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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.

Network220.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
220.0.0.0
Broadcast address
220.255.255.255
First usable
220.0.0.1
Last usable
220.255.255.254
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 DC000000 · Integer 3690987520 to 3707764735
Reverse DNS zone
220.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011100..00000000.00000000.00000000220.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11011100..00000000.00000000.00000000220.0.0.0
Broadcast11011100..11111111.11111111.11111111220.255.255.255
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)

220.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1220.0.0.0/15220.0.0.1 to 220.1.255.254220.1.255.255131,070
2220.2.0.0/15220.2.0.1 to 220.3.255.254220.3.255.255131,070
3220.4.0.0/15220.4.0.1 to 220.5.255.254220.5.255.255131,070
4220.6.0.0/15220.6.0.1 to 220.7.255.254220.7.255.255131,070
5220.8.0.0/15220.8.0.1 to 220.9.255.254220.9.255.255131,070
6220.10.0.0/15220.10.0.1 to 220.11.255.254220.11.255.255131,070
7220.12.0.0/15220.12.0.1 to 220.13.255.254220.13.255.255131,070
8220.14.0.0/15220.14.0.1 to 220.15.255.254220.15.255.255131,070
9220.16.0.0/15220.16.0.1 to 220.17.255.254220.17.255.255131,070
10220.18.0.0/15220.18.0.1 to 220.19.255.254220.19.255.255131,070
11220.20.0.0/15220.20.0.1 to 220.21.255.254220.21.255.255131,070
12220.22.0.0/15220.22.0.1 to 220.23.255.254220.23.255.255131,070
13220.24.0.0/15220.24.0.1 to 220.25.255.254220.25.255.255131,070
14220.26.0.0/15220.26.0.1 to 220.27.255.254220.27.255.255131,070
15220.28.0.0/15220.28.0.1 to 220.29.255.254220.29.255.255131,070
16220.30.0.0/15220.30.0.1 to 220.31.255.254220.31.255.255131,070
17220.32.0.0/15220.32.0.1 to 220.33.255.254220.33.255.255131,070
18220.34.0.0/15220.34.0.1 to 220.35.255.254220.35.255.255131,070
19220.36.0.0/15220.36.0.1 to 220.37.255.254220.37.255.255131,070
20220.38.0.0/15220.38.0.1 to 220.39.255.254220.39.255.255131,070
21220.40.0.0/15220.40.0.1 to 220.41.255.254220.41.255.255131,070
22220.42.0.0/15220.42.0.1 to 220.43.255.254220.43.255.255131,070
23220.44.0.0/15220.44.0.1 to 220.45.255.254220.45.255.255131,070
24220.46.0.0/15220.46.0.1 to 220.47.255.254220.47.255.255131,070
25220.48.0.0/15220.48.0.1 to 220.49.255.254220.49.255.255131,070
26220.50.0.0/15220.50.0.1 to 220.51.255.254220.51.255.255131,070
27220.52.0.0/15220.52.0.1 to 220.53.255.254220.53.255.255131,070
28220.54.0.0/15220.54.0.1 to 220.55.255.254220.55.255.255131,070
29220.56.0.0/15220.56.0.1 to 220.57.255.254220.57.255.255131,070
30220.58.0.0/15220.58.0.1 to 220.59.255.254220.59.255.255131,070
31220.60.0.0/15220.60.0.1 to 220.61.255.254220.61.255.255131,070
32220.62.0.0/15220.62.0.1 to 220.63.255.254220.63.255.255131,070
33220.64.0.0/15220.64.0.1 to 220.65.255.254220.65.255.255131,070
34220.66.0.0/15220.66.0.1 to 220.67.255.254220.67.255.255131,070
35220.68.0.0/15220.68.0.1 to 220.69.255.254220.69.255.255131,070
36220.70.0.0/15220.70.0.1 to 220.71.255.254220.71.255.255131,070
37220.72.0.0/15220.72.0.1 to 220.73.255.254220.73.255.255131,070
38220.74.0.0/15220.74.0.1 to 220.75.255.254220.75.255.255131,070
39220.76.0.0/15220.76.0.1 to 220.77.255.254220.77.255.255131,070
40220.78.0.0/15220.78.0.1 to 220.79.255.254220.79.255.255131,070
41220.80.0.0/15220.80.0.1 to 220.81.255.254220.81.255.255131,070
42220.82.0.0/15220.82.0.1 to 220.83.255.254220.83.255.255131,070
43220.84.0.0/15220.84.0.1 to 220.85.255.254220.85.255.255131,070
44220.86.0.0/15220.86.0.1 to 220.87.255.254220.87.255.255131,070
45220.88.0.0/15220.88.0.1 to 220.89.255.254220.89.255.255131,070
46220.90.0.0/15220.90.0.1 to 220.91.255.254220.91.255.255131,070
47220.92.0.0/15220.92.0.1 to 220.93.255.254220.93.255.255131,070
48220.94.0.0/15220.94.0.1 to 220.95.255.254220.95.255.255131,070
49220.96.0.0/15220.96.0.1 to 220.97.255.254220.97.255.255131,070
50220.98.0.0/15220.98.0.1 to 220.99.255.254220.99.255.255131,070
51220.100.0.0/15220.100.0.1 to 220.101.255.254220.101.255.255131,070
52220.102.0.0/15220.102.0.1 to 220.103.255.254220.103.255.255131,070
53220.104.0.0/15220.104.0.1 to 220.105.255.254220.105.255.255131,070
54220.106.0.0/15220.106.0.1 to 220.107.255.254220.107.255.255131,070
55220.108.0.0/15220.108.0.1 to 220.109.255.254220.109.255.255131,070
56220.110.0.0/15220.110.0.1 to 220.111.255.254220.111.255.255131,070
57220.112.0.0/15220.112.0.1 to 220.113.255.254220.113.255.255131,070
58220.114.0.0/15220.114.0.1 to 220.115.255.254220.115.255.255131,070
59220.116.0.0/15220.116.0.1 to 220.117.255.254220.117.255.255131,070
60220.118.0.0/15220.118.0.1 to 220.119.255.254220.119.255.255131,070
61220.120.0.0/15220.120.0.1 to 220.121.255.254220.121.255.255131,070
62220.122.0.0/15220.122.0.1 to 220.123.255.254220.123.255.255131,070
63220.124.0.0/15220.124.0.1 to 220.125.255.254220.125.255.255131,070
64220.126.0.0/15220.126.0.1 to 220.127.255.254220.127.255.255131,070
65220.128.0.0/15220.128.0.1 to 220.129.255.254220.129.255.255131,070
66220.130.0.0/15220.130.0.1 to 220.131.255.254220.131.255.255131,070
67220.132.0.0/15220.132.0.1 to 220.133.255.254220.133.255.255131,070
68220.134.0.0/15220.134.0.1 to 220.135.255.254220.135.255.255131,070
69220.136.0.0/15220.136.0.1 to 220.137.255.254220.137.255.255131,070
70220.138.0.0/15220.138.0.1 to 220.139.255.254220.139.255.255131,070
71220.140.0.0/15220.140.0.1 to 220.141.255.254220.141.255.255131,070
72220.142.0.0/15220.142.0.1 to 220.143.255.254220.143.255.255131,070
73220.144.0.0/15220.144.0.1 to 220.145.255.254220.145.255.255131,070
74220.146.0.0/15220.146.0.1 to 220.147.255.254220.147.255.255131,070
75220.148.0.0/15220.148.0.1 to 220.149.255.254220.149.255.255131,070
76220.150.0.0/15220.150.0.1 to 220.151.255.254220.151.255.255131,070
77220.152.0.0/15220.152.0.1 to 220.153.255.254220.153.255.255131,070
78220.154.0.0/15220.154.0.1 to 220.155.255.254220.155.255.255131,070
79220.156.0.0/15220.156.0.1 to 220.157.255.254220.157.255.255131,070
80220.158.0.0/15220.158.0.1 to 220.159.255.254220.159.255.255131,070
81220.160.0.0/15220.160.0.1 to 220.161.255.254220.161.255.255131,070
82220.162.0.0/15220.162.0.1 to 220.163.255.254220.163.255.255131,070
83220.164.0.0/15220.164.0.1 to 220.165.255.254220.165.255.255131,070
84220.166.0.0/15220.166.0.1 to 220.167.255.254220.167.255.255131,070
85220.168.0.0/15220.168.0.1 to 220.169.255.254220.169.255.255131,070
86220.170.0.0/15220.170.0.1 to 220.171.255.254220.171.255.255131,070
87220.172.0.0/15220.172.0.1 to 220.173.255.254220.173.255.255131,070
88220.174.0.0/15220.174.0.1 to 220.175.255.254220.175.255.255131,070
89220.176.0.0/15220.176.0.1 to 220.177.255.254220.177.255.255131,070
90220.178.0.0/15220.178.0.1 to 220.179.255.254220.179.255.255131,070
91220.180.0.0/15220.180.0.1 to 220.181.255.254220.181.255.255131,070
92220.182.0.0/15220.182.0.1 to 220.183.255.254220.183.255.255131,070
93220.184.0.0/15220.184.0.1 to 220.185.255.254220.185.255.255131,070
94220.186.0.0/15220.186.0.1 to 220.187.255.254220.187.255.255131,070
95220.188.0.0/15220.188.0.1 to 220.189.255.254220.189.255.255131,070
96220.190.0.0/15220.190.0.1 to 220.191.255.254220.191.255.255131,070
97220.192.0.0/15220.192.0.1 to 220.193.255.254220.193.255.255131,070
98220.194.0.0/15220.194.0.1 to 220.195.255.254220.195.255.255131,070
99220.196.0.0/15220.196.0.1 to 220.197.255.254220.197.255.255131,070
100220.198.0.0/15220.198.0.1 to 220.199.255.254220.199.255.255131,070
101220.200.0.0/15220.200.0.1 to 220.201.255.254220.201.255.255131,070
102220.202.0.0/15220.202.0.1 to 220.203.255.254220.203.255.255131,070
103220.204.0.0/15220.204.0.1 to 220.205.255.254220.205.255.255131,070
104220.206.0.0/15220.206.0.1 to 220.207.255.254220.207.255.255131,070
105220.208.0.0/15220.208.0.1 to 220.209.255.254220.209.255.255131,070
106220.210.0.0/15220.210.0.1 to 220.211.255.254220.211.255.255131,070
107220.212.0.0/15220.212.0.1 to 220.213.255.254220.213.255.255131,070
108220.214.0.0/15220.214.0.1 to 220.215.255.254220.215.255.255131,070
109220.216.0.0/15220.216.0.1 to 220.217.255.254220.217.255.255131,070
110220.218.0.0/15220.218.0.1 to 220.219.255.254220.219.255.255131,070
111220.220.0.0/15220.220.0.1 to 220.221.255.254220.221.255.255131,070
112220.222.0.0/15220.222.0.1 to 220.223.255.254220.223.255.255131,070
113220.224.0.0/15220.224.0.1 to 220.225.255.254220.225.255.255131,070
114220.226.0.0/15220.226.0.1 to 220.227.255.254220.227.255.255131,070
115220.228.0.0/15220.228.0.1 to 220.229.255.254220.229.255.255131,070
116220.230.0.0/15220.230.0.1 to 220.231.255.254220.231.255.255131,070
117220.232.0.0/15220.232.0.1 to 220.233.255.254220.233.255.255131,070
118220.234.0.0/15220.234.0.1 to 220.235.255.254220.235.255.255131,070
119220.236.0.0/15220.236.0.1 to 220.237.255.254220.237.255.255131,070
120220.238.0.0/15220.238.0.1 to 220.239.255.254220.239.255.255131,070
121220.240.0.0/15220.240.0.1 to 220.241.255.254220.241.255.255131,070
122220.242.0.0/15220.242.0.1 to 220.243.255.254220.243.255.255131,070
123220.244.0.0/15220.244.0.1 to 220.245.255.254220.245.255.255131,070
124220.246.0.0/15220.246.0.1 to 220.247.255.254220.247.255.255131,070
125220.248.0.0/15220.248.0.1 to 220.249.255.254220.249.255.255131,070
126220.250.0.0/15220.250.0.1 to 220.251.255.254220.251.255.255131,070
127220.252.0.0/15220.252.0.1 to 220.253.255.254220.253.255.255131,070
128220.254.0.0/15220.254.0.1 to 220.255.255.254220.255.255.255131,070

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.