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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.

Network219.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
219.0.0.0
Broadcast address
219.255.255.255
First usable
219.0.0.1
Last usable
219.255.255.254
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
C (default /24)
As numbers
Hex DB000000 · Integer 3674210304 to 3690987519
Reverse DNS zone
219.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011011..00000000.00000000.00000000219.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11011011..00000000.00000000.00000000219.0.0.0
Broadcast11011011..11111111.11111111.11111111219.255.255.255
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)

219.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1219.0.0.0/15219.0.0.1 to 219.1.255.254219.1.255.255131,070
2219.2.0.0/15219.2.0.1 to 219.3.255.254219.3.255.255131,070
3219.4.0.0/15219.4.0.1 to 219.5.255.254219.5.255.255131,070
4219.6.0.0/15219.6.0.1 to 219.7.255.254219.7.255.255131,070
5219.8.0.0/15219.8.0.1 to 219.9.255.254219.9.255.255131,070
6219.10.0.0/15219.10.0.1 to 219.11.255.254219.11.255.255131,070
7219.12.0.0/15219.12.0.1 to 219.13.255.254219.13.255.255131,070
8219.14.0.0/15219.14.0.1 to 219.15.255.254219.15.255.255131,070
9219.16.0.0/15219.16.0.1 to 219.17.255.254219.17.255.255131,070
10219.18.0.0/15219.18.0.1 to 219.19.255.254219.19.255.255131,070
11219.20.0.0/15219.20.0.1 to 219.21.255.254219.21.255.255131,070
12219.22.0.0/15219.22.0.1 to 219.23.255.254219.23.255.255131,070
13219.24.0.0/15219.24.0.1 to 219.25.255.254219.25.255.255131,070
14219.26.0.0/15219.26.0.1 to 219.27.255.254219.27.255.255131,070
15219.28.0.0/15219.28.0.1 to 219.29.255.254219.29.255.255131,070
16219.30.0.0/15219.30.0.1 to 219.31.255.254219.31.255.255131,070
17219.32.0.0/15219.32.0.1 to 219.33.255.254219.33.255.255131,070
18219.34.0.0/15219.34.0.1 to 219.35.255.254219.35.255.255131,070
19219.36.0.0/15219.36.0.1 to 219.37.255.254219.37.255.255131,070
20219.38.0.0/15219.38.0.1 to 219.39.255.254219.39.255.255131,070
21219.40.0.0/15219.40.0.1 to 219.41.255.254219.41.255.255131,070
22219.42.0.0/15219.42.0.1 to 219.43.255.254219.43.255.255131,070
23219.44.0.0/15219.44.0.1 to 219.45.255.254219.45.255.255131,070
24219.46.0.0/15219.46.0.1 to 219.47.255.254219.47.255.255131,070
25219.48.0.0/15219.48.0.1 to 219.49.255.254219.49.255.255131,070
26219.50.0.0/15219.50.0.1 to 219.51.255.254219.51.255.255131,070
27219.52.0.0/15219.52.0.1 to 219.53.255.254219.53.255.255131,070
28219.54.0.0/15219.54.0.1 to 219.55.255.254219.55.255.255131,070
29219.56.0.0/15219.56.0.1 to 219.57.255.254219.57.255.255131,070
30219.58.0.0/15219.58.0.1 to 219.59.255.254219.59.255.255131,070
31219.60.0.0/15219.60.0.1 to 219.61.255.254219.61.255.255131,070
32219.62.0.0/15219.62.0.1 to 219.63.255.254219.63.255.255131,070
33219.64.0.0/15219.64.0.1 to 219.65.255.254219.65.255.255131,070
34219.66.0.0/15219.66.0.1 to 219.67.255.254219.67.255.255131,070
35219.68.0.0/15219.68.0.1 to 219.69.255.254219.69.255.255131,070
36219.70.0.0/15219.70.0.1 to 219.71.255.254219.71.255.255131,070
37219.72.0.0/15219.72.0.1 to 219.73.255.254219.73.255.255131,070
38219.74.0.0/15219.74.0.1 to 219.75.255.254219.75.255.255131,070
39219.76.0.0/15219.76.0.1 to 219.77.255.254219.77.255.255131,070
40219.78.0.0/15219.78.0.1 to 219.79.255.254219.79.255.255131,070
41219.80.0.0/15219.80.0.1 to 219.81.255.254219.81.255.255131,070
42219.82.0.0/15219.82.0.1 to 219.83.255.254219.83.255.255131,070
43219.84.0.0/15219.84.0.1 to 219.85.255.254219.85.255.255131,070
44219.86.0.0/15219.86.0.1 to 219.87.255.254219.87.255.255131,070
45219.88.0.0/15219.88.0.1 to 219.89.255.254219.89.255.255131,070
46219.90.0.0/15219.90.0.1 to 219.91.255.254219.91.255.255131,070
47219.92.0.0/15219.92.0.1 to 219.93.255.254219.93.255.255131,070
48219.94.0.0/15219.94.0.1 to 219.95.255.254219.95.255.255131,070
49219.96.0.0/15219.96.0.1 to 219.97.255.254219.97.255.255131,070
50219.98.0.0/15219.98.0.1 to 219.99.255.254219.99.255.255131,070
51219.100.0.0/15219.100.0.1 to 219.101.255.254219.101.255.255131,070
52219.102.0.0/15219.102.0.1 to 219.103.255.254219.103.255.255131,070
53219.104.0.0/15219.104.0.1 to 219.105.255.254219.105.255.255131,070
54219.106.0.0/15219.106.0.1 to 219.107.255.254219.107.255.255131,070
55219.108.0.0/15219.108.0.1 to 219.109.255.254219.109.255.255131,070
56219.110.0.0/15219.110.0.1 to 219.111.255.254219.111.255.255131,070
57219.112.0.0/15219.112.0.1 to 219.113.255.254219.113.255.255131,070
58219.114.0.0/15219.114.0.1 to 219.115.255.254219.115.255.255131,070
59219.116.0.0/15219.116.0.1 to 219.117.255.254219.117.255.255131,070
60219.118.0.0/15219.118.0.1 to 219.119.255.254219.119.255.255131,070
61219.120.0.0/15219.120.0.1 to 219.121.255.254219.121.255.255131,070
62219.122.0.0/15219.122.0.1 to 219.123.255.254219.123.255.255131,070
63219.124.0.0/15219.124.0.1 to 219.125.255.254219.125.255.255131,070
64219.126.0.0/15219.126.0.1 to 219.127.255.254219.127.255.255131,070
65219.128.0.0/15219.128.0.1 to 219.129.255.254219.129.255.255131,070
66219.130.0.0/15219.130.0.1 to 219.131.255.254219.131.255.255131,070
67219.132.0.0/15219.132.0.1 to 219.133.255.254219.133.255.255131,070
68219.134.0.0/15219.134.0.1 to 219.135.255.254219.135.255.255131,070
69219.136.0.0/15219.136.0.1 to 219.137.255.254219.137.255.255131,070
70219.138.0.0/15219.138.0.1 to 219.139.255.254219.139.255.255131,070
71219.140.0.0/15219.140.0.1 to 219.141.255.254219.141.255.255131,070
72219.142.0.0/15219.142.0.1 to 219.143.255.254219.143.255.255131,070
73219.144.0.0/15219.144.0.1 to 219.145.255.254219.145.255.255131,070
74219.146.0.0/15219.146.0.1 to 219.147.255.254219.147.255.255131,070
75219.148.0.0/15219.148.0.1 to 219.149.255.254219.149.255.255131,070
76219.150.0.0/15219.150.0.1 to 219.151.255.254219.151.255.255131,070
77219.152.0.0/15219.152.0.1 to 219.153.255.254219.153.255.255131,070
78219.154.0.0/15219.154.0.1 to 219.155.255.254219.155.255.255131,070
79219.156.0.0/15219.156.0.1 to 219.157.255.254219.157.255.255131,070
80219.158.0.0/15219.158.0.1 to 219.159.255.254219.159.255.255131,070
81219.160.0.0/15219.160.0.1 to 219.161.255.254219.161.255.255131,070
82219.162.0.0/15219.162.0.1 to 219.163.255.254219.163.255.255131,070
83219.164.0.0/15219.164.0.1 to 219.165.255.254219.165.255.255131,070
84219.166.0.0/15219.166.0.1 to 219.167.255.254219.167.255.255131,070
85219.168.0.0/15219.168.0.1 to 219.169.255.254219.169.255.255131,070
86219.170.0.0/15219.170.0.1 to 219.171.255.254219.171.255.255131,070
87219.172.0.0/15219.172.0.1 to 219.173.255.254219.173.255.255131,070
88219.174.0.0/15219.174.0.1 to 219.175.255.254219.175.255.255131,070
89219.176.0.0/15219.176.0.1 to 219.177.255.254219.177.255.255131,070
90219.178.0.0/15219.178.0.1 to 219.179.255.254219.179.255.255131,070
91219.180.0.0/15219.180.0.1 to 219.181.255.254219.181.255.255131,070
92219.182.0.0/15219.182.0.1 to 219.183.255.254219.183.255.255131,070
93219.184.0.0/15219.184.0.1 to 219.185.255.254219.185.255.255131,070
94219.186.0.0/15219.186.0.1 to 219.187.255.254219.187.255.255131,070
95219.188.0.0/15219.188.0.1 to 219.189.255.254219.189.255.255131,070
96219.190.0.0/15219.190.0.1 to 219.191.255.254219.191.255.255131,070
97219.192.0.0/15219.192.0.1 to 219.193.255.254219.193.255.255131,070
98219.194.0.0/15219.194.0.1 to 219.195.255.254219.195.255.255131,070
99219.196.0.0/15219.196.0.1 to 219.197.255.254219.197.255.255131,070
100219.198.0.0/15219.198.0.1 to 219.199.255.254219.199.255.255131,070
101219.200.0.0/15219.200.0.1 to 219.201.255.254219.201.255.255131,070
102219.202.0.0/15219.202.0.1 to 219.203.255.254219.203.255.255131,070
103219.204.0.0/15219.204.0.1 to 219.205.255.254219.205.255.255131,070
104219.206.0.0/15219.206.0.1 to 219.207.255.254219.207.255.255131,070
105219.208.0.0/15219.208.0.1 to 219.209.255.254219.209.255.255131,070
106219.210.0.0/15219.210.0.1 to 219.211.255.254219.211.255.255131,070
107219.212.0.0/15219.212.0.1 to 219.213.255.254219.213.255.255131,070
108219.214.0.0/15219.214.0.1 to 219.215.255.254219.215.255.255131,070
109219.216.0.0/15219.216.0.1 to 219.217.255.254219.217.255.255131,070
110219.218.0.0/15219.218.0.1 to 219.219.255.254219.219.255.255131,070
111219.220.0.0/15219.220.0.1 to 219.221.255.254219.221.255.255131,070
112219.222.0.0/15219.222.0.1 to 219.223.255.254219.223.255.255131,070
113219.224.0.0/15219.224.0.1 to 219.225.255.254219.225.255.255131,070
114219.226.0.0/15219.226.0.1 to 219.227.255.254219.227.255.255131,070
115219.228.0.0/15219.228.0.1 to 219.229.255.254219.229.255.255131,070
116219.230.0.0/15219.230.0.1 to 219.231.255.254219.231.255.255131,070
117219.232.0.0/15219.232.0.1 to 219.233.255.254219.233.255.255131,070
118219.234.0.0/15219.234.0.1 to 219.235.255.254219.235.255.255131,070
119219.236.0.0/15219.236.0.1 to 219.237.255.254219.237.255.255131,070
120219.238.0.0/15219.238.0.1 to 219.239.255.254219.239.255.255131,070
121219.240.0.0/15219.240.0.1 to 219.241.255.254219.241.255.255131,070
122219.242.0.0/15219.242.0.1 to 219.243.255.254219.243.255.255131,070
123219.244.0.0/15219.244.0.1 to 219.245.255.254219.245.255.255131,070
124219.246.0.0/15219.246.0.1 to 219.247.255.254219.247.255.255131,070
125219.248.0.0/15219.248.0.1 to 219.249.255.254219.249.255.255131,070
126219.250.0.0/15219.250.0.1 to 219.251.255.254219.251.255.255131,070
127219.252.0.0/15219.252.0.1 to 219.253.255.254219.253.255.255131,070
128219.254.0.0/15219.254.0.1 to 219.255.255.254219.255.255.255131,070

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.