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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.

Network79.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
79.128.0.0
Broadcast address
79.255.255.255
First usable
79.128.0.1
Last usable
79.255.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 4F800000 · Integer 1333788672 to 1342177279
Reverse DNS zones
128.79.in-addr.arpa
129.79.in-addr.arpa
130.79.in-addr.arpa
131.79.in-addr.arpa
132.79.in-addr.arpa
133.79.in-addr.arpa
134.79.in-addr.arpa
135.79.in-addr.arpa
136.79.in-addr.arpa
137.79.in-addr.arpa
138.79.in-addr.arpa
139.79.in-addr.arpa
140.79.in-addr.arpa
141.79.in-addr.arpa
142.79.in-addr.arpa
143.79.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01001111.10000000.00000000.0000000079.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01001111.10000000.00000000.0000000079.128.0.0
Broadcast01001111.11111111.11111111.1111111179.255.255.255
Split into smaller subnets/16
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

79.128.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
179.128.0.0/1679.128.0.1 to 79.128.255.25479.128.255.25565,534
279.129.0.0/1679.129.0.1 to 79.129.255.25479.129.255.25565,534
379.130.0.0/1679.130.0.1 to 79.130.255.25479.130.255.25565,534
479.131.0.0/1679.131.0.1 to 79.131.255.25479.131.255.25565,534
579.132.0.0/1679.132.0.1 to 79.132.255.25479.132.255.25565,534
679.133.0.0/1679.133.0.1 to 79.133.255.25479.133.255.25565,534
779.134.0.0/1679.134.0.1 to 79.134.255.25479.134.255.25565,534
879.135.0.0/1679.135.0.1 to 79.135.255.25479.135.255.25565,534
979.136.0.0/1679.136.0.1 to 79.136.255.25479.136.255.25565,534
1079.137.0.0/1679.137.0.1 to 79.137.255.25479.137.255.25565,534
1179.138.0.0/1679.138.0.1 to 79.138.255.25479.138.255.25565,534
1279.139.0.0/1679.139.0.1 to 79.139.255.25479.139.255.25565,534
1379.140.0.0/1679.140.0.1 to 79.140.255.25479.140.255.25565,534
1479.141.0.0/1679.141.0.1 to 79.141.255.25479.141.255.25565,534
1579.142.0.0/1679.142.0.1 to 79.142.255.25479.142.255.25565,534
1679.143.0.0/1679.143.0.1 to 79.143.255.25479.143.255.25565,534
1779.144.0.0/1679.144.0.1 to 79.144.255.25479.144.255.25565,534
1879.145.0.0/1679.145.0.1 to 79.145.255.25479.145.255.25565,534
1979.146.0.0/1679.146.0.1 to 79.146.255.25479.146.255.25565,534
2079.147.0.0/1679.147.0.1 to 79.147.255.25479.147.255.25565,534
2179.148.0.0/1679.148.0.1 to 79.148.255.25479.148.255.25565,534
2279.149.0.0/1679.149.0.1 to 79.149.255.25479.149.255.25565,534
2379.150.0.0/1679.150.0.1 to 79.150.255.25479.150.255.25565,534
2479.151.0.0/1679.151.0.1 to 79.151.255.25479.151.255.25565,534
2579.152.0.0/1679.152.0.1 to 79.152.255.25479.152.255.25565,534
2679.153.0.0/1679.153.0.1 to 79.153.255.25479.153.255.25565,534
2779.154.0.0/1679.154.0.1 to 79.154.255.25479.154.255.25565,534
2879.155.0.0/1679.155.0.1 to 79.155.255.25479.155.255.25565,534
2979.156.0.0/1679.156.0.1 to 79.156.255.25479.156.255.25565,534
3079.157.0.0/1679.157.0.1 to 79.157.255.25479.157.255.25565,534
3179.158.0.0/1679.158.0.1 to 79.158.255.25479.158.255.25565,534
3279.159.0.0/1679.159.0.1 to 79.159.255.25479.159.255.25565,534
3379.160.0.0/1679.160.0.1 to 79.160.255.25479.160.255.25565,534
3479.161.0.0/1679.161.0.1 to 79.161.255.25479.161.255.25565,534
3579.162.0.0/1679.162.0.1 to 79.162.255.25479.162.255.25565,534
3679.163.0.0/1679.163.0.1 to 79.163.255.25479.163.255.25565,534
3779.164.0.0/1679.164.0.1 to 79.164.255.25479.164.255.25565,534
3879.165.0.0/1679.165.0.1 to 79.165.255.25479.165.255.25565,534
3979.166.0.0/1679.166.0.1 to 79.166.255.25479.166.255.25565,534
4079.167.0.0/1679.167.0.1 to 79.167.255.25479.167.255.25565,534
4179.168.0.0/1679.168.0.1 to 79.168.255.25479.168.255.25565,534
4279.169.0.0/1679.169.0.1 to 79.169.255.25479.169.255.25565,534
4379.170.0.0/1679.170.0.1 to 79.170.255.25479.170.255.25565,534
4479.171.0.0/1679.171.0.1 to 79.171.255.25479.171.255.25565,534
4579.172.0.0/1679.172.0.1 to 79.172.255.25479.172.255.25565,534
4679.173.0.0/1679.173.0.1 to 79.173.255.25479.173.255.25565,534
4779.174.0.0/1679.174.0.1 to 79.174.255.25479.174.255.25565,534
4879.175.0.0/1679.175.0.1 to 79.175.255.25479.175.255.25565,534
4979.176.0.0/1679.176.0.1 to 79.176.255.25479.176.255.25565,534
5079.177.0.0/1679.177.0.1 to 79.177.255.25479.177.255.25565,534
5179.178.0.0/1679.178.0.1 to 79.178.255.25479.178.255.25565,534
5279.179.0.0/1679.179.0.1 to 79.179.255.25479.179.255.25565,534
5379.180.0.0/1679.180.0.1 to 79.180.255.25479.180.255.25565,534
5479.181.0.0/1679.181.0.1 to 79.181.255.25479.181.255.25565,534
5579.182.0.0/1679.182.0.1 to 79.182.255.25479.182.255.25565,534
5679.183.0.0/1679.183.0.1 to 79.183.255.25479.183.255.25565,534
5779.184.0.0/1679.184.0.1 to 79.184.255.25479.184.255.25565,534
5879.185.0.0/1679.185.0.1 to 79.185.255.25479.185.255.25565,534
5979.186.0.0/1679.186.0.1 to 79.186.255.25479.186.255.25565,534
6079.187.0.0/1679.187.0.1 to 79.187.255.25479.187.255.25565,534
6179.188.0.0/1679.188.0.1 to 79.188.255.25479.188.255.25565,534
6279.189.0.0/1679.189.0.1 to 79.189.255.25479.189.255.25565,534
6379.190.0.0/1679.190.0.1 to 79.190.255.25479.190.255.25565,534
6479.191.0.0/1679.191.0.1 to 79.191.255.25479.191.255.25565,534
6579.192.0.0/1679.192.0.1 to 79.192.255.25479.192.255.25565,534
6679.193.0.0/1679.193.0.1 to 79.193.255.25479.193.255.25565,534
6779.194.0.0/1679.194.0.1 to 79.194.255.25479.194.255.25565,534
6879.195.0.0/1679.195.0.1 to 79.195.255.25479.195.255.25565,534
6979.196.0.0/1679.196.0.1 to 79.196.255.25479.196.255.25565,534
7079.197.0.0/1679.197.0.1 to 79.197.255.25479.197.255.25565,534
7179.198.0.0/1679.198.0.1 to 79.198.255.25479.198.255.25565,534
7279.199.0.0/1679.199.0.1 to 79.199.255.25479.199.255.25565,534
7379.200.0.0/1679.200.0.1 to 79.200.255.25479.200.255.25565,534
7479.201.0.0/1679.201.0.1 to 79.201.255.25479.201.255.25565,534
7579.202.0.0/1679.202.0.1 to 79.202.255.25479.202.255.25565,534
7679.203.0.0/1679.203.0.1 to 79.203.255.25479.203.255.25565,534
7779.204.0.0/1679.204.0.1 to 79.204.255.25479.204.255.25565,534
7879.205.0.0/1679.205.0.1 to 79.205.255.25479.205.255.25565,534
7979.206.0.0/1679.206.0.1 to 79.206.255.25479.206.255.25565,534
8079.207.0.0/1679.207.0.1 to 79.207.255.25479.207.255.25565,534
8179.208.0.0/1679.208.0.1 to 79.208.255.25479.208.255.25565,534
8279.209.0.0/1679.209.0.1 to 79.209.255.25479.209.255.25565,534
8379.210.0.0/1679.210.0.1 to 79.210.255.25479.210.255.25565,534
8479.211.0.0/1679.211.0.1 to 79.211.255.25479.211.255.25565,534
8579.212.0.0/1679.212.0.1 to 79.212.255.25479.212.255.25565,534
8679.213.0.0/1679.213.0.1 to 79.213.255.25479.213.255.25565,534
8779.214.0.0/1679.214.0.1 to 79.214.255.25479.214.255.25565,534
8879.215.0.0/1679.215.0.1 to 79.215.255.25479.215.255.25565,534
8979.216.0.0/1679.216.0.1 to 79.216.255.25479.216.255.25565,534
9079.217.0.0/1679.217.0.1 to 79.217.255.25479.217.255.25565,534
9179.218.0.0/1679.218.0.1 to 79.218.255.25479.218.255.25565,534
9279.219.0.0/1679.219.0.1 to 79.219.255.25479.219.255.25565,534
9379.220.0.0/1679.220.0.1 to 79.220.255.25479.220.255.25565,534
9479.221.0.0/1679.221.0.1 to 79.221.255.25479.221.255.25565,534
9579.222.0.0/1679.222.0.1 to 79.222.255.25479.222.255.25565,534
9679.223.0.0/1679.223.0.1 to 79.223.255.25479.223.255.25565,534
9779.224.0.0/1679.224.0.1 to 79.224.255.25479.224.255.25565,534
9879.225.0.0/1679.225.0.1 to 79.225.255.25479.225.255.25565,534
9979.226.0.0/1679.226.0.1 to 79.226.255.25479.226.255.25565,534
10079.227.0.0/1679.227.0.1 to 79.227.255.25479.227.255.25565,534
10179.228.0.0/1679.228.0.1 to 79.228.255.25479.228.255.25565,534
10279.229.0.0/1679.229.0.1 to 79.229.255.25479.229.255.25565,534
10379.230.0.0/1679.230.0.1 to 79.230.255.25479.230.255.25565,534
10479.231.0.0/1679.231.0.1 to 79.231.255.25479.231.255.25565,534
10579.232.0.0/1679.232.0.1 to 79.232.255.25479.232.255.25565,534
10679.233.0.0/1679.233.0.1 to 79.233.255.25479.233.255.25565,534
10779.234.0.0/1679.234.0.1 to 79.234.255.25479.234.255.25565,534
10879.235.0.0/1679.235.0.1 to 79.235.255.25479.235.255.25565,534
10979.236.0.0/1679.236.0.1 to 79.236.255.25479.236.255.25565,534
11079.237.0.0/1679.237.0.1 to 79.237.255.25479.237.255.25565,534
11179.238.0.0/1679.238.0.1 to 79.238.255.25479.238.255.25565,534
11279.239.0.0/1679.239.0.1 to 79.239.255.25479.239.255.25565,534
11379.240.0.0/1679.240.0.1 to 79.240.255.25479.240.255.25565,534
11479.241.0.0/1679.241.0.1 to 79.241.255.25479.241.255.25565,534
11579.242.0.0/1679.242.0.1 to 79.242.255.25479.242.255.25565,534
11679.243.0.0/1679.243.0.1 to 79.243.255.25479.243.255.25565,534
11779.244.0.0/1679.244.0.1 to 79.244.255.25479.244.255.25565,534
11879.245.0.0/1679.245.0.1 to 79.245.255.25479.245.255.25565,534
11979.246.0.0/1679.246.0.1 to 79.246.255.25479.246.255.25565,534
12079.247.0.0/1679.247.0.1 to 79.247.255.25479.247.255.25565,534
12179.248.0.0/1679.248.0.1 to 79.248.255.25479.248.255.25565,534
12279.249.0.0/1679.249.0.1 to 79.249.255.25479.249.255.25565,534
12379.250.0.0/1679.250.0.1 to 79.250.255.25479.250.255.25565,534
12479.251.0.0/1679.251.0.1 to 79.251.255.25479.251.255.25565,534
12579.252.0.0/1679.252.0.1 to 79.252.255.25479.252.255.25565,534
12679.253.0.0/1679.253.0.1 to 79.253.255.25479.253.255.25565,534
12779.254.0.0/1679.254.0.1 to 79.254.255.25479.254.255.25565,534
12879.255.0.0/1679.255.0.1 to 79.255.255.25479.255.255.25565,534

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.