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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/120
Addresses256
/64 networksPart of one
Network
2001:db8::c800/120
First address
2001:db8::c800
Last address
2001:db8::c8ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2001:0db8:0000:0000:0000:0000:0000:c800
Type
Documentation 2001:db8::/32
For examples; never used on a network
Reverse DNS zone
8.c.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa
Split into smaller subnets/128
/121 (2)/122 (4)/123 (8)/124 (16)/127 (128)/128 (256)

2001:db8::c800/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12001:db8::c800/1282001:db8::c800
22001:db8::c801/1282001:db8::c801
32001:db8::c802/1282001:db8::c802
42001:db8::c803/1282001:db8::c803
52001:db8::c804/1282001:db8::c804
62001:db8::c805/1282001:db8::c805
72001:db8::c806/1282001:db8::c806
82001:db8::c807/1282001:db8::c807
92001:db8::c808/1282001:db8::c808
102001:db8::c809/1282001:db8::c809
112001:db8::c80a/1282001:db8::c80a
122001:db8::c80b/1282001:db8::c80b
132001:db8::c80c/1282001:db8::c80c
142001:db8::c80d/1282001:db8::c80d
152001:db8::c80e/1282001:db8::c80e
162001:db8::c80f/1282001:db8::c80f
172001:db8::c810/1282001:db8::c810
182001:db8::c811/1282001:db8::c811
192001:db8::c812/1282001:db8::c812
202001:db8::c813/1282001:db8::c813
212001:db8::c814/1282001:db8::c814
222001:db8::c815/1282001:db8::c815
232001:db8::c816/1282001:db8::c816
242001:db8::c817/1282001:db8::c817
252001:db8::c818/1282001:db8::c818
262001:db8::c819/1282001:db8::c819
272001:db8::c81a/1282001:db8::c81a
282001:db8::c81b/1282001:db8::c81b
292001:db8::c81c/1282001:db8::c81c
302001:db8::c81d/1282001:db8::c81d
312001:db8::c81e/1282001:db8::c81e
322001:db8::c81f/1282001:db8::c81f
332001:db8::c820/1282001:db8::c820
342001:db8::c821/1282001:db8::c821
352001:db8::c822/1282001:db8::c822
362001:db8::c823/1282001:db8::c823
372001:db8::c824/1282001:db8::c824
382001:db8::c825/1282001:db8::c825
392001:db8::c826/1282001:db8::c826
402001:db8::c827/1282001:db8::c827
412001:db8::c828/1282001:db8::c828
422001:db8::c829/1282001:db8::c829
432001:db8::c82a/1282001:db8::c82a
442001:db8::c82b/1282001:db8::c82b
452001:db8::c82c/1282001:db8::c82c
462001:db8::c82d/1282001:db8::c82d
472001:db8::c82e/1282001:db8::c82e
482001:db8::c82f/1282001:db8::c82f
492001:db8::c830/1282001:db8::c830
502001:db8::c831/1282001:db8::c831
512001:db8::c832/1282001:db8::c832
522001:db8::c833/1282001:db8::c833
532001:db8::c834/1282001:db8::c834
542001:db8::c835/1282001:db8::c835
552001:db8::c836/1282001:db8::c836
562001:db8::c837/1282001:db8::c837
572001:db8::c838/1282001:db8::c838
582001:db8::c839/1282001:db8::c839
592001:db8::c83a/1282001:db8::c83a
602001:db8::c83b/1282001:db8::c83b
612001:db8::c83c/1282001:db8::c83c
622001:db8::c83d/1282001:db8::c83d
632001:db8::c83e/1282001:db8::c83e
642001:db8::c83f/1282001:db8::c83f
652001:db8::c840/1282001:db8::c840
662001:db8::c841/1282001:db8::c841
672001:db8::c842/1282001:db8::c842
682001:db8::c843/1282001:db8::c843
692001:db8::c844/1282001:db8::c844
702001:db8::c845/1282001:db8::c845
712001:db8::c846/1282001:db8::c846
722001:db8::c847/1282001:db8::c847
732001:db8::c848/1282001:db8::c848
742001:db8::c849/1282001:db8::c849
752001:db8::c84a/1282001:db8::c84a
762001:db8::c84b/1282001:db8::c84b
772001:db8::c84c/1282001:db8::c84c
782001:db8::c84d/1282001:db8::c84d
792001:db8::c84e/1282001:db8::c84e
802001:db8::c84f/1282001:db8::c84f
812001:db8::c850/1282001:db8::c850
822001:db8::c851/1282001:db8::c851
832001:db8::c852/1282001:db8::c852
842001:db8::c853/1282001:db8::c853
852001:db8::c854/1282001:db8::c854
862001:db8::c855/1282001:db8::c855
872001:db8::c856/1282001:db8::c856
882001:db8::c857/1282001:db8::c857
892001:db8::c858/1282001:db8::c858
902001:db8::c859/1282001:db8::c859
912001:db8::c85a/1282001:db8::c85a
922001:db8::c85b/1282001:db8::c85b
932001:db8::c85c/1282001:db8::c85c
942001:db8::c85d/1282001:db8::c85d
952001:db8::c85e/1282001:db8::c85e
962001:db8::c85f/1282001:db8::c85f
972001:db8::c860/1282001:db8::c860
982001:db8::c861/1282001:db8::c861
992001:db8::c862/1282001:db8::c862
1002001:db8::c863/1282001:db8::c863
1012001:db8::c864/1282001:db8::c864
1022001:db8::c865/1282001:db8::c865
1032001:db8::c866/1282001:db8::c866
1042001:db8::c867/1282001:db8::c867
1052001:db8::c868/1282001:db8::c868
1062001:db8::c869/1282001:db8::c869
1072001:db8::c86a/1282001:db8::c86a
1082001:db8::c86b/1282001:db8::c86b
1092001:db8::c86c/1282001:db8::c86c
1102001:db8::c86d/1282001:db8::c86d
1112001:db8::c86e/1282001:db8::c86e
1122001:db8::c86f/1282001:db8::c86f
1132001:db8::c870/1282001:db8::c870
1142001:db8::c871/1282001:db8::c871
1152001:db8::c872/1282001:db8::c872
1162001:db8::c873/1282001:db8::c873
1172001:db8::c874/1282001:db8::c874
1182001:db8::c875/1282001:db8::c875
1192001:db8::c876/1282001:db8::c876
1202001:db8::c877/1282001:db8::c877
1212001:db8::c878/1282001:db8::c878
1222001:db8::c879/1282001:db8::c879
1232001:db8::c87a/1282001:db8::c87a
1242001:db8::c87b/1282001:db8::c87b
1252001:db8::c87c/1282001:db8::c87c
1262001:db8::c87d/1282001:db8::c87d
1272001:db8::c87e/1282001:db8::c87e
1282001:db8::c87f/1282001:db8::c87f
1292001:db8::c880/1282001:db8::c880
1302001:db8::c881/1282001:db8::c881
1312001:db8::c882/1282001:db8::c882
1322001:db8::c883/1282001:db8::c883
1332001:db8::c884/1282001:db8::c884
1342001:db8::c885/1282001:db8::c885
1352001:db8::c886/1282001:db8::c886
1362001:db8::c887/1282001:db8::c887
1372001:db8::c888/1282001:db8::c888
1382001:db8::c889/1282001:db8::c889
1392001:db8::c88a/1282001:db8::c88a
1402001:db8::c88b/1282001:db8::c88b
1412001:db8::c88c/1282001:db8::c88c
1422001:db8::c88d/1282001:db8::c88d
1432001:db8::c88e/1282001:db8::c88e
1442001:db8::c88f/1282001:db8::c88f
1452001:db8::c890/1282001:db8::c890
1462001:db8::c891/1282001:db8::c891
1472001:db8::c892/1282001:db8::c892
1482001:db8::c893/1282001:db8::c893
1492001:db8::c894/1282001:db8::c894
1502001:db8::c895/1282001:db8::c895
1512001:db8::c896/1282001:db8::c896
1522001:db8::c897/1282001:db8::c897
1532001:db8::c898/1282001:db8::c898
1542001:db8::c899/1282001:db8::c899
1552001:db8::c89a/1282001:db8::c89a
1562001:db8::c89b/1282001:db8::c89b
1572001:db8::c89c/1282001:db8::c89c
1582001:db8::c89d/1282001:db8::c89d
1592001:db8::c89e/1282001:db8::c89e
1602001:db8::c89f/1282001:db8::c89f
1612001:db8::c8a0/1282001:db8::c8a0
1622001:db8::c8a1/1282001:db8::c8a1
1632001:db8::c8a2/1282001:db8::c8a2
1642001:db8::c8a3/1282001:db8::c8a3
1652001:db8::c8a4/1282001:db8::c8a4
1662001:db8::c8a5/1282001:db8::c8a5
1672001:db8::c8a6/1282001:db8::c8a6
1682001:db8::c8a7/1282001:db8::c8a7
1692001:db8::c8a8/1282001:db8::c8a8
1702001:db8::c8a9/1282001:db8::c8a9
1712001:db8::c8aa/1282001:db8::c8aa
1722001:db8::c8ab/1282001:db8::c8ab
1732001:db8::c8ac/1282001:db8::c8ac
1742001:db8::c8ad/1282001:db8::c8ad
1752001:db8::c8ae/1282001:db8::c8ae
1762001:db8::c8af/1282001:db8::c8af
1772001:db8::c8b0/1282001:db8::c8b0
1782001:db8::c8b1/1282001:db8::c8b1
1792001:db8::c8b2/1282001:db8::c8b2
1802001:db8::c8b3/1282001:db8::c8b3
1812001:db8::c8b4/1282001:db8::c8b4
1822001:db8::c8b5/1282001:db8::c8b5
1832001:db8::c8b6/1282001:db8::c8b6
1842001:db8::c8b7/1282001:db8::c8b7
1852001:db8::c8b8/1282001:db8::c8b8
1862001:db8::c8b9/1282001:db8::c8b9
1872001:db8::c8ba/1282001:db8::c8ba
1882001:db8::c8bb/1282001:db8::c8bb
1892001:db8::c8bc/1282001:db8::c8bc
1902001:db8::c8bd/1282001:db8::c8bd
1912001:db8::c8be/1282001:db8::c8be
1922001:db8::c8bf/1282001:db8::c8bf
1932001:db8::c8c0/1282001:db8::c8c0
1942001:db8::c8c1/1282001:db8::c8c1
1952001:db8::c8c2/1282001:db8::c8c2
1962001:db8::c8c3/1282001:db8::c8c3
1972001:db8::c8c4/1282001:db8::c8c4
1982001:db8::c8c5/1282001:db8::c8c5
1992001:db8::c8c6/1282001:db8::c8c6
2002001:db8::c8c7/1282001:db8::c8c7
2012001:db8::c8c8/1282001:db8::c8c8
2022001:db8::c8c9/1282001:db8::c8c9
2032001:db8::c8ca/1282001:db8::c8ca
2042001:db8::c8cb/1282001:db8::c8cb
2052001:db8::c8cc/1282001:db8::c8cc
2062001:db8::c8cd/1282001:db8::c8cd
2072001:db8::c8ce/1282001:db8::c8ce
2082001:db8::c8cf/1282001:db8::c8cf
2092001:db8::c8d0/1282001:db8::c8d0
2102001:db8::c8d1/1282001:db8::c8d1
2112001:db8::c8d2/1282001:db8::c8d2
2122001:db8::c8d3/1282001:db8::c8d3
2132001:db8::c8d4/1282001:db8::c8d4
2142001:db8::c8d5/1282001:db8::c8d5
2152001:db8::c8d6/1282001:db8::c8d6
2162001:db8::c8d7/1282001:db8::c8d7
2172001:db8::c8d8/1282001:db8::c8d8
2182001:db8::c8d9/1282001:db8::c8d9
2192001:db8::c8da/1282001:db8::c8da
2202001:db8::c8db/1282001:db8::c8db
2212001:db8::c8dc/1282001:db8::c8dc
2222001:db8::c8dd/1282001:db8::c8dd
2232001:db8::c8de/1282001:db8::c8de
2242001:db8::c8df/1282001:db8::c8df
2252001:db8::c8e0/1282001:db8::c8e0
2262001:db8::c8e1/1282001:db8::c8e1
2272001:db8::c8e2/1282001:db8::c8e2
2282001:db8::c8e3/1282001:db8::c8e3
2292001:db8::c8e4/1282001:db8::c8e4
2302001:db8::c8e5/1282001:db8::c8e5
2312001:db8::c8e6/1282001:db8::c8e6
2322001:db8::c8e7/1282001:db8::c8e7
2332001:db8::c8e8/1282001:db8::c8e8
2342001:db8::c8e9/1282001:db8::c8e9
2352001:db8::c8ea/1282001:db8::c8ea
2362001:db8::c8eb/1282001:db8::c8eb
2372001:db8::c8ec/1282001:db8::c8ec
2382001:db8::c8ed/1282001:db8::c8ed
2392001:db8::c8ee/1282001:db8::c8ee
2402001:db8::c8ef/1282001:db8::c8ef
2412001:db8::c8f0/1282001:db8::c8f0
2422001:db8::c8f1/1282001:db8::c8f1
2432001:db8::c8f2/1282001:db8::c8f2
2442001:db8::c8f3/1282001:db8::c8f3
2452001:db8::c8f4/1282001:db8::c8f4
2462001:db8::c8f5/1282001:db8::c8f5
2472001:db8::c8f6/1282001:db8::c8f6
2482001:db8::c8f7/1282001:db8::c8f7
2492001:db8::c8f8/1282001:db8::c8f8
2502001:db8::c8f9/1282001:db8::c8f9
2512001:db8::c8fa/1282001:db8::c8fa
2522001:db8::c8fb/1282001:db8::c8fb
2532001:db8::c8fc/1282001:db8::c8fc
2542001:db8::c8fd/1282001:db8::c8fd
2552001:db8::c8fe/1282001:db8::c8fe
2562001:db8::c8ff/1282001:db8::c8ff

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.