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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.

Network80.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
80.128.0.0
Broadcast address
80.255.255.255
First usable
80.128.0.1
Last usable
80.255.255.254
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 50800000 · Integer 1350565888 to 1358954495
Reverse DNS zones
128.80.in-addr.arpa
129.80.in-addr.arpa
130.80.in-addr.arpa
131.80.in-addr.arpa
132.80.in-addr.arpa
133.80.in-addr.arpa
134.80.in-addr.arpa
135.80.in-addr.arpa
136.80.in-addr.arpa
137.80.in-addr.arpa
138.80.in-addr.arpa
139.80.in-addr.arpa
140.80.in-addr.arpa
141.80.in-addr.arpa
142.80.in-addr.arpa
143.80.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
Address01010000.10000000.00000000.0000000080.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01010000.10000000.00000000.0000000080.128.0.0
Broadcast01010000.11111111.11111111.1111111180.255.255.255
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)

80.128.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
180.128.0.0/1680.128.0.1 to 80.128.255.25480.128.255.25565,534
280.129.0.0/1680.129.0.1 to 80.129.255.25480.129.255.25565,534
380.130.0.0/1680.130.0.1 to 80.130.255.25480.130.255.25565,534
480.131.0.0/1680.131.0.1 to 80.131.255.25480.131.255.25565,534
580.132.0.0/1680.132.0.1 to 80.132.255.25480.132.255.25565,534
680.133.0.0/1680.133.0.1 to 80.133.255.25480.133.255.25565,534
780.134.0.0/1680.134.0.1 to 80.134.255.25480.134.255.25565,534
880.135.0.0/1680.135.0.1 to 80.135.255.25480.135.255.25565,534
980.136.0.0/1680.136.0.1 to 80.136.255.25480.136.255.25565,534
1080.137.0.0/1680.137.0.1 to 80.137.255.25480.137.255.25565,534
1180.138.0.0/1680.138.0.1 to 80.138.255.25480.138.255.25565,534
1280.139.0.0/1680.139.0.1 to 80.139.255.25480.139.255.25565,534
1380.140.0.0/1680.140.0.1 to 80.140.255.25480.140.255.25565,534
1480.141.0.0/1680.141.0.1 to 80.141.255.25480.141.255.25565,534
1580.142.0.0/1680.142.0.1 to 80.142.255.25480.142.255.25565,534
1680.143.0.0/1680.143.0.1 to 80.143.255.25480.143.255.25565,534
1780.144.0.0/1680.144.0.1 to 80.144.255.25480.144.255.25565,534
1880.145.0.0/1680.145.0.1 to 80.145.255.25480.145.255.25565,534
1980.146.0.0/1680.146.0.1 to 80.146.255.25480.146.255.25565,534
2080.147.0.0/1680.147.0.1 to 80.147.255.25480.147.255.25565,534
2180.148.0.0/1680.148.0.1 to 80.148.255.25480.148.255.25565,534
2280.149.0.0/1680.149.0.1 to 80.149.255.25480.149.255.25565,534
2380.150.0.0/1680.150.0.1 to 80.150.255.25480.150.255.25565,534
2480.151.0.0/1680.151.0.1 to 80.151.255.25480.151.255.25565,534
2580.152.0.0/1680.152.0.1 to 80.152.255.25480.152.255.25565,534
2680.153.0.0/1680.153.0.1 to 80.153.255.25480.153.255.25565,534
2780.154.0.0/1680.154.0.1 to 80.154.255.25480.154.255.25565,534
2880.155.0.0/1680.155.0.1 to 80.155.255.25480.155.255.25565,534
2980.156.0.0/1680.156.0.1 to 80.156.255.25480.156.255.25565,534
3080.157.0.0/1680.157.0.1 to 80.157.255.25480.157.255.25565,534
3180.158.0.0/1680.158.0.1 to 80.158.255.25480.158.255.25565,534
3280.159.0.0/1680.159.0.1 to 80.159.255.25480.159.255.25565,534
3380.160.0.0/1680.160.0.1 to 80.160.255.25480.160.255.25565,534
3480.161.0.0/1680.161.0.1 to 80.161.255.25480.161.255.25565,534
3580.162.0.0/1680.162.0.1 to 80.162.255.25480.162.255.25565,534
3680.163.0.0/1680.163.0.1 to 80.163.255.25480.163.255.25565,534
3780.164.0.0/1680.164.0.1 to 80.164.255.25480.164.255.25565,534
3880.165.0.0/1680.165.0.1 to 80.165.255.25480.165.255.25565,534
3980.166.0.0/1680.166.0.1 to 80.166.255.25480.166.255.25565,534
4080.167.0.0/1680.167.0.1 to 80.167.255.25480.167.255.25565,534
4180.168.0.0/1680.168.0.1 to 80.168.255.25480.168.255.25565,534
4280.169.0.0/1680.169.0.1 to 80.169.255.25480.169.255.25565,534
4380.170.0.0/1680.170.0.1 to 80.170.255.25480.170.255.25565,534
4480.171.0.0/1680.171.0.1 to 80.171.255.25480.171.255.25565,534
4580.172.0.0/1680.172.0.1 to 80.172.255.25480.172.255.25565,534
4680.173.0.0/1680.173.0.1 to 80.173.255.25480.173.255.25565,534
4780.174.0.0/1680.174.0.1 to 80.174.255.25480.174.255.25565,534
4880.175.0.0/1680.175.0.1 to 80.175.255.25480.175.255.25565,534
4980.176.0.0/1680.176.0.1 to 80.176.255.25480.176.255.25565,534
5080.177.0.0/1680.177.0.1 to 80.177.255.25480.177.255.25565,534
5180.178.0.0/1680.178.0.1 to 80.178.255.25480.178.255.25565,534
5280.179.0.0/1680.179.0.1 to 80.179.255.25480.179.255.25565,534
5380.180.0.0/1680.180.0.1 to 80.180.255.25480.180.255.25565,534
5480.181.0.0/1680.181.0.1 to 80.181.255.25480.181.255.25565,534
5580.182.0.0/1680.182.0.1 to 80.182.255.25480.182.255.25565,534
5680.183.0.0/1680.183.0.1 to 80.183.255.25480.183.255.25565,534
5780.184.0.0/1680.184.0.1 to 80.184.255.25480.184.255.25565,534
5880.185.0.0/1680.185.0.1 to 80.185.255.25480.185.255.25565,534
5980.186.0.0/1680.186.0.1 to 80.186.255.25480.186.255.25565,534
6080.187.0.0/1680.187.0.1 to 80.187.255.25480.187.255.25565,534
6180.188.0.0/1680.188.0.1 to 80.188.255.25480.188.255.25565,534
6280.189.0.0/1680.189.0.1 to 80.189.255.25480.189.255.25565,534
6380.190.0.0/1680.190.0.1 to 80.190.255.25480.190.255.25565,534
6480.191.0.0/1680.191.0.1 to 80.191.255.25480.191.255.25565,534
6580.192.0.0/1680.192.0.1 to 80.192.255.25480.192.255.25565,534
6680.193.0.0/1680.193.0.1 to 80.193.255.25480.193.255.25565,534
6780.194.0.0/1680.194.0.1 to 80.194.255.25480.194.255.25565,534
6880.195.0.0/1680.195.0.1 to 80.195.255.25480.195.255.25565,534
6980.196.0.0/1680.196.0.1 to 80.196.255.25480.196.255.25565,534
7080.197.0.0/1680.197.0.1 to 80.197.255.25480.197.255.25565,534
7180.198.0.0/1680.198.0.1 to 80.198.255.25480.198.255.25565,534
7280.199.0.0/1680.199.0.1 to 80.199.255.25480.199.255.25565,534
7380.200.0.0/1680.200.0.1 to 80.200.255.25480.200.255.25565,534
7480.201.0.0/1680.201.0.1 to 80.201.255.25480.201.255.25565,534
7580.202.0.0/1680.202.0.1 to 80.202.255.25480.202.255.25565,534
7680.203.0.0/1680.203.0.1 to 80.203.255.25480.203.255.25565,534
7780.204.0.0/1680.204.0.1 to 80.204.255.25480.204.255.25565,534
7880.205.0.0/1680.205.0.1 to 80.205.255.25480.205.255.25565,534
7980.206.0.0/1680.206.0.1 to 80.206.255.25480.206.255.25565,534
8080.207.0.0/1680.207.0.1 to 80.207.255.25480.207.255.25565,534
8180.208.0.0/1680.208.0.1 to 80.208.255.25480.208.255.25565,534
8280.209.0.0/1680.209.0.1 to 80.209.255.25480.209.255.25565,534
8380.210.0.0/1680.210.0.1 to 80.210.255.25480.210.255.25565,534
8480.211.0.0/1680.211.0.1 to 80.211.255.25480.211.255.25565,534
8580.212.0.0/1680.212.0.1 to 80.212.255.25480.212.255.25565,534
8680.213.0.0/1680.213.0.1 to 80.213.255.25480.213.255.25565,534
8780.214.0.0/1680.214.0.1 to 80.214.255.25480.214.255.25565,534
8880.215.0.0/1680.215.0.1 to 80.215.255.25480.215.255.25565,534
8980.216.0.0/1680.216.0.1 to 80.216.255.25480.216.255.25565,534
9080.217.0.0/1680.217.0.1 to 80.217.255.25480.217.255.25565,534
9180.218.0.0/1680.218.0.1 to 80.218.255.25480.218.255.25565,534
9280.219.0.0/1680.219.0.1 to 80.219.255.25480.219.255.25565,534
9380.220.0.0/1680.220.0.1 to 80.220.255.25480.220.255.25565,534
9480.221.0.0/1680.221.0.1 to 80.221.255.25480.221.255.25565,534
9580.222.0.0/1680.222.0.1 to 80.222.255.25480.222.255.25565,534
9680.223.0.0/1680.223.0.1 to 80.223.255.25480.223.255.25565,534
9780.224.0.0/1680.224.0.1 to 80.224.255.25480.224.255.25565,534
9880.225.0.0/1680.225.0.1 to 80.225.255.25480.225.255.25565,534
9980.226.0.0/1680.226.0.1 to 80.226.255.25480.226.255.25565,534
10080.227.0.0/1680.227.0.1 to 80.227.255.25480.227.255.25565,534
10180.228.0.0/1680.228.0.1 to 80.228.255.25480.228.255.25565,534
10280.229.0.0/1680.229.0.1 to 80.229.255.25480.229.255.25565,534
10380.230.0.0/1680.230.0.1 to 80.230.255.25480.230.255.25565,534
10480.231.0.0/1680.231.0.1 to 80.231.255.25480.231.255.25565,534
10580.232.0.0/1680.232.0.1 to 80.232.255.25480.232.255.25565,534
10680.233.0.0/1680.233.0.1 to 80.233.255.25480.233.255.25565,534
10780.234.0.0/1680.234.0.1 to 80.234.255.25480.234.255.25565,534
10880.235.0.0/1680.235.0.1 to 80.235.255.25480.235.255.25565,534
10980.236.0.0/1680.236.0.1 to 80.236.255.25480.236.255.25565,534
11080.237.0.0/1680.237.0.1 to 80.237.255.25480.237.255.25565,534
11180.238.0.0/1680.238.0.1 to 80.238.255.25480.238.255.25565,534
11280.239.0.0/1680.239.0.1 to 80.239.255.25480.239.255.25565,534
11380.240.0.0/1680.240.0.1 to 80.240.255.25480.240.255.25565,534
11480.241.0.0/1680.241.0.1 to 80.241.255.25480.241.255.25565,534
11580.242.0.0/1680.242.0.1 to 80.242.255.25480.242.255.25565,534
11680.243.0.0/1680.243.0.1 to 80.243.255.25480.243.255.25565,534
11780.244.0.0/1680.244.0.1 to 80.244.255.25480.244.255.25565,534
11880.245.0.0/1680.245.0.1 to 80.245.255.25480.245.255.25565,534
11980.246.0.0/1680.246.0.1 to 80.246.255.25480.246.255.25565,534
12080.247.0.0/1680.247.0.1 to 80.247.255.25480.247.255.25565,534
12180.248.0.0/1680.248.0.1 to 80.248.255.25480.248.255.25565,534
12280.249.0.0/1680.249.0.1 to 80.249.255.25480.249.255.25565,534
12380.250.0.0/1680.250.0.1 to 80.250.255.25480.250.255.25565,534
12480.251.0.0/1680.251.0.1 to 80.251.255.25480.251.255.25565,534
12580.252.0.0/1680.252.0.1 to 80.252.255.25480.252.255.25565,534
12680.253.0.0/1680.253.0.1 to 80.253.255.25480.253.255.25565,534
12780.254.0.0/1680.254.0.1 to 80.254.255.25480.254.255.25565,534
12880.255.0.0/1680.255.0.1 to 80.255.255.25480.255.255.25565,534

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.