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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.

Network189.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
189.0.0.0
Broadcast address
189.255.255.255
First usable
189.0.0.1
Last usable
189.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex BD000000 · Integer 3170893824 to 3187671039
Reverse DNS zone
189.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111101..00000000.00000000.00000000189.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10111101..00000000.00000000.00000000189.0.0.0
Broadcast10111101..11111111.11111111.11111111189.255.255.255
Split into smaller subnets/15
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

189.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1189.0.0.0/15189.0.0.1 to 189.1.255.254189.1.255.255131,070
2189.2.0.0/15189.2.0.1 to 189.3.255.254189.3.255.255131,070
3189.4.0.0/15189.4.0.1 to 189.5.255.254189.5.255.255131,070
4189.6.0.0/15189.6.0.1 to 189.7.255.254189.7.255.255131,070
5189.8.0.0/15189.8.0.1 to 189.9.255.254189.9.255.255131,070
6189.10.0.0/15189.10.0.1 to 189.11.255.254189.11.255.255131,070
7189.12.0.0/15189.12.0.1 to 189.13.255.254189.13.255.255131,070
8189.14.0.0/15189.14.0.1 to 189.15.255.254189.15.255.255131,070
9189.16.0.0/15189.16.0.1 to 189.17.255.254189.17.255.255131,070
10189.18.0.0/15189.18.0.1 to 189.19.255.254189.19.255.255131,070
11189.20.0.0/15189.20.0.1 to 189.21.255.254189.21.255.255131,070
12189.22.0.0/15189.22.0.1 to 189.23.255.254189.23.255.255131,070
13189.24.0.0/15189.24.0.1 to 189.25.255.254189.25.255.255131,070
14189.26.0.0/15189.26.0.1 to 189.27.255.254189.27.255.255131,070
15189.28.0.0/15189.28.0.1 to 189.29.255.254189.29.255.255131,070
16189.30.0.0/15189.30.0.1 to 189.31.255.254189.31.255.255131,070
17189.32.0.0/15189.32.0.1 to 189.33.255.254189.33.255.255131,070
18189.34.0.0/15189.34.0.1 to 189.35.255.254189.35.255.255131,070
19189.36.0.0/15189.36.0.1 to 189.37.255.254189.37.255.255131,070
20189.38.0.0/15189.38.0.1 to 189.39.255.254189.39.255.255131,070
21189.40.0.0/15189.40.0.1 to 189.41.255.254189.41.255.255131,070
22189.42.0.0/15189.42.0.1 to 189.43.255.254189.43.255.255131,070
23189.44.0.0/15189.44.0.1 to 189.45.255.254189.45.255.255131,070
24189.46.0.0/15189.46.0.1 to 189.47.255.254189.47.255.255131,070
25189.48.0.0/15189.48.0.1 to 189.49.255.254189.49.255.255131,070
26189.50.0.0/15189.50.0.1 to 189.51.255.254189.51.255.255131,070
27189.52.0.0/15189.52.0.1 to 189.53.255.254189.53.255.255131,070
28189.54.0.0/15189.54.0.1 to 189.55.255.254189.55.255.255131,070
29189.56.0.0/15189.56.0.1 to 189.57.255.254189.57.255.255131,070
30189.58.0.0/15189.58.0.1 to 189.59.255.254189.59.255.255131,070
31189.60.0.0/15189.60.0.1 to 189.61.255.254189.61.255.255131,070
32189.62.0.0/15189.62.0.1 to 189.63.255.254189.63.255.255131,070
33189.64.0.0/15189.64.0.1 to 189.65.255.254189.65.255.255131,070
34189.66.0.0/15189.66.0.1 to 189.67.255.254189.67.255.255131,070
35189.68.0.0/15189.68.0.1 to 189.69.255.254189.69.255.255131,070
36189.70.0.0/15189.70.0.1 to 189.71.255.254189.71.255.255131,070
37189.72.0.0/15189.72.0.1 to 189.73.255.254189.73.255.255131,070
38189.74.0.0/15189.74.0.1 to 189.75.255.254189.75.255.255131,070
39189.76.0.0/15189.76.0.1 to 189.77.255.254189.77.255.255131,070
40189.78.0.0/15189.78.0.1 to 189.79.255.254189.79.255.255131,070
41189.80.0.0/15189.80.0.1 to 189.81.255.254189.81.255.255131,070
42189.82.0.0/15189.82.0.1 to 189.83.255.254189.83.255.255131,070
43189.84.0.0/15189.84.0.1 to 189.85.255.254189.85.255.255131,070
44189.86.0.0/15189.86.0.1 to 189.87.255.254189.87.255.255131,070
45189.88.0.0/15189.88.0.1 to 189.89.255.254189.89.255.255131,070
46189.90.0.0/15189.90.0.1 to 189.91.255.254189.91.255.255131,070
47189.92.0.0/15189.92.0.1 to 189.93.255.254189.93.255.255131,070
48189.94.0.0/15189.94.0.1 to 189.95.255.254189.95.255.255131,070
49189.96.0.0/15189.96.0.1 to 189.97.255.254189.97.255.255131,070
50189.98.0.0/15189.98.0.1 to 189.99.255.254189.99.255.255131,070
51189.100.0.0/15189.100.0.1 to 189.101.255.254189.101.255.255131,070
52189.102.0.0/15189.102.0.1 to 189.103.255.254189.103.255.255131,070
53189.104.0.0/15189.104.0.1 to 189.105.255.254189.105.255.255131,070
54189.106.0.0/15189.106.0.1 to 189.107.255.254189.107.255.255131,070
55189.108.0.0/15189.108.0.1 to 189.109.255.254189.109.255.255131,070
56189.110.0.0/15189.110.0.1 to 189.111.255.254189.111.255.255131,070
57189.112.0.0/15189.112.0.1 to 189.113.255.254189.113.255.255131,070
58189.114.0.0/15189.114.0.1 to 189.115.255.254189.115.255.255131,070
59189.116.0.0/15189.116.0.1 to 189.117.255.254189.117.255.255131,070
60189.118.0.0/15189.118.0.1 to 189.119.255.254189.119.255.255131,070
61189.120.0.0/15189.120.0.1 to 189.121.255.254189.121.255.255131,070
62189.122.0.0/15189.122.0.1 to 189.123.255.254189.123.255.255131,070
63189.124.0.0/15189.124.0.1 to 189.125.255.254189.125.255.255131,070
64189.126.0.0/15189.126.0.1 to 189.127.255.254189.127.255.255131,070
65189.128.0.0/15189.128.0.1 to 189.129.255.254189.129.255.255131,070
66189.130.0.0/15189.130.0.1 to 189.131.255.254189.131.255.255131,070
67189.132.0.0/15189.132.0.1 to 189.133.255.254189.133.255.255131,070
68189.134.0.0/15189.134.0.1 to 189.135.255.254189.135.255.255131,070
69189.136.0.0/15189.136.0.1 to 189.137.255.254189.137.255.255131,070
70189.138.0.0/15189.138.0.1 to 189.139.255.254189.139.255.255131,070
71189.140.0.0/15189.140.0.1 to 189.141.255.254189.141.255.255131,070
72189.142.0.0/15189.142.0.1 to 189.143.255.254189.143.255.255131,070
73189.144.0.0/15189.144.0.1 to 189.145.255.254189.145.255.255131,070
74189.146.0.0/15189.146.0.1 to 189.147.255.254189.147.255.255131,070
75189.148.0.0/15189.148.0.1 to 189.149.255.254189.149.255.255131,070
76189.150.0.0/15189.150.0.1 to 189.151.255.254189.151.255.255131,070
77189.152.0.0/15189.152.0.1 to 189.153.255.254189.153.255.255131,070
78189.154.0.0/15189.154.0.1 to 189.155.255.254189.155.255.255131,070
79189.156.0.0/15189.156.0.1 to 189.157.255.254189.157.255.255131,070
80189.158.0.0/15189.158.0.1 to 189.159.255.254189.159.255.255131,070
81189.160.0.0/15189.160.0.1 to 189.161.255.254189.161.255.255131,070
82189.162.0.0/15189.162.0.1 to 189.163.255.254189.163.255.255131,070
83189.164.0.0/15189.164.0.1 to 189.165.255.254189.165.255.255131,070
84189.166.0.0/15189.166.0.1 to 189.167.255.254189.167.255.255131,070
85189.168.0.0/15189.168.0.1 to 189.169.255.254189.169.255.255131,070
86189.170.0.0/15189.170.0.1 to 189.171.255.254189.171.255.255131,070
87189.172.0.0/15189.172.0.1 to 189.173.255.254189.173.255.255131,070
88189.174.0.0/15189.174.0.1 to 189.175.255.254189.175.255.255131,070
89189.176.0.0/15189.176.0.1 to 189.177.255.254189.177.255.255131,070
90189.178.0.0/15189.178.0.1 to 189.179.255.254189.179.255.255131,070
91189.180.0.0/15189.180.0.1 to 189.181.255.254189.181.255.255131,070
92189.182.0.0/15189.182.0.1 to 189.183.255.254189.183.255.255131,070
93189.184.0.0/15189.184.0.1 to 189.185.255.254189.185.255.255131,070
94189.186.0.0/15189.186.0.1 to 189.187.255.254189.187.255.255131,070
95189.188.0.0/15189.188.0.1 to 189.189.255.254189.189.255.255131,070
96189.190.0.0/15189.190.0.1 to 189.191.255.254189.191.255.255131,070
97189.192.0.0/15189.192.0.1 to 189.193.255.254189.193.255.255131,070
98189.194.0.0/15189.194.0.1 to 189.195.255.254189.195.255.255131,070
99189.196.0.0/15189.196.0.1 to 189.197.255.254189.197.255.255131,070
100189.198.0.0/15189.198.0.1 to 189.199.255.254189.199.255.255131,070
101189.200.0.0/15189.200.0.1 to 189.201.255.254189.201.255.255131,070
102189.202.0.0/15189.202.0.1 to 189.203.255.254189.203.255.255131,070
103189.204.0.0/15189.204.0.1 to 189.205.255.254189.205.255.255131,070
104189.206.0.0/15189.206.0.1 to 189.207.255.254189.207.255.255131,070
105189.208.0.0/15189.208.0.1 to 189.209.255.254189.209.255.255131,070
106189.210.0.0/15189.210.0.1 to 189.211.255.254189.211.255.255131,070
107189.212.0.0/15189.212.0.1 to 189.213.255.254189.213.255.255131,070
108189.214.0.0/15189.214.0.1 to 189.215.255.254189.215.255.255131,070
109189.216.0.0/15189.216.0.1 to 189.217.255.254189.217.255.255131,070
110189.218.0.0/15189.218.0.1 to 189.219.255.254189.219.255.255131,070
111189.220.0.0/15189.220.0.1 to 189.221.255.254189.221.255.255131,070
112189.222.0.0/15189.222.0.1 to 189.223.255.254189.223.255.255131,070
113189.224.0.0/15189.224.0.1 to 189.225.255.254189.225.255.255131,070
114189.226.0.0/15189.226.0.1 to 189.227.255.254189.227.255.255131,070
115189.228.0.0/15189.228.0.1 to 189.229.255.254189.229.255.255131,070
116189.230.0.0/15189.230.0.1 to 189.231.255.254189.231.255.255131,070
117189.232.0.0/15189.232.0.1 to 189.233.255.254189.233.255.255131,070
118189.234.0.0/15189.234.0.1 to 189.235.255.254189.235.255.255131,070
119189.236.0.0/15189.236.0.1 to 189.237.255.254189.237.255.255131,070
120189.238.0.0/15189.238.0.1 to 189.239.255.254189.239.255.255131,070
121189.240.0.0/15189.240.0.1 to 189.241.255.254189.241.255.255131,070
122189.242.0.0/15189.242.0.1 to 189.243.255.254189.243.255.255131,070
123189.244.0.0/15189.244.0.1 to 189.245.255.254189.245.255.255131,070
124189.246.0.0/15189.246.0.1 to 189.247.255.254189.247.255.255131,070
125189.248.0.0/15189.248.0.1 to 189.249.255.254189.249.255.255131,070
126189.250.0.0/15189.250.0.1 to 189.251.255.254189.251.255.255131,070
127189.252.0.0/15189.252.0.1 to 189.253.255.254189.253.255.255131,070
128189.254.0.0/15189.254.0.1 to 189.255.255.254189.255.255.255131,070

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.