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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.

Prefix/10
Addresses2^118
/64 networks2^54
Network
3fc0::/10
First address
3fc0::
Last address
3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
332,306,998,946,228,968,225,951,765,070,086,144 (2^118)
/64 networks (LANs)
18,014,398,509,481,984 (2^54)
Full form
3fc0:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
c.f.3.ip6.arpa
d.f.3.ip6.arpa
e.f.3.ip6.arpa
f.f.3.ip6.arpa
/10 is not on a 4-bit boundary, so it takes 4 /12 zones.
Split into smaller subnets/20
/11 (2)/12 (4)/13 (8)/14 (16)/16 (64)/20 (1,024)/24 (16,384)

3fc0::/10 makes 1,024 subnets of /20; the first 256 are listed.

Subnets
#SubnetLast address
13fc0::/203fc0:fff:ffff:ffff:ffff:ffff:ffff:ffff
23fc0:1000::/203fc0:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fc0:2000::/203fc0:2fff:ffff:ffff:ffff:ffff:ffff:ffff
43fc0:3000::/203fc0:3fff:ffff:ffff:ffff:ffff:ffff:ffff
53fc0:4000::/203fc0:4fff:ffff:ffff:ffff:ffff:ffff:ffff
63fc0:5000::/203fc0:5fff:ffff:ffff:ffff:ffff:ffff:ffff
73fc0:6000::/203fc0:6fff:ffff:ffff:ffff:ffff:ffff:ffff
83fc0:7000::/203fc0:7fff:ffff:ffff:ffff:ffff:ffff:ffff
93fc0:8000::/203fc0:8fff:ffff:ffff:ffff:ffff:ffff:ffff
103fc0:9000::/203fc0:9fff:ffff:ffff:ffff:ffff:ffff:ffff
113fc0:a000::/203fc0:afff:ffff:ffff:ffff:ffff:ffff:ffff
123fc0:b000::/203fc0:bfff:ffff:ffff:ffff:ffff:ffff:ffff
133fc0:c000::/203fc0:cfff:ffff:ffff:ffff:ffff:ffff:ffff
143fc0:d000::/203fc0:dfff:ffff:ffff:ffff:ffff:ffff:ffff
153fc0:e000::/203fc0:efff:ffff:ffff:ffff:ffff:ffff:ffff
163fc0:f000::/203fc0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
173fc1::/203fc1:fff:ffff:ffff:ffff:ffff:ffff:ffff
183fc1:1000::/203fc1:1fff:ffff:ffff:ffff:ffff:ffff:ffff
193fc1:2000::/203fc1:2fff:ffff:ffff:ffff:ffff:ffff:ffff
203fc1:3000::/203fc1:3fff:ffff:ffff:ffff:ffff:ffff:ffff
213fc1:4000::/203fc1:4fff:ffff:ffff:ffff:ffff:ffff:ffff
223fc1:5000::/203fc1:5fff:ffff:ffff:ffff:ffff:ffff:ffff
233fc1:6000::/203fc1:6fff:ffff:ffff:ffff:ffff:ffff:ffff
243fc1:7000::/203fc1:7fff:ffff:ffff:ffff:ffff:ffff:ffff
253fc1:8000::/203fc1:8fff:ffff:ffff:ffff:ffff:ffff:ffff
263fc1:9000::/203fc1:9fff:ffff:ffff:ffff:ffff:ffff:ffff
273fc1:a000::/203fc1:afff:ffff:ffff:ffff:ffff:ffff:ffff
283fc1:b000::/203fc1:bfff:ffff:ffff:ffff:ffff:ffff:ffff
293fc1:c000::/203fc1:cfff:ffff:ffff:ffff:ffff:ffff:ffff
303fc1:d000::/203fc1:dfff:ffff:ffff:ffff:ffff:ffff:ffff
313fc1:e000::/203fc1:efff:ffff:ffff:ffff:ffff:ffff:ffff
323fc1:f000::/203fc1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
333fc2::/203fc2:fff:ffff:ffff:ffff:ffff:ffff:ffff
343fc2:1000::/203fc2:1fff:ffff:ffff:ffff:ffff:ffff:ffff
353fc2:2000::/203fc2:2fff:ffff:ffff:ffff:ffff:ffff:ffff
363fc2:3000::/203fc2:3fff:ffff:ffff:ffff:ffff:ffff:ffff
373fc2:4000::/203fc2:4fff:ffff:ffff:ffff:ffff:ffff:ffff
383fc2:5000::/203fc2:5fff:ffff:ffff:ffff:ffff:ffff:ffff
393fc2:6000::/203fc2:6fff:ffff:ffff:ffff:ffff:ffff:ffff
403fc2:7000::/203fc2:7fff:ffff:ffff:ffff:ffff:ffff:ffff
413fc2:8000::/203fc2:8fff:ffff:ffff:ffff:ffff:ffff:ffff
423fc2:9000::/203fc2:9fff:ffff:ffff:ffff:ffff:ffff:ffff
433fc2:a000::/203fc2:afff:ffff:ffff:ffff:ffff:ffff:ffff
443fc2:b000::/203fc2:bfff:ffff:ffff:ffff:ffff:ffff:ffff
453fc2:c000::/203fc2:cfff:ffff:ffff:ffff:ffff:ffff:ffff
463fc2:d000::/203fc2:dfff:ffff:ffff:ffff:ffff:ffff:ffff
473fc2:e000::/203fc2:efff:ffff:ffff:ffff:ffff:ffff:ffff
483fc2:f000::/203fc2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
493fc3::/203fc3:fff:ffff:ffff:ffff:ffff:ffff:ffff
503fc3:1000::/203fc3:1fff:ffff:ffff:ffff:ffff:ffff:ffff
513fc3:2000::/203fc3:2fff:ffff:ffff:ffff:ffff:ffff:ffff
523fc3:3000::/203fc3:3fff:ffff:ffff:ffff:ffff:ffff:ffff
533fc3:4000::/203fc3:4fff:ffff:ffff:ffff:ffff:ffff:ffff
543fc3:5000::/203fc3:5fff:ffff:ffff:ffff:ffff:ffff:ffff
553fc3:6000::/203fc3:6fff:ffff:ffff:ffff:ffff:ffff:ffff
563fc3:7000::/203fc3:7fff:ffff:ffff:ffff:ffff:ffff:ffff
573fc3:8000::/203fc3:8fff:ffff:ffff:ffff:ffff:ffff:ffff
583fc3:9000::/203fc3:9fff:ffff:ffff:ffff:ffff:ffff:ffff
593fc3:a000::/203fc3:afff:ffff:ffff:ffff:ffff:ffff:ffff
603fc3:b000::/203fc3:bfff:ffff:ffff:ffff:ffff:ffff:ffff
613fc3:c000::/203fc3:cfff:ffff:ffff:ffff:ffff:ffff:ffff
623fc3:d000::/203fc3:dfff:ffff:ffff:ffff:ffff:ffff:ffff
633fc3:e000::/203fc3:efff:ffff:ffff:ffff:ffff:ffff:ffff
643fc3:f000::/203fc3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
653fc4::/203fc4:fff:ffff:ffff:ffff:ffff:ffff:ffff
663fc4:1000::/203fc4:1fff:ffff:ffff:ffff:ffff:ffff:ffff
673fc4:2000::/203fc4:2fff:ffff:ffff:ffff:ffff:ffff:ffff
683fc4:3000::/203fc4:3fff:ffff:ffff:ffff:ffff:ffff:ffff
693fc4:4000::/203fc4:4fff:ffff:ffff:ffff:ffff:ffff:ffff
703fc4:5000::/203fc4:5fff:ffff:ffff:ffff:ffff:ffff:ffff
713fc4:6000::/203fc4:6fff:ffff:ffff:ffff:ffff:ffff:ffff
723fc4:7000::/203fc4:7fff:ffff:ffff:ffff:ffff:ffff:ffff
733fc4:8000::/203fc4:8fff:ffff:ffff:ffff:ffff:ffff:ffff
743fc4:9000::/203fc4:9fff:ffff:ffff:ffff:ffff:ffff:ffff
753fc4:a000::/203fc4:afff:ffff:ffff:ffff:ffff:ffff:ffff
763fc4:b000::/203fc4:bfff:ffff:ffff:ffff:ffff:ffff:ffff
773fc4:c000::/203fc4:cfff:ffff:ffff:ffff:ffff:ffff:ffff
783fc4:d000::/203fc4:dfff:ffff:ffff:ffff:ffff:ffff:ffff
793fc4:e000::/203fc4:efff:ffff:ffff:ffff:ffff:ffff:ffff
803fc4:f000::/203fc4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
813fc5::/203fc5:fff:ffff:ffff:ffff:ffff:ffff:ffff
823fc5:1000::/203fc5:1fff:ffff:ffff:ffff:ffff:ffff:ffff
833fc5:2000::/203fc5:2fff:ffff:ffff:ffff:ffff:ffff:ffff
843fc5:3000::/203fc5:3fff:ffff:ffff:ffff:ffff:ffff:ffff
853fc5:4000::/203fc5:4fff:ffff:ffff:ffff:ffff:ffff:ffff
863fc5:5000::/203fc5:5fff:ffff:ffff:ffff:ffff:ffff:ffff
873fc5:6000::/203fc5:6fff:ffff:ffff:ffff:ffff:ffff:ffff
883fc5:7000::/203fc5:7fff:ffff:ffff:ffff:ffff:ffff:ffff
893fc5:8000::/203fc5:8fff:ffff:ffff:ffff:ffff:ffff:ffff
903fc5:9000::/203fc5:9fff:ffff:ffff:ffff:ffff:ffff:ffff
913fc5:a000::/203fc5:afff:ffff:ffff:ffff:ffff:ffff:ffff
923fc5:b000::/203fc5:bfff:ffff:ffff:ffff:ffff:ffff:ffff
933fc5:c000::/203fc5:cfff:ffff:ffff:ffff:ffff:ffff:ffff
943fc5:d000::/203fc5:dfff:ffff:ffff:ffff:ffff:ffff:ffff
953fc5:e000::/203fc5:efff:ffff:ffff:ffff:ffff:ffff:ffff
963fc5:f000::/203fc5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
973fc6::/203fc6:fff:ffff:ffff:ffff:ffff:ffff:ffff
983fc6:1000::/203fc6:1fff:ffff:ffff:ffff:ffff:ffff:ffff
993fc6:2000::/203fc6:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1003fc6:3000::/203fc6:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1013fc6:4000::/203fc6:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1023fc6:5000::/203fc6:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1033fc6:6000::/203fc6:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1043fc6:7000::/203fc6:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1053fc6:8000::/203fc6:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1063fc6:9000::/203fc6:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1073fc6:a000::/203fc6:afff:ffff:ffff:ffff:ffff:ffff:ffff
1083fc6:b000::/203fc6:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1093fc6:c000::/203fc6:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1103fc6:d000::/203fc6:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1113fc6:e000::/203fc6:efff:ffff:ffff:ffff:ffff:ffff:ffff
1123fc6:f000::/203fc6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1133fc7::/203fc7:fff:ffff:ffff:ffff:ffff:ffff:ffff
1143fc7:1000::/203fc7:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1153fc7:2000::/203fc7:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1163fc7:3000::/203fc7:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1173fc7:4000::/203fc7:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1183fc7:5000::/203fc7:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1193fc7:6000::/203fc7:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1203fc7:7000::/203fc7:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1213fc7:8000::/203fc7:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1223fc7:9000::/203fc7:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1233fc7:a000::/203fc7:afff:ffff:ffff:ffff:ffff:ffff:ffff
1243fc7:b000::/203fc7:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1253fc7:c000::/203fc7:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1263fc7:d000::/203fc7:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1273fc7:e000::/203fc7:efff:ffff:ffff:ffff:ffff:ffff:ffff
1283fc7:f000::/203fc7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1293fc8::/203fc8:fff:ffff:ffff:ffff:ffff:ffff:ffff
1303fc8:1000::/203fc8:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1313fc8:2000::/203fc8:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1323fc8:3000::/203fc8:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1333fc8:4000::/203fc8:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1343fc8:5000::/203fc8:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1353fc8:6000::/203fc8:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1363fc8:7000::/203fc8:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1373fc8:8000::/203fc8:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1383fc8:9000::/203fc8:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1393fc8:a000::/203fc8:afff:ffff:ffff:ffff:ffff:ffff:ffff
1403fc8:b000::/203fc8:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1413fc8:c000::/203fc8:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1423fc8:d000::/203fc8:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1433fc8:e000::/203fc8:efff:ffff:ffff:ffff:ffff:ffff:ffff
1443fc8:f000::/203fc8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1453fc9::/203fc9:fff:ffff:ffff:ffff:ffff:ffff:ffff
1463fc9:1000::/203fc9:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1473fc9:2000::/203fc9:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1483fc9:3000::/203fc9:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1493fc9:4000::/203fc9:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1503fc9:5000::/203fc9:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1513fc9:6000::/203fc9:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1523fc9:7000::/203fc9:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1533fc9:8000::/203fc9:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1543fc9:9000::/203fc9:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1553fc9:a000::/203fc9:afff:ffff:ffff:ffff:ffff:ffff:ffff
1563fc9:b000::/203fc9:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1573fc9:c000::/203fc9:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1583fc9:d000::/203fc9:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1593fc9:e000::/203fc9:efff:ffff:ffff:ffff:ffff:ffff:ffff
1603fc9:f000::/203fc9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1613fca::/203fca:fff:ffff:ffff:ffff:ffff:ffff:ffff
1623fca:1000::/203fca:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1633fca:2000::/203fca:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1643fca:3000::/203fca:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1653fca:4000::/203fca:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1663fca:5000::/203fca:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1673fca:6000::/203fca:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1683fca:7000::/203fca:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1693fca:8000::/203fca:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1703fca:9000::/203fca:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1713fca:a000::/203fca:afff:ffff:ffff:ffff:ffff:ffff:ffff
1723fca:b000::/203fca:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1733fca:c000::/203fca:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1743fca:d000::/203fca:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1753fca:e000::/203fca:efff:ffff:ffff:ffff:ffff:ffff:ffff
1763fca:f000::/203fca:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1773fcb::/203fcb:fff:ffff:ffff:ffff:ffff:ffff:ffff
1783fcb:1000::/203fcb:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1793fcb:2000::/203fcb:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1803fcb:3000::/203fcb:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1813fcb:4000::/203fcb:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1823fcb:5000::/203fcb:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1833fcb:6000::/203fcb:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1843fcb:7000::/203fcb:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1853fcb:8000::/203fcb:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1863fcb:9000::/203fcb:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1873fcb:a000::/203fcb:afff:ffff:ffff:ffff:ffff:ffff:ffff
1883fcb:b000::/203fcb:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1893fcb:c000::/203fcb:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1903fcb:d000::/203fcb:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1913fcb:e000::/203fcb:efff:ffff:ffff:ffff:ffff:ffff:ffff
1923fcb:f000::/203fcb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1933fcc::/203fcc:fff:ffff:ffff:ffff:ffff:ffff:ffff
1943fcc:1000::/203fcc:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1953fcc:2000::/203fcc:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1963fcc:3000::/203fcc:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1973fcc:4000::/203fcc:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1983fcc:5000::/203fcc:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1993fcc:6000::/203fcc:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2003fcc:7000::/203fcc:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2013fcc:8000::/203fcc:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2023fcc:9000::/203fcc:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2033fcc:a000::/203fcc:afff:ffff:ffff:ffff:ffff:ffff:ffff
2043fcc:b000::/203fcc:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2053fcc:c000::/203fcc:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2063fcc:d000::/203fcc:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2073fcc:e000::/203fcc:efff:ffff:ffff:ffff:ffff:ffff:ffff
2083fcc:f000::/203fcc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2093fcd::/203fcd:fff:ffff:ffff:ffff:ffff:ffff:ffff
2103fcd:1000::/203fcd:1fff:ffff:ffff:ffff:ffff:ffff:ffff
2113fcd:2000::/203fcd:2fff:ffff:ffff:ffff:ffff:ffff:ffff
2123fcd:3000::/203fcd:3fff:ffff:ffff:ffff:ffff:ffff:ffff
2133fcd:4000::/203fcd:4fff:ffff:ffff:ffff:ffff:ffff:ffff
2143fcd:5000::/203fcd:5fff:ffff:ffff:ffff:ffff:ffff:ffff
2153fcd:6000::/203fcd:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2163fcd:7000::/203fcd:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2173fcd:8000::/203fcd:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2183fcd:9000::/203fcd:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2193fcd:a000::/203fcd:afff:ffff:ffff:ffff:ffff:ffff:ffff
2203fcd:b000::/203fcd:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2213fcd:c000::/203fcd:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2223fcd:d000::/203fcd:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2233fcd:e000::/203fcd:efff:ffff:ffff:ffff:ffff:ffff:ffff
2243fcd:f000::/203fcd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2253fce::/203fce:fff:ffff:ffff:ffff:ffff:ffff:ffff
2263fce:1000::/203fce:1fff:ffff:ffff:ffff:ffff:ffff:ffff
2273fce:2000::/203fce:2fff:ffff:ffff:ffff:ffff:ffff:ffff
2283fce:3000::/203fce:3fff:ffff:ffff:ffff:ffff:ffff:ffff
2293fce:4000::/203fce:4fff:ffff:ffff:ffff:ffff:ffff:ffff
2303fce:5000::/203fce:5fff:ffff:ffff:ffff:ffff:ffff:ffff
2313fce:6000::/203fce:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2323fce:7000::/203fce:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2333fce:8000::/203fce:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2343fce:9000::/203fce:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2353fce:a000::/203fce:afff:ffff:ffff:ffff:ffff:ffff:ffff
2363fce:b000::/203fce:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2373fce:c000::/203fce:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2383fce:d000::/203fce:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2393fce:e000::/203fce:efff:ffff:ffff:ffff:ffff:ffff:ffff
2403fce:f000::/203fce:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2413fcf::/203fcf:fff:ffff:ffff:ffff:ffff:ffff:ffff
2423fcf:1000::/203fcf:1fff:ffff:ffff:ffff:ffff:ffff:ffff
2433fcf:2000::/203fcf:2fff:ffff:ffff:ffff:ffff:ffff:ffff
2443fcf:3000::/203fcf:3fff:ffff:ffff:ffff:ffff:ffff:ffff
2453fcf:4000::/203fcf:4fff:ffff:ffff:ffff:ffff:ffff:ffff
2463fcf:5000::/203fcf:5fff:ffff:ffff:ffff:ffff:ffff:ffff
2473fcf:6000::/203fcf:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2483fcf:7000::/203fcf:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2493fcf:8000::/203fcf:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2503fcf:9000::/203fcf:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2513fcf:a000::/203fcf:afff:ffff:ffff:ffff:ffff:ffff:ffff
2523fcf:b000::/203fcf:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2533fcf:c000::/203fcf:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2543fcf:d000::/203fcf:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2553fcf:e000::/203fcf:efff:ffff:ffff:ffff:ffff:ffff:ffff
2563fcf:f000::/203fcf:ffff:ffff:ffff:ffff:ffff:ffff:ffff

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.