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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.

Network136.112.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
136.112.0.0
Broadcast address
136.127.255.255
First usable
136.112.0.1
Last usable
136.127.255.254
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 88700000 · Integer 2289041408 to 2290089983
Reverse DNS zones
112.136.in-addr.arpa
113.136.in-addr.arpa
114.136.in-addr.arpa
115.136.in-addr.arpa
116.136.in-addr.arpa
117.136.in-addr.arpa
118.136.in-addr.arpa
119.136.in-addr.arpa
120.136.in-addr.arpa
121.136.in-addr.arpa
122.136.in-addr.arpa
123.136.in-addr.arpa
124.136.in-addr.arpa
125.136.in-addr.arpa
126.136.in-addr.arpa
127.136.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
Address10001000.01110000.00000000.00000000136.112.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10001000.01110000.00000000.00000000136.112.0.0
Broadcast10001000.01111111.11111111.11111111136.127.255.255
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)

136.112.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1136.112.0.0/19136.112.0.1 to 136.112.31.254136.112.31.2558,190
2136.112.32.0/19136.112.32.1 to 136.112.63.254136.112.63.2558,190
3136.112.64.0/19136.112.64.1 to 136.112.95.254136.112.95.2558,190
4136.112.96.0/19136.112.96.1 to 136.112.127.254136.112.127.2558,190
5136.112.128.0/19136.112.128.1 to 136.112.159.254136.112.159.2558,190
6136.112.160.0/19136.112.160.1 to 136.112.191.254136.112.191.2558,190
7136.112.192.0/19136.112.192.1 to 136.112.223.254136.112.223.2558,190
8136.112.224.0/19136.112.224.1 to 136.112.255.254136.112.255.2558,190
9136.113.0.0/19136.113.0.1 to 136.113.31.254136.113.31.2558,190
10136.113.32.0/19136.113.32.1 to 136.113.63.254136.113.63.2558,190
11136.113.64.0/19136.113.64.1 to 136.113.95.254136.113.95.2558,190
12136.113.96.0/19136.113.96.1 to 136.113.127.254136.113.127.2558,190
13136.113.128.0/19136.113.128.1 to 136.113.159.254136.113.159.2558,190
14136.113.160.0/19136.113.160.1 to 136.113.191.254136.113.191.2558,190
15136.113.192.0/19136.113.192.1 to 136.113.223.254136.113.223.2558,190
16136.113.224.0/19136.113.224.1 to 136.113.255.254136.113.255.2558,190
17136.114.0.0/19136.114.0.1 to 136.114.31.254136.114.31.2558,190
18136.114.32.0/19136.114.32.1 to 136.114.63.254136.114.63.2558,190
19136.114.64.0/19136.114.64.1 to 136.114.95.254136.114.95.2558,190
20136.114.96.0/19136.114.96.1 to 136.114.127.254136.114.127.2558,190
21136.114.128.0/19136.114.128.1 to 136.114.159.254136.114.159.2558,190
22136.114.160.0/19136.114.160.1 to 136.114.191.254136.114.191.2558,190
23136.114.192.0/19136.114.192.1 to 136.114.223.254136.114.223.2558,190
24136.114.224.0/19136.114.224.1 to 136.114.255.254136.114.255.2558,190
25136.115.0.0/19136.115.0.1 to 136.115.31.254136.115.31.2558,190
26136.115.32.0/19136.115.32.1 to 136.115.63.254136.115.63.2558,190
27136.115.64.0/19136.115.64.1 to 136.115.95.254136.115.95.2558,190
28136.115.96.0/19136.115.96.1 to 136.115.127.254136.115.127.2558,190
29136.115.128.0/19136.115.128.1 to 136.115.159.254136.115.159.2558,190
30136.115.160.0/19136.115.160.1 to 136.115.191.254136.115.191.2558,190
31136.115.192.0/19136.115.192.1 to 136.115.223.254136.115.223.2558,190
32136.115.224.0/19136.115.224.1 to 136.115.255.254136.115.255.2558,190
33136.116.0.0/19136.116.0.1 to 136.116.31.254136.116.31.2558,190
34136.116.32.0/19136.116.32.1 to 136.116.63.254136.116.63.2558,190
35136.116.64.0/19136.116.64.1 to 136.116.95.254136.116.95.2558,190
36136.116.96.0/19136.116.96.1 to 136.116.127.254136.116.127.2558,190
37136.116.128.0/19136.116.128.1 to 136.116.159.254136.116.159.2558,190
38136.116.160.0/19136.116.160.1 to 136.116.191.254136.116.191.2558,190
39136.116.192.0/19136.116.192.1 to 136.116.223.254136.116.223.2558,190
40136.116.224.0/19136.116.224.1 to 136.116.255.254136.116.255.2558,190
41136.117.0.0/19136.117.0.1 to 136.117.31.254136.117.31.2558,190
42136.117.32.0/19136.117.32.1 to 136.117.63.254136.117.63.2558,190
43136.117.64.0/19136.117.64.1 to 136.117.95.254136.117.95.2558,190
44136.117.96.0/19136.117.96.1 to 136.117.127.254136.117.127.2558,190
45136.117.128.0/19136.117.128.1 to 136.117.159.254136.117.159.2558,190
46136.117.160.0/19136.117.160.1 to 136.117.191.254136.117.191.2558,190
47136.117.192.0/19136.117.192.1 to 136.117.223.254136.117.223.2558,190
48136.117.224.0/19136.117.224.1 to 136.117.255.254136.117.255.2558,190
49136.118.0.0/19136.118.0.1 to 136.118.31.254136.118.31.2558,190
50136.118.32.0/19136.118.32.1 to 136.118.63.254136.118.63.2558,190
51136.118.64.0/19136.118.64.1 to 136.118.95.254136.118.95.2558,190
52136.118.96.0/19136.118.96.1 to 136.118.127.254136.118.127.2558,190
53136.118.128.0/19136.118.128.1 to 136.118.159.254136.118.159.2558,190
54136.118.160.0/19136.118.160.1 to 136.118.191.254136.118.191.2558,190
55136.118.192.0/19136.118.192.1 to 136.118.223.254136.118.223.2558,190
56136.118.224.0/19136.118.224.1 to 136.118.255.254136.118.255.2558,190
57136.119.0.0/19136.119.0.1 to 136.119.31.254136.119.31.2558,190
58136.119.32.0/19136.119.32.1 to 136.119.63.254136.119.63.2558,190
59136.119.64.0/19136.119.64.1 to 136.119.95.254136.119.95.2558,190
60136.119.96.0/19136.119.96.1 to 136.119.127.254136.119.127.2558,190
61136.119.128.0/19136.119.128.1 to 136.119.159.254136.119.159.2558,190
62136.119.160.0/19136.119.160.1 to 136.119.191.254136.119.191.2558,190
63136.119.192.0/19136.119.192.1 to 136.119.223.254136.119.223.2558,190
64136.119.224.0/19136.119.224.1 to 136.119.255.254136.119.255.2558,190
65136.120.0.0/19136.120.0.1 to 136.120.31.254136.120.31.2558,190
66136.120.32.0/19136.120.32.1 to 136.120.63.254136.120.63.2558,190
67136.120.64.0/19136.120.64.1 to 136.120.95.254136.120.95.2558,190
68136.120.96.0/19136.120.96.1 to 136.120.127.254136.120.127.2558,190
69136.120.128.0/19136.120.128.1 to 136.120.159.254136.120.159.2558,190
70136.120.160.0/19136.120.160.1 to 136.120.191.254136.120.191.2558,190
71136.120.192.0/19136.120.192.1 to 136.120.223.254136.120.223.2558,190
72136.120.224.0/19136.120.224.1 to 136.120.255.254136.120.255.2558,190
73136.121.0.0/19136.121.0.1 to 136.121.31.254136.121.31.2558,190
74136.121.32.0/19136.121.32.1 to 136.121.63.254136.121.63.2558,190
75136.121.64.0/19136.121.64.1 to 136.121.95.254136.121.95.2558,190
76136.121.96.0/19136.121.96.1 to 136.121.127.254136.121.127.2558,190
77136.121.128.0/19136.121.128.1 to 136.121.159.254136.121.159.2558,190
78136.121.160.0/19136.121.160.1 to 136.121.191.254136.121.191.2558,190
79136.121.192.0/19136.121.192.1 to 136.121.223.254136.121.223.2558,190
80136.121.224.0/19136.121.224.1 to 136.121.255.254136.121.255.2558,190
81136.122.0.0/19136.122.0.1 to 136.122.31.254136.122.31.2558,190
82136.122.32.0/19136.122.32.1 to 136.122.63.254136.122.63.2558,190
83136.122.64.0/19136.122.64.1 to 136.122.95.254136.122.95.2558,190
84136.122.96.0/19136.122.96.1 to 136.122.127.254136.122.127.2558,190
85136.122.128.0/19136.122.128.1 to 136.122.159.254136.122.159.2558,190
86136.122.160.0/19136.122.160.1 to 136.122.191.254136.122.191.2558,190
87136.122.192.0/19136.122.192.1 to 136.122.223.254136.122.223.2558,190
88136.122.224.0/19136.122.224.1 to 136.122.255.254136.122.255.2558,190
89136.123.0.0/19136.123.0.1 to 136.123.31.254136.123.31.2558,190
90136.123.32.0/19136.123.32.1 to 136.123.63.254136.123.63.2558,190
91136.123.64.0/19136.123.64.1 to 136.123.95.254136.123.95.2558,190
92136.123.96.0/19136.123.96.1 to 136.123.127.254136.123.127.2558,190
93136.123.128.0/19136.123.128.1 to 136.123.159.254136.123.159.2558,190
94136.123.160.0/19136.123.160.1 to 136.123.191.254136.123.191.2558,190
95136.123.192.0/19136.123.192.1 to 136.123.223.254136.123.223.2558,190
96136.123.224.0/19136.123.224.1 to 136.123.255.254136.123.255.2558,190
97136.124.0.0/19136.124.0.1 to 136.124.31.254136.124.31.2558,190
98136.124.32.0/19136.124.32.1 to 136.124.63.254136.124.63.2558,190
99136.124.64.0/19136.124.64.1 to 136.124.95.254136.124.95.2558,190
100136.124.96.0/19136.124.96.1 to 136.124.127.254136.124.127.2558,190
101136.124.128.0/19136.124.128.1 to 136.124.159.254136.124.159.2558,190
102136.124.160.0/19136.124.160.1 to 136.124.191.254136.124.191.2558,190
103136.124.192.0/19136.124.192.1 to 136.124.223.254136.124.223.2558,190
104136.124.224.0/19136.124.224.1 to 136.124.255.254136.124.255.2558,190
105136.125.0.0/19136.125.0.1 to 136.125.31.254136.125.31.2558,190
106136.125.32.0/19136.125.32.1 to 136.125.63.254136.125.63.2558,190
107136.125.64.0/19136.125.64.1 to 136.125.95.254136.125.95.2558,190
108136.125.96.0/19136.125.96.1 to 136.125.127.254136.125.127.2558,190
109136.125.128.0/19136.125.128.1 to 136.125.159.254136.125.159.2558,190
110136.125.160.0/19136.125.160.1 to 136.125.191.254136.125.191.2558,190
111136.125.192.0/19136.125.192.1 to 136.125.223.254136.125.223.2558,190
112136.125.224.0/19136.125.224.1 to 136.125.255.254136.125.255.2558,190
113136.126.0.0/19136.126.0.1 to 136.126.31.254136.126.31.2558,190
114136.126.32.0/19136.126.32.1 to 136.126.63.254136.126.63.2558,190
115136.126.64.0/19136.126.64.1 to 136.126.95.254136.126.95.2558,190
116136.126.96.0/19136.126.96.1 to 136.126.127.254136.126.127.2558,190
117136.126.128.0/19136.126.128.1 to 136.126.159.254136.126.159.2558,190
118136.126.160.0/19136.126.160.1 to 136.126.191.254136.126.191.2558,190
119136.126.192.0/19136.126.192.1 to 136.126.223.254136.126.223.2558,190
120136.126.224.0/19136.126.224.1 to 136.126.255.254136.126.255.2558,190
121136.127.0.0/19136.127.0.1 to 136.127.31.254136.127.31.2558,190
122136.127.32.0/19136.127.32.1 to 136.127.63.254136.127.63.2558,190
123136.127.64.0/19136.127.64.1 to 136.127.95.254136.127.95.2558,190
124136.127.96.0/19136.127.96.1 to 136.127.127.254136.127.127.2558,190
125136.127.128.0/19136.127.128.1 to 136.127.159.254136.127.159.2558,190
126136.127.160.0/19136.127.160.1 to 136.127.191.254136.127.191.2558,190
127136.127.192.0/19136.127.192.1 to 136.127.223.254136.127.223.2558,190
128136.127.224.0/19136.127.224.1 to 136.127.255.254136.127.255.2558,190

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.