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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/7
Addresses2^121
/64 networks2^57
Network
3a00::/7
First address
3a00::
Last address
3bff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
2,658,455,991,569,831,745,807,614,120,560,689,152 (2^121)
/64 networks (LANs)
144,115,188,075,855,872 (2^57)
Full form
3a00:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
a.3.ip6.arpa
b.3.ip6.arpa
/7 is not on a 4-bit boundary, so it takes 2 /8 zones.
Split into smaller subnets/20
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/16 (512)/20 (8,192)

3a00::/7 makes 8,192 subnets of /20; the first 256 are listed.

Subnets
#SubnetLast address
13a00::/203a00:fff:ffff:ffff:ffff:ffff:ffff:ffff
23a00:1000::/203a00:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33a00:2000::/203a00:2fff:ffff:ffff:ffff:ffff:ffff:ffff
43a00:3000::/203a00:3fff:ffff:ffff:ffff:ffff:ffff:ffff
53a00:4000::/203a00:4fff:ffff:ffff:ffff:ffff:ffff:ffff
63a00:5000::/203a00:5fff:ffff:ffff:ffff:ffff:ffff:ffff
73a00:6000::/203a00:6fff:ffff:ffff:ffff:ffff:ffff:ffff
83a00:7000::/203a00:7fff:ffff:ffff:ffff:ffff:ffff:ffff
93a00:8000::/203a00:8fff:ffff:ffff:ffff:ffff:ffff:ffff
103a00:9000::/203a00:9fff:ffff:ffff:ffff:ffff:ffff:ffff
113a00:a000::/203a00:afff:ffff:ffff:ffff:ffff:ffff:ffff
123a00:b000::/203a00:bfff:ffff:ffff:ffff:ffff:ffff:ffff
133a00:c000::/203a00:cfff:ffff:ffff:ffff:ffff:ffff:ffff
143a00:d000::/203a00:dfff:ffff:ffff:ffff:ffff:ffff:ffff
153a00:e000::/203a00:efff:ffff:ffff:ffff:ffff:ffff:ffff
163a00:f000::/203a00:ffff:ffff:ffff:ffff:ffff:ffff:ffff
173a01::/203a01:fff:ffff:ffff:ffff:ffff:ffff:ffff
183a01:1000::/203a01:1fff:ffff:ffff:ffff:ffff:ffff:ffff
193a01:2000::/203a01:2fff:ffff:ffff:ffff:ffff:ffff:ffff
203a01:3000::/203a01:3fff:ffff:ffff:ffff:ffff:ffff:ffff
213a01:4000::/203a01:4fff:ffff:ffff:ffff:ffff:ffff:ffff
223a01:5000::/203a01:5fff:ffff:ffff:ffff:ffff:ffff:ffff
233a01:6000::/203a01:6fff:ffff:ffff:ffff:ffff:ffff:ffff
243a01:7000::/203a01:7fff:ffff:ffff:ffff:ffff:ffff:ffff
253a01:8000::/203a01:8fff:ffff:ffff:ffff:ffff:ffff:ffff
263a01:9000::/203a01:9fff:ffff:ffff:ffff:ffff:ffff:ffff
273a01:a000::/203a01:afff:ffff:ffff:ffff:ffff:ffff:ffff
283a01:b000::/203a01:bfff:ffff:ffff:ffff:ffff:ffff:ffff
293a01:c000::/203a01:cfff:ffff:ffff:ffff:ffff:ffff:ffff
303a01:d000::/203a01:dfff:ffff:ffff:ffff:ffff:ffff:ffff
313a01:e000::/203a01:efff:ffff:ffff:ffff:ffff:ffff:ffff
323a01:f000::/203a01:ffff:ffff:ffff:ffff:ffff:ffff:ffff
333a02::/203a02:fff:ffff:ffff:ffff:ffff:ffff:ffff
343a02:1000::/203a02:1fff:ffff:ffff:ffff:ffff:ffff:ffff
353a02:2000::/203a02:2fff:ffff:ffff:ffff:ffff:ffff:ffff
363a02:3000::/203a02:3fff:ffff:ffff:ffff:ffff:ffff:ffff
373a02:4000::/203a02:4fff:ffff:ffff:ffff:ffff:ffff:ffff
383a02:5000::/203a02:5fff:ffff:ffff:ffff:ffff:ffff:ffff
393a02:6000::/203a02:6fff:ffff:ffff:ffff:ffff:ffff:ffff
403a02:7000::/203a02:7fff:ffff:ffff:ffff:ffff:ffff:ffff
413a02:8000::/203a02:8fff:ffff:ffff:ffff:ffff:ffff:ffff
423a02:9000::/203a02:9fff:ffff:ffff:ffff:ffff:ffff:ffff
433a02:a000::/203a02:afff:ffff:ffff:ffff:ffff:ffff:ffff
443a02:b000::/203a02:bfff:ffff:ffff:ffff:ffff:ffff:ffff
453a02:c000::/203a02:cfff:ffff:ffff:ffff:ffff:ffff:ffff
463a02:d000::/203a02:dfff:ffff:ffff:ffff:ffff:ffff:ffff
473a02:e000::/203a02:efff:ffff:ffff:ffff:ffff:ffff:ffff
483a02:f000::/203a02:ffff:ffff:ffff:ffff:ffff:ffff:ffff
493a03::/203a03:fff:ffff:ffff:ffff:ffff:ffff:ffff
503a03:1000::/203a03:1fff:ffff:ffff:ffff:ffff:ffff:ffff
513a03:2000::/203a03:2fff:ffff:ffff:ffff:ffff:ffff:ffff
523a03:3000::/203a03:3fff:ffff:ffff:ffff:ffff:ffff:ffff
533a03:4000::/203a03:4fff:ffff:ffff:ffff:ffff:ffff:ffff
543a03:5000::/203a03:5fff:ffff:ffff:ffff:ffff:ffff:ffff
553a03:6000::/203a03:6fff:ffff:ffff:ffff:ffff:ffff:ffff
563a03:7000::/203a03:7fff:ffff:ffff:ffff:ffff:ffff:ffff
573a03:8000::/203a03:8fff:ffff:ffff:ffff:ffff:ffff:ffff
583a03:9000::/203a03:9fff:ffff:ffff:ffff:ffff:ffff:ffff
593a03:a000::/203a03:afff:ffff:ffff:ffff:ffff:ffff:ffff
603a03:b000::/203a03:bfff:ffff:ffff:ffff:ffff:ffff:ffff
613a03:c000::/203a03:cfff:ffff:ffff:ffff:ffff:ffff:ffff
623a03:d000::/203a03:dfff:ffff:ffff:ffff:ffff:ffff:ffff
633a03:e000::/203a03:efff:ffff:ffff:ffff:ffff:ffff:ffff
643a03:f000::/203a03:ffff:ffff:ffff:ffff:ffff:ffff:ffff
653a04::/203a04:fff:ffff:ffff:ffff:ffff:ffff:ffff
663a04:1000::/203a04:1fff:ffff:ffff:ffff:ffff:ffff:ffff
673a04:2000::/203a04:2fff:ffff:ffff:ffff:ffff:ffff:ffff
683a04:3000::/203a04:3fff:ffff:ffff:ffff:ffff:ffff:ffff
693a04:4000::/203a04:4fff:ffff:ffff:ffff:ffff:ffff:ffff
703a04:5000::/203a04:5fff:ffff:ffff:ffff:ffff:ffff:ffff
713a04:6000::/203a04:6fff:ffff:ffff:ffff:ffff:ffff:ffff
723a04:7000::/203a04:7fff:ffff:ffff:ffff:ffff:ffff:ffff
733a04:8000::/203a04:8fff:ffff:ffff:ffff:ffff:ffff:ffff
743a04:9000::/203a04:9fff:ffff:ffff:ffff:ffff:ffff:ffff
753a04:a000::/203a04:afff:ffff:ffff:ffff:ffff:ffff:ffff
763a04:b000::/203a04:bfff:ffff:ffff:ffff:ffff:ffff:ffff
773a04:c000::/203a04:cfff:ffff:ffff:ffff:ffff:ffff:ffff
783a04:d000::/203a04:dfff:ffff:ffff:ffff:ffff:ffff:ffff
793a04:e000::/203a04:efff:ffff:ffff:ffff:ffff:ffff:ffff
803a04:f000::/203a04:ffff:ffff:ffff:ffff:ffff:ffff:ffff
813a05::/203a05:fff:ffff:ffff:ffff:ffff:ffff:ffff
823a05:1000::/203a05:1fff:ffff:ffff:ffff:ffff:ffff:ffff
833a05:2000::/203a05:2fff:ffff:ffff:ffff:ffff:ffff:ffff
843a05:3000::/203a05:3fff:ffff:ffff:ffff:ffff:ffff:ffff
853a05:4000::/203a05:4fff:ffff:ffff:ffff:ffff:ffff:ffff
863a05:5000::/203a05:5fff:ffff:ffff:ffff:ffff:ffff:ffff
873a05:6000::/203a05:6fff:ffff:ffff:ffff:ffff:ffff:ffff
883a05:7000::/203a05:7fff:ffff:ffff:ffff:ffff:ffff:ffff
893a05:8000::/203a05:8fff:ffff:ffff:ffff:ffff:ffff:ffff
903a05:9000::/203a05:9fff:ffff:ffff:ffff:ffff:ffff:ffff
913a05:a000::/203a05:afff:ffff:ffff:ffff:ffff:ffff:ffff
923a05:b000::/203a05:bfff:ffff:ffff:ffff:ffff:ffff:ffff
933a05:c000::/203a05:cfff:ffff:ffff:ffff:ffff:ffff:ffff
943a05:d000::/203a05:dfff:ffff:ffff:ffff:ffff:ffff:ffff
953a05:e000::/203a05:efff:ffff:ffff:ffff:ffff:ffff:ffff
963a05:f000::/203a05:ffff:ffff:ffff:ffff:ffff:ffff:ffff
973a06::/203a06:fff:ffff:ffff:ffff:ffff:ffff:ffff
983a06:1000::/203a06:1fff:ffff:ffff:ffff:ffff:ffff:ffff
993a06:2000::/203a06:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1003a06:3000::/203a06:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1013a06:4000::/203a06:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1023a06:5000::/203a06:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1033a06:6000::/203a06:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1043a06:7000::/203a06:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1053a06:8000::/203a06:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1063a06:9000::/203a06:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1073a06:a000::/203a06:afff:ffff:ffff:ffff:ffff:ffff:ffff
1083a06:b000::/203a06:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1093a06:c000::/203a06:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1103a06:d000::/203a06:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1113a06:e000::/203a06:efff:ffff:ffff:ffff:ffff:ffff:ffff
1123a06:f000::/203a06:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1133a07::/203a07:fff:ffff:ffff:ffff:ffff:ffff:ffff
1143a07:1000::/203a07:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1153a07:2000::/203a07:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1163a07:3000::/203a07:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1173a07:4000::/203a07:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1183a07:5000::/203a07:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1193a07:6000::/203a07:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1203a07:7000::/203a07:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1213a07:8000::/203a07:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1223a07:9000::/203a07:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1233a07:a000::/203a07:afff:ffff:ffff:ffff:ffff:ffff:ffff
1243a07:b000::/203a07:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1253a07:c000::/203a07:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1263a07:d000::/203a07:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1273a07:e000::/203a07:efff:ffff:ffff:ffff:ffff:ffff:ffff
1283a07:f000::/203a07:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1293a08::/203a08:fff:ffff:ffff:ffff:ffff:ffff:ffff
1303a08:1000::/203a08:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1313a08:2000::/203a08:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1323a08:3000::/203a08:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1333a08:4000::/203a08:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1343a08:5000::/203a08:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1353a08:6000::/203a08:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1363a08:7000::/203a08:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1373a08:8000::/203a08:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1383a08:9000::/203a08:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1393a08:a000::/203a08:afff:ffff:ffff:ffff:ffff:ffff:ffff
1403a08:b000::/203a08:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1413a08:c000::/203a08:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1423a08:d000::/203a08:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1433a08:e000::/203a08:efff:ffff:ffff:ffff:ffff:ffff:ffff
1443a08:f000::/203a08:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1453a09::/203a09:fff:ffff:ffff:ffff:ffff:ffff:ffff
1463a09:1000::/203a09:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1473a09:2000::/203a09:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1483a09:3000::/203a09:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1493a09:4000::/203a09:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1503a09:5000::/203a09:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1513a09:6000::/203a09:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1523a09:7000::/203a09:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1533a09:8000::/203a09:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1543a09:9000::/203a09:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1553a09:a000::/203a09:afff:ffff:ffff:ffff:ffff:ffff:ffff
1563a09:b000::/203a09:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1573a09:c000::/203a09:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1583a09:d000::/203a09:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1593a09:e000::/203a09:efff:ffff:ffff:ffff:ffff:ffff:ffff
1603a09:f000::/203a09:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1613a0a::/203a0a:fff:ffff:ffff:ffff:ffff:ffff:ffff
1623a0a:1000::/203a0a:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1633a0a:2000::/203a0a:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1643a0a:3000::/203a0a:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1653a0a:4000::/203a0a:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1663a0a:5000::/203a0a:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1673a0a:6000::/203a0a:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1683a0a:7000::/203a0a:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1693a0a:8000::/203a0a:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1703a0a:9000::/203a0a:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1713a0a:a000::/203a0a:afff:ffff:ffff:ffff:ffff:ffff:ffff
1723a0a:b000::/203a0a:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1733a0a:c000::/203a0a:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1743a0a:d000::/203a0a:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1753a0a:e000::/203a0a:efff:ffff:ffff:ffff:ffff:ffff:ffff
1763a0a:f000::/203a0a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1773a0b::/203a0b:fff:ffff:ffff:ffff:ffff:ffff:ffff
1783a0b:1000::/203a0b:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1793a0b:2000::/203a0b:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1803a0b:3000::/203a0b:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1813a0b:4000::/203a0b:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1823a0b:5000::/203a0b:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1833a0b:6000::/203a0b:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1843a0b:7000::/203a0b:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1853a0b:8000::/203a0b:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1863a0b:9000::/203a0b:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1873a0b:a000::/203a0b:afff:ffff:ffff:ffff:ffff:ffff:ffff
1883a0b:b000::/203a0b:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1893a0b:c000::/203a0b:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1903a0b:d000::/203a0b:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1913a0b:e000::/203a0b:efff:ffff:ffff:ffff:ffff:ffff:ffff
1923a0b:f000::/203a0b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1933a0c::/203a0c:fff:ffff:ffff:ffff:ffff:ffff:ffff
1943a0c:1000::/203a0c:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1953a0c:2000::/203a0c:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1963a0c:3000::/203a0c:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1973a0c:4000::/203a0c:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1983a0c:5000::/203a0c:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1993a0c:6000::/203a0c:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2003a0c:7000::/203a0c:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2013a0c:8000::/203a0c:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2023a0c:9000::/203a0c:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2033a0c:a000::/203a0c:afff:ffff:ffff:ffff:ffff:ffff:ffff
2043a0c:b000::/203a0c:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2053a0c:c000::/203a0c:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2063a0c:d000::/203a0c:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2073a0c:e000::/203a0c:efff:ffff:ffff:ffff:ffff:ffff:ffff
2083a0c:f000::/203a0c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2093a0d::/203a0d:fff:ffff:ffff:ffff:ffff:ffff:ffff
2103a0d:1000::/203a0d:1fff:ffff:ffff:ffff:ffff:ffff:ffff
2113a0d:2000::/203a0d:2fff:ffff:ffff:ffff:ffff:ffff:ffff
2123a0d:3000::/203a0d:3fff:ffff:ffff:ffff:ffff:ffff:ffff
2133a0d:4000::/203a0d:4fff:ffff:ffff:ffff:ffff:ffff:ffff
2143a0d:5000::/203a0d:5fff:ffff:ffff:ffff:ffff:ffff:ffff
2153a0d:6000::/203a0d:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2163a0d:7000::/203a0d:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2173a0d:8000::/203a0d:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2183a0d:9000::/203a0d:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2193a0d:a000::/203a0d:afff:ffff:ffff:ffff:ffff:ffff:ffff
2203a0d:b000::/203a0d:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2213a0d:c000::/203a0d:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2223a0d:d000::/203a0d:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2233a0d:e000::/203a0d:efff:ffff:ffff:ffff:ffff:ffff:ffff
2243a0d:f000::/203a0d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2253a0e::/203a0e:fff:ffff:ffff:ffff:ffff:ffff:ffff
2263a0e:1000::/203a0e:1fff:ffff:ffff:ffff:ffff:ffff:ffff
2273a0e:2000::/203a0e:2fff:ffff:ffff:ffff:ffff:ffff:ffff
2283a0e:3000::/203a0e:3fff:ffff:ffff:ffff:ffff:ffff:ffff
2293a0e:4000::/203a0e:4fff:ffff:ffff:ffff:ffff:ffff:ffff
2303a0e:5000::/203a0e:5fff:ffff:ffff:ffff:ffff:ffff:ffff
2313a0e:6000::/203a0e:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2323a0e:7000::/203a0e:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2333a0e:8000::/203a0e:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2343a0e:9000::/203a0e:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2353a0e:a000::/203a0e:afff:ffff:ffff:ffff:ffff:ffff:ffff
2363a0e:b000::/203a0e:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2373a0e:c000::/203a0e:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2383a0e:d000::/203a0e:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2393a0e:e000::/203a0e:efff:ffff:ffff:ffff:ffff:ffff:ffff
2403a0e:f000::/203a0e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2413a0f::/203a0f:fff:ffff:ffff:ffff:ffff:ffff:ffff
2423a0f:1000::/203a0f:1fff:ffff:ffff:ffff:ffff:ffff:ffff
2433a0f:2000::/203a0f:2fff:ffff:ffff:ffff:ffff:ffff:ffff
2443a0f:3000::/203a0f:3fff:ffff:ffff:ffff:ffff:ffff:ffff
2453a0f:4000::/203a0f:4fff:ffff:ffff:ffff:ffff:ffff:ffff
2463a0f:5000::/203a0f:5fff:ffff:ffff:ffff:ffff:ffff:ffff
2473a0f:6000::/203a0f:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2483a0f:7000::/203a0f:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2493a0f:8000::/203a0f:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2503a0f:9000::/203a0f:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2513a0f:a000::/203a0f:afff:ffff:ffff:ffff:ffff:ffff:ffff
2523a0f:b000::/203a0f:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2533a0f:c000::/203a0f:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2543a0f:d000::/203a0f:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2553a0f:e000::/203a0f:efff:ffff:ffff:ffff:ffff:ffff:ffff
2563a0f:f000::/203a0f: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.