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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.

Network126.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
126.0.0.0
Broadcast address
126.255.255.255
First usable
126.0.0.1
Last usable
126.255.255.254
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
A (default /8)
As numbers
Hex 7E000000 · Integer 2113929216 to 2130706431
Reverse DNS zone
126.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01111110..00000000.00000000.00000000126.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network01111110..00000000.00000000.00000000126.0.0.0
Broadcast01111110..11111111.11111111.11111111126.255.255.255
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)

126.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1126.0.0.0/15126.0.0.1 to 126.1.255.254126.1.255.255131,070
2126.2.0.0/15126.2.0.1 to 126.3.255.254126.3.255.255131,070
3126.4.0.0/15126.4.0.1 to 126.5.255.254126.5.255.255131,070
4126.6.0.0/15126.6.0.1 to 126.7.255.254126.7.255.255131,070
5126.8.0.0/15126.8.0.1 to 126.9.255.254126.9.255.255131,070
6126.10.0.0/15126.10.0.1 to 126.11.255.254126.11.255.255131,070
7126.12.0.0/15126.12.0.1 to 126.13.255.254126.13.255.255131,070
8126.14.0.0/15126.14.0.1 to 126.15.255.254126.15.255.255131,070
9126.16.0.0/15126.16.0.1 to 126.17.255.254126.17.255.255131,070
10126.18.0.0/15126.18.0.1 to 126.19.255.254126.19.255.255131,070
11126.20.0.0/15126.20.0.1 to 126.21.255.254126.21.255.255131,070
12126.22.0.0/15126.22.0.1 to 126.23.255.254126.23.255.255131,070
13126.24.0.0/15126.24.0.1 to 126.25.255.254126.25.255.255131,070
14126.26.0.0/15126.26.0.1 to 126.27.255.254126.27.255.255131,070
15126.28.0.0/15126.28.0.1 to 126.29.255.254126.29.255.255131,070
16126.30.0.0/15126.30.0.1 to 126.31.255.254126.31.255.255131,070
17126.32.0.0/15126.32.0.1 to 126.33.255.254126.33.255.255131,070
18126.34.0.0/15126.34.0.1 to 126.35.255.254126.35.255.255131,070
19126.36.0.0/15126.36.0.1 to 126.37.255.254126.37.255.255131,070
20126.38.0.0/15126.38.0.1 to 126.39.255.254126.39.255.255131,070
21126.40.0.0/15126.40.0.1 to 126.41.255.254126.41.255.255131,070
22126.42.0.0/15126.42.0.1 to 126.43.255.254126.43.255.255131,070
23126.44.0.0/15126.44.0.1 to 126.45.255.254126.45.255.255131,070
24126.46.0.0/15126.46.0.1 to 126.47.255.254126.47.255.255131,070
25126.48.0.0/15126.48.0.1 to 126.49.255.254126.49.255.255131,070
26126.50.0.0/15126.50.0.1 to 126.51.255.254126.51.255.255131,070
27126.52.0.0/15126.52.0.1 to 126.53.255.254126.53.255.255131,070
28126.54.0.0/15126.54.0.1 to 126.55.255.254126.55.255.255131,070
29126.56.0.0/15126.56.0.1 to 126.57.255.254126.57.255.255131,070
30126.58.0.0/15126.58.0.1 to 126.59.255.254126.59.255.255131,070
31126.60.0.0/15126.60.0.1 to 126.61.255.254126.61.255.255131,070
32126.62.0.0/15126.62.0.1 to 126.63.255.254126.63.255.255131,070
33126.64.0.0/15126.64.0.1 to 126.65.255.254126.65.255.255131,070
34126.66.0.0/15126.66.0.1 to 126.67.255.254126.67.255.255131,070
35126.68.0.0/15126.68.0.1 to 126.69.255.254126.69.255.255131,070
36126.70.0.0/15126.70.0.1 to 126.71.255.254126.71.255.255131,070
37126.72.0.0/15126.72.0.1 to 126.73.255.254126.73.255.255131,070
38126.74.0.0/15126.74.0.1 to 126.75.255.254126.75.255.255131,070
39126.76.0.0/15126.76.0.1 to 126.77.255.254126.77.255.255131,070
40126.78.0.0/15126.78.0.1 to 126.79.255.254126.79.255.255131,070
41126.80.0.0/15126.80.0.1 to 126.81.255.254126.81.255.255131,070
42126.82.0.0/15126.82.0.1 to 126.83.255.254126.83.255.255131,070
43126.84.0.0/15126.84.0.1 to 126.85.255.254126.85.255.255131,070
44126.86.0.0/15126.86.0.1 to 126.87.255.254126.87.255.255131,070
45126.88.0.0/15126.88.0.1 to 126.89.255.254126.89.255.255131,070
46126.90.0.0/15126.90.0.1 to 126.91.255.254126.91.255.255131,070
47126.92.0.0/15126.92.0.1 to 126.93.255.254126.93.255.255131,070
48126.94.0.0/15126.94.0.1 to 126.95.255.254126.95.255.255131,070
49126.96.0.0/15126.96.0.1 to 126.97.255.254126.97.255.255131,070
50126.98.0.0/15126.98.0.1 to 126.99.255.254126.99.255.255131,070
51126.100.0.0/15126.100.0.1 to 126.101.255.254126.101.255.255131,070
52126.102.0.0/15126.102.0.1 to 126.103.255.254126.103.255.255131,070
53126.104.0.0/15126.104.0.1 to 126.105.255.254126.105.255.255131,070
54126.106.0.0/15126.106.0.1 to 126.107.255.254126.107.255.255131,070
55126.108.0.0/15126.108.0.1 to 126.109.255.254126.109.255.255131,070
56126.110.0.0/15126.110.0.1 to 126.111.255.254126.111.255.255131,070
57126.112.0.0/15126.112.0.1 to 126.113.255.254126.113.255.255131,070
58126.114.0.0/15126.114.0.1 to 126.115.255.254126.115.255.255131,070
59126.116.0.0/15126.116.0.1 to 126.117.255.254126.117.255.255131,070
60126.118.0.0/15126.118.0.1 to 126.119.255.254126.119.255.255131,070
61126.120.0.0/15126.120.0.1 to 126.121.255.254126.121.255.255131,070
62126.122.0.0/15126.122.0.1 to 126.123.255.254126.123.255.255131,070
63126.124.0.0/15126.124.0.1 to 126.125.255.254126.125.255.255131,070
64126.126.0.0/15126.126.0.1 to 126.127.255.254126.127.255.255131,070
65126.128.0.0/15126.128.0.1 to 126.129.255.254126.129.255.255131,070
66126.130.0.0/15126.130.0.1 to 126.131.255.254126.131.255.255131,070
67126.132.0.0/15126.132.0.1 to 126.133.255.254126.133.255.255131,070
68126.134.0.0/15126.134.0.1 to 126.135.255.254126.135.255.255131,070
69126.136.0.0/15126.136.0.1 to 126.137.255.254126.137.255.255131,070
70126.138.0.0/15126.138.0.1 to 126.139.255.254126.139.255.255131,070
71126.140.0.0/15126.140.0.1 to 126.141.255.254126.141.255.255131,070
72126.142.0.0/15126.142.0.1 to 126.143.255.254126.143.255.255131,070
73126.144.0.0/15126.144.0.1 to 126.145.255.254126.145.255.255131,070
74126.146.0.0/15126.146.0.1 to 126.147.255.254126.147.255.255131,070
75126.148.0.0/15126.148.0.1 to 126.149.255.254126.149.255.255131,070
76126.150.0.0/15126.150.0.1 to 126.151.255.254126.151.255.255131,070
77126.152.0.0/15126.152.0.1 to 126.153.255.254126.153.255.255131,070
78126.154.0.0/15126.154.0.1 to 126.155.255.254126.155.255.255131,070
79126.156.0.0/15126.156.0.1 to 126.157.255.254126.157.255.255131,070
80126.158.0.0/15126.158.0.1 to 126.159.255.254126.159.255.255131,070
81126.160.0.0/15126.160.0.1 to 126.161.255.254126.161.255.255131,070
82126.162.0.0/15126.162.0.1 to 126.163.255.254126.163.255.255131,070
83126.164.0.0/15126.164.0.1 to 126.165.255.254126.165.255.255131,070
84126.166.0.0/15126.166.0.1 to 126.167.255.254126.167.255.255131,070
85126.168.0.0/15126.168.0.1 to 126.169.255.254126.169.255.255131,070
86126.170.0.0/15126.170.0.1 to 126.171.255.254126.171.255.255131,070
87126.172.0.0/15126.172.0.1 to 126.173.255.254126.173.255.255131,070
88126.174.0.0/15126.174.0.1 to 126.175.255.254126.175.255.255131,070
89126.176.0.0/15126.176.0.1 to 126.177.255.254126.177.255.255131,070
90126.178.0.0/15126.178.0.1 to 126.179.255.254126.179.255.255131,070
91126.180.0.0/15126.180.0.1 to 126.181.255.254126.181.255.255131,070
92126.182.0.0/15126.182.0.1 to 126.183.255.254126.183.255.255131,070
93126.184.0.0/15126.184.0.1 to 126.185.255.254126.185.255.255131,070
94126.186.0.0/15126.186.0.1 to 126.187.255.254126.187.255.255131,070
95126.188.0.0/15126.188.0.1 to 126.189.255.254126.189.255.255131,070
96126.190.0.0/15126.190.0.1 to 126.191.255.254126.191.255.255131,070
97126.192.0.0/15126.192.0.1 to 126.193.255.254126.193.255.255131,070
98126.194.0.0/15126.194.0.1 to 126.195.255.254126.195.255.255131,070
99126.196.0.0/15126.196.0.1 to 126.197.255.254126.197.255.255131,070
100126.198.0.0/15126.198.0.1 to 126.199.255.254126.199.255.255131,070
101126.200.0.0/15126.200.0.1 to 126.201.255.254126.201.255.255131,070
102126.202.0.0/15126.202.0.1 to 126.203.255.254126.203.255.255131,070
103126.204.0.0/15126.204.0.1 to 126.205.255.254126.205.255.255131,070
104126.206.0.0/15126.206.0.1 to 126.207.255.254126.207.255.255131,070
105126.208.0.0/15126.208.0.1 to 126.209.255.254126.209.255.255131,070
106126.210.0.0/15126.210.0.1 to 126.211.255.254126.211.255.255131,070
107126.212.0.0/15126.212.0.1 to 126.213.255.254126.213.255.255131,070
108126.214.0.0/15126.214.0.1 to 126.215.255.254126.215.255.255131,070
109126.216.0.0/15126.216.0.1 to 126.217.255.254126.217.255.255131,070
110126.218.0.0/15126.218.0.1 to 126.219.255.254126.219.255.255131,070
111126.220.0.0/15126.220.0.1 to 126.221.255.254126.221.255.255131,070
112126.222.0.0/15126.222.0.1 to 126.223.255.254126.223.255.255131,070
113126.224.0.0/15126.224.0.1 to 126.225.255.254126.225.255.255131,070
114126.226.0.0/15126.226.0.1 to 126.227.255.254126.227.255.255131,070
115126.228.0.0/15126.228.0.1 to 126.229.255.254126.229.255.255131,070
116126.230.0.0/15126.230.0.1 to 126.231.255.254126.231.255.255131,070
117126.232.0.0/15126.232.0.1 to 126.233.255.254126.233.255.255131,070
118126.234.0.0/15126.234.0.1 to 126.235.255.254126.235.255.255131,070
119126.236.0.0/15126.236.0.1 to 126.237.255.254126.237.255.255131,070
120126.238.0.0/15126.238.0.1 to 126.239.255.254126.239.255.255131,070
121126.240.0.0/15126.240.0.1 to 126.241.255.254126.241.255.255131,070
122126.242.0.0/15126.242.0.1 to 126.243.255.254126.243.255.255131,070
123126.244.0.0/15126.244.0.1 to 126.245.255.254126.245.255.255131,070
124126.246.0.0/15126.246.0.1 to 126.247.255.254126.247.255.255131,070
125126.248.0.0/15126.248.0.1 to 126.249.255.254126.249.255.255131,070
126126.250.0.0/15126.250.0.1 to 126.251.255.254126.251.255.255131,070
127126.252.0.0/15126.252.0.1 to 126.253.255.254126.253.255.255131,070
128126.254.0.0/15126.254.0.1 to 126.255.255.254126.255.255.255131,070

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.