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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.

Network209.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
209.0.0.0
Broadcast address
209.255.255.255
First usable
209.0.0.1
Last usable
209.255.255.254
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 D1000000 · Integer 3506438144 to 3523215359
Reverse DNS zone
209.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010001..00000000.00000000.00000000209.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11010001..00000000.00000000.00000000209.0.0.0
Broadcast11010001..11111111.11111111.11111111209.255.255.255
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)

209.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1209.0.0.0/15209.0.0.1 to 209.1.255.254209.1.255.255131,070
2209.2.0.0/15209.2.0.1 to 209.3.255.254209.3.255.255131,070
3209.4.0.0/15209.4.0.1 to 209.5.255.254209.5.255.255131,070
4209.6.0.0/15209.6.0.1 to 209.7.255.254209.7.255.255131,070
5209.8.0.0/15209.8.0.1 to 209.9.255.254209.9.255.255131,070
6209.10.0.0/15209.10.0.1 to 209.11.255.254209.11.255.255131,070
7209.12.0.0/15209.12.0.1 to 209.13.255.254209.13.255.255131,070
8209.14.0.0/15209.14.0.1 to 209.15.255.254209.15.255.255131,070
9209.16.0.0/15209.16.0.1 to 209.17.255.254209.17.255.255131,070
10209.18.0.0/15209.18.0.1 to 209.19.255.254209.19.255.255131,070
11209.20.0.0/15209.20.0.1 to 209.21.255.254209.21.255.255131,070
12209.22.0.0/15209.22.0.1 to 209.23.255.254209.23.255.255131,070
13209.24.0.0/15209.24.0.1 to 209.25.255.254209.25.255.255131,070
14209.26.0.0/15209.26.0.1 to 209.27.255.254209.27.255.255131,070
15209.28.0.0/15209.28.0.1 to 209.29.255.254209.29.255.255131,070
16209.30.0.0/15209.30.0.1 to 209.31.255.254209.31.255.255131,070
17209.32.0.0/15209.32.0.1 to 209.33.255.254209.33.255.255131,070
18209.34.0.0/15209.34.0.1 to 209.35.255.254209.35.255.255131,070
19209.36.0.0/15209.36.0.1 to 209.37.255.254209.37.255.255131,070
20209.38.0.0/15209.38.0.1 to 209.39.255.254209.39.255.255131,070
21209.40.0.0/15209.40.0.1 to 209.41.255.254209.41.255.255131,070
22209.42.0.0/15209.42.0.1 to 209.43.255.254209.43.255.255131,070
23209.44.0.0/15209.44.0.1 to 209.45.255.254209.45.255.255131,070
24209.46.0.0/15209.46.0.1 to 209.47.255.254209.47.255.255131,070
25209.48.0.0/15209.48.0.1 to 209.49.255.254209.49.255.255131,070
26209.50.0.0/15209.50.0.1 to 209.51.255.254209.51.255.255131,070
27209.52.0.0/15209.52.0.1 to 209.53.255.254209.53.255.255131,070
28209.54.0.0/15209.54.0.1 to 209.55.255.254209.55.255.255131,070
29209.56.0.0/15209.56.0.1 to 209.57.255.254209.57.255.255131,070
30209.58.0.0/15209.58.0.1 to 209.59.255.254209.59.255.255131,070
31209.60.0.0/15209.60.0.1 to 209.61.255.254209.61.255.255131,070
32209.62.0.0/15209.62.0.1 to 209.63.255.254209.63.255.255131,070
33209.64.0.0/15209.64.0.1 to 209.65.255.254209.65.255.255131,070
34209.66.0.0/15209.66.0.1 to 209.67.255.254209.67.255.255131,070
35209.68.0.0/15209.68.0.1 to 209.69.255.254209.69.255.255131,070
36209.70.0.0/15209.70.0.1 to 209.71.255.254209.71.255.255131,070
37209.72.0.0/15209.72.0.1 to 209.73.255.254209.73.255.255131,070
38209.74.0.0/15209.74.0.1 to 209.75.255.254209.75.255.255131,070
39209.76.0.0/15209.76.0.1 to 209.77.255.254209.77.255.255131,070
40209.78.0.0/15209.78.0.1 to 209.79.255.254209.79.255.255131,070
41209.80.0.0/15209.80.0.1 to 209.81.255.254209.81.255.255131,070
42209.82.0.0/15209.82.0.1 to 209.83.255.254209.83.255.255131,070
43209.84.0.0/15209.84.0.1 to 209.85.255.254209.85.255.255131,070
44209.86.0.0/15209.86.0.1 to 209.87.255.254209.87.255.255131,070
45209.88.0.0/15209.88.0.1 to 209.89.255.254209.89.255.255131,070
46209.90.0.0/15209.90.0.1 to 209.91.255.254209.91.255.255131,070
47209.92.0.0/15209.92.0.1 to 209.93.255.254209.93.255.255131,070
48209.94.0.0/15209.94.0.1 to 209.95.255.254209.95.255.255131,070
49209.96.0.0/15209.96.0.1 to 209.97.255.254209.97.255.255131,070
50209.98.0.0/15209.98.0.1 to 209.99.255.254209.99.255.255131,070
51209.100.0.0/15209.100.0.1 to 209.101.255.254209.101.255.255131,070
52209.102.0.0/15209.102.0.1 to 209.103.255.254209.103.255.255131,070
53209.104.0.0/15209.104.0.1 to 209.105.255.254209.105.255.255131,070
54209.106.0.0/15209.106.0.1 to 209.107.255.254209.107.255.255131,070
55209.108.0.0/15209.108.0.1 to 209.109.255.254209.109.255.255131,070
56209.110.0.0/15209.110.0.1 to 209.111.255.254209.111.255.255131,070
57209.112.0.0/15209.112.0.1 to 209.113.255.254209.113.255.255131,070
58209.114.0.0/15209.114.0.1 to 209.115.255.254209.115.255.255131,070
59209.116.0.0/15209.116.0.1 to 209.117.255.254209.117.255.255131,070
60209.118.0.0/15209.118.0.1 to 209.119.255.254209.119.255.255131,070
61209.120.0.0/15209.120.0.1 to 209.121.255.254209.121.255.255131,070
62209.122.0.0/15209.122.0.1 to 209.123.255.254209.123.255.255131,070
63209.124.0.0/15209.124.0.1 to 209.125.255.254209.125.255.255131,070
64209.126.0.0/15209.126.0.1 to 209.127.255.254209.127.255.255131,070
65209.128.0.0/15209.128.0.1 to 209.129.255.254209.129.255.255131,070
66209.130.0.0/15209.130.0.1 to 209.131.255.254209.131.255.255131,070
67209.132.0.0/15209.132.0.1 to 209.133.255.254209.133.255.255131,070
68209.134.0.0/15209.134.0.1 to 209.135.255.254209.135.255.255131,070
69209.136.0.0/15209.136.0.1 to 209.137.255.254209.137.255.255131,070
70209.138.0.0/15209.138.0.1 to 209.139.255.254209.139.255.255131,070
71209.140.0.0/15209.140.0.1 to 209.141.255.254209.141.255.255131,070
72209.142.0.0/15209.142.0.1 to 209.143.255.254209.143.255.255131,070
73209.144.0.0/15209.144.0.1 to 209.145.255.254209.145.255.255131,070
74209.146.0.0/15209.146.0.1 to 209.147.255.254209.147.255.255131,070
75209.148.0.0/15209.148.0.1 to 209.149.255.254209.149.255.255131,070
76209.150.0.0/15209.150.0.1 to 209.151.255.254209.151.255.255131,070
77209.152.0.0/15209.152.0.1 to 209.153.255.254209.153.255.255131,070
78209.154.0.0/15209.154.0.1 to 209.155.255.254209.155.255.255131,070
79209.156.0.0/15209.156.0.1 to 209.157.255.254209.157.255.255131,070
80209.158.0.0/15209.158.0.1 to 209.159.255.254209.159.255.255131,070
81209.160.0.0/15209.160.0.1 to 209.161.255.254209.161.255.255131,070
82209.162.0.0/15209.162.0.1 to 209.163.255.254209.163.255.255131,070
83209.164.0.0/15209.164.0.1 to 209.165.255.254209.165.255.255131,070
84209.166.0.0/15209.166.0.1 to 209.167.255.254209.167.255.255131,070
85209.168.0.0/15209.168.0.1 to 209.169.255.254209.169.255.255131,070
86209.170.0.0/15209.170.0.1 to 209.171.255.254209.171.255.255131,070
87209.172.0.0/15209.172.0.1 to 209.173.255.254209.173.255.255131,070
88209.174.0.0/15209.174.0.1 to 209.175.255.254209.175.255.255131,070
89209.176.0.0/15209.176.0.1 to 209.177.255.254209.177.255.255131,070
90209.178.0.0/15209.178.0.1 to 209.179.255.254209.179.255.255131,070
91209.180.0.0/15209.180.0.1 to 209.181.255.254209.181.255.255131,070
92209.182.0.0/15209.182.0.1 to 209.183.255.254209.183.255.255131,070
93209.184.0.0/15209.184.0.1 to 209.185.255.254209.185.255.255131,070
94209.186.0.0/15209.186.0.1 to 209.187.255.254209.187.255.255131,070
95209.188.0.0/15209.188.0.1 to 209.189.255.254209.189.255.255131,070
96209.190.0.0/15209.190.0.1 to 209.191.255.254209.191.255.255131,070
97209.192.0.0/15209.192.0.1 to 209.193.255.254209.193.255.255131,070
98209.194.0.0/15209.194.0.1 to 209.195.255.254209.195.255.255131,070
99209.196.0.0/15209.196.0.1 to 209.197.255.254209.197.255.255131,070
100209.198.0.0/15209.198.0.1 to 209.199.255.254209.199.255.255131,070
101209.200.0.0/15209.200.0.1 to 209.201.255.254209.201.255.255131,070
102209.202.0.0/15209.202.0.1 to 209.203.255.254209.203.255.255131,070
103209.204.0.0/15209.204.0.1 to 209.205.255.254209.205.255.255131,070
104209.206.0.0/15209.206.0.1 to 209.207.255.254209.207.255.255131,070
105209.208.0.0/15209.208.0.1 to 209.209.255.254209.209.255.255131,070
106209.210.0.0/15209.210.0.1 to 209.211.255.254209.211.255.255131,070
107209.212.0.0/15209.212.0.1 to 209.213.255.254209.213.255.255131,070
108209.214.0.0/15209.214.0.1 to 209.215.255.254209.215.255.255131,070
109209.216.0.0/15209.216.0.1 to 209.217.255.254209.217.255.255131,070
110209.218.0.0/15209.218.0.1 to 209.219.255.254209.219.255.255131,070
111209.220.0.0/15209.220.0.1 to 209.221.255.254209.221.255.255131,070
112209.222.0.0/15209.222.0.1 to 209.223.255.254209.223.255.255131,070
113209.224.0.0/15209.224.0.1 to 209.225.255.254209.225.255.255131,070
114209.226.0.0/15209.226.0.1 to 209.227.255.254209.227.255.255131,070
115209.228.0.0/15209.228.0.1 to 209.229.255.254209.229.255.255131,070
116209.230.0.0/15209.230.0.1 to 209.231.255.254209.231.255.255131,070
117209.232.0.0/15209.232.0.1 to 209.233.255.254209.233.255.255131,070
118209.234.0.0/15209.234.0.1 to 209.235.255.254209.235.255.255131,070
119209.236.0.0/15209.236.0.1 to 209.237.255.254209.237.255.255131,070
120209.238.0.0/15209.238.0.1 to 209.239.255.254209.239.255.255131,070
121209.240.0.0/15209.240.0.1 to 209.241.255.254209.241.255.255131,070
122209.242.0.0/15209.242.0.1 to 209.243.255.254209.243.255.255131,070
123209.244.0.0/15209.244.0.1 to 209.245.255.254209.245.255.255131,070
124209.246.0.0/15209.246.0.1 to 209.247.255.254209.247.255.255131,070
125209.248.0.0/15209.248.0.1 to 209.249.255.254209.249.255.255131,070
126209.250.0.0/15209.250.0.1 to 209.251.255.254209.251.255.255131,070
127209.252.0.0/15209.252.0.1 to 209.253.255.254209.253.255.255131,070
128209.254.0.0/15209.254.0.1 to 209.255.255.254209.255.255.255131,070

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.