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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.

Network80.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
80.0.0.0
Broadcast address
81.255.255.255
First usable
80.0.0.1
Last usable
81.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
A (default /8)
As numbers
Hex 50000000 · Integer 1342177280 to 1375731711
Reverse DNS zones
80.in-addr.arpa
81.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010000.00000000.00000000.0000000080.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network01010000.00000000.00000000.0000000080.0.0.0
Broadcast01010001.11111111.11111111.1111111181.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

80.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
180.0.0.0/1480.0.0.1 to 80.3.255.25480.3.255.255262,142
280.4.0.0/1480.4.0.1 to 80.7.255.25480.7.255.255262,142
380.8.0.0/1480.8.0.1 to 80.11.255.25480.11.255.255262,142
480.12.0.0/1480.12.0.1 to 80.15.255.25480.15.255.255262,142
580.16.0.0/1480.16.0.1 to 80.19.255.25480.19.255.255262,142
680.20.0.0/1480.20.0.1 to 80.23.255.25480.23.255.255262,142
780.24.0.0/1480.24.0.1 to 80.27.255.25480.27.255.255262,142
880.28.0.0/1480.28.0.1 to 80.31.255.25480.31.255.255262,142
980.32.0.0/1480.32.0.1 to 80.35.255.25480.35.255.255262,142
1080.36.0.0/1480.36.0.1 to 80.39.255.25480.39.255.255262,142
1180.40.0.0/1480.40.0.1 to 80.43.255.25480.43.255.255262,142
1280.44.0.0/1480.44.0.1 to 80.47.255.25480.47.255.255262,142
1380.48.0.0/1480.48.0.1 to 80.51.255.25480.51.255.255262,142
1480.52.0.0/1480.52.0.1 to 80.55.255.25480.55.255.255262,142
1580.56.0.0/1480.56.0.1 to 80.59.255.25480.59.255.255262,142
1680.60.0.0/1480.60.0.1 to 80.63.255.25480.63.255.255262,142
1780.64.0.0/1480.64.0.1 to 80.67.255.25480.67.255.255262,142
1880.68.0.0/1480.68.0.1 to 80.71.255.25480.71.255.255262,142
1980.72.0.0/1480.72.0.1 to 80.75.255.25480.75.255.255262,142
2080.76.0.0/1480.76.0.1 to 80.79.255.25480.79.255.255262,142
2180.80.0.0/1480.80.0.1 to 80.83.255.25480.83.255.255262,142
2280.84.0.0/1480.84.0.1 to 80.87.255.25480.87.255.255262,142
2380.88.0.0/1480.88.0.1 to 80.91.255.25480.91.255.255262,142
2480.92.0.0/1480.92.0.1 to 80.95.255.25480.95.255.255262,142
2580.96.0.0/1480.96.0.1 to 80.99.255.25480.99.255.255262,142
2680.100.0.0/1480.100.0.1 to 80.103.255.25480.103.255.255262,142
2780.104.0.0/1480.104.0.1 to 80.107.255.25480.107.255.255262,142
2880.108.0.0/1480.108.0.1 to 80.111.255.25480.111.255.255262,142
2980.112.0.0/1480.112.0.1 to 80.115.255.25480.115.255.255262,142
3080.116.0.0/1480.116.0.1 to 80.119.255.25480.119.255.255262,142
3180.120.0.0/1480.120.0.1 to 80.123.255.25480.123.255.255262,142
3280.124.0.0/1480.124.0.1 to 80.127.255.25480.127.255.255262,142
3380.128.0.0/1480.128.0.1 to 80.131.255.25480.131.255.255262,142
3480.132.0.0/1480.132.0.1 to 80.135.255.25480.135.255.255262,142
3580.136.0.0/1480.136.0.1 to 80.139.255.25480.139.255.255262,142
3680.140.0.0/1480.140.0.1 to 80.143.255.25480.143.255.255262,142
3780.144.0.0/1480.144.0.1 to 80.147.255.25480.147.255.255262,142
3880.148.0.0/1480.148.0.1 to 80.151.255.25480.151.255.255262,142
3980.152.0.0/1480.152.0.1 to 80.155.255.25480.155.255.255262,142
4080.156.0.0/1480.156.0.1 to 80.159.255.25480.159.255.255262,142
4180.160.0.0/1480.160.0.1 to 80.163.255.25480.163.255.255262,142
4280.164.0.0/1480.164.0.1 to 80.167.255.25480.167.255.255262,142
4380.168.0.0/1480.168.0.1 to 80.171.255.25480.171.255.255262,142
4480.172.0.0/1480.172.0.1 to 80.175.255.25480.175.255.255262,142
4580.176.0.0/1480.176.0.1 to 80.179.255.25480.179.255.255262,142
4680.180.0.0/1480.180.0.1 to 80.183.255.25480.183.255.255262,142
4780.184.0.0/1480.184.0.1 to 80.187.255.25480.187.255.255262,142
4880.188.0.0/1480.188.0.1 to 80.191.255.25480.191.255.255262,142
4980.192.0.0/1480.192.0.1 to 80.195.255.25480.195.255.255262,142
5080.196.0.0/1480.196.0.1 to 80.199.255.25480.199.255.255262,142
5180.200.0.0/1480.200.0.1 to 80.203.255.25480.203.255.255262,142
5280.204.0.0/1480.204.0.1 to 80.207.255.25480.207.255.255262,142
5380.208.0.0/1480.208.0.1 to 80.211.255.25480.211.255.255262,142
5480.212.0.0/1480.212.0.1 to 80.215.255.25480.215.255.255262,142
5580.216.0.0/1480.216.0.1 to 80.219.255.25480.219.255.255262,142
5680.220.0.0/1480.220.0.1 to 80.223.255.25480.223.255.255262,142
5780.224.0.0/1480.224.0.1 to 80.227.255.25480.227.255.255262,142
5880.228.0.0/1480.228.0.1 to 80.231.255.25480.231.255.255262,142
5980.232.0.0/1480.232.0.1 to 80.235.255.25480.235.255.255262,142
6080.236.0.0/1480.236.0.1 to 80.239.255.25480.239.255.255262,142
6180.240.0.0/1480.240.0.1 to 80.243.255.25480.243.255.255262,142
6280.244.0.0/1480.244.0.1 to 80.247.255.25480.247.255.255262,142
6380.248.0.0/1480.248.0.1 to 80.251.255.25480.251.255.255262,142
6480.252.0.0/1480.252.0.1 to 80.255.255.25480.255.255.255262,142
6581.0.0.0/1481.0.0.1 to 81.3.255.25481.3.255.255262,142
6681.4.0.0/1481.4.0.1 to 81.7.255.25481.7.255.255262,142
6781.8.0.0/1481.8.0.1 to 81.11.255.25481.11.255.255262,142
6881.12.0.0/1481.12.0.1 to 81.15.255.25481.15.255.255262,142
6981.16.0.0/1481.16.0.1 to 81.19.255.25481.19.255.255262,142
7081.20.0.0/1481.20.0.1 to 81.23.255.25481.23.255.255262,142
7181.24.0.0/1481.24.0.1 to 81.27.255.25481.27.255.255262,142
7281.28.0.0/1481.28.0.1 to 81.31.255.25481.31.255.255262,142
7381.32.0.0/1481.32.0.1 to 81.35.255.25481.35.255.255262,142
7481.36.0.0/1481.36.0.1 to 81.39.255.25481.39.255.255262,142
7581.40.0.0/1481.40.0.1 to 81.43.255.25481.43.255.255262,142
7681.44.0.0/1481.44.0.1 to 81.47.255.25481.47.255.255262,142
7781.48.0.0/1481.48.0.1 to 81.51.255.25481.51.255.255262,142
7881.52.0.0/1481.52.0.1 to 81.55.255.25481.55.255.255262,142
7981.56.0.0/1481.56.0.1 to 81.59.255.25481.59.255.255262,142
8081.60.0.0/1481.60.0.1 to 81.63.255.25481.63.255.255262,142
8181.64.0.0/1481.64.0.1 to 81.67.255.25481.67.255.255262,142
8281.68.0.0/1481.68.0.1 to 81.71.255.25481.71.255.255262,142
8381.72.0.0/1481.72.0.1 to 81.75.255.25481.75.255.255262,142
8481.76.0.0/1481.76.0.1 to 81.79.255.25481.79.255.255262,142
8581.80.0.0/1481.80.0.1 to 81.83.255.25481.83.255.255262,142
8681.84.0.0/1481.84.0.1 to 81.87.255.25481.87.255.255262,142
8781.88.0.0/1481.88.0.1 to 81.91.255.25481.91.255.255262,142
8881.92.0.0/1481.92.0.1 to 81.95.255.25481.95.255.255262,142
8981.96.0.0/1481.96.0.1 to 81.99.255.25481.99.255.255262,142
9081.100.0.0/1481.100.0.1 to 81.103.255.25481.103.255.255262,142
9181.104.0.0/1481.104.0.1 to 81.107.255.25481.107.255.255262,142
9281.108.0.0/1481.108.0.1 to 81.111.255.25481.111.255.255262,142
9381.112.0.0/1481.112.0.1 to 81.115.255.25481.115.255.255262,142
9481.116.0.0/1481.116.0.1 to 81.119.255.25481.119.255.255262,142
9581.120.0.0/1481.120.0.1 to 81.123.255.25481.123.255.255262,142
9681.124.0.0/1481.124.0.1 to 81.127.255.25481.127.255.255262,142
9781.128.0.0/1481.128.0.1 to 81.131.255.25481.131.255.255262,142
9881.132.0.0/1481.132.0.1 to 81.135.255.25481.135.255.255262,142
9981.136.0.0/1481.136.0.1 to 81.139.255.25481.139.255.255262,142
10081.140.0.0/1481.140.0.1 to 81.143.255.25481.143.255.255262,142
10181.144.0.0/1481.144.0.1 to 81.147.255.25481.147.255.255262,142
10281.148.0.0/1481.148.0.1 to 81.151.255.25481.151.255.255262,142
10381.152.0.0/1481.152.0.1 to 81.155.255.25481.155.255.255262,142
10481.156.0.0/1481.156.0.1 to 81.159.255.25481.159.255.255262,142
10581.160.0.0/1481.160.0.1 to 81.163.255.25481.163.255.255262,142
10681.164.0.0/1481.164.0.1 to 81.167.255.25481.167.255.255262,142
10781.168.0.0/1481.168.0.1 to 81.171.255.25481.171.255.255262,142
10881.172.0.0/1481.172.0.1 to 81.175.255.25481.175.255.255262,142
10981.176.0.0/1481.176.0.1 to 81.179.255.25481.179.255.255262,142
11081.180.0.0/1481.180.0.1 to 81.183.255.25481.183.255.255262,142
11181.184.0.0/1481.184.0.1 to 81.187.255.25481.187.255.255262,142
11281.188.0.0/1481.188.0.1 to 81.191.255.25481.191.255.255262,142
11381.192.0.0/1481.192.0.1 to 81.195.255.25481.195.255.255262,142
11481.196.0.0/1481.196.0.1 to 81.199.255.25481.199.255.255262,142
11581.200.0.0/1481.200.0.1 to 81.203.255.25481.203.255.255262,142
11681.204.0.0/1481.204.0.1 to 81.207.255.25481.207.255.255262,142
11781.208.0.0/1481.208.0.1 to 81.211.255.25481.211.255.255262,142
11881.212.0.0/1481.212.0.1 to 81.215.255.25481.215.255.255262,142
11981.216.0.0/1481.216.0.1 to 81.219.255.25481.219.255.255262,142
12081.220.0.0/1481.220.0.1 to 81.223.255.25481.223.255.255262,142
12181.224.0.0/1481.224.0.1 to 81.227.255.25481.227.255.255262,142
12281.228.0.0/1481.228.0.1 to 81.231.255.25481.231.255.255262,142
12381.232.0.0/1481.232.0.1 to 81.235.255.25481.235.255.255262,142
12481.236.0.0/1481.236.0.1 to 81.239.255.25481.239.255.255262,142
12581.240.0.0/1481.240.0.1 to 81.243.255.25481.243.255.255262,142
12681.244.0.0/1481.244.0.1 to 81.247.255.25481.247.255.255262,142
12781.248.0.0/1481.248.0.1 to 81.251.255.25481.251.255.255262,142
12881.252.0.0/1481.252.0.1 to 81.255.255.25481.255.255.255262,142

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.