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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.

Network164.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
164.0.0.0
Broadcast address
167.255.255.255
First usable
164.0.0.1
Last usable
167.255.255.254
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 A4000000 · Integer 2751463424 to 2818572287
Reverse DNS zones
164.in-addr.arpa
165.in-addr.arpa
166.in-addr.arpa
167.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
Address10100100.00000000.00000000.00000000164.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network10100100.00000000.00000000.00000000164.0.0.0
Broadcast10100111.11111111.11111111.11111111167.255.255.255
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)

164.0.0.0/6 makes 128 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1164.0.0.0/13164.0.0.1 to 164.7.255.254164.7.255.255524,286
2164.8.0.0/13164.8.0.1 to 164.15.255.254164.15.255.255524,286
3164.16.0.0/13164.16.0.1 to 164.23.255.254164.23.255.255524,286
4164.24.0.0/13164.24.0.1 to 164.31.255.254164.31.255.255524,286
5164.32.0.0/13164.32.0.1 to 164.39.255.254164.39.255.255524,286
6164.40.0.0/13164.40.0.1 to 164.47.255.254164.47.255.255524,286
7164.48.0.0/13164.48.0.1 to 164.55.255.254164.55.255.255524,286
8164.56.0.0/13164.56.0.1 to 164.63.255.254164.63.255.255524,286
9164.64.0.0/13164.64.0.1 to 164.71.255.254164.71.255.255524,286
10164.72.0.0/13164.72.0.1 to 164.79.255.254164.79.255.255524,286
11164.80.0.0/13164.80.0.1 to 164.87.255.254164.87.255.255524,286
12164.88.0.0/13164.88.0.1 to 164.95.255.254164.95.255.255524,286
13164.96.0.0/13164.96.0.1 to 164.103.255.254164.103.255.255524,286
14164.104.0.0/13164.104.0.1 to 164.111.255.254164.111.255.255524,286
15164.112.0.0/13164.112.0.1 to 164.119.255.254164.119.255.255524,286
16164.120.0.0/13164.120.0.1 to 164.127.255.254164.127.255.255524,286
17164.128.0.0/13164.128.0.1 to 164.135.255.254164.135.255.255524,286
18164.136.0.0/13164.136.0.1 to 164.143.255.254164.143.255.255524,286
19164.144.0.0/13164.144.0.1 to 164.151.255.254164.151.255.255524,286
20164.152.0.0/13164.152.0.1 to 164.159.255.254164.159.255.255524,286
21164.160.0.0/13164.160.0.1 to 164.167.255.254164.167.255.255524,286
22164.168.0.0/13164.168.0.1 to 164.175.255.254164.175.255.255524,286
23164.176.0.0/13164.176.0.1 to 164.183.255.254164.183.255.255524,286
24164.184.0.0/13164.184.0.1 to 164.191.255.254164.191.255.255524,286
25164.192.0.0/13164.192.0.1 to 164.199.255.254164.199.255.255524,286
26164.200.0.0/13164.200.0.1 to 164.207.255.254164.207.255.255524,286
27164.208.0.0/13164.208.0.1 to 164.215.255.254164.215.255.255524,286
28164.216.0.0/13164.216.0.1 to 164.223.255.254164.223.255.255524,286
29164.224.0.0/13164.224.0.1 to 164.231.255.254164.231.255.255524,286
30164.232.0.0/13164.232.0.1 to 164.239.255.254164.239.255.255524,286
31164.240.0.0/13164.240.0.1 to 164.247.255.254164.247.255.255524,286
32164.248.0.0/13164.248.0.1 to 164.255.255.254164.255.255.255524,286
33165.0.0.0/13165.0.0.1 to 165.7.255.254165.7.255.255524,286
34165.8.0.0/13165.8.0.1 to 165.15.255.254165.15.255.255524,286
35165.16.0.0/13165.16.0.1 to 165.23.255.254165.23.255.255524,286
36165.24.0.0/13165.24.0.1 to 165.31.255.254165.31.255.255524,286
37165.32.0.0/13165.32.0.1 to 165.39.255.254165.39.255.255524,286
38165.40.0.0/13165.40.0.1 to 165.47.255.254165.47.255.255524,286
39165.48.0.0/13165.48.0.1 to 165.55.255.254165.55.255.255524,286
40165.56.0.0/13165.56.0.1 to 165.63.255.254165.63.255.255524,286
41165.64.0.0/13165.64.0.1 to 165.71.255.254165.71.255.255524,286
42165.72.0.0/13165.72.0.1 to 165.79.255.254165.79.255.255524,286
43165.80.0.0/13165.80.0.1 to 165.87.255.254165.87.255.255524,286
44165.88.0.0/13165.88.0.1 to 165.95.255.254165.95.255.255524,286
45165.96.0.0/13165.96.0.1 to 165.103.255.254165.103.255.255524,286
46165.104.0.0/13165.104.0.1 to 165.111.255.254165.111.255.255524,286
47165.112.0.0/13165.112.0.1 to 165.119.255.254165.119.255.255524,286
48165.120.0.0/13165.120.0.1 to 165.127.255.254165.127.255.255524,286
49165.128.0.0/13165.128.0.1 to 165.135.255.254165.135.255.255524,286
50165.136.0.0/13165.136.0.1 to 165.143.255.254165.143.255.255524,286
51165.144.0.0/13165.144.0.1 to 165.151.255.254165.151.255.255524,286
52165.152.0.0/13165.152.0.1 to 165.159.255.254165.159.255.255524,286
53165.160.0.0/13165.160.0.1 to 165.167.255.254165.167.255.255524,286
54165.168.0.0/13165.168.0.1 to 165.175.255.254165.175.255.255524,286
55165.176.0.0/13165.176.0.1 to 165.183.255.254165.183.255.255524,286
56165.184.0.0/13165.184.0.1 to 165.191.255.254165.191.255.255524,286
57165.192.0.0/13165.192.0.1 to 165.199.255.254165.199.255.255524,286
58165.200.0.0/13165.200.0.1 to 165.207.255.254165.207.255.255524,286
59165.208.0.0/13165.208.0.1 to 165.215.255.254165.215.255.255524,286
60165.216.0.0/13165.216.0.1 to 165.223.255.254165.223.255.255524,286
61165.224.0.0/13165.224.0.1 to 165.231.255.254165.231.255.255524,286
62165.232.0.0/13165.232.0.1 to 165.239.255.254165.239.255.255524,286
63165.240.0.0/13165.240.0.1 to 165.247.255.254165.247.255.255524,286
64165.248.0.0/13165.248.0.1 to 165.255.255.254165.255.255.255524,286
65166.0.0.0/13166.0.0.1 to 166.7.255.254166.7.255.255524,286
66166.8.0.0/13166.8.0.1 to 166.15.255.254166.15.255.255524,286
67166.16.0.0/13166.16.0.1 to 166.23.255.254166.23.255.255524,286
68166.24.0.0/13166.24.0.1 to 166.31.255.254166.31.255.255524,286
69166.32.0.0/13166.32.0.1 to 166.39.255.254166.39.255.255524,286
70166.40.0.0/13166.40.0.1 to 166.47.255.254166.47.255.255524,286
71166.48.0.0/13166.48.0.1 to 166.55.255.254166.55.255.255524,286
72166.56.0.0/13166.56.0.1 to 166.63.255.254166.63.255.255524,286
73166.64.0.0/13166.64.0.1 to 166.71.255.254166.71.255.255524,286
74166.72.0.0/13166.72.0.1 to 166.79.255.254166.79.255.255524,286
75166.80.0.0/13166.80.0.1 to 166.87.255.254166.87.255.255524,286
76166.88.0.0/13166.88.0.1 to 166.95.255.254166.95.255.255524,286
77166.96.0.0/13166.96.0.1 to 166.103.255.254166.103.255.255524,286
78166.104.0.0/13166.104.0.1 to 166.111.255.254166.111.255.255524,286
79166.112.0.0/13166.112.0.1 to 166.119.255.254166.119.255.255524,286
80166.120.0.0/13166.120.0.1 to 166.127.255.254166.127.255.255524,286
81166.128.0.0/13166.128.0.1 to 166.135.255.254166.135.255.255524,286
82166.136.0.0/13166.136.0.1 to 166.143.255.254166.143.255.255524,286
83166.144.0.0/13166.144.0.1 to 166.151.255.254166.151.255.255524,286
84166.152.0.0/13166.152.0.1 to 166.159.255.254166.159.255.255524,286
85166.160.0.0/13166.160.0.1 to 166.167.255.254166.167.255.255524,286
86166.168.0.0/13166.168.0.1 to 166.175.255.254166.175.255.255524,286
87166.176.0.0/13166.176.0.1 to 166.183.255.254166.183.255.255524,286
88166.184.0.0/13166.184.0.1 to 166.191.255.254166.191.255.255524,286
89166.192.0.0/13166.192.0.1 to 166.199.255.254166.199.255.255524,286
90166.200.0.0/13166.200.0.1 to 166.207.255.254166.207.255.255524,286
91166.208.0.0/13166.208.0.1 to 166.215.255.254166.215.255.255524,286
92166.216.0.0/13166.216.0.1 to 166.223.255.254166.223.255.255524,286
93166.224.0.0/13166.224.0.1 to 166.231.255.254166.231.255.255524,286
94166.232.0.0/13166.232.0.1 to 166.239.255.254166.239.255.255524,286
95166.240.0.0/13166.240.0.1 to 166.247.255.254166.247.255.255524,286
96166.248.0.0/13166.248.0.1 to 166.255.255.254166.255.255.255524,286
97167.0.0.0/13167.0.0.1 to 167.7.255.254167.7.255.255524,286
98167.8.0.0/13167.8.0.1 to 167.15.255.254167.15.255.255524,286
99167.16.0.0/13167.16.0.1 to 167.23.255.254167.23.255.255524,286
100167.24.0.0/13167.24.0.1 to 167.31.255.254167.31.255.255524,286
101167.32.0.0/13167.32.0.1 to 167.39.255.254167.39.255.255524,286
102167.40.0.0/13167.40.0.1 to 167.47.255.254167.47.255.255524,286
103167.48.0.0/13167.48.0.1 to 167.55.255.254167.55.255.255524,286
104167.56.0.0/13167.56.0.1 to 167.63.255.254167.63.255.255524,286
105167.64.0.0/13167.64.0.1 to 167.71.255.254167.71.255.255524,286
106167.72.0.0/13167.72.0.1 to 167.79.255.254167.79.255.255524,286
107167.80.0.0/13167.80.0.1 to 167.87.255.254167.87.255.255524,286
108167.88.0.0/13167.88.0.1 to 167.95.255.254167.95.255.255524,286
109167.96.0.0/13167.96.0.1 to 167.103.255.254167.103.255.255524,286
110167.104.0.0/13167.104.0.1 to 167.111.255.254167.111.255.255524,286
111167.112.0.0/13167.112.0.1 to 167.119.255.254167.119.255.255524,286
112167.120.0.0/13167.120.0.1 to 167.127.255.254167.127.255.255524,286
113167.128.0.0/13167.128.0.1 to 167.135.255.254167.135.255.255524,286
114167.136.0.0/13167.136.0.1 to 167.143.255.254167.143.255.255524,286
115167.144.0.0/13167.144.0.1 to 167.151.255.254167.151.255.255524,286
116167.152.0.0/13167.152.0.1 to 167.159.255.254167.159.255.255524,286
117167.160.0.0/13167.160.0.1 to 167.167.255.254167.167.255.255524,286
118167.168.0.0/13167.168.0.1 to 167.175.255.254167.175.255.255524,286
119167.176.0.0/13167.176.0.1 to 167.183.255.254167.183.255.255524,286
120167.184.0.0/13167.184.0.1 to 167.191.255.254167.191.255.255524,286
121167.192.0.0/13167.192.0.1 to 167.199.255.254167.199.255.255524,286
122167.200.0.0/13167.200.0.1 to 167.207.255.254167.207.255.255524,286
123167.208.0.0/13167.208.0.1 to 167.215.255.254167.215.255.255524,286
124167.216.0.0/13167.216.0.1 to 167.223.255.254167.223.255.255524,286
125167.224.0.0/13167.224.0.1 to 167.231.255.254167.231.255.255524,286
126167.232.0.0/13167.232.0.1 to 167.239.255.254167.239.255.255524,286
127167.240.0.0/13167.240.0.1 to 167.247.255.254167.247.255.255524,286
128167.248.0.0/13167.248.0.1 to 167.255.255.254167.255.255.255524,286

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.