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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.

Network212.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
212.0.0.0
Broadcast address
212.255.255.255
First usable
212.0.0.1
Last usable
212.255.255.254
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 D4000000 · Integer 3556769792 to 3573547007
Reverse DNS zone
212.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010100..00000000.00000000.00000000212.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11010100..00000000.00000000.00000000212.0.0.0
Broadcast11010100..11111111.11111111.11111111212.255.255.255
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)

212.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1212.0.0.0/15212.0.0.1 to 212.1.255.254212.1.255.255131,070
2212.2.0.0/15212.2.0.1 to 212.3.255.254212.3.255.255131,070
3212.4.0.0/15212.4.0.1 to 212.5.255.254212.5.255.255131,070
4212.6.0.0/15212.6.0.1 to 212.7.255.254212.7.255.255131,070
5212.8.0.0/15212.8.0.1 to 212.9.255.254212.9.255.255131,070
6212.10.0.0/15212.10.0.1 to 212.11.255.254212.11.255.255131,070
7212.12.0.0/15212.12.0.1 to 212.13.255.254212.13.255.255131,070
8212.14.0.0/15212.14.0.1 to 212.15.255.254212.15.255.255131,070
9212.16.0.0/15212.16.0.1 to 212.17.255.254212.17.255.255131,070
10212.18.0.0/15212.18.0.1 to 212.19.255.254212.19.255.255131,070
11212.20.0.0/15212.20.0.1 to 212.21.255.254212.21.255.255131,070
12212.22.0.0/15212.22.0.1 to 212.23.255.254212.23.255.255131,070
13212.24.0.0/15212.24.0.1 to 212.25.255.254212.25.255.255131,070
14212.26.0.0/15212.26.0.1 to 212.27.255.254212.27.255.255131,070
15212.28.0.0/15212.28.0.1 to 212.29.255.254212.29.255.255131,070
16212.30.0.0/15212.30.0.1 to 212.31.255.254212.31.255.255131,070
17212.32.0.0/15212.32.0.1 to 212.33.255.254212.33.255.255131,070
18212.34.0.0/15212.34.0.1 to 212.35.255.254212.35.255.255131,070
19212.36.0.0/15212.36.0.1 to 212.37.255.254212.37.255.255131,070
20212.38.0.0/15212.38.0.1 to 212.39.255.254212.39.255.255131,070
21212.40.0.0/15212.40.0.1 to 212.41.255.254212.41.255.255131,070
22212.42.0.0/15212.42.0.1 to 212.43.255.254212.43.255.255131,070
23212.44.0.0/15212.44.0.1 to 212.45.255.254212.45.255.255131,070
24212.46.0.0/15212.46.0.1 to 212.47.255.254212.47.255.255131,070
25212.48.0.0/15212.48.0.1 to 212.49.255.254212.49.255.255131,070
26212.50.0.0/15212.50.0.1 to 212.51.255.254212.51.255.255131,070
27212.52.0.0/15212.52.0.1 to 212.53.255.254212.53.255.255131,070
28212.54.0.0/15212.54.0.1 to 212.55.255.254212.55.255.255131,070
29212.56.0.0/15212.56.0.1 to 212.57.255.254212.57.255.255131,070
30212.58.0.0/15212.58.0.1 to 212.59.255.254212.59.255.255131,070
31212.60.0.0/15212.60.0.1 to 212.61.255.254212.61.255.255131,070
32212.62.0.0/15212.62.0.1 to 212.63.255.254212.63.255.255131,070
33212.64.0.0/15212.64.0.1 to 212.65.255.254212.65.255.255131,070
34212.66.0.0/15212.66.0.1 to 212.67.255.254212.67.255.255131,070
35212.68.0.0/15212.68.0.1 to 212.69.255.254212.69.255.255131,070
36212.70.0.0/15212.70.0.1 to 212.71.255.254212.71.255.255131,070
37212.72.0.0/15212.72.0.1 to 212.73.255.254212.73.255.255131,070
38212.74.0.0/15212.74.0.1 to 212.75.255.254212.75.255.255131,070
39212.76.0.0/15212.76.0.1 to 212.77.255.254212.77.255.255131,070
40212.78.0.0/15212.78.0.1 to 212.79.255.254212.79.255.255131,070
41212.80.0.0/15212.80.0.1 to 212.81.255.254212.81.255.255131,070
42212.82.0.0/15212.82.0.1 to 212.83.255.254212.83.255.255131,070
43212.84.0.0/15212.84.0.1 to 212.85.255.254212.85.255.255131,070
44212.86.0.0/15212.86.0.1 to 212.87.255.254212.87.255.255131,070
45212.88.0.0/15212.88.0.1 to 212.89.255.254212.89.255.255131,070
46212.90.0.0/15212.90.0.1 to 212.91.255.254212.91.255.255131,070
47212.92.0.0/15212.92.0.1 to 212.93.255.254212.93.255.255131,070
48212.94.0.0/15212.94.0.1 to 212.95.255.254212.95.255.255131,070
49212.96.0.0/15212.96.0.1 to 212.97.255.254212.97.255.255131,070
50212.98.0.0/15212.98.0.1 to 212.99.255.254212.99.255.255131,070
51212.100.0.0/15212.100.0.1 to 212.101.255.254212.101.255.255131,070
52212.102.0.0/15212.102.0.1 to 212.103.255.254212.103.255.255131,070
53212.104.0.0/15212.104.0.1 to 212.105.255.254212.105.255.255131,070
54212.106.0.0/15212.106.0.1 to 212.107.255.254212.107.255.255131,070
55212.108.0.0/15212.108.0.1 to 212.109.255.254212.109.255.255131,070
56212.110.0.0/15212.110.0.1 to 212.111.255.254212.111.255.255131,070
57212.112.0.0/15212.112.0.1 to 212.113.255.254212.113.255.255131,070
58212.114.0.0/15212.114.0.1 to 212.115.255.254212.115.255.255131,070
59212.116.0.0/15212.116.0.1 to 212.117.255.254212.117.255.255131,070
60212.118.0.0/15212.118.0.1 to 212.119.255.254212.119.255.255131,070
61212.120.0.0/15212.120.0.1 to 212.121.255.254212.121.255.255131,070
62212.122.0.0/15212.122.0.1 to 212.123.255.254212.123.255.255131,070
63212.124.0.0/15212.124.0.1 to 212.125.255.254212.125.255.255131,070
64212.126.0.0/15212.126.0.1 to 212.127.255.254212.127.255.255131,070
65212.128.0.0/15212.128.0.1 to 212.129.255.254212.129.255.255131,070
66212.130.0.0/15212.130.0.1 to 212.131.255.254212.131.255.255131,070
67212.132.0.0/15212.132.0.1 to 212.133.255.254212.133.255.255131,070
68212.134.0.0/15212.134.0.1 to 212.135.255.254212.135.255.255131,070
69212.136.0.0/15212.136.0.1 to 212.137.255.254212.137.255.255131,070
70212.138.0.0/15212.138.0.1 to 212.139.255.254212.139.255.255131,070
71212.140.0.0/15212.140.0.1 to 212.141.255.254212.141.255.255131,070
72212.142.0.0/15212.142.0.1 to 212.143.255.254212.143.255.255131,070
73212.144.0.0/15212.144.0.1 to 212.145.255.254212.145.255.255131,070
74212.146.0.0/15212.146.0.1 to 212.147.255.254212.147.255.255131,070
75212.148.0.0/15212.148.0.1 to 212.149.255.254212.149.255.255131,070
76212.150.0.0/15212.150.0.1 to 212.151.255.254212.151.255.255131,070
77212.152.0.0/15212.152.0.1 to 212.153.255.254212.153.255.255131,070
78212.154.0.0/15212.154.0.1 to 212.155.255.254212.155.255.255131,070
79212.156.0.0/15212.156.0.1 to 212.157.255.254212.157.255.255131,070
80212.158.0.0/15212.158.0.1 to 212.159.255.254212.159.255.255131,070
81212.160.0.0/15212.160.0.1 to 212.161.255.254212.161.255.255131,070
82212.162.0.0/15212.162.0.1 to 212.163.255.254212.163.255.255131,070
83212.164.0.0/15212.164.0.1 to 212.165.255.254212.165.255.255131,070
84212.166.0.0/15212.166.0.1 to 212.167.255.254212.167.255.255131,070
85212.168.0.0/15212.168.0.1 to 212.169.255.254212.169.255.255131,070
86212.170.0.0/15212.170.0.1 to 212.171.255.254212.171.255.255131,070
87212.172.0.0/15212.172.0.1 to 212.173.255.254212.173.255.255131,070
88212.174.0.0/15212.174.0.1 to 212.175.255.254212.175.255.255131,070
89212.176.0.0/15212.176.0.1 to 212.177.255.254212.177.255.255131,070
90212.178.0.0/15212.178.0.1 to 212.179.255.254212.179.255.255131,070
91212.180.0.0/15212.180.0.1 to 212.181.255.254212.181.255.255131,070
92212.182.0.0/15212.182.0.1 to 212.183.255.254212.183.255.255131,070
93212.184.0.0/15212.184.0.1 to 212.185.255.254212.185.255.255131,070
94212.186.0.0/15212.186.0.1 to 212.187.255.254212.187.255.255131,070
95212.188.0.0/15212.188.0.1 to 212.189.255.254212.189.255.255131,070
96212.190.0.0/15212.190.0.1 to 212.191.255.254212.191.255.255131,070
97212.192.0.0/15212.192.0.1 to 212.193.255.254212.193.255.255131,070
98212.194.0.0/15212.194.0.1 to 212.195.255.254212.195.255.255131,070
99212.196.0.0/15212.196.0.1 to 212.197.255.254212.197.255.255131,070
100212.198.0.0/15212.198.0.1 to 212.199.255.254212.199.255.255131,070
101212.200.0.0/15212.200.0.1 to 212.201.255.254212.201.255.255131,070
102212.202.0.0/15212.202.0.1 to 212.203.255.254212.203.255.255131,070
103212.204.0.0/15212.204.0.1 to 212.205.255.254212.205.255.255131,070
104212.206.0.0/15212.206.0.1 to 212.207.255.254212.207.255.255131,070
105212.208.0.0/15212.208.0.1 to 212.209.255.254212.209.255.255131,070
106212.210.0.0/15212.210.0.1 to 212.211.255.254212.211.255.255131,070
107212.212.0.0/15212.212.0.1 to 212.213.255.254212.213.255.255131,070
108212.214.0.0/15212.214.0.1 to 212.215.255.254212.215.255.255131,070
109212.216.0.0/15212.216.0.1 to 212.217.255.254212.217.255.255131,070
110212.218.0.0/15212.218.0.1 to 212.219.255.254212.219.255.255131,070
111212.220.0.0/15212.220.0.1 to 212.221.255.254212.221.255.255131,070
112212.222.0.0/15212.222.0.1 to 212.223.255.254212.223.255.255131,070
113212.224.0.0/15212.224.0.1 to 212.225.255.254212.225.255.255131,070
114212.226.0.0/15212.226.0.1 to 212.227.255.254212.227.255.255131,070
115212.228.0.0/15212.228.0.1 to 212.229.255.254212.229.255.255131,070
116212.230.0.0/15212.230.0.1 to 212.231.255.254212.231.255.255131,070
117212.232.0.0/15212.232.0.1 to 212.233.255.254212.233.255.255131,070
118212.234.0.0/15212.234.0.1 to 212.235.255.254212.235.255.255131,070
119212.236.0.0/15212.236.0.1 to 212.237.255.254212.237.255.255131,070
120212.238.0.0/15212.238.0.1 to 212.239.255.254212.239.255.255131,070
121212.240.0.0/15212.240.0.1 to 212.241.255.254212.241.255.255131,070
122212.242.0.0/15212.242.0.1 to 212.243.255.254212.243.255.255131,070
123212.244.0.0/15212.244.0.1 to 212.245.255.254212.245.255.255131,070
124212.246.0.0/15212.246.0.1 to 212.247.255.254212.247.255.255131,070
125212.248.0.0/15212.248.0.1 to 212.249.255.254212.249.255.255131,070
126212.250.0.0/15212.250.0.1 to 212.251.255.254212.251.255.255131,070
127212.252.0.0/15212.252.0.1 to 212.253.255.254212.253.255.255131,070
128212.254.0.0/15212.254.0.1 to 212.255.255.254212.255.255.255131,070

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.