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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/116
Addresses4,096
/64 networksPart of one
Network
2001:db8::2000/116
First address
2001:db8::2000
Last address
2001:db8::2fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2001:0db8:0000:0000:0000:0000:0000:2000
Type
Documentation 2001:db8::/32
For examples; never used on a network
Reverse DNS zone
2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa
Split into smaller subnets/124
/117 (2)/118 (4)/119 (8)/120 (16)/124 (256)/127 (2,048)/128 (4,096)

2001:db8::2000/116 makes 256 subnets of /124.

Subnets
#SubnetLast address
12001:db8::2000/1242001:db8::200f
22001:db8::2010/1242001:db8::201f
32001:db8::2020/1242001:db8::202f
42001:db8::2030/1242001:db8::203f
52001:db8::2040/1242001:db8::204f
62001:db8::2050/1242001:db8::205f
72001:db8::2060/1242001:db8::206f
82001:db8::2070/1242001:db8::207f
92001:db8::2080/1242001:db8::208f
102001:db8::2090/1242001:db8::209f
112001:db8::20a0/1242001:db8::20af
122001:db8::20b0/1242001:db8::20bf
132001:db8::20c0/1242001:db8::20cf
142001:db8::20d0/1242001:db8::20df
152001:db8::20e0/1242001:db8::20ef
162001:db8::20f0/1242001:db8::20ff
172001:db8::2100/1242001:db8::210f
182001:db8::2110/1242001:db8::211f
192001:db8::2120/1242001:db8::212f
202001:db8::2130/1242001:db8::213f
212001:db8::2140/1242001:db8::214f
222001:db8::2150/1242001:db8::215f
232001:db8::2160/1242001:db8::216f
242001:db8::2170/1242001:db8::217f
252001:db8::2180/1242001:db8::218f
262001:db8::2190/1242001:db8::219f
272001:db8::21a0/1242001:db8::21af
282001:db8::21b0/1242001:db8::21bf
292001:db8::21c0/1242001:db8::21cf
302001:db8::21d0/1242001:db8::21df
312001:db8::21e0/1242001:db8::21ef
322001:db8::21f0/1242001:db8::21ff
332001:db8::2200/1242001:db8::220f
342001:db8::2210/1242001:db8::221f
352001:db8::2220/1242001:db8::222f
362001:db8::2230/1242001:db8::223f
372001:db8::2240/1242001:db8::224f
382001:db8::2250/1242001:db8::225f
392001:db8::2260/1242001:db8::226f
402001:db8::2270/1242001:db8::227f
412001:db8::2280/1242001:db8::228f
422001:db8::2290/1242001:db8::229f
432001:db8::22a0/1242001:db8::22af
442001:db8::22b0/1242001:db8::22bf
452001:db8::22c0/1242001:db8::22cf
462001:db8::22d0/1242001:db8::22df
472001:db8::22e0/1242001:db8::22ef
482001:db8::22f0/1242001:db8::22ff
492001:db8::2300/1242001:db8::230f
502001:db8::2310/1242001:db8::231f
512001:db8::2320/1242001:db8::232f
522001:db8::2330/1242001:db8::233f
532001:db8::2340/1242001:db8::234f
542001:db8::2350/1242001:db8::235f
552001:db8::2360/1242001:db8::236f
562001:db8::2370/1242001:db8::237f
572001:db8::2380/1242001:db8::238f
582001:db8::2390/1242001:db8::239f
592001:db8::23a0/1242001:db8::23af
602001:db8::23b0/1242001:db8::23bf
612001:db8::23c0/1242001:db8::23cf
622001:db8::23d0/1242001:db8::23df
632001:db8::23e0/1242001:db8::23ef
642001:db8::23f0/1242001:db8::23ff
652001:db8::2400/1242001:db8::240f
662001:db8::2410/1242001:db8::241f
672001:db8::2420/1242001:db8::242f
682001:db8::2430/1242001:db8::243f
692001:db8::2440/1242001:db8::244f
702001:db8::2450/1242001:db8::245f
712001:db8::2460/1242001:db8::246f
722001:db8::2470/1242001:db8::247f
732001:db8::2480/1242001:db8::248f
742001:db8::2490/1242001:db8::249f
752001:db8::24a0/1242001:db8::24af
762001:db8::24b0/1242001:db8::24bf
772001:db8::24c0/1242001:db8::24cf
782001:db8::24d0/1242001:db8::24df
792001:db8::24e0/1242001:db8::24ef
802001:db8::24f0/1242001:db8::24ff
812001:db8::2500/1242001:db8::250f
822001:db8::2510/1242001:db8::251f
832001:db8::2520/1242001:db8::252f
842001:db8::2530/1242001:db8::253f
852001:db8::2540/1242001:db8::254f
862001:db8::2550/1242001:db8::255f
872001:db8::2560/1242001:db8::256f
882001:db8::2570/1242001:db8::257f
892001:db8::2580/1242001:db8::258f
902001:db8::2590/1242001:db8::259f
912001:db8::25a0/1242001:db8::25af
922001:db8::25b0/1242001:db8::25bf
932001:db8::25c0/1242001:db8::25cf
942001:db8::25d0/1242001:db8::25df
952001:db8::25e0/1242001:db8::25ef
962001:db8::25f0/1242001:db8::25ff
972001:db8::2600/1242001:db8::260f
982001:db8::2610/1242001:db8::261f
992001:db8::2620/1242001:db8::262f
1002001:db8::2630/1242001:db8::263f
1012001:db8::2640/1242001:db8::264f
1022001:db8::2650/1242001:db8::265f
1032001:db8::2660/1242001:db8::266f
1042001:db8::2670/1242001:db8::267f
1052001:db8::2680/1242001:db8::268f
1062001:db8::2690/1242001:db8::269f
1072001:db8::26a0/1242001:db8::26af
1082001:db8::26b0/1242001:db8::26bf
1092001:db8::26c0/1242001:db8::26cf
1102001:db8::26d0/1242001:db8::26df
1112001:db8::26e0/1242001:db8::26ef
1122001:db8::26f0/1242001:db8::26ff
1132001:db8::2700/1242001:db8::270f
1142001:db8::2710/1242001:db8::271f
1152001:db8::2720/1242001:db8::272f
1162001:db8::2730/1242001:db8::273f
1172001:db8::2740/1242001:db8::274f
1182001:db8::2750/1242001:db8::275f
1192001:db8::2760/1242001:db8::276f
1202001:db8::2770/1242001:db8::277f
1212001:db8::2780/1242001:db8::278f
1222001:db8::2790/1242001:db8::279f
1232001:db8::27a0/1242001:db8::27af
1242001:db8::27b0/1242001:db8::27bf
1252001:db8::27c0/1242001:db8::27cf
1262001:db8::27d0/1242001:db8::27df
1272001:db8::27e0/1242001:db8::27ef
1282001:db8::27f0/1242001:db8::27ff
1292001:db8::2800/1242001:db8::280f
1302001:db8::2810/1242001:db8::281f
1312001:db8::2820/1242001:db8::282f
1322001:db8::2830/1242001:db8::283f
1332001:db8::2840/1242001:db8::284f
1342001:db8::2850/1242001:db8::285f
1352001:db8::2860/1242001:db8::286f
1362001:db8::2870/1242001:db8::287f
1372001:db8::2880/1242001:db8::288f
1382001:db8::2890/1242001:db8::289f
1392001:db8::28a0/1242001:db8::28af
1402001:db8::28b0/1242001:db8::28bf
1412001:db8::28c0/1242001:db8::28cf
1422001:db8::28d0/1242001:db8::28df
1432001:db8::28e0/1242001:db8::28ef
1442001:db8::28f0/1242001:db8::28ff
1452001:db8::2900/1242001:db8::290f
1462001:db8::2910/1242001:db8::291f
1472001:db8::2920/1242001:db8::292f
1482001:db8::2930/1242001:db8::293f
1492001:db8::2940/1242001:db8::294f
1502001:db8::2950/1242001:db8::295f
1512001:db8::2960/1242001:db8::296f
1522001:db8::2970/1242001:db8::297f
1532001:db8::2980/1242001:db8::298f
1542001:db8::2990/1242001:db8::299f
1552001:db8::29a0/1242001:db8::29af
1562001:db8::29b0/1242001:db8::29bf
1572001:db8::29c0/1242001:db8::29cf
1582001:db8::29d0/1242001:db8::29df
1592001:db8::29e0/1242001:db8::29ef
1602001:db8::29f0/1242001:db8::29ff
1612001:db8::2a00/1242001:db8::2a0f
1622001:db8::2a10/1242001:db8::2a1f
1632001:db8::2a20/1242001:db8::2a2f
1642001:db8::2a30/1242001:db8::2a3f
1652001:db8::2a40/1242001:db8::2a4f
1662001:db8::2a50/1242001:db8::2a5f
1672001:db8::2a60/1242001:db8::2a6f
1682001:db8::2a70/1242001:db8::2a7f
1692001:db8::2a80/1242001:db8::2a8f
1702001:db8::2a90/1242001:db8::2a9f
1712001:db8::2aa0/1242001:db8::2aaf
1722001:db8::2ab0/1242001:db8::2abf
1732001:db8::2ac0/1242001:db8::2acf
1742001:db8::2ad0/1242001:db8::2adf
1752001:db8::2ae0/1242001:db8::2aef
1762001:db8::2af0/1242001:db8::2aff
1772001:db8::2b00/1242001:db8::2b0f
1782001:db8::2b10/1242001:db8::2b1f
1792001:db8::2b20/1242001:db8::2b2f
1802001:db8::2b30/1242001:db8::2b3f
1812001:db8::2b40/1242001:db8::2b4f
1822001:db8::2b50/1242001:db8::2b5f
1832001:db8::2b60/1242001:db8::2b6f
1842001:db8::2b70/1242001:db8::2b7f
1852001:db8::2b80/1242001:db8::2b8f
1862001:db8::2b90/1242001:db8::2b9f
1872001:db8::2ba0/1242001:db8::2baf
1882001:db8::2bb0/1242001:db8::2bbf
1892001:db8::2bc0/1242001:db8::2bcf
1902001:db8::2bd0/1242001:db8::2bdf
1912001:db8::2be0/1242001:db8::2bef
1922001:db8::2bf0/1242001:db8::2bff
1932001:db8::2c00/1242001:db8::2c0f
1942001:db8::2c10/1242001:db8::2c1f
1952001:db8::2c20/1242001:db8::2c2f
1962001:db8::2c30/1242001:db8::2c3f
1972001:db8::2c40/1242001:db8::2c4f
1982001:db8::2c50/1242001:db8::2c5f
1992001:db8::2c60/1242001:db8::2c6f
2002001:db8::2c70/1242001:db8::2c7f
2012001:db8::2c80/1242001:db8::2c8f
2022001:db8::2c90/1242001:db8::2c9f
2032001:db8::2ca0/1242001:db8::2caf
2042001:db8::2cb0/1242001:db8::2cbf
2052001:db8::2cc0/1242001:db8::2ccf
2062001:db8::2cd0/1242001:db8::2cdf
2072001:db8::2ce0/1242001:db8::2cef
2082001:db8::2cf0/1242001:db8::2cff
2092001:db8::2d00/1242001:db8::2d0f
2102001:db8::2d10/1242001:db8::2d1f
2112001:db8::2d20/1242001:db8::2d2f
2122001:db8::2d30/1242001:db8::2d3f
2132001:db8::2d40/1242001:db8::2d4f
2142001:db8::2d50/1242001:db8::2d5f
2152001:db8::2d60/1242001:db8::2d6f
2162001:db8::2d70/1242001:db8::2d7f
2172001:db8::2d80/1242001:db8::2d8f
2182001:db8::2d90/1242001:db8::2d9f
2192001:db8::2da0/1242001:db8::2daf
2202001:db8::2db0/1242001:db8::2dbf
2212001:db8::2dc0/1242001:db8::2dcf
2222001:db8::2dd0/1242001:db8::2ddf
2232001:db8::2de0/1242001:db8::2def
2242001:db8::2df0/1242001:db8::2dff
2252001:db8::2e00/1242001:db8::2e0f
2262001:db8::2e10/1242001:db8::2e1f
2272001:db8::2e20/1242001:db8::2e2f
2282001:db8::2e30/1242001:db8::2e3f
2292001:db8::2e40/1242001:db8::2e4f
2302001:db8::2e50/1242001:db8::2e5f
2312001:db8::2e60/1242001:db8::2e6f
2322001:db8::2e70/1242001:db8::2e7f
2332001:db8::2e80/1242001:db8::2e8f
2342001:db8::2e90/1242001:db8::2e9f
2352001:db8::2ea0/1242001:db8::2eaf
2362001:db8::2eb0/1242001:db8::2ebf
2372001:db8::2ec0/1242001:db8::2ecf
2382001:db8::2ed0/1242001:db8::2edf
2392001:db8::2ee0/1242001:db8::2eef
2402001:db8::2ef0/1242001:db8::2eff
2412001:db8::2f00/1242001:db8::2f0f
2422001:db8::2f10/1242001:db8::2f1f
2432001:db8::2f20/1242001:db8::2f2f
2442001:db8::2f30/1242001:db8::2f3f
2452001:db8::2f40/1242001:db8::2f4f
2462001:db8::2f50/1242001:db8::2f5f
2472001:db8::2f60/1242001:db8::2f6f
2482001:db8::2f70/1242001:db8::2f7f
2492001:db8::2f80/1242001:db8::2f8f
2502001:db8::2f90/1242001:db8::2f9f
2512001:db8::2fa0/1242001:db8::2faf
2522001:db8::2fb0/1242001:db8::2fbf
2532001:db8::2fc0/1242001:db8::2fcf
2542001:db8::2fd0/1242001:db8::2fdf
2552001:db8::2fe0/1242001:db8::2fef
2562001:db8::2ff0/1242001:db8::2fff

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.