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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.

Network181.76.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
181.76.0.0
Broadcast address
181.79.255.255
First usable
181.76.0.1
Last usable
181.79.255.254
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 B54C0000 · Integer 3041656832 to 3041918975
Reverse DNS zones
76.181.in-addr.arpa
77.181.in-addr.arpa
78.181.in-addr.arpa
79.181.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
Address10110101.01001100.00000000.00000000181.76.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network10110101.01001100.00000000.00000000181.76.0.0
Broadcast10110101.01001111.11111111.11111111181.79.255.255
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)

181.76.0.0/14 makes 128 subnets of /21.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1181.76.0.0/21181.76.0.1 to 181.76.7.254181.76.7.2552,046
2181.76.8.0/21181.76.8.1 to 181.76.15.254181.76.15.2552,046
3181.76.16.0/21181.76.16.1 to 181.76.23.254181.76.23.2552,046
4181.76.24.0/21181.76.24.1 to 181.76.31.254181.76.31.2552,046
5181.76.32.0/21181.76.32.1 to 181.76.39.254181.76.39.2552,046
6181.76.40.0/21181.76.40.1 to 181.76.47.254181.76.47.2552,046
7181.76.48.0/21181.76.48.1 to 181.76.55.254181.76.55.2552,046
8181.76.56.0/21181.76.56.1 to 181.76.63.254181.76.63.2552,046
9181.76.64.0/21181.76.64.1 to 181.76.71.254181.76.71.2552,046
10181.76.72.0/21181.76.72.1 to 181.76.79.254181.76.79.2552,046
11181.76.80.0/21181.76.80.1 to 181.76.87.254181.76.87.2552,046
12181.76.88.0/21181.76.88.1 to 181.76.95.254181.76.95.2552,046
13181.76.96.0/21181.76.96.1 to 181.76.103.254181.76.103.2552,046
14181.76.104.0/21181.76.104.1 to 181.76.111.254181.76.111.2552,046
15181.76.112.0/21181.76.112.1 to 181.76.119.254181.76.119.2552,046
16181.76.120.0/21181.76.120.1 to 181.76.127.254181.76.127.2552,046
17181.76.128.0/21181.76.128.1 to 181.76.135.254181.76.135.2552,046
18181.76.136.0/21181.76.136.1 to 181.76.143.254181.76.143.2552,046
19181.76.144.0/21181.76.144.1 to 181.76.151.254181.76.151.2552,046
20181.76.152.0/21181.76.152.1 to 181.76.159.254181.76.159.2552,046
21181.76.160.0/21181.76.160.1 to 181.76.167.254181.76.167.2552,046
22181.76.168.0/21181.76.168.1 to 181.76.175.254181.76.175.2552,046
23181.76.176.0/21181.76.176.1 to 181.76.183.254181.76.183.2552,046
24181.76.184.0/21181.76.184.1 to 181.76.191.254181.76.191.2552,046
25181.76.192.0/21181.76.192.1 to 181.76.199.254181.76.199.2552,046
26181.76.200.0/21181.76.200.1 to 181.76.207.254181.76.207.2552,046
27181.76.208.0/21181.76.208.1 to 181.76.215.254181.76.215.2552,046
28181.76.216.0/21181.76.216.1 to 181.76.223.254181.76.223.2552,046
29181.76.224.0/21181.76.224.1 to 181.76.231.254181.76.231.2552,046
30181.76.232.0/21181.76.232.1 to 181.76.239.254181.76.239.2552,046
31181.76.240.0/21181.76.240.1 to 181.76.247.254181.76.247.2552,046
32181.76.248.0/21181.76.248.1 to 181.76.255.254181.76.255.2552,046
33181.77.0.0/21181.77.0.1 to 181.77.7.254181.77.7.2552,046
34181.77.8.0/21181.77.8.1 to 181.77.15.254181.77.15.2552,046
35181.77.16.0/21181.77.16.1 to 181.77.23.254181.77.23.2552,046
36181.77.24.0/21181.77.24.1 to 181.77.31.254181.77.31.2552,046
37181.77.32.0/21181.77.32.1 to 181.77.39.254181.77.39.2552,046
38181.77.40.0/21181.77.40.1 to 181.77.47.254181.77.47.2552,046
39181.77.48.0/21181.77.48.1 to 181.77.55.254181.77.55.2552,046
40181.77.56.0/21181.77.56.1 to 181.77.63.254181.77.63.2552,046
41181.77.64.0/21181.77.64.1 to 181.77.71.254181.77.71.2552,046
42181.77.72.0/21181.77.72.1 to 181.77.79.254181.77.79.2552,046
43181.77.80.0/21181.77.80.1 to 181.77.87.254181.77.87.2552,046
44181.77.88.0/21181.77.88.1 to 181.77.95.254181.77.95.2552,046
45181.77.96.0/21181.77.96.1 to 181.77.103.254181.77.103.2552,046
46181.77.104.0/21181.77.104.1 to 181.77.111.254181.77.111.2552,046
47181.77.112.0/21181.77.112.1 to 181.77.119.254181.77.119.2552,046
48181.77.120.0/21181.77.120.1 to 181.77.127.254181.77.127.2552,046
49181.77.128.0/21181.77.128.1 to 181.77.135.254181.77.135.2552,046
50181.77.136.0/21181.77.136.1 to 181.77.143.254181.77.143.2552,046
51181.77.144.0/21181.77.144.1 to 181.77.151.254181.77.151.2552,046
52181.77.152.0/21181.77.152.1 to 181.77.159.254181.77.159.2552,046
53181.77.160.0/21181.77.160.1 to 181.77.167.254181.77.167.2552,046
54181.77.168.0/21181.77.168.1 to 181.77.175.254181.77.175.2552,046
55181.77.176.0/21181.77.176.1 to 181.77.183.254181.77.183.2552,046
56181.77.184.0/21181.77.184.1 to 181.77.191.254181.77.191.2552,046
57181.77.192.0/21181.77.192.1 to 181.77.199.254181.77.199.2552,046
58181.77.200.0/21181.77.200.1 to 181.77.207.254181.77.207.2552,046
59181.77.208.0/21181.77.208.1 to 181.77.215.254181.77.215.2552,046
60181.77.216.0/21181.77.216.1 to 181.77.223.254181.77.223.2552,046
61181.77.224.0/21181.77.224.1 to 181.77.231.254181.77.231.2552,046
62181.77.232.0/21181.77.232.1 to 181.77.239.254181.77.239.2552,046
63181.77.240.0/21181.77.240.1 to 181.77.247.254181.77.247.2552,046
64181.77.248.0/21181.77.248.1 to 181.77.255.254181.77.255.2552,046
65181.78.0.0/21181.78.0.1 to 181.78.7.254181.78.7.2552,046
66181.78.8.0/21181.78.8.1 to 181.78.15.254181.78.15.2552,046
67181.78.16.0/21181.78.16.1 to 181.78.23.254181.78.23.2552,046
68181.78.24.0/21181.78.24.1 to 181.78.31.254181.78.31.2552,046
69181.78.32.0/21181.78.32.1 to 181.78.39.254181.78.39.2552,046
70181.78.40.0/21181.78.40.1 to 181.78.47.254181.78.47.2552,046
71181.78.48.0/21181.78.48.1 to 181.78.55.254181.78.55.2552,046
72181.78.56.0/21181.78.56.1 to 181.78.63.254181.78.63.2552,046
73181.78.64.0/21181.78.64.1 to 181.78.71.254181.78.71.2552,046
74181.78.72.0/21181.78.72.1 to 181.78.79.254181.78.79.2552,046
75181.78.80.0/21181.78.80.1 to 181.78.87.254181.78.87.2552,046
76181.78.88.0/21181.78.88.1 to 181.78.95.254181.78.95.2552,046
77181.78.96.0/21181.78.96.1 to 181.78.103.254181.78.103.2552,046
78181.78.104.0/21181.78.104.1 to 181.78.111.254181.78.111.2552,046
79181.78.112.0/21181.78.112.1 to 181.78.119.254181.78.119.2552,046
80181.78.120.0/21181.78.120.1 to 181.78.127.254181.78.127.2552,046
81181.78.128.0/21181.78.128.1 to 181.78.135.254181.78.135.2552,046
82181.78.136.0/21181.78.136.1 to 181.78.143.254181.78.143.2552,046
83181.78.144.0/21181.78.144.1 to 181.78.151.254181.78.151.2552,046
84181.78.152.0/21181.78.152.1 to 181.78.159.254181.78.159.2552,046
85181.78.160.0/21181.78.160.1 to 181.78.167.254181.78.167.2552,046
86181.78.168.0/21181.78.168.1 to 181.78.175.254181.78.175.2552,046
87181.78.176.0/21181.78.176.1 to 181.78.183.254181.78.183.2552,046
88181.78.184.0/21181.78.184.1 to 181.78.191.254181.78.191.2552,046
89181.78.192.0/21181.78.192.1 to 181.78.199.254181.78.199.2552,046
90181.78.200.0/21181.78.200.1 to 181.78.207.254181.78.207.2552,046
91181.78.208.0/21181.78.208.1 to 181.78.215.254181.78.215.2552,046
92181.78.216.0/21181.78.216.1 to 181.78.223.254181.78.223.2552,046
93181.78.224.0/21181.78.224.1 to 181.78.231.254181.78.231.2552,046
94181.78.232.0/21181.78.232.1 to 181.78.239.254181.78.239.2552,046
95181.78.240.0/21181.78.240.1 to 181.78.247.254181.78.247.2552,046
96181.78.248.0/21181.78.248.1 to 181.78.255.254181.78.255.2552,046
97181.79.0.0/21181.79.0.1 to 181.79.7.254181.79.7.2552,046
98181.79.8.0/21181.79.8.1 to 181.79.15.254181.79.15.2552,046
99181.79.16.0/21181.79.16.1 to 181.79.23.254181.79.23.2552,046
100181.79.24.0/21181.79.24.1 to 181.79.31.254181.79.31.2552,046
101181.79.32.0/21181.79.32.1 to 181.79.39.254181.79.39.2552,046
102181.79.40.0/21181.79.40.1 to 181.79.47.254181.79.47.2552,046
103181.79.48.0/21181.79.48.1 to 181.79.55.254181.79.55.2552,046
104181.79.56.0/21181.79.56.1 to 181.79.63.254181.79.63.2552,046
105181.79.64.0/21181.79.64.1 to 181.79.71.254181.79.71.2552,046
106181.79.72.0/21181.79.72.1 to 181.79.79.254181.79.79.2552,046
107181.79.80.0/21181.79.80.1 to 181.79.87.254181.79.87.2552,046
108181.79.88.0/21181.79.88.1 to 181.79.95.254181.79.95.2552,046
109181.79.96.0/21181.79.96.1 to 181.79.103.254181.79.103.2552,046
110181.79.104.0/21181.79.104.1 to 181.79.111.254181.79.111.2552,046
111181.79.112.0/21181.79.112.1 to 181.79.119.254181.79.119.2552,046
112181.79.120.0/21181.79.120.1 to 181.79.127.254181.79.127.2552,046
113181.79.128.0/21181.79.128.1 to 181.79.135.254181.79.135.2552,046
114181.79.136.0/21181.79.136.1 to 181.79.143.254181.79.143.2552,046
115181.79.144.0/21181.79.144.1 to 181.79.151.254181.79.151.2552,046
116181.79.152.0/21181.79.152.1 to 181.79.159.254181.79.159.2552,046
117181.79.160.0/21181.79.160.1 to 181.79.167.254181.79.167.2552,046
118181.79.168.0/21181.79.168.1 to 181.79.175.254181.79.175.2552,046
119181.79.176.0/21181.79.176.1 to 181.79.183.254181.79.183.2552,046
120181.79.184.0/21181.79.184.1 to 181.79.191.254181.79.191.2552,046
121181.79.192.0/21181.79.192.1 to 181.79.199.254181.79.199.2552,046
122181.79.200.0/21181.79.200.1 to 181.79.207.254181.79.207.2552,046
123181.79.208.0/21181.79.208.1 to 181.79.215.254181.79.215.2552,046
124181.79.216.0/21181.79.216.1 to 181.79.223.254181.79.223.2552,046
125181.79.224.0/21181.79.224.1 to 181.79.231.254181.79.231.2552,046
126181.79.232.0/21181.79.232.1 to 181.79.239.254181.79.239.2552,046
127181.79.240.0/21181.79.240.1 to 181.79.247.254181.79.247.2552,046
128181.79.248.0/21181.79.248.1 to 181.79.255.254181.79.255.2552,046

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.