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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.

Network188.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
188.0.0.0
Broadcast address
191.255.255.255
First usable
188.0.0.1
Last usable
191.255.255.254
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 BC000000 · Integer 3154116608 to 3221225471
Reverse DNS zones
188.in-addr.arpa
189.in-addr.arpa
190.in-addr.arpa
191.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
Address10111100.00000000.00000000.00000000188.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network10111100.00000000.00000000.00000000188.0.0.0
Broadcast10111111.11111111.11111111.11111111191.255.255.255
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)

188.0.0.0/6 makes 128 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1188.0.0.0/13188.0.0.1 to 188.7.255.254188.7.255.255524,286
2188.8.0.0/13188.8.0.1 to 188.15.255.254188.15.255.255524,286
3188.16.0.0/13188.16.0.1 to 188.23.255.254188.23.255.255524,286
4188.24.0.0/13188.24.0.1 to 188.31.255.254188.31.255.255524,286
5188.32.0.0/13188.32.0.1 to 188.39.255.254188.39.255.255524,286
6188.40.0.0/13188.40.0.1 to 188.47.255.254188.47.255.255524,286
7188.48.0.0/13188.48.0.1 to 188.55.255.254188.55.255.255524,286
8188.56.0.0/13188.56.0.1 to 188.63.255.254188.63.255.255524,286
9188.64.0.0/13188.64.0.1 to 188.71.255.254188.71.255.255524,286
10188.72.0.0/13188.72.0.1 to 188.79.255.254188.79.255.255524,286
11188.80.0.0/13188.80.0.1 to 188.87.255.254188.87.255.255524,286
12188.88.0.0/13188.88.0.1 to 188.95.255.254188.95.255.255524,286
13188.96.0.0/13188.96.0.1 to 188.103.255.254188.103.255.255524,286
14188.104.0.0/13188.104.0.1 to 188.111.255.254188.111.255.255524,286
15188.112.0.0/13188.112.0.1 to 188.119.255.254188.119.255.255524,286
16188.120.0.0/13188.120.0.1 to 188.127.255.254188.127.255.255524,286
17188.128.0.0/13188.128.0.1 to 188.135.255.254188.135.255.255524,286
18188.136.0.0/13188.136.0.1 to 188.143.255.254188.143.255.255524,286
19188.144.0.0/13188.144.0.1 to 188.151.255.254188.151.255.255524,286
20188.152.0.0/13188.152.0.1 to 188.159.255.254188.159.255.255524,286
21188.160.0.0/13188.160.0.1 to 188.167.255.254188.167.255.255524,286
22188.168.0.0/13188.168.0.1 to 188.175.255.254188.175.255.255524,286
23188.176.0.0/13188.176.0.1 to 188.183.255.254188.183.255.255524,286
24188.184.0.0/13188.184.0.1 to 188.191.255.254188.191.255.255524,286
25188.192.0.0/13188.192.0.1 to 188.199.255.254188.199.255.255524,286
26188.200.0.0/13188.200.0.1 to 188.207.255.254188.207.255.255524,286
27188.208.0.0/13188.208.0.1 to 188.215.255.254188.215.255.255524,286
28188.216.0.0/13188.216.0.1 to 188.223.255.254188.223.255.255524,286
29188.224.0.0/13188.224.0.1 to 188.231.255.254188.231.255.255524,286
30188.232.0.0/13188.232.0.1 to 188.239.255.254188.239.255.255524,286
31188.240.0.0/13188.240.0.1 to 188.247.255.254188.247.255.255524,286
32188.248.0.0/13188.248.0.1 to 188.255.255.254188.255.255.255524,286
33189.0.0.0/13189.0.0.1 to 189.7.255.254189.7.255.255524,286
34189.8.0.0/13189.8.0.1 to 189.15.255.254189.15.255.255524,286
35189.16.0.0/13189.16.0.1 to 189.23.255.254189.23.255.255524,286
36189.24.0.0/13189.24.0.1 to 189.31.255.254189.31.255.255524,286
37189.32.0.0/13189.32.0.1 to 189.39.255.254189.39.255.255524,286
38189.40.0.0/13189.40.0.1 to 189.47.255.254189.47.255.255524,286
39189.48.0.0/13189.48.0.1 to 189.55.255.254189.55.255.255524,286
40189.56.0.0/13189.56.0.1 to 189.63.255.254189.63.255.255524,286
41189.64.0.0/13189.64.0.1 to 189.71.255.254189.71.255.255524,286
42189.72.0.0/13189.72.0.1 to 189.79.255.254189.79.255.255524,286
43189.80.0.0/13189.80.0.1 to 189.87.255.254189.87.255.255524,286
44189.88.0.0/13189.88.0.1 to 189.95.255.254189.95.255.255524,286
45189.96.0.0/13189.96.0.1 to 189.103.255.254189.103.255.255524,286
46189.104.0.0/13189.104.0.1 to 189.111.255.254189.111.255.255524,286
47189.112.0.0/13189.112.0.1 to 189.119.255.254189.119.255.255524,286
48189.120.0.0/13189.120.0.1 to 189.127.255.254189.127.255.255524,286
49189.128.0.0/13189.128.0.1 to 189.135.255.254189.135.255.255524,286
50189.136.0.0/13189.136.0.1 to 189.143.255.254189.143.255.255524,286
51189.144.0.0/13189.144.0.1 to 189.151.255.254189.151.255.255524,286
52189.152.0.0/13189.152.0.1 to 189.159.255.254189.159.255.255524,286
53189.160.0.0/13189.160.0.1 to 189.167.255.254189.167.255.255524,286
54189.168.0.0/13189.168.0.1 to 189.175.255.254189.175.255.255524,286
55189.176.0.0/13189.176.0.1 to 189.183.255.254189.183.255.255524,286
56189.184.0.0/13189.184.0.1 to 189.191.255.254189.191.255.255524,286
57189.192.0.0/13189.192.0.1 to 189.199.255.254189.199.255.255524,286
58189.200.0.0/13189.200.0.1 to 189.207.255.254189.207.255.255524,286
59189.208.0.0/13189.208.0.1 to 189.215.255.254189.215.255.255524,286
60189.216.0.0/13189.216.0.1 to 189.223.255.254189.223.255.255524,286
61189.224.0.0/13189.224.0.1 to 189.231.255.254189.231.255.255524,286
62189.232.0.0/13189.232.0.1 to 189.239.255.254189.239.255.255524,286
63189.240.0.0/13189.240.0.1 to 189.247.255.254189.247.255.255524,286
64189.248.0.0/13189.248.0.1 to 189.255.255.254189.255.255.255524,286
65190.0.0.0/13190.0.0.1 to 190.7.255.254190.7.255.255524,286
66190.8.0.0/13190.8.0.1 to 190.15.255.254190.15.255.255524,286
67190.16.0.0/13190.16.0.1 to 190.23.255.254190.23.255.255524,286
68190.24.0.0/13190.24.0.1 to 190.31.255.254190.31.255.255524,286
69190.32.0.0/13190.32.0.1 to 190.39.255.254190.39.255.255524,286
70190.40.0.0/13190.40.0.1 to 190.47.255.254190.47.255.255524,286
71190.48.0.0/13190.48.0.1 to 190.55.255.254190.55.255.255524,286
72190.56.0.0/13190.56.0.1 to 190.63.255.254190.63.255.255524,286
73190.64.0.0/13190.64.0.1 to 190.71.255.254190.71.255.255524,286
74190.72.0.0/13190.72.0.1 to 190.79.255.254190.79.255.255524,286
75190.80.0.0/13190.80.0.1 to 190.87.255.254190.87.255.255524,286
76190.88.0.0/13190.88.0.1 to 190.95.255.254190.95.255.255524,286
77190.96.0.0/13190.96.0.1 to 190.103.255.254190.103.255.255524,286
78190.104.0.0/13190.104.0.1 to 190.111.255.254190.111.255.255524,286
79190.112.0.0/13190.112.0.1 to 190.119.255.254190.119.255.255524,286
80190.120.0.0/13190.120.0.1 to 190.127.255.254190.127.255.255524,286
81190.128.0.0/13190.128.0.1 to 190.135.255.254190.135.255.255524,286
82190.136.0.0/13190.136.0.1 to 190.143.255.254190.143.255.255524,286
83190.144.0.0/13190.144.0.1 to 190.151.255.254190.151.255.255524,286
84190.152.0.0/13190.152.0.1 to 190.159.255.254190.159.255.255524,286
85190.160.0.0/13190.160.0.1 to 190.167.255.254190.167.255.255524,286
86190.168.0.0/13190.168.0.1 to 190.175.255.254190.175.255.255524,286
87190.176.0.0/13190.176.0.1 to 190.183.255.254190.183.255.255524,286
88190.184.0.0/13190.184.0.1 to 190.191.255.254190.191.255.255524,286
89190.192.0.0/13190.192.0.1 to 190.199.255.254190.199.255.255524,286
90190.200.0.0/13190.200.0.1 to 190.207.255.254190.207.255.255524,286
91190.208.0.0/13190.208.0.1 to 190.215.255.254190.215.255.255524,286
92190.216.0.0/13190.216.0.1 to 190.223.255.254190.223.255.255524,286
93190.224.0.0/13190.224.0.1 to 190.231.255.254190.231.255.255524,286
94190.232.0.0/13190.232.0.1 to 190.239.255.254190.239.255.255524,286
95190.240.0.0/13190.240.0.1 to 190.247.255.254190.247.255.255524,286
96190.248.0.0/13190.248.0.1 to 190.255.255.254190.255.255.255524,286
97191.0.0.0/13191.0.0.1 to 191.7.255.254191.7.255.255524,286
98191.8.0.0/13191.8.0.1 to 191.15.255.254191.15.255.255524,286
99191.16.0.0/13191.16.0.1 to 191.23.255.254191.23.255.255524,286
100191.24.0.0/13191.24.0.1 to 191.31.255.254191.31.255.255524,286
101191.32.0.0/13191.32.0.1 to 191.39.255.254191.39.255.255524,286
102191.40.0.0/13191.40.0.1 to 191.47.255.254191.47.255.255524,286
103191.48.0.0/13191.48.0.1 to 191.55.255.254191.55.255.255524,286
104191.56.0.0/13191.56.0.1 to 191.63.255.254191.63.255.255524,286
105191.64.0.0/13191.64.0.1 to 191.71.255.254191.71.255.255524,286
106191.72.0.0/13191.72.0.1 to 191.79.255.254191.79.255.255524,286
107191.80.0.0/13191.80.0.1 to 191.87.255.254191.87.255.255524,286
108191.88.0.0/13191.88.0.1 to 191.95.255.254191.95.255.255524,286
109191.96.0.0/13191.96.0.1 to 191.103.255.254191.103.255.255524,286
110191.104.0.0/13191.104.0.1 to 191.111.255.254191.111.255.255524,286
111191.112.0.0/13191.112.0.1 to 191.119.255.254191.119.255.255524,286
112191.120.0.0/13191.120.0.1 to 191.127.255.254191.127.255.255524,286
113191.128.0.0/13191.128.0.1 to 191.135.255.254191.135.255.255524,286
114191.136.0.0/13191.136.0.1 to 191.143.255.254191.143.255.255524,286
115191.144.0.0/13191.144.0.1 to 191.151.255.254191.151.255.255524,286
116191.152.0.0/13191.152.0.1 to 191.159.255.254191.159.255.255524,286
117191.160.0.0/13191.160.0.1 to 191.167.255.254191.167.255.255524,286
118191.168.0.0/13191.168.0.1 to 191.175.255.254191.175.255.255524,286
119191.176.0.0/13191.176.0.1 to 191.183.255.254191.183.255.255524,286
120191.184.0.0/13191.184.0.1 to 191.191.255.254191.191.255.255524,286
121191.192.0.0/13191.192.0.1 to 191.199.255.254191.199.255.255524,286
122191.200.0.0/13191.200.0.1 to 191.207.255.254191.207.255.255524,286
123191.208.0.0/13191.208.0.1 to 191.215.255.254191.215.255.255524,286
124191.216.0.0/13191.216.0.1 to 191.223.255.254191.223.255.255524,286
125191.224.0.0/13191.224.0.1 to 191.231.255.254191.231.255.255524,286
126191.232.0.0/13191.232.0.1 to 191.239.255.254191.239.255.255524,286
127191.240.0.0/13191.240.0.1 to 191.247.255.254191.247.255.255524,286
128191.248.0.0/13191.248.0.1 to 191.255.255.254191.255.255.255524,286

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.