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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.

Network201.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
201.0.0.0
Broadcast address
201.255.255.255
First usable
201.0.0.1
Last usable
201.255.255.254
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 C9000000 · Integer 3372220416 to 3388997631
Reverse DNS zone
201.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001001..00000000.00000000.00000000201.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11001001..00000000.00000000.00000000201.0.0.0
Broadcast11001001..11111111.11111111.11111111201.255.255.255
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)

201.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1201.0.0.0/15201.0.0.1 to 201.1.255.254201.1.255.255131,070
2201.2.0.0/15201.2.0.1 to 201.3.255.254201.3.255.255131,070
3201.4.0.0/15201.4.0.1 to 201.5.255.254201.5.255.255131,070
4201.6.0.0/15201.6.0.1 to 201.7.255.254201.7.255.255131,070
5201.8.0.0/15201.8.0.1 to 201.9.255.254201.9.255.255131,070
6201.10.0.0/15201.10.0.1 to 201.11.255.254201.11.255.255131,070
7201.12.0.0/15201.12.0.1 to 201.13.255.254201.13.255.255131,070
8201.14.0.0/15201.14.0.1 to 201.15.255.254201.15.255.255131,070
9201.16.0.0/15201.16.0.1 to 201.17.255.254201.17.255.255131,070
10201.18.0.0/15201.18.0.1 to 201.19.255.254201.19.255.255131,070
11201.20.0.0/15201.20.0.1 to 201.21.255.254201.21.255.255131,070
12201.22.0.0/15201.22.0.1 to 201.23.255.254201.23.255.255131,070
13201.24.0.0/15201.24.0.1 to 201.25.255.254201.25.255.255131,070
14201.26.0.0/15201.26.0.1 to 201.27.255.254201.27.255.255131,070
15201.28.0.0/15201.28.0.1 to 201.29.255.254201.29.255.255131,070
16201.30.0.0/15201.30.0.1 to 201.31.255.254201.31.255.255131,070
17201.32.0.0/15201.32.0.1 to 201.33.255.254201.33.255.255131,070
18201.34.0.0/15201.34.0.1 to 201.35.255.254201.35.255.255131,070
19201.36.0.0/15201.36.0.1 to 201.37.255.254201.37.255.255131,070
20201.38.0.0/15201.38.0.1 to 201.39.255.254201.39.255.255131,070
21201.40.0.0/15201.40.0.1 to 201.41.255.254201.41.255.255131,070
22201.42.0.0/15201.42.0.1 to 201.43.255.254201.43.255.255131,070
23201.44.0.0/15201.44.0.1 to 201.45.255.254201.45.255.255131,070
24201.46.0.0/15201.46.0.1 to 201.47.255.254201.47.255.255131,070
25201.48.0.0/15201.48.0.1 to 201.49.255.254201.49.255.255131,070
26201.50.0.0/15201.50.0.1 to 201.51.255.254201.51.255.255131,070
27201.52.0.0/15201.52.0.1 to 201.53.255.254201.53.255.255131,070
28201.54.0.0/15201.54.0.1 to 201.55.255.254201.55.255.255131,070
29201.56.0.0/15201.56.0.1 to 201.57.255.254201.57.255.255131,070
30201.58.0.0/15201.58.0.1 to 201.59.255.254201.59.255.255131,070
31201.60.0.0/15201.60.0.1 to 201.61.255.254201.61.255.255131,070
32201.62.0.0/15201.62.0.1 to 201.63.255.254201.63.255.255131,070
33201.64.0.0/15201.64.0.1 to 201.65.255.254201.65.255.255131,070
34201.66.0.0/15201.66.0.1 to 201.67.255.254201.67.255.255131,070
35201.68.0.0/15201.68.0.1 to 201.69.255.254201.69.255.255131,070
36201.70.0.0/15201.70.0.1 to 201.71.255.254201.71.255.255131,070
37201.72.0.0/15201.72.0.1 to 201.73.255.254201.73.255.255131,070
38201.74.0.0/15201.74.0.1 to 201.75.255.254201.75.255.255131,070
39201.76.0.0/15201.76.0.1 to 201.77.255.254201.77.255.255131,070
40201.78.0.0/15201.78.0.1 to 201.79.255.254201.79.255.255131,070
41201.80.0.0/15201.80.0.1 to 201.81.255.254201.81.255.255131,070
42201.82.0.0/15201.82.0.1 to 201.83.255.254201.83.255.255131,070
43201.84.0.0/15201.84.0.1 to 201.85.255.254201.85.255.255131,070
44201.86.0.0/15201.86.0.1 to 201.87.255.254201.87.255.255131,070
45201.88.0.0/15201.88.0.1 to 201.89.255.254201.89.255.255131,070
46201.90.0.0/15201.90.0.1 to 201.91.255.254201.91.255.255131,070
47201.92.0.0/15201.92.0.1 to 201.93.255.254201.93.255.255131,070
48201.94.0.0/15201.94.0.1 to 201.95.255.254201.95.255.255131,070
49201.96.0.0/15201.96.0.1 to 201.97.255.254201.97.255.255131,070
50201.98.0.0/15201.98.0.1 to 201.99.255.254201.99.255.255131,070
51201.100.0.0/15201.100.0.1 to 201.101.255.254201.101.255.255131,070
52201.102.0.0/15201.102.0.1 to 201.103.255.254201.103.255.255131,070
53201.104.0.0/15201.104.0.1 to 201.105.255.254201.105.255.255131,070
54201.106.0.0/15201.106.0.1 to 201.107.255.254201.107.255.255131,070
55201.108.0.0/15201.108.0.1 to 201.109.255.254201.109.255.255131,070
56201.110.0.0/15201.110.0.1 to 201.111.255.254201.111.255.255131,070
57201.112.0.0/15201.112.0.1 to 201.113.255.254201.113.255.255131,070
58201.114.0.0/15201.114.0.1 to 201.115.255.254201.115.255.255131,070
59201.116.0.0/15201.116.0.1 to 201.117.255.254201.117.255.255131,070
60201.118.0.0/15201.118.0.1 to 201.119.255.254201.119.255.255131,070
61201.120.0.0/15201.120.0.1 to 201.121.255.254201.121.255.255131,070
62201.122.0.0/15201.122.0.1 to 201.123.255.254201.123.255.255131,070
63201.124.0.0/15201.124.0.1 to 201.125.255.254201.125.255.255131,070
64201.126.0.0/15201.126.0.1 to 201.127.255.254201.127.255.255131,070
65201.128.0.0/15201.128.0.1 to 201.129.255.254201.129.255.255131,070
66201.130.0.0/15201.130.0.1 to 201.131.255.254201.131.255.255131,070
67201.132.0.0/15201.132.0.1 to 201.133.255.254201.133.255.255131,070
68201.134.0.0/15201.134.0.1 to 201.135.255.254201.135.255.255131,070
69201.136.0.0/15201.136.0.1 to 201.137.255.254201.137.255.255131,070
70201.138.0.0/15201.138.0.1 to 201.139.255.254201.139.255.255131,070
71201.140.0.0/15201.140.0.1 to 201.141.255.254201.141.255.255131,070
72201.142.0.0/15201.142.0.1 to 201.143.255.254201.143.255.255131,070
73201.144.0.0/15201.144.0.1 to 201.145.255.254201.145.255.255131,070
74201.146.0.0/15201.146.0.1 to 201.147.255.254201.147.255.255131,070
75201.148.0.0/15201.148.0.1 to 201.149.255.254201.149.255.255131,070
76201.150.0.0/15201.150.0.1 to 201.151.255.254201.151.255.255131,070
77201.152.0.0/15201.152.0.1 to 201.153.255.254201.153.255.255131,070
78201.154.0.0/15201.154.0.1 to 201.155.255.254201.155.255.255131,070
79201.156.0.0/15201.156.0.1 to 201.157.255.254201.157.255.255131,070
80201.158.0.0/15201.158.0.1 to 201.159.255.254201.159.255.255131,070
81201.160.0.0/15201.160.0.1 to 201.161.255.254201.161.255.255131,070
82201.162.0.0/15201.162.0.1 to 201.163.255.254201.163.255.255131,070
83201.164.0.0/15201.164.0.1 to 201.165.255.254201.165.255.255131,070
84201.166.0.0/15201.166.0.1 to 201.167.255.254201.167.255.255131,070
85201.168.0.0/15201.168.0.1 to 201.169.255.254201.169.255.255131,070
86201.170.0.0/15201.170.0.1 to 201.171.255.254201.171.255.255131,070
87201.172.0.0/15201.172.0.1 to 201.173.255.254201.173.255.255131,070
88201.174.0.0/15201.174.0.1 to 201.175.255.254201.175.255.255131,070
89201.176.0.0/15201.176.0.1 to 201.177.255.254201.177.255.255131,070
90201.178.0.0/15201.178.0.1 to 201.179.255.254201.179.255.255131,070
91201.180.0.0/15201.180.0.1 to 201.181.255.254201.181.255.255131,070
92201.182.0.0/15201.182.0.1 to 201.183.255.254201.183.255.255131,070
93201.184.0.0/15201.184.0.1 to 201.185.255.254201.185.255.255131,070
94201.186.0.0/15201.186.0.1 to 201.187.255.254201.187.255.255131,070
95201.188.0.0/15201.188.0.1 to 201.189.255.254201.189.255.255131,070
96201.190.0.0/15201.190.0.1 to 201.191.255.254201.191.255.255131,070
97201.192.0.0/15201.192.0.1 to 201.193.255.254201.193.255.255131,070
98201.194.0.0/15201.194.0.1 to 201.195.255.254201.195.255.255131,070
99201.196.0.0/15201.196.0.1 to 201.197.255.254201.197.255.255131,070
100201.198.0.0/15201.198.0.1 to 201.199.255.254201.199.255.255131,070
101201.200.0.0/15201.200.0.1 to 201.201.255.254201.201.255.255131,070
102201.202.0.0/15201.202.0.1 to 201.203.255.254201.203.255.255131,070
103201.204.0.0/15201.204.0.1 to 201.205.255.254201.205.255.255131,070
104201.206.0.0/15201.206.0.1 to 201.207.255.254201.207.255.255131,070
105201.208.0.0/15201.208.0.1 to 201.209.255.254201.209.255.255131,070
106201.210.0.0/15201.210.0.1 to 201.211.255.254201.211.255.255131,070
107201.212.0.0/15201.212.0.1 to 201.213.255.254201.213.255.255131,070
108201.214.0.0/15201.214.0.1 to 201.215.255.254201.215.255.255131,070
109201.216.0.0/15201.216.0.1 to 201.217.255.254201.217.255.255131,070
110201.218.0.0/15201.218.0.1 to 201.219.255.254201.219.255.255131,070
111201.220.0.0/15201.220.0.1 to 201.221.255.254201.221.255.255131,070
112201.222.0.0/15201.222.0.1 to 201.223.255.254201.223.255.255131,070
113201.224.0.0/15201.224.0.1 to 201.225.255.254201.225.255.255131,070
114201.226.0.0/15201.226.0.1 to 201.227.255.254201.227.255.255131,070
115201.228.0.0/15201.228.0.1 to 201.229.255.254201.229.255.255131,070
116201.230.0.0/15201.230.0.1 to 201.231.255.254201.231.255.255131,070
117201.232.0.0/15201.232.0.1 to 201.233.255.254201.233.255.255131,070
118201.234.0.0/15201.234.0.1 to 201.235.255.254201.235.255.255131,070
119201.236.0.0/15201.236.0.1 to 201.237.255.254201.237.255.255131,070
120201.238.0.0/15201.238.0.1 to 201.239.255.254201.239.255.255131,070
121201.240.0.0/15201.240.0.1 to 201.241.255.254201.241.255.255131,070
122201.242.0.0/15201.242.0.1 to 201.243.255.254201.243.255.255131,070
123201.244.0.0/15201.244.0.1 to 201.245.255.254201.245.255.255131,070
124201.246.0.0/15201.246.0.1 to 201.247.255.254201.247.255.255131,070
125201.248.0.0/15201.248.0.1 to 201.249.255.254201.249.255.255131,070
126201.250.0.0/15201.250.0.1 to 201.251.255.254201.251.255.255131,070
127201.252.0.0/15201.252.0.1 to 201.253.255.254201.253.255.255131,070
128201.254.0.0/15201.254.0.1 to 201.255.255.254201.255.255.255131,070

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.