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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.

Network124.8.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
124.8.0.0
Broadcast address
124.8.255.255
First usable
124.8.0.1
Last usable
124.8.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
A (default /8)
As numbers
Hex 7C080000 · Integer 2080899072 to 2080964607
Reverse DNS zone
8.124.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01111100.00001000..00000000.00000000124.8.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network01111100.00001000..00000000.00000000124.8.0.0
Broadcast01111100.00001000..11111111.11111111124.8.255.255
Split into smaller subnets/23
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

124.8.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1124.8.0.0/23124.8.0.1 to 124.8.1.254124.8.1.255510
2124.8.2.0/23124.8.2.1 to 124.8.3.254124.8.3.255510
3124.8.4.0/23124.8.4.1 to 124.8.5.254124.8.5.255510
4124.8.6.0/23124.8.6.1 to 124.8.7.254124.8.7.255510
5124.8.8.0/23124.8.8.1 to 124.8.9.254124.8.9.255510
6124.8.10.0/23124.8.10.1 to 124.8.11.254124.8.11.255510
7124.8.12.0/23124.8.12.1 to 124.8.13.254124.8.13.255510
8124.8.14.0/23124.8.14.1 to 124.8.15.254124.8.15.255510
9124.8.16.0/23124.8.16.1 to 124.8.17.254124.8.17.255510
10124.8.18.0/23124.8.18.1 to 124.8.19.254124.8.19.255510
11124.8.20.0/23124.8.20.1 to 124.8.21.254124.8.21.255510
12124.8.22.0/23124.8.22.1 to 124.8.23.254124.8.23.255510
13124.8.24.0/23124.8.24.1 to 124.8.25.254124.8.25.255510
14124.8.26.0/23124.8.26.1 to 124.8.27.254124.8.27.255510
15124.8.28.0/23124.8.28.1 to 124.8.29.254124.8.29.255510
16124.8.30.0/23124.8.30.1 to 124.8.31.254124.8.31.255510
17124.8.32.0/23124.8.32.1 to 124.8.33.254124.8.33.255510
18124.8.34.0/23124.8.34.1 to 124.8.35.254124.8.35.255510
19124.8.36.0/23124.8.36.1 to 124.8.37.254124.8.37.255510
20124.8.38.0/23124.8.38.1 to 124.8.39.254124.8.39.255510
21124.8.40.0/23124.8.40.1 to 124.8.41.254124.8.41.255510
22124.8.42.0/23124.8.42.1 to 124.8.43.254124.8.43.255510
23124.8.44.0/23124.8.44.1 to 124.8.45.254124.8.45.255510
24124.8.46.0/23124.8.46.1 to 124.8.47.254124.8.47.255510
25124.8.48.0/23124.8.48.1 to 124.8.49.254124.8.49.255510
26124.8.50.0/23124.8.50.1 to 124.8.51.254124.8.51.255510
27124.8.52.0/23124.8.52.1 to 124.8.53.254124.8.53.255510
28124.8.54.0/23124.8.54.1 to 124.8.55.254124.8.55.255510
29124.8.56.0/23124.8.56.1 to 124.8.57.254124.8.57.255510
30124.8.58.0/23124.8.58.1 to 124.8.59.254124.8.59.255510
31124.8.60.0/23124.8.60.1 to 124.8.61.254124.8.61.255510
32124.8.62.0/23124.8.62.1 to 124.8.63.254124.8.63.255510
33124.8.64.0/23124.8.64.1 to 124.8.65.254124.8.65.255510
34124.8.66.0/23124.8.66.1 to 124.8.67.254124.8.67.255510
35124.8.68.0/23124.8.68.1 to 124.8.69.254124.8.69.255510
36124.8.70.0/23124.8.70.1 to 124.8.71.254124.8.71.255510
37124.8.72.0/23124.8.72.1 to 124.8.73.254124.8.73.255510
38124.8.74.0/23124.8.74.1 to 124.8.75.254124.8.75.255510
39124.8.76.0/23124.8.76.1 to 124.8.77.254124.8.77.255510
40124.8.78.0/23124.8.78.1 to 124.8.79.254124.8.79.255510
41124.8.80.0/23124.8.80.1 to 124.8.81.254124.8.81.255510
42124.8.82.0/23124.8.82.1 to 124.8.83.254124.8.83.255510
43124.8.84.0/23124.8.84.1 to 124.8.85.254124.8.85.255510
44124.8.86.0/23124.8.86.1 to 124.8.87.254124.8.87.255510
45124.8.88.0/23124.8.88.1 to 124.8.89.254124.8.89.255510
46124.8.90.0/23124.8.90.1 to 124.8.91.254124.8.91.255510
47124.8.92.0/23124.8.92.1 to 124.8.93.254124.8.93.255510
48124.8.94.0/23124.8.94.1 to 124.8.95.254124.8.95.255510
49124.8.96.0/23124.8.96.1 to 124.8.97.254124.8.97.255510
50124.8.98.0/23124.8.98.1 to 124.8.99.254124.8.99.255510
51124.8.100.0/23124.8.100.1 to 124.8.101.254124.8.101.255510
52124.8.102.0/23124.8.102.1 to 124.8.103.254124.8.103.255510
53124.8.104.0/23124.8.104.1 to 124.8.105.254124.8.105.255510
54124.8.106.0/23124.8.106.1 to 124.8.107.254124.8.107.255510
55124.8.108.0/23124.8.108.1 to 124.8.109.254124.8.109.255510
56124.8.110.0/23124.8.110.1 to 124.8.111.254124.8.111.255510
57124.8.112.0/23124.8.112.1 to 124.8.113.254124.8.113.255510
58124.8.114.0/23124.8.114.1 to 124.8.115.254124.8.115.255510
59124.8.116.0/23124.8.116.1 to 124.8.117.254124.8.117.255510
60124.8.118.0/23124.8.118.1 to 124.8.119.254124.8.119.255510
61124.8.120.0/23124.8.120.1 to 124.8.121.254124.8.121.255510
62124.8.122.0/23124.8.122.1 to 124.8.123.254124.8.123.255510
63124.8.124.0/23124.8.124.1 to 124.8.125.254124.8.125.255510
64124.8.126.0/23124.8.126.1 to 124.8.127.254124.8.127.255510
65124.8.128.0/23124.8.128.1 to 124.8.129.254124.8.129.255510
66124.8.130.0/23124.8.130.1 to 124.8.131.254124.8.131.255510
67124.8.132.0/23124.8.132.1 to 124.8.133.254124.8.133.255510
68124.8.134.0/23124.8.134.1 to 124.8.135.254124.8.135.255510
69124.8.136.0/23124.8.136.1 to 124.8.137.254124.8.137.255510
70124.8.138.0/23124.8.138.1 to 124.8.139.254124.8.139.255510
71124.8.140.0/23124.8.140.1 to 124.8.141.254124.8.141.255510
72124.8.142.0/23124.8.142.1 to 124.8.143.254124.8.143.255510
73124.8.144.0/23124.8.144.1 to 124.8.145.254124.8.145.255510
74124.8.146.0/23124.8.146.1 to 124.8.147.254124.8.147.255510
75124.8.148.0/23124.8.148.1 to 124.8.149.254124.8.149.255510
76124.8.150.0/23124.8.150.1 to 124.8.151.254124.8.151.255510
77124.8.152.0/23124.8.152.1 to 124.8.153.254124.8.153.255510
78124.8.154.0/23124.8.154.1 to 124.8.155.254124.8.155.255510
79124.8.156.0/23124.8.156.1 to 124.8.157.254124.8.157.255510
80124.8.158.0/23124.8.158.1 to 124.8.159.254124.8.159.255510
81124.8.160.0/23124.8.160.1 to 124.8.161.254124.8.161.255510
82124.8.162.0/23124.8.162.1 to 124.8.163.254124.8.163.255510
83124.8.164.0/23124.8.164.1 to 124.8.165.254124.8.165.255510
84124.8.166.0/23124.8.166.1 to 124.8.167.254124.8.167.255510
85124.8.168.0/23124.8.168.1 to 124.8.169.254124.8.169.255510
86124.8.170.0/23124.8.170.1 to 124.8.171.254124.8.171.255510
87124.8.172.0/23124.8.172.1 to 124.8.173.254124.8.173.255510
88124.8.174.0/23124.8.174.1 to 124.8.175.254124.8.175.255510
89124.8.176.0/23124.8.176.1 to 124.8.177.254124.8.177.255510
90124.8.178.0/23124.8.178.1 to 124.8.179.254124.8.179.255510
91124.8.180.0/23124.8.180.1 to 124.8.181.254124.8.181.255510
92124.8.182.0/23124.8.182.1 to 124.8.183.254124.8.183.255510
93124.8.184.0/23124.8.184.1 to 124.8.185.254124.8.185.255510
94124.8.186.0/23124.8.186.1 to 124.8.187.254124.8.187.255510
95124.8.188.0/23124.8.188.1 to 124.8.189.254124.8.189.255510
96124.8.190.0/23124.8.190.1 to 124.8.191.254124.8.191.255510
97124.8.192.0/23124.8.192.1 to 124.8.193.254124.8.193.255510
98124.8.194.0/23124.8.194.1 to 124.8.195.254124.8.195.255510
99124.8.196.0/23124.8.196.1 to 124.8.197.254124.8.197.255510
100124.8.198.0/23124.8.198.1 to 124.8.199.254124.8.199.255510
101124.8.200.0/23124.8.200.1 to 124.8.201.254124.8.201.255510
102124.8.202.0/23124.8.202.1 to 124.8.203.254124.8.203.255510
103124.8.204.0/23124.8.204.1 to 124.8.205.254124.8.205.255510
104124.8.206.0/23124.8.206.1 to 124.8.207.254124.8.207.255510
105124.8.208.0/23124.8.208.1 to 124.8.209.254124.8.209.255510
106124.8.210.0/23124.8.210.1 to 124.8.211.254124.8.211.255510
107124.8.212.0/23124.8.212.1 to 124.8.213.254124.8.213.255510
108124.8.214.0/23124.8.214.1 to 124.8.215.254124.8.215.255510
109124.8.216.0/23124.8.216.1 to 124.8.217.254124.8.217.255510
110124.8.218.0/23124.8.218.1 to 124.8.219.254124.8.219.255510
111124.8.220.0/23124.8.220.1 to 124.8.221.254124.8.221.255510
112124.8.222.0/23124.8.222.1 to 124.8.223.254124.8.223.255510
113124.8.224.0/23124.8.224.1 to 124.8.225.254124.8.225.255510
114124.8.226.0/23124.8.226.1 to 124.8.227.254124.8.227.255510
115124.8.228.0/23124.8.228.1 to 124.8.229.254124.8.229.255510
116124.8.230.0/23124.8.230.1 to 124.8.231.254124.8.231.255510
117124.8.232.0/23124.8.232.1 to 124.8.233.254124.8.233.255510
118124.8.234.0/23124.8.234.1 to 124.8.235.254124.8.235.255510
119124.8.236.0/23124.8.236.1 to 124.8.237.254124.8.237.255510
120124.8.238.0/23124.8.238.1 to 124.8.239.254124.8.239.255510
121124.8.240.0/23124.8.240.1 to 124.8.241.254124.8.241.255510
122124.8.242.0/23124.8.242.1 to 124.8.243.254124.8.243.255510
123124.8.244.0/23124.8.244.1 to 124.8.245.254124.8.245.255510
124124.8.246.0/23124.8.246.1 to 124.8.247.254124.8.247.255510
125124.8.248.0/23124.8.248.1 to 124.8.249.254124.8.249.255510
126124.8.250.0/23124.8.250.1 to 124.8.251.254124.8.251.255510
127124.8.252.0/23124.8.252.1 to 124.8.253.254124.8.253.255510
128124.8.254.0/23124.8.254.1 to 124.8.255.254124.8.255.255510

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.