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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.

Network183.2.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
183.2.0.0
Broadcast address
183.3.255.255
First usable
183.2.0.1
Last usable
183.3.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
B (default /16)
As numbers
Hex B7020000 · Integer 3070361600 to 3070492671
Reverse DNS zones
2.183.in-addr.arpa
3.183.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110111.00000010.00000000.00000000183.2.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network10110111.00000010.00000000.00000000183.2.0.0
Broadcast10110111.00000011.11111111.11111111183.3.255.255
Split into smaller subnets/22
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

183.2.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1183.2.0.0/22183.2.0.1 to 183.2.3.254183.2.3.2551,022
2183.2.4.0/22183.2.4.1 to 183.2.7.254183.2.7.2551,022
3183.2.8.0/22183.2.8.1 to 183.2.11.254183.2.11.2551,022
4183.2.12.0/22183.2.12.1 to 183.2.15.254183.2.15.2551,022
5183.2.16.0/22183.2.16.1 to 183.2.19.254183.2.19.2551,022
6183.2.20.0/22183.2.20.1 to 183.2.23.254183.2.23.2551,022
7183.2.24.0/22183.2.24.1 to 183.2.27.254183.2.27.2551,022
8183.2.28.0/22183.2.28.1 to 183.2.31.254183.2.31.2551,022
9183.2.32.0/22183.2.32.1 to 183.2.35.254183.2.35.2551,022
10183.2.36.0/22183.2.36.1 to 183.2.39.254183.2.39.2551,022
11183.2.40.0/22183.2.40.1 to 183.2.43.254183.2.43.2551,022
12183.2.44.0/22183.2.44.1 to 183.2.47.254183.2.47.2551,022
13183.2.48.0/22183.2.48.1 to 183.2.51.254183.2.51.2551,022
14183.2.52.0/22183.2.52.1 to 183.2.55.254183.2.55.2551,022
15183.2.56.0/22183.2.56.1 to 183.2.59.254183.2.59.2551,022
16183.2.60.0/22183.2.60.1 to 183.2.63.254183.2.63.2551,022
17183.2.64.0/22183.2.64.1 to 183.2.67.254183.2.67.2551,022
18183.2.68.0/22183.2.68.1 to 183.2.71.254183.2.71.2551,022
19183.2.72.0/22183.2.72.1 to 183.2.75.254183.2.75.2551,022
20183.2.76.0/22183.2.76.1 to 183.2.79.254183.2.79.2551,022
21183.2.80.0/22183.2.80.1 to 183.2.83.254183.2.83.2551,022
22183.2.84.0/22183.2.84.1 to 183.2.87.254183.2.87.2551,022
23183.2.88.0/22183.2.88.1 to 183.2.91.254183.2.91.2551,022
24183.2.92.0/22183.2.92.1 to 183.2.95.254183.2.95.2551,022
25183.2.96.0/22183.2.96.1 to 183.2.99.254183.2.99.2551,022
26183.2.100.0/22183.2.100.1 to 183.2.103.254183.2.103.2551,022
27183.2.104.0/22183.2.104.1 to 183.2.107.254183.2.107.2551,022
28183.2.108.0/22183.2.108.1 to 183.2.111.254183.2.111.2551,022
29183.2.112.0/22183.2.112.1 to 183.2.115.254183.2.115.2551,022
30183.2.116.0/22183.2.116.1 to 183.2.119.254183.2.119.2551,022
31183.2.120.0/22183.2.120.1 to 183.2.123.254183.2.123.2551,022
32183.2.124.0/22183.2.124.1 to 183.2.127.254183.2.127.2551,022
33183.2.128.0/22183.2.128.1 to 183.2.131.254183.2.131.2551,022
34183.2.132.0/22183.2.132.1 to 183.2.135.254183.2.135.2551,022
35183.2.136.0/22183.2.136.1 to 183.2.139.254183.2.139.2551,022
36183.2.140.0/22183.2.140.1 to 183.2.143.254183.2.143.2551,022
37183.2.144.0/22183.2.144.1 to 183.2.147.254183.2.147.2551,022
38183.2.148.0/22183.2.148.1 to 183.2.151.254183.2.151.2551,022
39183.2.152.0/22183.2.152.1 to 183.2.155.254183.2.155.2551,022
40183.2.156.0/22183.2.156.1 to 183.2.159.254183.2.159.2551,022
41183.2.160.0/22183.2.160.1 to 183.2.163.254183.2.163.2551,022
42183.2.164.0/22183.2.164.1 to 183.2.167.254183.2.167.2551,022
43183.2.168.0/22183.2.168.1 to 183.2.171.254183.2.171.2551,022
44183.2.172.0/22183.2.172.1 to 183.2.175.254183.2.175.2551,022
45183.2.176.0/22183.2.176.1 to 183.2.179.254183.2.179.2551,022
46183.2.180.0/22183.2.180.1 to 183.2.183.254183.2.183.2551,022
47183.2.184.0/22183.2.184.1 to 183.2.187.254183.2.187.2551,022
48183.2.188.0/22183.2.188.1 to 183.2.191.254183.2.191.2551,022
49183.2.192.0/22183.2.192.1 to 183.2.195.254183.2.195.2551,022
50183.2.196.0/22183.2.196.1 to 183.2.199.254183.2.199.2551,022
51183.2.200.0/22183.2.200.1 to 183.2.203.254183.2.203.2551,022
52183.2.204.0/22183.2.204.1 to 183.2.207.254183.2.207.2551,022
53183.2.208.0/22183.2.208.1 to 183.2.211.254183.2.211.2551,022
54183.2.212.0/22183.2.212.1 to 183.2.215.254183.2.215.2551,022
55183.2.216.0/22183.2.216.1 to 183.2.219.254183.2.219.2551,022
56183.2.220.0/22183.2.220.1 to 183.2.223.254183.2.223.2551,022
57183.2.224.0/22183.2.224.1 to 183.2.227.254183.2.227.2551,022
58183.2.228.0/22183.2.228.1 to 183.2.231.254183.2.231.2551,022
59183.2.232.0/22183.2.232.1 to 183.2.235.254183.2.235.2551,022
60183.2.236.0/22183.2.236.1 to 183.2.239.254183.2.239.2551,022
61183.2.240.0/22183.2.240.1 to 183.2.243.254183.2.243.2551,022
62183.2.244.0/22183.2.244.1 to 183.2.247.254183.2.247.2551,022
63183.2.248.0/22183.2.248.1 to 183.2.251.254183.2.251.2551,022
64183.2.252.0/22183.2.252.1 to 183.2.255.254183.2.255.2551,022
65183.3.0.0/22183.3.0.1 to 183.3.3.254183.3.3.2551,022
66183.3.4.0/22183.3.4.1 to 183.3.7.254183.3.7.2551,022
67183.3.8.0/22183.3.8.1 to 183.3.11.254183.3.11.2551,022
68183.3.12.0/22183.3.12.1 to 183.3.15.254183.3.15.2551,022
69183.3.16.0/22183.3.16.1 to 183.3.19.254183.3.19.2551,022
70183.3.20.0/22183.3.20.1 to 183.3.23.254183.3.23.2551,022
71183.3.24.0/22183.3.24.1 to 183.3.27.254183.3.27.2551,022
72183.3.28.0/22183.3.28.1 to 183.3.31.254183.3.31.2551,022
73183.3.32.0/22183.3.32.1 to 183.3.35.254183.3.35.2551,022
74183.3.36.0/22183.3.36.1 to 183.3.39.254183.3.39.2551,022
75183.3.40.0/22183.3.40.1 to 183.3.43.254183.3.43.2551,022
76183.3.44.0/22183.3.44.1 to 183.3.47.254183.3.47.2551,022
77183.3.48.0/22183.3.48.1 to 183.3.51.254183.3.51.2551,022
78183.3.52.0/22183.3.52.1 to 183.3.55.254183.3.55.2551,022
79183.3.56.0/22183.3.56.1 to 183.3.59.254183.3.59.2551,022
80183.3.60.0/22183.3.60.1 to 183.3.63.254183.3.63.2551,022
81183.3.64.0/22183.3.64.1 to 183.3.67.254183.3.67.2551,022
82183.3.68.0/22183.3.68.1 to 183.3.71.254183.3.71.2551,022
83183.3.72.0/22183.3.72.1 to 183.3.75.254183.3.75.2551,022
84183.3.76.0/22183.3.76.1 to 183.3.79.254183.3.79.2551,022
85183.3.80.0/22183.3.80.1 to 183.3.83.254183.3.83.2551,022
86183.3.84.0/22183.3.84.1 to 183.3.87.254183.3.87.2551,022
87183.3.88.0/22183.3.88.1 to 183.3.91.254183.3.91.2551,022
88183.3.92.0/22183.3.92.1 to 183.3.95.254183.3.95.2551,022
89183.3.96.0/22183.3.96.1 to 183.3.99.254183.3.99.2551,022
90183.3.100.0/22183.3.100.1 to 183.3.103.254183.3.103.2551,022
91183.3.104.0/22183.3.104.1 to 183.3.107.254183.3.107.2551,022
92183.3.108.0/22183.3.108.1 to 183.3.111.254183.3.111.2551,022
93183.3.112.0/22183.3.112.1 to 183.3.115.254183.3.115.2551,022
94183.3.116.0/22183.3.116.1 to 183.3.119.254183.3.119.2551,022
95183.3.120.0/22183.3.120.1 to 183.3.123.254183.3.123.2551,022
96183.3.124.0/22183.3.124.1 to 183.3.127.254183.3.127.2551,022
97183.3.128.0/22183.3.128.1 to 183.3.131.254183.3.131.2551,022
98183.3.132.0/22183.3.132.1 to 183.3.135.254183.3.135.2551,022
99183.3.136.0/22183.3.136.1 to 183.3.139.254183.3.139.2551,022
100183.3.140.0/22183.3.140.1 to 183.3.143.254183.3.143.2551,022
101183.3.144.0/22183.3.144.1 to 183.3.147.254183.3.147.2551,022
102183.3.148.0/22183.3.148.1 to 183.3.151.254183.3.151.2551,022
103183.3.152.0/22183.3.152.1 to 183.3.155.254183.3.155.2551,022
104183.3.156.0/22183.3.156.1 to 183.3.159.254183.3.159.2551,022
105183.3.160.0/22183.3.160.1 to 183.3.163.254183.3.163.2551,022
106183.3.164.0/22183.3.164.1 to 183.3.167.254183.3.167.2551,022
107183.3.168.0/22183.3.168.1 to 183.3.171.254183.3.171.2551,022
108183.3.172.0/22183.3.172.1 to 183.3.175.254183.3.175.2551,022
109183.3.176.0/22183.3.176.1 to 183.3.179.254183.3.179.2551,022
110183.3.180.0/22183.3.180.1 to 183.3.183.254183.3.183.2551,022
111183.3.184.0/22183.3.184.1 to 183.3.187.254183.3.187.2551,022
112183.3.188.0/22183.3.188.1 to 183.3.191.254183.3.191.2551,022
113183.3.192.0/22183.3.192.1 to 183.3.195.254183.3.195.2551,022
114183.3.196.0/22183.3.196.1 to 183.3.199.254183.3.199.2551,022
115183.3.200.0/22183.3.200.1 to 183.3.203.254183.3.203.2551,022
116183.3.204.0/22183.3.204.1 to 183.3.207.254183.3.207.2551,022
117183.3.208.0/22183.3.208.1 to 183.3.211.254183.3.211.2551,022
118183.3.212.0/22183.3.212.1 to 183.3.215.254183.3.215.2551,022
119183.3.216.0/22183.3.216.1 to 183.3.219.254183.3.219.2551,022
120183.3.220.0/22183.3.220.1 to 183.3.223.254183.3.223.2551,022
121183.3.224.0/22183.3.224.1 to 183.3.227.254183.3.227.2551,022
122183.3.228.0/22183.3.228.1 to 183.3.231.254183.3.231.2551,022
123183.3.232.0/22183.3.232.1 to 183.3.235.254183.3.235.2551,022
124183.3.236.0/22183.3.236.1 to 183.3.239.254183.3.239.2551,022
125183.3.240.0/22183.3.240.1 to 183.3.243.254183.3.243.2551,022
126183.3.244.0/22183.3.244.1 to 183.3.247.254183.3.247.2551,022
127183.3.248.0/22183.3.248.1 to 183.3.251.254183.3.251.2551,022
128183.3.252.0/22183.3.252.1 to 183.3.255.254183.3.255.2551,022

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.