63.2554,094
2454.15.64.0/204.15.64.1 to 4.15.79.2544.15.79.2554,094
2464.15.80.0/204.15.80.1 to 4.15.95.2544.15.95.2554,094
2474.15.96.0/204.15.96.1 to 4.15.111.2544.15.111.2554,094
2484.15.112.0/204.15.112.1 to 4.15.127.2544.15.127.2554,094
2494.15.128.0/204.15.128.1 to 4.15.143.2544.15.143.2554,094
2504.15.144.0/204.15.144.1 to 4.15.159.2544.15.159.2554,094
2514.15.160.0/204.15.160.1 to 4.15.175.2544.15.175.2554,094
2524.15.176.0/204.15.176.1 to 4.15.191.2544.15.191.2554,094
2534.15.192.0/204.15.192.1 to 4.15.207.2544.15.207.2554,094
2544.15.208.0/204.15.208.1 to 4.15.223.2544.15.223.2554,094
2554.15.224.0/204.15.224.1 to 4.15.239.2544.15.239.2554,094
2564.15.240.0/204.15.240.1 to 4.15.255.2544.15.255.2554,094

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.