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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.

Network162.0.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
162.0.0.0
Broadcast address
162.15.255.255
First usable
162.0.0.1
Last usable
162.15.255.254
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 A2000000 · Integer 2717908992 to 2718957567
Reverse DNS zones
0.162.in-addr.arpa
1.162.in-addr.arpa
2.162.in-addr.arpa
3.162.in-addr.arpa
4.162.in-addr.arpa
5.162.in-addr.arpa
6.162.in-addr.arpa
7.162.in-addr.arpa
8.162.in-addr.arpa
9.162.in-addr.arpa
10.162.in-addr.arpa
11.162.in-addr.arpa
12.162.in-addr.arpa
13.162.in-addr.arpa
14.162.in-addr.arpa
15.162.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
Address10100010.00000000.00000000.00000000162.0.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10100010.00000000.00000000.00000000162.0.0.0
Broadcast10100010.00001111.11111111.11111111162.15.255.255
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)

162.0.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1162.0.0.0/19162.0.0.1 to 162.0.31.254162.0.31.2558,190
2162.0.32.0/19162.0.32.1 to 162.0.63.254162.0.63.2558,190
3162.0.64.0/19162.0.64.1 to 162.0.95.254162.0.95.2558,190
4162.0.96.0/19162.0.96.1 to 162.0.127.254162.0.127.2558,190
5162.0.128.0/19162.0.128.1 to 162.0.159.254162.0.159.2558,190
6162.0.160.0/19162.0.160.1 to 162.0.191.254162.0.191.2558,190
7162.0.192.0/19162.0.192.1 to 162.0.223.254162.0.223.2558,190
8162.0.224.0/19162.0.224.1 to 162.0.255.254162.0.255.2558,190
9162.1.0.0/19162.1.0.1 to 162.1.31.254162.1.31.2558,190
10162.1.32.0/19162.1.32.1 to 162.1.63.254162.1.63.2558,190
11162.1.64.0/19162.1.64.1 to 162.1.95.254162.1.95.2558,190
12162.1.96.0/19162.1.96.1 to 162.1.127.254162.1.127.2558,190
13162.1.128.0/19162.1.128.1 to 162.1.159.254162.1.159.2558,190
14162.1.160.0/19162.1.160.1 to 162.1.191.254162.1.191.2558,190
15162.1.192.0/19162.1.192.1 to 162.1.223.254162.1.223.2558,190
16162.1.224.0/19162.1.224.1 to 162.1.255.254162.1.255.2558,190
17162.2.0.0/19162.2.0.1 to 162.2.31.254162.2.31.2558,190
18162.2.32.0/19162.2.32.1 to 162.2.63.254162.2.63.2558,190
19162.2.64.0/19162.2.64.1 to 162.2.95.254162.2.95.2558,190
20162.2.96.0/19162.2.96.1 to 162.2.127.254162.2.127.2558,190
21162.2.128.0/19162.2.128.1 to 162.2.159.254162.2.159.2558,190
22162.2.160.0/19162.2.160.1 to 162.2.191.254162.2.191.2558,190
23162.2.192.0/19162.2.192.1 to 162.2.223.254162.2.223.2558,190
24162.2.224.0/19162.2.224.1 to 162.2.255.254162.2.255.2558,190
25162.3.0.0/19162.3.0.1 to 162.3.31.254162.3.31.2558,190
26162.3.32.0/19162.3.32.1 to 162.3.63.254162.3.63.2558,190
27162.3.64.0/19162.3.64.1 to 162.3.95.254162.3.95.2558,190
28162.3.96.0/19162.3.96.1 to 162.3.127.254162.3.127.2558,190
29162.3.128.0/19162.3.128.1 to 162.3.159.254162.3.159.2558,190
30162.3.160.0/19162.3.160.1 to 162.3.191.254162.3.191.2558,190
31162.3.192.0/19162.3.192.1 to 162.3.223.254162.3.223.2558,190
32162.3.224.0/19162.3.224.1 to 162.3.255.254162.3.255.2558,190
33162.4.0.0/19162.4.0.1 to 162.4.31.254162.4.31.2558,190
34162.4.32.0/19162.4.32.1 to 162.4.63.254162.4.63.2558,190
35162.4.64.0/19162.4.64.1 to 162.4.95.254162.4.95.2558,190
36162.4.96.0/19162.4.96.1 to 162.4.127.254162.4.127.2558,190
37162.4.128.0/19162.4.128.1 to 162.4.159.254162.4.159.2558,190
38162.4.160.0/19162.4.160.1 to 162.4.191.254162.4.191.2558,190
39162.4.192.0/19162.4.192.1 to 162.4.223.254162.4.223.2558,190
40162.4.224.0/19162.4.224.1 to 162.4.255.254162.4.255.2558,190
41162.5.0.0/19162.5.0.1 to 162.5.31.254162.5.31.2558,190
42162.5.32.0/19162.5.32.1 to 162.5.63.254162.5.63.2558,190
43162.5.64.0/19162.5.64.1 to 162.5.95.254162.5.95.2558,190
44162.5.96.0/19162.5.96.1 to 162.5.127.254162.5.127.2558,190
45162.5.128.0/19162.5.128.1 to 162.5.159.254162.5.159.2558,190
46162.5.160.0/19162.5.160.1 to 162.5.191.254162.5.191.2558,190
47162.5.192.0/19162.5.192.1 to 162.5.223.254162.5.223.2558,190
48162.5.224.0/19162.5.224.1 to 162.5.255.254162.5.255.2558,190
49162.6.0.0/19162.6.0.1 to 162.6.31.254162.6.31.2558,190
50162.6.32.0/19162.6.32.1 to 162.6.63.254162.6.63.2558,190
51162.6.64.0/19162.6.64.1 to 162.6.95.254162.6.95.2558,190
52162.6.96.0/19162.6.96.1 to 162.6.127.254162.6.127.2558,190
53162.6.128.0/19162.6.128.1 to 162.6.159.254162.6.159.2558,190
54162.6.160.0/19162.6.160.1 to 162.6.191.254162.6.191.2558,190
55162.6.192.0/19162.6.192.1 to 162.6.223.254162.6.223.2558,190
56162.6.224.0/19162.6.224.1 to 162.6.255.254162.6.255.2558,190
57162.7.0.0/19162.7.0.1 to 162.7.31.254162.7.31.2558,190
58162.7.32.0/19162.7.32.1 to 162.7.63.254162.7.63.2558,190
59162.7.64.0/19162.7.64.1 to 162.7.95.254162.7.95.2558,190
60162.7.96.0/19162.7.96.1 to 162.7.127.254162.7.127.2558,190
61162.7.128.0/19162.7.128.1 to 162.7.159.254162.7.159.2558,190
62162.7.160.0/19162.7.160.1 to 162.7.191.254162.7.191.2558,190
63162.7.192.0/19162.7.192.1 to 162.7.223.254162.7.223.2558,190
64162.7.224.0/19162.7.224.1 to 162.7.255.254162.7.255.2558,190
65162.8.0.0/19162.8.0.1 to 162.8.31.254162.8.31.2558,190
66162.8.32.0/19162.8.32.1 to 162.8.63.254162.8.63.2558,190
67162.8.64.0/19162.8.64.1 to 162.8.95.254162.8.95.2558,190
68162.8.96.0/19162.8.96.1 to 162.8.127.254162.8.127.2558,190
69162.8.128.0/19162.8.128.1 to 162.8.159.254162.8.159.2558,190
70162.8.160.0/19162.8.160.1 to 162.8.191.254162.8.191.2558,190
71162.8.192.0/19162.8.192.1 to 162.8.223.254162.8.223.2558,190
72162.8.224.0/19162.8.224.1 to 162.8.255.254162.8.255.2558,190
73162.9.0.0/19162.9.0.1 to 162.9.31.254162.9.31.2558,190
74162.9.32.0/19162.9.32.1 to 162.9.63.254162.9.63.2558,190
75162.9.64.0/19162.9.64.1 to 162.9.95.254162.9.95.2558,190
76162.9.96.0/19162.9.96.1 to 162.9.127.254162.9.127.2558,190
77162.9.128.0/19162.9.128.1 to 162.9.159.254162.9.159.2558,190
78162.9.160.0/19162.9.160.1 to 162.9.191.254162.9.191.2558,190
79162.9.192.0/19162.9.192.1 to 162.9.223.254162.9.223.2558,190
80162.9.224.0/19162.9.224.1 to 162.9.255.254162.9.255.2558,190
81162.10.0.0/19162.10.0.1 to 162.10.31.254162.10.31.2558,190
82162.10.32.0/19162.10.32.1 to 162.10.63.254162.10.63.2558,190
83162.10.64.0/19162.10.64.1 to 162.10.95.254162.10.95.2558,190
84162.10.96.0/19162.10.96.1 to 162.10.127.254162.10.127.2558,190
85162.10.128.0/19162.10.128.1 to 162.10.159.254162.10.159.2558,190
86162.10.160.0/19162.10.160.1 to 162.10.191.254162.10.191.2558,190
87162.10.192.0/19162.10.192.1 to 162.10.223.254162.10.223.2558,190
88162.10.224.0/19162.10.224.1 to 162.10.255.254162.10.255.2558,190
89162.11.0.0/19162.11.0.1 to 162.11.31.254162.11.31.2558,190
90162.11.32.0/19162.11.32.1 to 162.11.63.254162.11.63.2558,190
91162.11.64.0/19162.11.64.1 to 162.11.95.254162.11.95.2558,190
92162.11.96.0/19162.11.96.1 to 162.11.127.254162.11.127.2558,190
93162.11.128.0/19162.11.128.1 to 162.11.159.254162.11.159.2558,190
94162.11.160.0/19162.11.160.1 to 162.11.191.254162.11.191.2558,190
95162.11.192.0/19162.11.192.1 to 162.11.223.254162.11.223.2558,190
96162.11.224.0/19162.11.224.1 to 162.11.255.254162.11.255.2558,190
97162.12.0.0/19162.12.0.1 to 162.12.31.254162.12.31.2558,190
98162.12.32.0/19162.12.32.1 to 162.12.63.254162.12.63.2558,190
99162.12.64.0/19162.12.64.1 to 162.12.95.254162.12.95.2558,190
100162.12.96.0/19162.12.96.1 to 162.12.127.254162.12.127.2558,190
101162.12.128.0/19162.12.128.1 to 162.12.159.254162.12.159.2558,190
102162.12.160.0/19162.12.160.1 to 162.12.191.254162.12.191.2558,190
103162.12.192.0/19162.12.192.1 to 162.12.223.254162.12.223.2558,190
104162.12.224.0/19162.12.224.1 to 162.12.255.254162.12.255.2558,190
105162.13.0.0/19162.13.0.1 to 162.13.31.254162.13.31.2558,190
106162.13.32.0/19162.13.32.1 to 162.13.63.254162.13.63.2558,190
107162.13.64.0/19162.13.64.1 to 162.13.95.254162.13.95.2558,190
108162.13.96.0/19162.13.96.1 to 162.13.127.254162.13.127.2558,190
109162.13.128.0/19162.13.128.1 to 162.13.159.254162.13.159.2558,190
110162.13.160.0/19162.13.160.1 to 162.13.191.254162.13.191.2558,190
111162.13.192.0/19162.13.192.1 to 162.13.223.254162.13.223.2558,190
112162.13.224.0/19162.13.224.1 to 162.13.255.254162.13.255.2558,190
113162.14.0.0/19162.14.0.1 to 162.14.31.254162.14.31.2558,190
114162.14.32.0/19162.14.32.1 to 162.14.63.254162.14.63.2558,190
115162.14.64.0/19162.14.64.1 to 162.14.95.254162.14.95.2558,190
116162.14.96.0/19162.14.96.1 to 162.14.127.254162.14.127.2558,190
117162.14.128.0/19162.14.128.1 to 162.14.159.254162.14.159.2558,190
118162.14.160.0/19162.14.160.1 to 162.14.191.254162.14.191.2558,190
119162.14.192.0/19162.14.192.1 to 162.14.223.254162.14.223.2558,190
120162.14.224.0/19162.14.224.1 to 162.14.255.254162.14.255.2558,190
121162.15.0.0/19162.15.0.1 to 162.15.31.254162.15.31.2558,190
122162.15.32.0/19162.15.32.1 to 162.15.63.254162.15.63.2558,190
123162.15.64.0/19162.15.64.1 to 162.15.95.254162.15.95.2558,190
124162.15.96.0/19162.15.96.1 to 162.15.127.254162.15.127.2558,190
125162.15.128.0/19162.15.128.1 to 162.15.159.254162.15.159.2558,190
126162.15.160.0/19162.15.160.1 to 162.15.191.254162.15.191.2558,190
127162.15.192.0/19162.15.192.1 to 162.15.223.254162.15.223.2558,190
128162.15.224.0/19162.15.224.1 to 162.15.255.254162.15.255.2558,190

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.