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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.

Network167.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
167.128.0.0
Broadcast address
167.255.255.255
First usable
167.128.0.1
Last usable
167.255.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
B (default /16)
As numbers
Hex A7800000 · Integer 2810183680 to 2818572287
Reverse DNS zones
128.167.in-addr.arpa
129.167.in-addr.arpa
130.167.in-addr.arpa
131.167.in-addr.arpa
132.167.in-addr.arpa
133.167.in-addr.arpa
134.167.in-addr.arpa
135.167.in-addr.arpa
136.167.in-addr.arpa
137.167.in-addr.arpa
138.167.in-addr.arpa
139.167.in-addr.arpa
140.167.in-addr.arpa
141.167.in-addr.arpa
142.167.in-addr.arpa
143.167.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100111.10000000.00000000.00000000167.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network10100111.10000000.00000000.00000000167.128.0.0
Broadcast10100111.11111111.11111111.11111111167.255.255.255
Split into smaller subnets/16
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

167.128.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1167.128.0.0/16167.128.0.1 to 167.128.255.254167.128.255.25565,534
2167.129.0.0/16167.129.0.1 to 167.129.255.254167.129.255.25565,534
3167.130.0.0/16167.130.0.1 to 167.130.255.254167.130.255.25565,534
4167.131.0.0/16167.131.0.1 to 167.131.255.254167.131.255.25565,534
5167.132.0.0/16167.132.0.1 to 167.132.255.254167.132.255.25565,534
6167.133.0.0/16167.133.0.1 to 167.133.255.254167.133.255.25565,534
7167.134.0.0/16167.134.0.1 to 167.134.255.254167.134.255.25565,534
8167.135.0.0/16167.135.0.1 to 167.135.255.254167.135.255.25565,534
9167.136.0.0/16167.136.0.1 to 167.136.255.254167.136.255.25565,534
10167.137.0.0/16167.137.0.1 to 167.137.255.254167.137.255.25565,534
11167.138.0.0/16167.138.0.1 to 167.138.255.254167.138.255.25565,534
12167.139.0.0/16167.139.0.1 to 167.139.255.254167.139.255.25565,534
13167.140.0.0/16167.140.0.1 to 167.140.255.254167.140.255.25565,534
14167.141.0.0/16167.141.0.1 to 167.141.255.254167.141.255.25565,534
15167.142.0.0/16167.142.0.1 to 167.142.255.254167.142.255.25565,534
16167.143.0.0/16167.143.0.1 to 167.143.255.254167.143.255.25565,534
17167.144.0.0/16167.144.0.1 to 167.144.255.254167.144.255.25565,534
18167.145.0.0/16167.145.0.1 to 167.145.255.254167.145.255.25565,534
19167.146.0.0/16167.146.0.1 to 167.146.255.254167.146.255.25565,534
20167.147.0.0/16167.147.0.1 to 167.147.255.254167.147.255.25565,534
21167.148.0.0/16167.148.0.1 to 167.148.255.254167.148.255.25565,534
22167.149.0.0/16167.149.0.1 to 167.149.255.254167.149.255.25565,534
23167.150.0.0/16167.150.0.1 to 167.150.255.254167.150.255.25565,534
24167.151.0.0/16167.151.0.1 to 167.151.255.254167.151.255.25565,534
25167.152.0.0/16167.152.0.1 to 167.152.255.254167.152.255.25565,534
26167.153.0.0/16167.153.0.1 to 167.153.255.254167.153.255.25565,534
27167.154.0.0/16167.154.0.1 to 167.154.255.254167.154.255.25565,534
28167.155.0.0/16167.155.0.1 to 167.155.255.254167.155.255.25565,534
29167.156.0.0/16167.156.0.1 to 167.156.255.254167.156.255.25565,534
30167.157.0.0/16167.157.0.1 to 167.157.255.254167.157.255.25565,534
31167.158.0.0/16167.158.0.1 to 167.158.255.254167.158.255.25565,534
32167.159.0.0/16167.159.0.1 to 167.159.255.254167.159.255.25565,534
33167.160.0.0/16167.160.0.1 to 167.160.255.254167.160.255.25565,534
34167.161.0.0/16167.161.0.1 to 167.161.255.254167.161.255.25565,534
35167.162.0.0/16167.162.0.1 to 167.162.255.254167.162.255.25565,534
36167.163.0.0/16167.163.0.1 to 167.163.255.254167.163.255.25565,534
37167.164.0.0/16167.164.0.1 to 167.164.255.254167.164.255.25565,534
38167.165.0.0/16167.165.0.1 to 167.165.255.254167.165.255.25565,534
39167.166.0.0/16167.166.0.1 to 167.166.255.254167.166.255.25565,534
40167.167.0.0/16167.167.0.1 to 167.167.255.254167.167.255.25565,534
41167.168.0.0/16167.168.0.1 to 167.168.255.254167.168.255.25565,534
42167.169.0.0/16167.169.0.1 to 167.169.255.254167.169.255.25565,534
43167.170.0.0/16167.170.0.1 to 167.170.255.254167.170.255.25565,534
44167.171.0.0/16167.171.0.1 to 167.171.255.254167.171.255.25565,534
45167.172.0.0/16167.172.0.1 to 167.172.255.254167.172.255.25565,534
46167.173.0.0/16167.173.0.1 to 167.173.255.254167.173.255.25565,534
47167.174.0.0/16167.174.0.1 to 167.174.255.254167.174.255.25565,534
48167.175.0.0/16167.175.0.1 to 167.175.255.254167.175.255.25565,534
49167.176.0.0/16167.176.0.1 to 167.176.255.254167.176.255.25565,534
50167.177.0.0/16167.177.0.1 to 167.177.255.254167.177.255.25565,534
51167.178.0.0/16167.178.0.1 to 167.178.255.254167.178.255.25565,534
52167.179.0.0/16167.179.0.1 to 167.179.255.254167.179.255.25565,534
53167.180.0.0/16167.180.0.1 to 167.180.255.254167.180.255.25565,534
54167.181.0.0/16167.181.0.1 to 167.181.255.254167.181.255.25565,534
55167.182.0.0/16167.182.0.1 to 167.182.255.254167.182.255.25565,534
56167.183.0.0/16167.183.0.1 to 167.183.255.254167.183.255.25565,534
57167.184.0.0/16167.184.0.1 to 167.184.255.254167.184.255.25565,534
58167.185.0.0/16167.185.0.1 to 167.185.255.254167.185.255.25565,534
59167.186.0.0/16167.186.0.1 to 167.186.255.254167.186.255.25565,534
60167.187.0.0/16167.187.0.1 to 167.187.255.254167.187.255.25565,534
61167.188.0.0/16167.188.0.1 to 167.188.255.254167.188.255.25565,534
62167.189.0.0/16167.189.0.1 to 167.189.255.254167.189.255.25565,534
63167.190.0.0/16167.190.0.1 to 167.190.255.254167.190.255.25565,534
64167.191.0.0/16167.191.0.1 to 167.191.255.254167.191.255.25565,534
65167.192.0.0/16167.192.0.1 to 167.192.255.254167.192.255.25565,534
66167.193.0.0/16167.193.0.1 to 167.193.255.254167.193.255.25565,534
67167.194.0.0/16167.194.0.1 to 167.194.255.254167.194.255.25565,534
68167.195.0.0/16167.195.0.1 to 167.195.255.254167.195.255.25565,534
69167.196.0.0/16167.196.0.1 to 167.196.255.254167.196.255.25565,534
70167.197.0.0/16167.197.0.1 to 167.197.255.254167.197.255.25565,534
71167.198.0.0/16167.198.0.1 to 167.198.255.254167.198.255.25565,534
72167.199.0.0/16167.199.0.1 to 167.199.255.254167.199.255.25565,534
73167.200.0.0/16167.200.0.1 to 167.200.255.254167.200.255.25565,534
74167.201.0.0/16167.201.0.1 to 167.201.255.254167.201.255.25565,534
75167.202.0.0/16167.202.0.1 to 167.202.255.254167.202.255.25565,534
76167.203.0.0/16167.203.0.1 to 167.203.255.254167.203.255.25565,534
77167.204.0.0/16167.204.0.1 to 167.204.255.254167.204.255.25565,534
78167.205.0.0/16167.205.0.1 to 167.205.255.254167.205.255.25565,534
79167.206.0.0/16167.206.0.1 to 167.206.255.254167.206.255.25565,534
80167.207.0.0/16167.207.0.1 to 167.207.255.254167.207.255.25565,534
81167.208.0.0/16167.208.0.1 to 167.208.255.254167.208.255.25565,534
82167.209.0.0/16167.209.0.1 to 167.209.255.254167.209.255.25565,534
83167.210.0.0/16167.210.0.1 to 167.210.255.254167.210.255.25565,534
84167.211.0.0/16167.211.0.1 to 167.211.255.254167.211.255.25565,534
85167.212.0.0/16167.212.0.1 to 167.212.255.254167.212.255.25565,534
86167.213.0.0/16167.213.0.1 to 167.213.255.254167.213.255.25565,534
87167.214.0.0/16167.214.0.1 to 167.214.255.254167.214.255.25565,534
88167.215.0.0/16167.215.0.1 to 167.215.255.254167.215.255.25565,534
89167.216.0.0/16167.216.0.1 to 167.216.255.254167.216.255.25565,534
90167.217.0.0/16167.217.0.1 to 167.217.255.254167.217.255.25565,534
91167.218.0.0/16167.218.0.1 to 167.218.255.254167.218.255.25565,534
92167.219.0.0/16167.219.0.1 to 167.219.255.254167.219.255.25565,534
93167.220.0.0/16167.220.0.1 to 167.220.255.254167.220.255.25565,534
94167.221.0.0/16167.221.0.1 to 167.221.255.254167.221.255.25565,534
95167.222.0.0/16167.222.0.1 to 167.222.255.254167.222.255.25565,534
96167.223.0.0/16167.223.0.1 to 167.223.255.254167.223.255.25565,534
97167.224.0.0/16167.224.0.1 to 167.224.255.254167.224.255.25565,534
98167.225.0.0/16167.225.0.1 to 167.225.255.254167.225.255.25565,534
99167.226.0.0/16167.226.0.1 to 167.226.255.254167.226.255.25565,534
100167.227.0.0/16167.227.0.1 to 167.227.255.254167.227.255.25565,534
101167.228.0.0/16167.228.0.1 to 167.228.255.254167.228.255.25565,534
102167.229.0.0/16167.229.0.1 to 167.229.255.254167.229.255.25565,534
103167.230.0.0/16167.230.0.1 to 167.230.255.254167.230.255.25565,534
104167.231.0.0/16167.231.0.1 to 167.231.255.254167.231.255.25565,534
105167.232.0.0/16167.232.0.1 to 167.232.255.254167.232.255.25565,534
106167.233.0.0/16167.233.0.1 to 167.233.255.254167.233.255.25565,534
107167.234.0.0/16167.234.0.1 to 167.234.255.254167.234.255.25565,534
108167.235.0.0/16167.235.0.1 to 167.235.255.254167.235.255.25565,534
109167.236.0.0/16167.236.0.1 to 167.236.255.254167.236.255.25565,534
110167.237.0.0/16167.237.0.1 to 167.237.255.254167.237.255.25565,534
111167.238.0.0/16167.238.0.1 to 167.238.255.254167.238.255.25565,534
112167.239.0.0/16167.239.0.1 to 167.239.255.254167.239.255.25565,534
113167.240.0.0/16167.240.0.1 to 167.240.255.254167.240.255.25565,534
114167.241.0.0/16167.241.0.1 to 167.241.255.254167.241.255.25565,534
115167.242.0.0/16167.242.0.1 to 167.242.255.254167.242.255.25565,534
116167.243.0.0/16167.243.0.1 to 167.243.255.254167.243.255.25565,534
117167.244.0.0/16167.244.0.1 to 167.244.255.254167.244.255.25565,534
118167.245.0.0/16167.245.0.1 to 167.245.255.254167.245.255.25565,534
119167.246.0.0/16167.246.0.1 to 167.246.255.254167.246.255.25565,534
120167.247.0.0/16167.247.0.1 to 167.247.255.254167.247.255.25565,534
121167.248.0.0/16167.248.0.1 to 167.248.255.254167.248.255.25565,534
122167.249.0.0/16167.249.0.1 to 167.249.255.254167.249.255.25565,534
123167.250.0.0/16167.250.0.1 to 167.250.255.254167.250.255.25565,534
124167.251.0.0/16167.251.0.1 to 167.251.255.254167.251.255.25565,534
125167.252.0.0/16167.252.0.1 to 167.252.255.254167.252.255.25565,534
126167.253.0.0/16167.253.0.1 to 167.253.255.254167.253.255.25565,534
127167.254.0.0/16167.254.0.1 to 167.254.255.254167.254.255.25565,534
128167.255.0.0/16167.255.0.1 to 167.255.255.254167.255.255.25565,534

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.