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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.

Network145.4.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
145.4.0.0
Broadcast address
145.7.255.255
First usable
145.4.0.1
Last usable
145.7.255.254
Usable hosts
262,142 (262,144 less the network and broadcast addresses)
Subnet mask
255.252.0.0
Wildcard mask
0.3.255.255 (Cisco ACLs, OSPF)
Prefix length
/14
Type
Public public
Old class
B (default /16)
As numbers
Hex 91040000 · Integer 2432958464 to 2433220607
Reverse DNS zones
4.145.in-addr.arpa
5.145.in-addr.arpa
6.145.in-addr.arpa
7.145.in-addr.arpa
/14 is not on a 8-bit boundary, so it takes 4 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010001.00000100.00000000.00000000145.4.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network10010001.00000100.00000000.00000000145.4.0.0
Broadcast10010001.00000111.11111111.11111111145.7.255.255
Split into smaller subnets/21
/15 (2)/16 (4)/17 (8)/18 (16)/19 (32)/20 (64)/21 (128)/22 (256)/23 (512)/24 (1,024)/25 (2,048)/26 (4,096)

145.4.0.0/14 makes 128 subnets of /21.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1145.4.0.0/21145.4.0.1 to 145.4.7.254145.4.7.2552,046
2145.4.8.0/21145.4.8.1 to 145.4.15.254145.4.15.2552,046
3145.4.16.0/21145.4.16.1 to 145.4.23.254145.4.23.2552,046
4145.4.24.0/21145.4.24.1 to 145.4.31.254145.4.31.2552,046
5145.4.32.0/21145.4.32.1 to 145.4.39.254145.4.39.2552,046
6145.4.40.0/21145.4.40.1 to 145.4.47.254145.4.47.2552,046
7145.4.48.0/21145.4.48.1 to 145.4.55.254145.4.55.2552,046
8145.4.56.0/21145.4.56.1 to 145.4.63.254145.4.63.2552,046
9145.4.64.0/21145.4.64.1 to 145.4.71.254145.4.71.2552,046
10145.4.72.0/21145.4.72.1 to 145.4.79.254145.4.79.2552,046
11145.4.80.0/21145.4.80.1 to 145.4.87.254145.4.87.2552,046
12145.4.88.0/21145.4.88.1 to 145.4.95.254145.4.95.2552,046
13145.4.96.0/21145.4.96.1 to 145.4.103.254145.4.103.2552,046
14145.4.104.0/21145.4.104.1 to 145.4.111.254145.4.111.2552,046
15145.4.112.0/21145.4.112.1 to 145.4.119.254145.4.119.2552,046
16145.4.120.0/21145.4.120.1 to 145.4.127.254145.4.127.2552,046
17145.4.128.0/21145.4.128.1 to 145.4.135.254145.4.135.2552,046
18145.4.136.0/21145.4.136.1 to 145.4.143.254145.4.143.2552,046
19145.4.144.0/21145.4.144.1 to 145.4.151.254145.4.151.2552,046
20145.4.152.0/21145.4.152.1 to 145.4.159.254145.4.159.2552,046
21145.4.160.0/21145.4.160.1 to 145.4.167.254145.4.167.2552,046
22145.4.168.0/21145.4.168.1 to 145.4.175.254145.4.175.2552,046
23145.4.176.0/21145.4.176.1 to 145.4.183.254145.4.183.2552,046
24145.4.184.0/21145.4.184.1 to 145.4.191.254145.4.191.2552,046
25145.4.192.0/21145.4.192.1 to 145.4.199.254145.4.199.2552,046
26145.4.200.0/21145.4.200.1 to 145.4.207.254145.4.207.2552,046
27145.4.208.0/21145.4.208.1 to 145.4.215.254145.4.215.2552,046
28145.4.216.0/21145.4.216.1 to 145.4.223.254145.4.223.2552,046
29145.4.224.0/21145.4.224.1 to 145.4.231.254145.4.231.2552,046
30145.4.232.0/21145.4.232.1 to 145.4.239.254145.4.239.2552,046
31145.4.240.0/21145.4.240.1 to 145.4.247.254145.4.247.2552,046
32145.4.248.0/21145.4.248.1 to 145.4.255.254145.4.255.2552,046
33145.5.0.0/21145.5.0.1 to 145.5.7.254145.5.7.2552,046
34145.5.8.0/21145.5.8.1 to 145.5.15.254145.5.15.2552,046
35145.5.16.0/21145.5.16.1 to 145.5.23.254145.5.23.2552,046
36145.5.24.0/21145.5.24.1 to 145.5.31.254145.5.31.2552,046
37145.5.32.0/21145.5.32.1 to 145.5.39.254145.5.39.2552,046
38145.5.40.0/21145.5.40.1 to 145.5.47.254145.5.47.2552,046
39145.5.48.0/21145.5.48.1 to 145.5.55.254145.5.55.2552,046
40145.5.56.0/21145.5.56.1 to 145.5.63.254145.5.63.2552,046
41145.5.64.0/21145.5.64.1 to 145.5.71.254145.5.71.2552,046
42145.5.72.0/21145.5.72.1 to 145.5.79.254145.5.79.2552,046
43145.5.80.0/21145.5.80.1 to 145.5.87.254145.5.87.2552,046
44145.5.88.0/21145.5.88.1 to 145.5.95.254145.5.95.2552,046
45145.5.96.0/21145.5.96.1 to 145.5.103.254145.5.103.2552,046
46145.5.104.0/21145.5.104.1 to 145.5.111.254145.5.111.2552,046
47145.5.112.0/21145.5.112.1 to 145.5.119.254145.5.119.2552,046
48145.5.120.0/21145.5.120.1 to 145.5.127.254145.5.127.2552,046
49145.5.128.0/21145.5.128.1 to 145.5.135.254145.5.135.2552,046
50145.5.136.0/21145.5.136.1 to 145.5.143.254145.5.143.2552,046
51145.5.144.0/21145.5.144.1 to 145.5.151.254145.5.151.2552,046
52145.5.152.0/21145.5.152.1 to 145.5.159.254145.5.159.2552,046
53145.5.160.0/21145.5.160.1 to 145.5.167.254145.5.167.2552,046
54145.5.168.0/21145.5.168.1 to 145.5.175.254145.5.175.2552,046
55145.5.176.0/21145.5.176.1 to 145.5.183.254145.5.183.2552,046
56145.5.184.0/21145.5.184.1 to 145.5.191.254145.5.191.2552,046
57145.5.192.0/21145.5.192.1 to 145.5.199.254145.5.199.2552,046
58145.5.200.0/21145.5.200.1 to 145.5.207.254145.5.207.2552,046
59145.5.208.0/21145.5.208.1 to 145.5.215.254145.5.215.2552,046
60145.5.216.0/21145.5.216.1 to 145.5.223.254145.5.223.2552,046
61145.5.224.0/21145.5.224.1 to 145.5.231.254145.5.231.2552,046
62145.5.232.0/21145.5.232.1 to 145.5.239.254145.5.239.2552,046
63145.5.240.0/21145.5.240.1 to 145.5.247.254145.5.247.2552,046
64145.5.248.0/21145.5.248.1 to 145.5.255.254145.5.255.2552,046
65145.6.0.0/21145.6.0.1 to 145.6.7.254145.6.7.2552,046
66145.6.8.0/21145.6.8.1 to 145.6.15.254145.6.15.2552,046
67145.6.16.0/21145.6.16.1 to 145.6.23.254145.6.23.2552,046
68145.6.24.0/21145.6.24.1 to 145.6.31.254145.6.31.2552,046
69145.6.32.0/21145.6.32.1 to 145.6.39.254145.6.39.2552,046
70145.6.40.0/21145.6.40.1 to 145.6.47.254145.6.47.2552,046
71145.6.48.0/21145.6.48.1 to 145.6.55.254145.6.55.2552,046
72145.6.56.0/21145.6.56.1 to 145.6.63.254145.6.63.2552,046
73145.6.64.0/21145.6.64.1 to 145.6.71.254145.6.71.2552,046
74145.6.72.0/21145.6.72.1 to 145.6.79.254145.6.79.2552,046
75145.6.80.0/21145.6.80.1 to 145.6.87.254145.6.87.2552,046
76145.6.88.0/21145.6.88.1 to 145.6.95.254145.6.95.2552,046
77145.6.96.0/21145.6.96.1 to 145.6.103.254145.6.103.2552,046
78145.6.104.0/21145.6.104.1 to 145.6.111.254145.6.111.2552,046
79145.6.112.0/21145.6.112.1 to 145.6.119.254145.6.119.2552,046
80145.6.120.0/21145.6.120.1 to 145.6.127.254145.6.127.2552,046
81145.6.128.0/21145.6.128.1 to 145.6.135.254145.6.135.2552,046
82145.6.136.0/21145.6.136.1 to 145.6.143.254145.6.143.2552,046
83145.6.144.0/21145.6.144.1 to 145.6.151.254145.6.151.2552,046
84145.6.152.0/21145.6.152.1 to 145.6.159.254145.6.159.2552,046
85145.6.160.0/21145.6.160.1 to 145.6.167.254145.6.167.2552,046
86145.6.168.0/21145.6.168.1 to 145.6.175.254145.6.175.2552,046
87145.6.176.0/21145.6.176.1 to 145.6.183.254145.6.183.2552,046
88145.6.184.0/21145.6.184.1 to 145.6.191.254145.6.191.2552,046
89145.6.192.0/21145.6.192.1 to 145.6.199.254145.6.199.2552,046
90145.6.200.0/21145.6.200.1 to 145.6.207.254145.6.207.2552,046
91145.6.208.0/21145.6.208.1 to 145.6.215.254145.6.215.2552,046
92145.6.216.0/21145.6.216.1 to 145.6.223.254145.6.223.2552,046
93145.6.224.0/21145.6.224.1 to 145.6.231.254145.6.231.2552,046
94145.6.232.0/21145.6.232.1 to 145.6.239.254145.6.239.2552,046
95145.6.240.0/21145.6.240.1 to 145.6.247.254145.6.247.2552,046
96145.6.248.0/21145.6.248.1 to 145.6.255.254145.6.255.2552,046
97145.7.0.0/21145.7.0.1 to 145.7.7.254145.7.7.2552,046
98145.7.8.0/21145.7.8.1 to 145.7.15.254145.7.15.2552,046
99145.7.16.0/21145.7.16.1 to 145.7.23.254145.7.23.2552,046
100145.7.24.0/21145.7.24.1 to 145.7.31.254145.7.31.2552,046
101145.7.32.0/21145.7.32.1 to 145.7.39.254145.7.39.2552,046
102145.7.40.0/21145.7.40.1 to 145.7.47.254145.7.47.2552,046
103145.7.48.0/21145.7.48.1 to 145.7.55.254145.7.55.2552,046
104145.7.56.0/21145.7.56.1 to 145.7.63.254145.7.63.2552,046
105145.7.64.0/21145.7.64.1 to 145.7.71.254145.7.71.2552,046
106145.7.72.0/21145.7.72.1 to 145.7.79.254145.7.79.2552,046
107145.7.80.0/21145.7.80.1 to 145.7.87.254145.7.87.2552,046
108145.7.88.0/21145.7.88.1 to 145.7.95.254145.7.95.2552,046
109145.7.96.0/21145.7.96.1 to 145.7.103.254145.7.103.2552,046
110145.7.104.0/21145.7.104.1 to 145.7.111.254145.7.111.2552,046
111145.7.112.0/21145.7.112.1 to 145.7.119.254145.7.119.2552,046
112145.7.120.0/21145.7.120.1 to 145.7.127.254145.7.127.2552,046
113145.7.128.0/21145.7.128.1 to 145.7.135.254145.7.135.2552,046
114145.7.136.0/21145.7.136.1 to 145.7.143.254145.7.143.2552,046
115145.7.144.0/21145.7.144.1 to 145.7.151.254145.7.151.2552,046
116145.7.152.0/21145.7.152.1 to 145.7.159.254145.7.159.2552,046
117145.7.160.0/21145.7.160.1 to 145.7.167.254145.7.167.2552,046
118145.7.168.0/21145.7.168.1 to 145.7.175.254145.7.175.2552,046
119145.7.176.0/21145.7.176.1 to 145.7.183.254145.7.183.2552,046
120145.7.184.0/21145.7.184.1 to 145.7.191.254145.7.191.2552,046
121145.7.192.0/21145.7.192.1 to 145.7.199.254145.7.199.2552,046
122145.7.200.0/21145.7.200.1 to 145.7.207.254145.7.207.2552,046
123145.7.208.0/21145.7.208.1 to 145.7.215.254145.7.215.2552,046
124145.7.216.0/21145.7.216.1 to 145.7.223.254145.7.223.2552,046
125145.7.224.0/21145.7.224.1 to 145.7.231.254145.7.231.2552,046
126145.7.232.0/21145.7.232.1 to 145.7.239.254145.7.239.2552,046
127145.7.240.0/21145.7.240.1 to 145.7.247.254145.7.247.2552,046
128145.7.248.0/21145.7.248.1 to 145.7.255.254145.7.255.2552,046

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.