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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.

Network180.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
180.0.0.0
Broadcast address
183.255.255.255
First usable
180.0.0.1
Last usable
183.255.255.254
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
B (default /16)
As numbers
Hex B4000000 · Integer 3019898880 to 3087007743
Reverse DNS zones
180.in-addr.arpa
181.in-addr.arpa
182.in-addr.arpa
183.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
Address10110100.00000000.00000000.00000000180.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network10110100.00000000.00000000.00000000180.0.0.0
Broadcast10110111.11111111.11111111.11111111183.255.255.255
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)

180.0.0.0/6 makes 128 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1180.0.0.0/13180.0.0.1 to 180.7.255.254180.7.255.255524,286
2180.8.0.0/13180.8.0.1 to 180.15.255.254180.15.255.255524,286
3180.16.0.0/13180.16.0.1 to 180.23.255.254180.23.255.255524,286
4180.24.0.0/13180.24.0.1 to 180.31.255.254180.31.255.255524,286
5180.32.0.0/13180.32.0.1 to 180.39.255.254180.39.255.255524,286
6180.40.0.0/13180.40.0.1 to 180.47.255.254180.47.255.255524,286
7180.48.0.0/13180.48.0.1 to 180.55.255.254180.55.255.255524,286
8180.56.0.0/13180.56.0.1 to 180.63.255.254180.63.255.255524,286
9180.64.0.0/13180.64.0.1 to 180.71.255.254180.71.255.255524,286
10180.72.0.0/13180.72.0.1 to 180.79.255.254180.79.255.255524,286
11180.80.0.0/13180.80.0.1 to 180.87.255.254180.87.255.255524,286
12180.88.0.0/13180.88.0.1 to 180.95.255.254180.95.255.255524,286
13180.96.0.0/13180.96.0.1 to 180.103.255.254180.103.255.255524,286
14180.104.0.0/13180.104.0.1 to 180.111.255.254180.111.255.255524,286
15180.112.0.0/13180.112.0.1 to 180.119.255.254180.119.255.255524,286
16180.120.0.0/13180.120.0.1 to 180.127.255.254180.127.255.255524,286
17180.128.0.0/13180.128.0.1 to 180.135.255.254180.135.255.255524,286
18180.136.0.0/13180.136.0.1 to 180.143.255.254180.143.255.255524,286
19180.144.0.0/13180.144.0.1 to 180.151.255.254180.151.255.255524,286
20180.152.0.0/13180.152.0.1 to 180.159.255.254180.159.255.255524,286
21180.160.0.0/13180.160.0.1 to 180.167.255.254180.167.255.255524,286
22180.168.0.0/13180.168.0.1 to 180.175.255.254180.175.255.255524,286
23180.176.0.0/13180.176.0.1 to 180.183.255.254180.183.255.255524,286
24180.184.0.0/13180.184.0.1 to 180.191.255.254180.191.255.255524,286
25180.192.0.0/13180.192.0.1 to 180.199.255.254180.199.255.255524,286
26180.200.0.0/13180.200.0.1 to 180.207.255.254180.207.255.255524,286
27180.208.0.0/13180.208.0.1 to 180.215.255.254180.215.255.255524,286
28180.216.0.0/13180.216.0.1 to 180.223.255.254180.223.255.255524,286
29180.224.0.0/13180.224.0.1 to 180.231.255.254180.231.255.255524,286
30180.232.0.0/13180.232.0.1 to 180.239.255.254180.239.255.255524,286
31180.240.0.0/13180.240.0.1 to 180.247.255.254180.247.255.255524,286
32180.248.0.0/13180.248.0.1 to 180.255.255.254180.255.255.255524,286
33181.0.0.0/13181.0.0.1 to 181.7.255.254181.7.255.255524,286
34181.8.0.0/13181.8.0.1 to 181.15.255.254181.15.255.255524,286
35181.16.0.0/13181.16.0.1 to 181.23.255.254181.23.255.255524,286
36181.24.0.0/13181.24.0.1 to 181.31.255.254181.31.255.255524,286
37181.32.0.0/13181.32.0.1 to 181.39.255.254181.39.255.255524,286
38181.40.0.0/13181.40.0.1 to 181.47.255.254181.47.255.255524,286
39181.48.0.0/13181.48.0.1 to 181.55.255.254181.55.255.255524,286
40181.56.0.0/13181.56.0.1 to 181.63.255.254181.63.255.255524,286
41181.64.0.0/13181.64.0.1 to 181.71.255.254181.71.255.255524,286
42181.72.0.0/13181.72.0.1 to 181.79.255.254181.79.255.255524,286
43181.80.0.0/13181.80.0.1 to 181.87.255.254181.87.255.255524,286
44181.88.0.0/13181.88.0.1 to 181.95.255.254181.95.255.255524,286
45181.96.0.0/13181.96.0.1 to 181.103.255.254181.103.255.255524,286
46181.104.0.0/13181.104.0.1 to 181.111.255.254181.111.255.255524,286
47181.112.0.0/13181.112.0.1 to 181.119.255.254181.119.255.255524,286
48181.120.0.0/13181.120.0.1 to 181.127.255.254181.127.255.255524,286
49181.128.0.0/13181.128.0.1 to 181.135.255.254181.135.255.255524,286
50181.136.0.0/13181.136.0.1 to 181.143.255.254181.143.255.255524,286
51181.144.0.0/13181.144.0.1 to 181.151.255.254181.151.255.255524,286
52181.152.0.0/13181.152.0.1 to 181.159.255.254181.159.255.255524,286
53181.160.0.0/13181.160.0.1 to 181.167.255.254181.167.255.255524,286
54181.168.0.0/13181.168.0.1 to 181.175.255.254181.175.255.255524,286
55181.176.0.0/13181.176.0.1 to 181.183.255.254181.183.255.255524,286
56181.184.0.0/13181.184.0.1 to 181.191.255.254181.191.255.255524,286
57181.192.0.0/13181.192.0.1 to 181.199.255.254181.199.255.255524,286
58181.200.0.0/13181.200.0.1 to 181.207.255.254181.207.255.255524,286
59181.208.0.0/13181.208.0.1 to 181.215.255.254181.215.255.255524,286
60181.216.0.0/13181.216.0.1 to 181.223.255.254181.223.255.255524,286
61181.224.0.0/13181.224.0.1 to 181.231.255.254181.231.255.255524,286
62181.232.0.0/13181.232.0.1 to 181.239.255.254181.239.255.255524,286
63181.240.0.0/13181.240.0.1 to 181.247.255.254181.247.255.255524,286
64181.248.0.0/13181.248.0.1 to 181.255.255.254181.255.255.255524,286
65182.0.0.0/13182.0.0.1 to 182.7.255.254182.7.255.255524,286
66182.8.0.0/13182.8.0.1 to 182.15.255.254182.15.255.255524,286
67182.16.0.0/13182.16.0.1 to 182.23.255.254182.23.255.255524,286
68182.24.0.0/13182.24.0.1 to 182.31.255.254182.31.255.255524,286
69182.32.0.0/13182.32.0.1 to 182.39.255.254182.39.255.255524,286
70182.40.0.0/13182.40.0.1 to 182.47.255.254182.47.255.255524,286
71182.48.0.0/13182.48.0.1 to 182.55.255.254182.55.255.255524,286
72182.56.0.0/13182.56.0.1 to 182.63.255.254182.63.255.255524,286
73182.64.0.0/13182.64.0.1 to 182.71.255.254182.71.255.255524,286
74182.72.0.0/13182.72.0.1 to 182.79.255.254182.79.255.255524,286
75182.80.0.0/13182.80.0.1 to 182.87.255.254182.87.255.255524,286
76182.88.0.0/13182.88.0.1 to 182.95.255.254182.95.255.255524,286
77182.96.0.0/13182.96.0.1 to 182.103.255.254182.103.255.255524,286
78182.104.0.0/13182.104.0.1 to 182.111.255.254182.111.255.255524,286
79182.112.0.0/13182.112.0.1 to 182.119.255.254182.119.255.255524,286
80182.120.0.0/13182.120.0.1 to 182.127.255.254182.127.255.255524,286
81182.128.0.0/13182.128.0.1 to 182.135.255.254182.135.255.255524,286
82182.136.0.0/13182.136.0.1 to 182.143.255.254182.143.255.255524,286
83182.144.0.0/13182.144.0.1 to 182.151.255.254182.151.255.255524,286
84182.152.0.0/13182.152.0.1 to 182.159.255.254182.159.255.255524,286
85182.160.0.0/13182.160.0.1 to 182.167.255.254182.167.255.255524,286
86182.168.0.0/13182.168.0.1 to 182.175.255.254182.175.255.255524,286
87182.176.0.0/13182.176.0.1 to 182.183.255.254182.183.255.255524,286
88182.184.0.0/13182.184.0.1 to 182.191.255.254182.191.255.255524,286
89182.192.0.0/13182.192.0.1 to 182.199.255.254182.199.255.255524,286
90182.200.0.0/13182.200.0.1 to 182.207.255.254182.207.255.255524,286
91182.208.0.0/13182.208.0.1 to 182.215.255.254182.215.255.255524,286
92182.216.0.0/13182.216.0.1 to 182.223.255.254182.223.255.255524,286
93182.224.0.0/13182.224.0.1 to 182.231.255.254182.231.255.255524,286
94182.232.0.0/13182.232.0.1 to 182.239.255.254182.239.255.255524,286
95182.240.0.0/13182.240.0.1 to 182.247.255.254182.247.255.255524,286
96182.248.0.0/13182.248.0.1 to 182.255.255.254182.255.255.255524,286
97183.0.0.0/13183.0.0.1 to 183.7.255.254183.7.255.255524,286
98183.8.0.0/13183.8.0.1 to 183.15.255.254183.15.255.255524,286
99183.16.0.0/13183.16.0.1 to 183.23.255.254183.23.255.255524,286
100183.24.0.0/13183.24.0.1 to 183.31.255.254183.31.255.255524,286
101183.32.0.0/13183.32.0.1 to 183.39.255.254183.39.255.255524,286
102183.40.0.0/13183.40.0.1 to 183.47.255.254183.47.255.255524,286
103183.48.0.0/13183.48.0.1 to 183.55.255.254183.55.255.255524,286
104183.56.0.0/13183.56.0.1 to 183.63.255.254183.63.255.255524,286
105183.64.0.0/13183.64.0.1 to 183.71.255.254183.71.255.255524,286
106183.72.0.0/13183.72.0.1 to 183.79.255.254183.79.255.255524,286
107183.80.0.0/13183.80.0.1 to 183.87.255.254183.87.255.255524,286
108183.88.0.0/13183.88.0.1 to 183.95.255.254183.95.255.255524,286
109183.96.0.0/13183.96.0.1 to 183.103.255.254183.103.255.255524,286
110183.104.0.0/13183.104.0.1 to 183.111.255.254183.111.255.255524,286
111183.112.0.0/13183.112.0.1 to 183.119.255.254183.119.255.255524,286
112183.120.0.0/13183.120.0.1 to 183.127.255.254183.127.255.255524,286
113183.128.0.0/13183.128.0.1 to 183.135.255.254183.135.255.255524,286
114183.136.0.0/13183.136.0.1 to 183.143.255.254183.143.255.255524,286
115183.144.0.0/13183.144.0.1 to 183.151.255.254183.151.255.255524,286
116183.152.0.0/13183.152.0.1 to 183.159.255.254183.159.255.255524,286
117183.160.0.0/13183.160.0.1 to 183.167.255.254183.167.255.255524,286
118183.168.0.0/13183.168.0.1 to 183.175.255.254183.175.255.255524,286
119183.176.0.0/13183.176.0.1 to 183.183.255.254183.183.255.255524,286
120183.184.0.0/13183.184.0.1 to 183.191.255.254183.191.255.255524,286
121183.192.0.0/13183.192.0.1 to 183.199.255.254183.199.255.255524,286
122183.200.0.0/13183.200.0.1 to 183.207.255.254183.207.255.255524,286
123183.208.0.0/13183.208.0.1 to 183.215.255.254183.215.255.255524,286
124183.216.0.0/13183.216.0.1 to 183.223.255.254183.223.255.255524,286
125183.224.0.0/13183.224.0.1 to 183.231.255.254183.231.255.255524,286
126183.232.0.0/13183.232.0.1 to 183.239.255.254183.239.255.255524,286
127183.240.0.0/13183.240.0.1 to 183.247.255.254183.247.255.255524,286
128183.248.0.0/13183.248.0.1 to 183.255.255.254183.255.255.255524,286

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.