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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.

Network183.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
183.0.0.0
Broadcast address
183.255.255.255
First usable
183.0.0.1
Last usable
183.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex B7000000 · Integer 3070230528 to 3087007743
Reverse DNS zone
183.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110111..00000000.00000000.00000000183.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10110111..00000000.00000000.00000000183.0.0.0
Broadcast10110111..11111111.11111111.11111111183.255.255.255
Split into smaller subnets/15
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

183.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1183.0.0.0/15183.0.0.1 to 183.1.255.254183.1.255.255131,070
2183.2.0.0/15183.2.0.1 to 183.3.255.254183.3.255.255131,070
3183.4.0.0/15183.4.0.1 to 183.5.255.254183.5.255.255131,070
4183.6.0.0/15183.6.0.1 to 183.7.255.254183.7.255.255131,070
5183.8.0.0/15183.8.0.1 to 183.9.255.254183.9.255.255131,070
6183.10.0.0/15183.10.0.1 to 183.11.255.254183.11.255.255131,070
7183.12.0.0/15183.12.0.1 to 183.13.255.254183.13.255.255131,070
8183.14.0.0/15183.14.0.1 to 183.15.255.254183.15.255.255131,070
9183.16.0.0/15183.16.0.1 to 183.17.255.254183.17.255.255131,070
10183.18.0.0/15183.18.0.1 to 183.19.255.254183.19.255.255131,070
11183.20.0.0/15183.20.0.1 to 183.21.255.254183.21.255.255131,070
12183.22.0.0/15183.22.0.1 to 183.23.255.254183.23.255.255131,070
13183.24.0.0/15183.24.0.1 to 183.25.255.254183.25.255.255131,070
14183.26.0.0/15183.26.0.1 to 183.27.255.254183.27.255.255131,070
15183.28.0.0/15183.28.0.1 to 183.29.255.254183.29.255.255131,070
16183.30.0.0/15183.30.0.1 to 183.31.255.254183.31.255.255131,070
17183.32.0.0/15183.32.0.1 to 183.33.255.254183.33.255.255131,070
18183.34.0.0/15183.34.0.1 to 183.35.255.254183.35.255.255131,070
19183.36.0.0/15183.36.0.1 to 183.37.255.254183.37.255.255131,070
20183.38.0.0/15183.38.0.1 to 183.39.255.254183.39.255.255131,070
21183.40.0.0/15183.40.0.1 to 183.41.255.254183.41.255.255131,070
22183.42.0.0/15183.42.0.1 to 183.43.255.254183.43.255.255131,070
23183.44.0.0/15183.44.0.1 to 183.45.255.254183.45.255.255131,070
24183.46.0.0/15183.46.0.1 to 183.47.255.254183.47.255.255131,070
25183.48.0.0/15183.48.0.1 to 183.49.255.254183.49.255.255131,070
26183.50.0.0/15183.50.0.1 to 183.51.255.254183.51.255.255131,070
27183.52.0.0/15183.52.0.1 to 183.53.255.254183.53.255.255131,070
28183.54.0.0/15183.54.0.1 to 183.55.255.254183.55.255.255131,070
29183.56.0.0/15183.56.0.1 to 183.57.255.254183.57.255.255131,070
30183.58.0.0/15183.58.0.1 to 183.59.255.254183.59.255.255131,070
31183.60.0.0/15183.60.0.1 to 183.61.255.254183.61.255.255131,070
32183.62.0.0/15183.62.0.1 to 183.63.255.254183.63.255.255131,070
33183.64.0.0/15183.64.0.1 to 183.65.255.254183.65.255.255131,070
34183.66.0.0/15183.66.0.1 to 183.67.255.254183.67.255.255131,070
35183.68.0.0/15183.68.0.1 to 183.69.255.254183.69.255.255131,070
36183.70.0.0/15183.70.0.1 to 183.71.255.254183.71.255.255131,070
37183.72.0.0/15183.72.0.1 to 183.73.255.254183.73.255.255131,070
38183.74.0.0/15183.74.0.1 to 183.75.255.254183.75.255.255131,070
39183.76.0.0/15183.76.0.1 to 183.77.255.254183.77.255.255131,070
40183.78.0.0/15183.78.0.1 to 183.79.255.254183.79.255.255131,070
41183.80.0.0/15183.80.0.1 to 183.81.255.254183.81.255.255131,070
42183.82.0.0/15183.82.0.1 to 183.83.255.254183.83.255.255131,070
43183.84.0.0/15183.84.0.1 to 183.85.255.254183.85.255.255131,070
44183.86.0.0/15183.86.0.1 to 183.87.255.254183.87.255.255131,070
45183.88.0.0/15183.88.0.1 to 183.89.255.254183.89.255.255131,070
46183.90.0.0/15183.90.0.1 to 183.91.255.254183.91.255.255131,070
47183.92.0.0/15183.92.0.1 to 183.93.255.254183.93.255.255131,070
48183.94.0.0/15183.94.0.1 to 183.95.255.254183.95.255.255131,070
49183.96.0.0/15183.96.0.1 to 183.97.255.254183.97.255.255131,070
50183.98.0.0/15183.98.0.1 to 183.99.255.254183.99.255.255131,070
51183.100.0.0/15183.100.0.1 to 183.101.255.254183.101.255.255131,070
52183.102.0.0/15183.102.0.1 to 183.103.255.254183.103.255.255131,070
53183.104.0.0/15183.104.0.1 to 183.105.255.254183.105.255.255131,070
54183.106.0.0/15183.106.0.1 to 183.107.255.254183.107.255.255131,070
55183.108.0.0/15183.108.0.1 to 183.109.255.254183.109.255.255131,070
56183.110.0.0/15183.110.0.1 to 183.111.255.254183.111.255.255131,070
57183.112.0.0/15183.112.0.1 to 183.113.255.254183.113.255.255131,070
58183.114.0.0/15183.114.0.1 to 183.115.255.254183.115.255.255131,070
59183.116.0.0/15183.116.0.1 to 183.117.255.254183.117.255.255131,070
60183.118.0.0/15183.118.0.1 to 183.119.255.254183.119.255.255131,070
61183.120.0.0/15183.120.0.1 to 183.121.255.254183.121.255.255131,070
62183.122.0.0/15183.122.0.1 to 183.123.255.254183.123.255.255131,070
63183.124.0.0/15183.124.0.1 to 183.125.255.254183.125.255.255131,070
64183.126.0.0/15183.126.0.1 to 183.127.255.254183.127.255.255131,070
65183.128.0.0/15183.128.0.1 to 183.129.255.254183.129.255.255131,070
66183.130.0.0/15183.130.0.1 to 183.131.255.254183.131.255.255131,070
67183.132.0.0/15183.132.0.1 to 183.133.255.254183.133.255.255131,070
68183.134.0.0/15183.134.0.1 to 183.135.255.254183.135.255.255131,070
69183.136.0.0/15183.136.0.1 to 183.137.255.254183.137.255.255131,070
70183.138.0.0/15183.138.0.1 to 183.139.255.254183.139.255.255131,070
71183.140.0.0/15183.140.0.1 to 183.141.255.254183.141.255.255131,070
72183.142.0.0/15183.142.0.1 to 183.143.255.254183.143.255.255131,070
73183.144.0.0/15183.144.0.1 to 183.145.255.254183.145.255.255131,070
74183.146.0.0/15183.146.0.1 to 183.147.255.254183.147.255.255131,070
75183.148.0.0/15183.148.0.1 to 183.149.255.254183.149.255.255131,070
76183.150.0.0/15183.150.0.1 to 183.151.255.254183.151.255.255131,070
77183.152.0.0/15183.152.0.1 to 183.153.255.254183.153.255.255131,070
78183.154.0.0/15183.154.0.1 to 183.155.255.254183.155.255.255131,070
79183.156.0.0/15183.156.0.1 to 183.157.255.254183.157.255.255131,070
80183.158.0.0/15183.158.0.1 to 183.159.255.254183.159.255.255131,070
81183.160.0.0/15183.160.0.1 to 183.161.255.254183.161.255.255131,070
82183.162.0.0/15183.162.0.1 to 183.163.255.254183.163.255.255131,070
83183.164.0.0/15183.164.0.1 to 183.165.255.254183.165.255.255131,070
84183.166.0.0/15183.166.0.1 to 183.167.255.254183.167.255.255131,070
85183.168.0.0/15183.168.0.1 to 183.169.255.254183.169.255.255131,070
86183.170.0.0/15183.170.0.1 to 183.171.255.254183.171.255.255131,070
87183.172.0.0/15183.172.0.1 to 183.173.255.254183.173.255.255131,070
88183.174.0.0/15183.174.0.1 to 183.175.255.254183.175.255.255131,070
89183.176.0.0/15183.176.0.1 to 183.177.255.254183.177.255.255131,070
90183.178.0.0/15183.178.0.1 to 183.179.255.254183.179.255.255131,070
91183.180.0.0/15183.180.0.1 to 183.181.255.254183.181.255.255131,070
92183.182.0.0/15183.182.0.1 to 183.183.255.254183.183.255.255131,070
93183.184.0.0/15183.184.0.1 to 183.185.255.254183.185.255.255131,070
94183.186.0.0/15183.186.0.1 to 183.187.255.254183.187.255.255131,070
95183.188.0.0/15183.188.0.1 to 183.189.255.254183.189.255.255131,070
96183.190.0.0/15183.190.0.1 to 183.191.255.254183.191.255.255131,070
97183.192.0.0/15183.192.0.1 to 183.193.255.254183.193.255.255131,070
98183.194.0.0/15183.194.0.1 to 183.195.255.254183.195.255.255131,070
99183.196.0.0/15183.196.0.1 to 183.197.255.254183.197.255.255131,070
100183.198.0.0/15183.198.0.1 to 183.199.255.254183.199.255.255131,070
101183.200.0.0/15183.200.0.1 to 183.201.255.254183.201.255.255131,070
102183.202.0.0/15183.202.0.1 to 183.203.255.254183.203.255.255131,070
103183.204.0.0/15183.204.0.1 to 183.205.255.254183.205.255.255131,070
104183.206.0.0/15183.206.0.1 to 183.207.255.254183.207.255.255131,070
105183.208.0.0/15183.208.0.1 to 183.209.255.254183.209.255.255131,070
106183.210.0.0/15183.210.0.1 to 183.211.255.254183.211.255.255131,070
107183.212.0.0/15183.212.0.1 to 183.213.255.254183.213.255.255131,070
108183.214.0.0/15183.214.0.1 to 183.215.255.254183.215.255.255131,070
109183.216.0.0/15183.216.0.1 to 183.217.255.254183.217.255.255131,070
110183.218.0.0/15183.218.0.1 to 183.219.255.254183.219.255.255131,070
111183.220.0.0/15183.220.0.1 to 183.221.255.254183.221.255.255131,070
112183.222.0.0/15183.222.0.1 to 183.223.255.254183.223.255.255131,070
113183.224.0.0/15183.224.0.1 to 183.225.255.254183.225.255.255131,070
114183.226.0.0/15183.226.0.1 to 183.227.255.254183.227.255.255131,070
115183.228.0.0/15183.228.0.1 to 183.229.255.254183.229.255.255131,070
116183.230.0.0/15183.230.0.1 to 183.231.255.254183.231.255.255131,070
117183.232.0.0/15183.232.0.1 to 183.233.255.254183.233.255.255131,070
118183.234.0.0/15183.234.0.1 to 183.235.255.254183.235.255.255131,070
119183.236.0.0/15183.236.0.1 to 183.237.255.254183.237.255.255131,070
120183.238.0.0/15183.238.0.1 to 183.239.255.254183.239.255.255131,070
121183.240.0.0/15183.240.0.1 to 183.241.255.254183.241.255.255131,070
122183.242.0.0/15183.242.0.1 to 183.243.255.254183.243.255.255131,070
123183.244.0.0/15183.244.0.1 to 183.245.255.254183.245.255.255131,070
124183.246.0.0/15183.246.0.1 to 183.247.255.254183.247.255.255131,070
125183.248.0.0/15183.248.0.1 to 183.249.255.254183.249.255.255131,070
126183.250.0.0/15183.250.0.1 to 183.251.255.254183.251.255.255131,070
127183.252.0.0/15183.252.0.1 to 183.253.255.254183.253.255.255131,070
128183.254.0.0/15183.254.0.1 to 183.255.255.254183.255.255.255131,070

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.