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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.

Network167.64.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
167.64.0.0
Broadcast address
167.79.255.255
First usable
167.64.0.1
Last usable
167.79.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
B (default /16)
As numbers
Hex A7400000 · Integer 2805989376 to 2807037951
Reverse DNS zones
64.167.in-addr.arpa
65.167.in-addr.arpa
66.167.in-addr.arpa
67.167.in-addr.arpa
68.167.in-addr.arpa
69.167.in-addr.arpa
70.167.in-addr.arpa
71.167.in-addr.arpa
72.167.in-addr.arpa
73.167.in-addr.arpa
74.167.in-addr.arpa
75.167.in-addr.arpa
76.167.in-addr.arpa
77.167.in-addr.arpa
78.167.in-addr.arpa
79.167.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100111.01000000.00000000.00000000167.64.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10100111.01000000.00000000.00000000167.64.0.0
Broadcast10100111.01001111.11111111.11111111167.79.255.255
Split into smaller subnets/19
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

167.64.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1167.64.0.0/19167.64.0.1 to 167.64.31.254167.64.31.2558,190
2167.64.32.0/19167.64.32.1 to 167.64.63.254167.64.63.2558,190
3167.64.64.0/19167.64.64.1 to 167.64.95.254167.64.95.2558,190
4167.64.96.0/19167.64.96.1 to 167.64.127.254167.64.127.2558,190
5167.64.128.0/19167.64.128.1 to 167.64.159.254167.64.159.2558,190
6167.64.160.0/19167.64.160.1 to 167.64.191.254167.64.191.2558,190
7167.64.192.0/19167.64.192.1 to 167.64.223.254167.64.223.2558,190
8167.64.224.0/19167.64.224.1 to 167.64.255.254167.64.255.2558,190
9167.65.0.0/19167.65.0.1 to 167.65.31.254167.65.31.2558,190
10167.65.32.0/19167.65.32.1 to 167.65.63.254167.65.63.2558,190
11167.65.64.0/19167.65.64.1 to 167.65.95.254167.65.95.2558,190
12167.65.96.0/19167.65.96.1 to 167.65.127.254167.65.127.2558,190
13167.65.128.0/19167.65.128.1 to 167.65.159.254167.65.159.2558,190
14167.65.160.0/19167.65.160.1 to 167.65.191.254167.65.191.2558,190
15167.65.192.0/19167.65.192.1 to 167.65.223.254167.65.223.2558,190
16167.65.224.0/19167.65.224.1 to 167.65.255.254167.65.255.2558,190
17167.66.0.0/19167.66.0.1 to 167.66.31.254167.66.31.2558,190
18167.66.32.0/19167.66.32.1 to 167.66.63.254167.66.63.2558,190
19167.66.64.0/19167.66.64.1 to 167.66.95.254167.66.95.2558,190
20167.66.96.0/19167.66.96.1 to 167.66.127.254167.66.127.2558,190
21167.66.128.0/19167.66.128.1 to 167.66.159.254167.66.159.2558,190
22167.66.160.0/19167.66.160.1 to 167.66.191.254167.66.191.2558,190
23167.66.192.0/19167.66.192.1 to 167.66.223.254167.66.223.2558,190
24167.66.224.0/19167.66.224.1 to 167.66.255.254167.66.255.2558,190
25167.67.0.0/19167.67.0.1 to 167.67.31.254167.67.31.2558,190
26167.67.32.0/19167.67.32.1 to 167.67.63.254167.67.63.2558,190
27167.67.64.0/19167.67.64.1 to 167.67.95.254167.67.95.2558,190
28167.67.96.0/19167.67.96.1 to 167.67.127.254167.67.127.2558,190
29167.67.128.0/19167.67.128.1 to 167.67.159.254167.67.159.2558,190
30167.67.160.0/19167.67.160.1 to 167.67.191.254167.67.191.2558,190
31167.67.192.0/19167.67.192.1 to 167.67.223.254167.67.223.2558,190
32167.67.224.0/19167.67.224.1 to 167.67.255.254167.67.255.2558,190
33167.68.0.0/19167.68.0.1 to 167.68.31.254167.68.31.2558,190
34167.68.32.0/19167.68.32.1 to 167.68.63.254167.68.63.2558,190
35167.68.64.0/19167.68.64.1 to 167.68.95.254167.68.95.2558,190
36167.68.96.0/19167.68.96.1 to 167.68.127.254167.68.127.2558,190
37167.68.128.0/19167.68.128.1 to 167.68.159.254167.68.159.2558,190
38167.68.160.0/19167.68.160.1 to 167.68.191.254167.68.191.2558,190
39167.68.192.0/19167.68.192.1 to 167.68.223.254167.68.223.2558,190
40167.68.224.0/19167.68.224.1 to 167.68.255.254167.68.255.2558,190
41167.69.0.0/19167.69.0.1 to 167.69.31.254167.69.31.2558,190
42167.69.32.0/19167.69.32.1 to 167.69.63.254167.69.63.2558,190
43167.69.64.0/19167.69.64.1 to 167.69.95.254167.69.95.2558,190
44167.69.96.0/19167.69.96.1 to 167.69.127.254167.69.127.2558,190
45167.69.128.0/19167.69.128.1 to 167.69.159.254167.69.159.2558,190
46167.69.160.0/19167.69.160.1 to 167.69.191.254167.69.191.2558,190
47167.69.192.0/19167.69.192.1 to 167.69.223.254167.69.223.2558,190
48167.69.224.0/19167.69.224.1 to 167.69.255.254167.69.255.2558,190
49167.70.0.0/19167.70.0.1 to 167.70.31.254167.70.31.2558,190
50167.70.32.0/19167.70.32.1 to 167.70.63.254167.70.63.2558,190
51167.70.64.0/19167.70.64.1 to 167.70.95.254167.70.95.2558,190
52167.70.96.0/19167.70.96.1 to 167.70.127.254167.70.127.2558,190
53167.70.128.0/19167.70.128.1 to 167.70.159.254167.70.159.2558,190
54167.70.160.0/19167.70.160.1 to 167.70.191.254167.70.191.2558,190
55167.70.192.0/19167.70.192.1 to 167.70.223.254167.70.223.2558,190
56167.70.224.0/19167.70.224.1 to 167.70.255.254167.70.255.2558,190
57167.71.0.0/19167.71.0.1 to 167.71.31.254167.71.31.2558,190
58167.71.32.0/19167.71.32.1 to 167.71.63.254167.71.63.2558,190
59167.71.64.0/19167.71.64.1 to 167.71.95.254167.71.95.2558,190
60167.71.96.0/19167.71.96.1 to 167.71.127.254167.71.127.2558,190
61167.71.128.0/19167.71.128.1 to 167.71.159.254167.71.159.2558,190
62167.71.160.0/19167.71.160.1 to 167.71.191.254167.71.191.2558,190
63167.71.192.0/19167.71.192.1 to 167.71.223.254167.71.223.2558,190
64167.71.224.0/19167.71.224.1 to 167.71.255.254167.71.255.2558,190
65167.72.0.0/19167.72.0.1 to 167.72.31.254167.72.31.2558,190
66167.72.32.0/19167.72.32.1 to 167.72.63.254167.72.63.2558,190
67167.72.64.0/19167.72.64.1 to 167.72.95.254167.72.95.2558,190
68167.72.96.0/19167.72.96.1 to 167.72.127.254167.72.127.2558,190
69167.72.128.0/19167.72.128.1 to 167.72.159.254167.72.159.2558,190
70167.72.160.0/19167.72.160.1 to 167.72.191.254167.72.191.2558,190
71167.72.192.0/19167.72.192.1 to 167.72.223.254167.72.223.2558,190
72167.72.224.0/19167.72.224.1 to 167.72.255.254167.72.255.2558,190
73167.73.0.0/19167.73.0.1 to 167.73.31.254167.73.31.2558,190
74167.73.32.0/19167.73.32.1 to 167.73.63.254167.73.63.2558,190
75167.73.64.0/19167.73.64.1 to 167.73.95.254167.73.95.2558,190
76167.73.96.0/19167.73.96.1 to 167.73.127.254167.73.127.2558,190
77167.73.128.0/19167.73.128.1 to 167.73.159.254167.73.159.2558,190
78167.73.160.0/19167.73.160.1 to 167.73.191.254167.73.191.2558,190
79167.73.192.0/19167.73.192.1 to 167.73.223.254167.73.223.2558,190
80167.73.224.0/19167.73.224.1 to 167.73.255.254167.73.255.2558,190
81167.74.0.0/19167.74.0.1 to 167.74.31.254167.74.31.2558,190
82167.74.32.0/19167.74.32.1 to 167.74.63.254167.74.63.2558,190
83167.74.64.0/19167.74.64.1 to 167.74.95.254167.74.95.2558,190
84167.74.96.0/19167.74.96.1 to 167.74.127.254167.74.127.2558,190
85167.74.128.0/19167.74.128.1 to 167.74.159.254167.74.159.2558,190
86167.74.160.0/19167.74.160.1 to 167.74.191.254167.74.191.2558,190
87167.74.192.0/19167.74.192.1 to 167.74.223.254167.74.223.2558,190
88167.74.224.0/19167.74.224.1 to 167.74.255.254167.74.255.2558,190
89167.75.0.0/19167.75.0.1 to 167.75.31.254167.75.31.2558,190
90167.75.32.0/19167.75.32.1 to 167.75.63.254167.75.63.2558,190
91167.75.64.0/19167.75.64.1 to 167.75.95.254167.75.95.2558,190
92167.75.96.0/19167.75.96.1 to 167.75.127.254167.75.127.2558,190
93167.75.128.0/19167.75.128.1 to 167.75.159.254167.75.159.2558,190
94167.75.160.0/19167.75.160.1 to 167.75.191.254167.75.191.2558,190
95167.75.192.0/19167.75.192.1 to 167.75.223.254167.75.223.2558,190
96167.75.224.0/19167.75.224.1 to 167.75.255.254167.75.255.2558,190
97167.76.0.0/19167.76.0.1 to 167.76.31.254167.76.31.2558,190
98167.76.32.0/19167.76.32.1 to 167.76.63.254167.76.63.2558,190
99167.76.64.0/19167.76.64.1 to 167.76.95.254167.76.95.2558,190
100167.76.96.0/19167.76.96.1 to 167.76.127.254167.76.127.2558,190
101167.76.128.0/19167.76.128.1 to 167.76.159.254167.76.159.2558,190
102167.76.160.0/19167.76.160.1 to 167.76.191.254167.76.191.2558,190
103167.76.192.0/19167.76.192.1 to 167.76.223.254167.76.223.2558,190
104167.76.224.0/19167.76.224.1 to 167.76.255.254167.76.255.2558,190
105167.77.0.0/19167.77.0.1 to 167.77.31.254167.77.31.2558,190
106167.77.32.0/19167.77.32.1 to 167.77.63.254167.77.63.2558,190
107167.77.64.0/19167.77.64.1 to 167.77.95.254167.77.95.2558,190
108167.77.96.0/19167.77.96.1 to 167.77.127.254167.77.127.2558,190
109167.77.128.0/19167.77.128.1 to 167.77.159.254167.77.159.2558,190
110167.77.160.0/19167.77.160.1 to 167.77.191.254167.77.191.2558,190
111167.77.192.0/19167.77.192.1 to 167.77.223.254167.77.223.2558,190
112167.77.224.0/19167.77.224.1 to 167.77.255.254167.77.255.2558,190
113167.78.0.0/19167.78.0.1 to 167.78.31.254167.78.31.2558,190
114167.78.32.0/19167.78.32.1 to 167.78.63.254167.78.63.2558,190
115167.78.64.0/19167.78.64.1 to 167.78.95.254167.78.95.2558,190
116167.78.96.0/19167.78.96.1 to 167.78.127.254167.78.127.2558,190
117167.78.128.0/19167.78.128.1 to 167.78.159.254167.78.159.2558,190
118167.78.160.0/19167.78.160.1 to 167.78.191.254167.78.191.2558,190
119167.78.192.0/19167.78.192.1 to 167.78.223.254167.78.223.2558,190
120167.78.224.0/19167.78.224.1 to 167.78.255.254167.78.255.2558,190
121167.79.0.0/19167.79.0.1 to 167.79.31.254167.79.31.2558,190
122167.79.32.0/19167.79.32.1 to 167.79.63.254167.79.63.2558,190
123167.79.64.0/19167.79.64.1 to 167.79.95.254167.79.95.2558,190
124167.79.96.0/19167.79.96.1 to 167.79.127.254167.79.127.2558,190
125167.79.128.0/19167.79.128.1 to 167.79.159.254167.79.159.2558,190
126167.79.160.0/19167.79.160.1 to 167.79.191.254167.79.191.2558,190
127167.79.192.0/19167.79.192.1 to 167.79.223.254167.79.223.2558,190
128167.79.224.0/19167.79.224.1 to 167.79.255.254167.79.255.2558,190

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.