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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.

Network80.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
80.0.0.0
Broadcast address
83.255.255.255
First usable
80.0.0.1
Last usable
83.255.255.254
Usable hosts
67,108,862 (67,108,864 less the network and broadcast addresses)
Subnet mask
252.0.0.0
Wildcard mask
3.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/6
Type
Public public
Old class
A (default /8)
As numbers
Hex 50000000 · Integer 1342177280 to 1409286143
Reverse DNS zones
80.in-addr.arpa
81.in-addr.arpa
82.in-addr.arpa
83.in-addr.arpa
/6 is not on a 8-bit boundary, so it takes 4 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010000.00000000.00000000.0000000080.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network01010000.00000000.00000000.0000000080.0.0.0
Broadcast01010011.11111111.11111111.1111111183.255.255.255
Split into smaller subnets/13
/7 (2)/8 (4)/9 (8)/10 (16)/11 (32)/12 (64)/13 (128)/14 (256)/15 (512)/16 (1,024)/17 (2,048)/18 (4,096)

80.0.0.0/6 makes 128 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
180.0.0.0/1380.0.0.1 to 80.7.255.25480.7.255.255524,286
280.8.0.0/1380.8.0.1 to 80.15.255.25480.15.255.255524,286
380.16.0.0/1380.16.0.1 to 80.23.255.25480.23.255.255524,286
480.24.0.0/1380.24.0.1 to 80.31.255.25480.31.255.255524,286
580.32.0.0/1380.32.0.1 to 80.39.255.25480.39.255.255524,286
680.40.0.0/1380.40.0.1 to 80.47.255.25480.47.255.255524,286
780.48.0.0/1380.48.0.1 to 80.55.255.25480.55.255.255524,286
880.56.0.0/1380.56.0.1 to 80.63.255.25480.63.255.255524,286
980.64.0.0/1380.64.0.1 to 80.71.255.25480.71.255.255524,286
1080.72.0.0/1380.72.0.1 to 80.79.255.25480.79.255.255524,286
1180.80.0.0/1380.80.0.1 to 80.87.255.25480.87.255.255524,286
1280.88.0.0/1380.88.0.1 to 80.95.255.25480.95.255.255524,286
1380.96.0.0/1380.96.0.1 to 80.103.255.25480.103.255.255524,286
1480.104.0.0/1380.104.0.1 to 80.111.255.25480.111.255.255524,286
1580.112.0.0/1380.112.0.1 to 80.119.255.25480.119.255.255524,286
1680.120.0.0/1380.120.0.1 to 80.127.255.25480.127.255.255524,286
1780.128.0.0/1380.128.0.1 to 80.135.255.25480.135.255.255524,286
1880.136.0.0/1380.136.0.1 to 80.143.255.25480.143.255.255524,286
1980.144.0.0/1380.144.0.1 to 80.151.255.25480.151.255.255524,286
2080.152.0.0/1380.152.0.1 to 80.159.255.25480.159.255.255524,286
2180.160.0.0/1380.160.0.1 to 80.167.255.25480.167.255.255524,286
2280.168.0.0/1380.168.0.1 to 80.175.255.25480.175.255.255524,286
2380.176.0.0/1380.176.0.1 to 80.183.255.25480.183.255.255524,286
2480.184.0.0/1380.184.0.1 to 80.191.255.25480.191.255.255524,286
2580.192.0.0/1380.192.0.1 to 80.199.255.25480.199.255.255524,286
2680.200.0.0/1380.200.0.1 to 80.207.255.25480.207.255.255524,286
2780.208.0.0/1380.208.0.1 to 80.215.255.25480.215.255.255524,286
2880.216.0.0/1380.216.0.1 to 80.223.255.25480.223.255.255524,286
2980.224.0.0/1380.224.0.1 to 80.231.255.25480.231.255.255524,286
3080.232.0.0/1380.232.0.1 to 80.239.255.25480.239.255.255524,286
3180.240.0.0/1380.240.0.1 to 80.247.255.25480.247.255.255524,286
3280.248.0.0/1380.248.0.1 to 80.255.255.25480.255.255.255524,286
3381.0.0.0/1381.0.0.1 to 81.7.255.25481.7.255.255524,286
3481.8.0.0/1381.8.0.1 to 81.15.255.25481.15.255.255524,286
3581.16.0.0/1381.16.0.1 to 81.23.255.25481.23.255.255524,286
3681.24.0.0/1381.24.0.1 to 81.31.255.25481.31.255.255524,286
3781.32.0.0/1381.32.0.1 to 81.39.255.25481.39.255.255524,286
3881.40.0.0/1381.40.0.1 to 81.47.255.25481.47.255.255524,286
3981.48.0.0/1381.48.0.1 to 81.55.255.25481.55.255.255524,286
4081.56.0.0/1381.56.0.1 to 81.63.255.25481.63.255.255524,286
4181.64.0.0/1381.64.0.1 to 81.71.255.25481.71.255.255524,286
4281.72.0.0/1381.72.0.1 to 81.79.255.25481.79.255.255524,286
4381.80.0.0/1381.80.0.1 to 81.87.255.25481.87.255.255524,286
4481.88.0.0/1381.88.0.1 to 81.95.255.25481.95.255.255524,286
4581.96.0.0/1381.96.0.1 to 81.103.255.25481.103.255.255524,286
4681.104.0.0/1381.104.0.1 to 81.111.255.25481.111.255.255524,286
4781.112.0.0/1381.112.0.1 to 81.119.255.25481.119.255.255524,286
4881.120.0.0/1381.120.0.1 to 81.127.255.25481.127.255.255524,286
4981.128.0.0/1381.128.0.1 to 81.135.255.25481.135.255.255524,286
5081.136.0.0/1381.136.0.1 to 81.143.255.25481.143.255.255524,286
5181.144.0.0/1381.144.0.1 to 81.151.255.25481.151.255.255524,286
5281.152.0.0/1381.152.0.1 to 81.159.255.25481.159.255.255524,286
5381.160.0.0/1381.160.0.1 to 81.167.255.25481.167.255.255524,286
5481.168.0.0/1381.168.0.1 to 81.175.255.25481.175.255.255524,286
5581.176.0.0/1381.176.0.1 to 81.183.255.25481.183.255.255524,286
5681.184.0.0/1381.184.0.1 to 81.191.255.25481.191.255.255524,286
5781.192.0.0/1381.192.0.1 to 81.199.255.25481.199.255.255524,286
5881.200.0.0/1381.200.0.1 to 81.207.255.25481.207.255.255524,286
5981.208.0.0/1381.208.0.1 to 81.215.255.25481.215.255.255524,286
6081.216.0.0/1381.216.0.1 to 81.223.255.25481.223.255.255524,286
6181.224.0.0/1381.224.0.1 to 81.231.255.25481.231.255.255524,286
6281.232.0.0/1381.232.0.1 to 81.239.255.25481.239.255.255524,286
6381.240.0.0/1381.240.0.1 to 81.247.255.25481.247.255.255524,286
6481.248.0.0/1381.248.0.1 to 81.255.255.25481.255.255.255524,286
6582.0.0.0/1382.0.0.1 to 82.7.255.25482.7.255.255524,286
6682.8.0.0/1382.8.0.1 to 82.15.255.25482.15.255.255524,286
6782.16.0.0/1382.16.0.1 to 82.23.255.25482.23.255.255524,286
6882.24.0.0/1382.24.0.1 to 82.31.255.25482.31.255.255524,286
6982.32.0.0/1382.32.0.1 to 82.39.255.25482.39.255.255524,286
7082.40.0.0/1382.40.0.1 to 82.47.255.25482.47.255.255524,286
7182.48.0.0/1382.48.0.1 to 82.55.255.25482.55.255.255524,286
7282.56.0.0/1382.56.0.1 to 82.63.255.25482.63.255.255524,286
7382.64.0.0/1382.64.0.1 to 82.71.255.25482.71.255.255524,286
7482.72.0.0/1382.72.0.1 to 82.79.255.25482.79.255.255524,286
7582.80.0.0/1382.80.0.1 to 82.87.255.25482.87.255.255524,286
7682.88.0.0/1382.88.0.1 to 82.95.255.25482.95.255.255524,286
7782.96.0.0/1382.96.0.1 to 82.103.255.25482.103.255.255524,286
7882.104.0.0/1382.104.0.1 to 82.111.255.25482.111.255.255524,286
7982.112.0.0/1382.112.0.1 to 82.119.255.25482.119.255.255524,286
8082.120.0.0/1382.120.0.1 to 82.127.255.25482.127.255.255524,286
8182.128.0.0/1382.128.0.1 to 82.135.255.25482.135.255.255524,286
8282.136.0.0/1382.136.0.1 to 82.143.255.25482.143.255.255524,286
8382.144.0.0/1382.144.0.1 to 82.151.255.25482.151.255.255524,286
8482.152.0.0/1382.152.0.1 to 82.159.255.25482.159.255.255524,286
8582.160.0.0/1382.160.0.1 to 82.167.255.25482.167.255.255524,286
8682.168.0.0/1382.168.0.1 to 82.175.255.25482.175.255.255524,286
8782.176.0.0/1382.176.0.1 to 82.183.255.25482.183.255.255524,286
8882.184.0.0/1382.184.0.1 to 82.191.255.25482.191.255.255524,286
8982.192.0.0/1382.192.0.1 to 82.199.255.25482.199.255.255524,286
9082.200.0.0/1382.200.0.1 to 82.207.255.25482.207.255.255524,286
9182.208.0.0/1382.208.0.1 to 82.215.255.25482.215.255.255524,286
9282.216.0.0/1382.216.0.1 to 82.223.255.25482.223.255.255524,286
9382.224.0.0/1382.224.0.1 to 82.231.255.25482.231.255.255524,286
9482.232.0.0/1382.232.0.1 to 82.239.255.25482.239.255.255524,286
9582.240.0.0/1382.240.0.1 to 82.247.255.25482.247.255.255524,286
9682.248.0.0/1382.248.0.1 to 82.255.255.25482.255.255.255524,286
9783.0.0.0/1383.0.0.1 to 83.7.255.25483.7.255.255524,286
9883.8.0.0/1383.8.0.1 to 83.15.255.25483.15.255.255524,286
9983.16.0.0/1383.16.0.1 to 83.23.255.25483.23.255.255524,286
10083.24.0.0/1383.24.0.1 to 83.31.255.25483.31.255.255524,286
10183.32.0.0/1383.32.0.1 to 83.39.255.25483.39.255.255524,286
10283.40.0.0/1383.40.0.1 to 83.47.255.25483.47.255.255524,286
10383.48.0.0/1383.48.0.1 to 83.55.255.25483.55.255.255524,286
10483.56.0.0/1383.56.0.1 to 83.63.255.25483.63.255.255524,286
10583.64.0.0/1383.64.0.1 to 83.71.255.25483.71.255.255524,286
10683.72.0.0/1383.72.0.1 to 83.79.255.25483.79.255.255524,286
10783.80.0.0/1383.80.0.1 to 83.87.255.25483.87.255.255524,286
10883.88.0.0/1383.88.0.1 to 83.95.255.25483.95.255.255524,286
10983.96.0.0/1383.96.0.1 to 83.103.255.25483.103.255.255524,286
11083.104.0.0/1383.104.0.1 to 83.111.255.25483.111.255.255524,286
11183.112.0.0/1383.112.0.1 to 83.119.255.25483.119.255.255524,286
11283.120.0.0/1383.120.0.1 to 83.127.255.25483.127.255.255524,286
11383.128.0.0/1383.128.0.1 to 83.135.255.25483.135.255.255524,286
11483.136.0.0/1383.136.0.1 to 83.143.255.25483.143.255.255524,286
11583.144.0.0/1383.144.0.1 to 83.151.255.25483.151.255.255524,286
11683.152.0.0/1383.152.0.1 to 83.159.255.25483.159.255.255524,286
11783.160.0.0/1383.160.0.1 to 83.167.255.25483.167.255.255524,286
11883.168.0.0/1383.168.0.1 to 83.175.255.25483.175.255.255524,286
11983.176.0.0/1383.176.0.1 to 83.183.255.25483.183.255.255524,286
12083.184.0.0/1383.184.0.1 to 83.191.255.25483.191.255.255524,286
12183.192.0.0/1383.192.0.1 to 83.199.255.25483.199.255.255524,286
12283.200.0.0/1383.200.0.1 to 83.207.255.25483.207.255.255524,286
12383.208.0.0/1383.208.0.1 to 83.215.255.25483.215.255.255524,286
12483.216.0.0/1383.216.0.1 to 83.223.255.25483.223.255.255524,286
12583.224.0.0/1383.224.0.1 to 83.231.255.25483.231.255.255524,286
12683.232.0.0/1383.232.0.1 to 83.239.255.25483.239.255.255524,286
12783.240.0.0/1383.240.0.1 to 83.247.255.25483.247.255.255524,286
12883.248.0.0/1383.248.0.1 to 83.255.255.25483.255.255.255524,286

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.