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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.

Network255.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
255.0.0.0
Broadcast address
255.255.255.255
First usable
255.0.0.1
Last usable
255.255.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FF000000 · Integer 4278190080 to 4294967295
Reverse DNS zone
255.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111111..00000000.00000000.00000000255.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11111111..00000000.00000000.00000000255.0.0.0
Broadcast11111111..11111111.11111111.11111111255.255.255.255
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)

255.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1255.0.0.0/15255.0.0.1 to 255.1.255.254255.1.255.255131,070
2255.2.0.0/15255.2.0.1 to 255.3.255.254255.3.255.255131,070
3255.4.0.0/15255.4.0.1 to 255.5.255.254255.5.255.255131,070
4255.6.0.0/15255.6.0.1 to 255.7.255.254255.7.255.255131,070
5255.8.0.0/15255.8.0.1 to 255.9.255.254255.9.255.255131,070
6255.10.0.0/15255.10.0.1 to 255.11.255.254255.11.255.255131,070
7255.12.0.0/15255.12.0.1 to 255.13.255.254255.13.255.255131,070
8255.14.0.0/15255.14.0.1 to 255.15.255.254255.15.255.255131,070
9255.16.0.0/15255.16.0.1 to 255.17.255.254255.17.255.255131,070
10255.18.0.0/15255.18.0.1 to 255.19.255.254255.19.255.255131,070
11255.20.0.0/15255.20.0.1 to 255.21.255.254255.21.255.255131,070
12255.22.0.0/15255.22.0.1 to 255.23.255.254255.23.255.255131,070
13255.24.0.0/15255.24.0.1 to 255.25.255.254255.25.255.255131,070
14255.26.0.0/15255.26.0.1 to 255.27.255.254255.27.255.255131,070
15255.28.0.0/15255.28.0.1 to 255.29.255.254255.29.255.255131,070
16255.30.0.0/15255.30.0.1 to 255.31.255.254255.31.255.255131,070
17255.32.0.0/15255.32.0.1 to 255.33.255.254255.33.255.255131,070
18255.34.0.0/15255.34.0.1 to 255.35.255.254255.35.255.255131,070
19255.36.0.0/15255.36.0.1 to 255.37.255.254255.37.255.255131,070
20255.38.0.0/15255.38.0.1 to 255.39.255.254255.39.255.255131,070
21255.40.0.0/15255.40.0.1 to 255.41.255.254255.41.255.255131,070
22255.42.0.0/15255.42.0.1 to 255.43.255.254255.43.255.255131,070
23255.44.0.0/15255.44.0.1 to 255.45.255.254255.45.255.255131,070
24255.46.0.0/15255.46.0.1 to 255.47.255.254255.47.255.255131,070
25255.48.0.0/15255.48.0.1 to 255.49.255.254255.49.255.255131,070
26255.50.0.0/15255.50.0.1 to 255.51.255.254255.51.255.255131,070
27255.52.0.0/15255.52.0.1 to 255.53.255.254255.53.255.255131,070
28255.54.0.0/15255.54.0.1 to 255.55.255.254255.55.255.255131,070
29255.56.0.0/15255.56.0.1 to 255.57.255.254255.57.255.255131,070
30255.58.0.0/15255.58.0.1 to 255.59.255.254255.59.255.255131,070
31255.60.0.0/15255.60.0.1 to 255.61.255.254255.61.255.255131,070
32255.62.0.0/15255.62.0.1 to 255.63.255.254255.63.255.255131,070
33255.64.0.0/15255.64.0.1 to 255.65.255.254255.65.255.255131,070
34255.66.0.0/15255.66.0.1 to 255.67.255.254255.67.255.255131,070
35255.68.0.0/15255.68.0.1 to 255.69.255.254255.69.255.255131,070
36255.70.0.0/15255.70.0.1 to 255.71.255.254255.71.255.255131,070
37255.72.0.0/15255.72.0.1 to 255.73.255.254255.73.255.255131,070
38255.74.0.0/15255.74.0.1 to 255.75.255.254255.75.255.255131,070
39255.76.0.0/15255.76.0.1 to 255.77.255.254255.77.255.255131,070
40255.78.0.0/15255.78.0.1 to 255.79.255.254255.79.255.255131,070
41255.80.0.0/15255.80.0.1 to 255.81.255.254255.81.255.255131,070
42255.82.0.0/15255.82.0.1 to 255.83.255.254255.83.255.255131,070
43255.84.0.0/15255.84.0.1 to 255.85.255.254255.85.255.255131,070
44255.86.0.0/15255.86.0.1 to 255.87.255.254255.87.255.255131,070
45255.88.0.0/15255.88.0.1 to 255.89.255.254255.89.255.255131,070
46255.90.0.0/15255.90.0.1 to 255.91.255.254255.91.255.255131,070
47255.92.0.0/15255.92.0.1 to 255.93.255.254255.93.255.255131,070
48255.94.0.0/15255.94.0.1 to 255.95.255.254255.95.255.255131,070
49255.96.0.0/15255.96.0.1 to 255.97.255.254255.97.255.255131,070
50255.98.0.0/15255.98.0.1 to 255.99.255.254255.99.255.255131,070
51255.100.0.0/15255.100.0.1 to 255.101.255.254255.101.255.255131,070
52255.102.0.0/15255.102.0.1 to 255.103.255.254255.103.255.255131,070
53255.104.0.0/15255.104.0.1 to 255.105.255.254255.105.255.255131,070
54255.106.0.0/15255.106.0.1 to 255.107.255.254255.107.255.255131,070
55255.108.0.0/15255.108.0.1 to 255.109.255.254255.109.255.255131,070
56255.110.0.0/15255.110.0.1 to 255.111.255.254255.111.255.255131,070
57255.112.0.0/15255.112.0.1 to 255.113.255.254255.113.255.255131,070
58255.114.0.0/15255.114.0.1 to 255.115.255.254255.115.255.255131,070
59255.116.0.0/15255.116.0.1 to 255.117.255.254255.117.255.255131,070
60255.118.0.0/15255.118.0.1 to 255.119.255.254255.119.255.255131,070
61255.120.0.0/15255.120.0.1 to 255.121.255.254255.121.255.255131,070
62255.122.0.0/15255.122.0.1 to 255.123.255.254255.123.255.255131,070
63255.124.0.0/15255.124.0.1 to 255.125.255.254255.125.255.255131,070
64255.126.0.0/15255.126.0.1 to 255.127.255.254255.127.255.255131,070
65255.128.0.0/15255.128.0.1 to 255.129.255.254255.129.255.255131,070
66255.130.0.0/15255.130.0.1 to 255.131.255.254255.131.255.255131,070
67255.132.0.0/15255.132.0.1 to 255.133.255.254255.133.255.255131,070
68255.134.0.0/15255.134.0.1 to 255.135.255.254255.135.255.255131,070
69255.136.0.0/15255.136.0.1 to 255.137.255.254255.137.255.255131,070
70255.138.0.0/15255.138.0.1 to 255.139.255.254255.139.255.255131,070
71255.140.0.0/15255.140.0.1 to 255.141.255.254255.141.255.255131,070
72255.142.0.0/15255.142.0.1 to 255.143.255.254255.143.255.255131,070
73255.144.0.0/15255.144.0.1 to 255.145.255.254255.145.255.255131,070
74255.146.0.0/15255.146.0.1 to 255.147.255.254255.147.255.255131,070
75255.148.0.0/15255.148.0.1 to 255.149.255.254255.149.255.255131,070
76255.150.0.0/15255.150.0.1 to 255.151.255.254255.151.255.255131,070
77255.152.0.0/15255.152.0.1 to 255.153.255.254255.153.255.255131,070
78255.154.0.0/15255.154.0.1 to 255.155.255.254255.155.255.255131,070
79255.156.0.0/15255.156.0.1 to 255.157.255.254255.157.255.255131,070
80255.158.0.0/15255.158.0.1 to 255.159.255.254255.159.255.255131,070
81255.160.0.0/15255.160.0.1 to 255.161.255.254255.161.255.255131,070
82255.162.0.0/15255.162.0.1 to 255.163.255.254255.163.255.255131,070
83255.164.0.0/15255.164.0.1 to 255.165.255.254255.165.255.255131,070
84255.166.0.0/15255.166.0.1 to 255.167.255.254255.167.255.255131,070
85255.168.0.0/15255.168.0.1 to 255.169.255.254255.169.255.255131,070
86255.170.0.0/15255.170.0.1 to 255.171.255.254255.171.255.255131,070
87255.172.0.0/15255.172.0.1 to 255.173.255.254255.173.255.255131,070
88255.174.0.0/15255.174.0.1 to 255.175.255.254255.175.255.255131,070
89255.176.0.0/15255.176.0.1 to 255.177.255.254255.177.255.255131,070
90255.178.0.0/15255.178.0.1 to 255.179.255.254255.179.255.255131,070
91255.180.0.0/15255.180.0.1 to 255.181.255.254255.181.255.255131,070
92255.182.0.0/15255.182.0.1 to 255.183.255.254255.183.255.255131,070
93255.184.0.0/15255.184.0.1 to 255.185.255.254255.185.255.255131,070
94255.186.0.0/15255.186.0.1 to 255.187.255.254255.187.255.255131,070
95255.188.0.0/15255.188.0.1 to 255.189.255.254255.189.255.255131,070
96255.190.0.0/15255.190.0.1 to 255.191.255.254255.191.255.255131,070
97255.192.0.0/15255.192.0.1 to 255.193.255.254255.193.255.255131,070
98255.194.0.0/15255.194.0.1 to 255.195.255.254255.195.255.255131,070
99255.196.0.0/15255.196.0.1 to 255.197.255.254255.197.255.255131,070
100255.198.0.0/15255.198.0.1 to 255.199.255.254255.199.255.255131,070
101255.200.0.0/15255.200.0.1 to 255.201.255.254255.201.255.255131,070
102255.202.0.0/15255.202.0.1 to 255.203.255.254255.203.255.255131,070
103255.204.0.0/15255.204.0.1 to 255.205.255.254255.205.255.255131,070
104255.206.0.0/15255.206.0.1 to 255.207.255.254255.207.255.255131,070
105255.208.0.0/15255.208.0.1 to 255.209.255.254255.209.255.255131,070
106255.210.0.0/15255.210.0.1 to 255.211.255.254255.211.255.255131,070
107255.212.0.0/15255.212.0.1 to 255.213.255.254255.213.255.255131,070
108255.214.0.0/15255.214.0.1 to 255.215.255.254255.215.255.255131,070
109255.216.0.0/15255.216.0.1 to 255.217.255.254255.217.255.255131,070
110255.218.0.0/15255.218.0.1 to 255.219.255.254255.219.255.255131,070
111255.220.0.0/15255.220.0.1 to 255.221.255.254255.221.255.255131,070
112255.222.0.0/15255.222.0.1 to 255.223.255.254255.223.255.255131,070
113255.224.0.0/15255.224.0.1 to 255.225.255.254255.225.255.255131,070
114255.226.0.0/15255.226.0.1 to 255.227.255.254255.227.255.255131,070
115255.228.0.0/15255.228.0.1 to 255.229.255.254255.229.255.255131,070
116255.230.0.0/15255.230.0.1 to 255.231.255.254255.231.255.255131,070
117255.232.0.0/15255.232.0.1 to 255.233.255.254255.233.255.255131,070
118255.234.0.0/15255.234.0.1 to 255.235.255.254255.235.255.255131,070
119255.236.0.0/15255.236.0.1 to 255.237.255.254255.237.255.255131,070
120255.238.0.0/15255.238.0.1 to 255.239.255.254255.239.255.255131,070
121255.240.0.0/15255.240.0.1 to 255.241.255.254255.241.255.255131,070
122255.242.0.0/15255.242.0.1 to 255.243.255.254255.243.255.255131,070
123255.244.0.0/15255.244.0.1 to 255.245.255.254255.245.255.255131,070
124255.246.0.0/15255.246.0.1 to 255.247.255.254255.247.255.255131,070
125255.248.0.0/15255.248.0.1 to 255.249.255.254255.249.255.255131,070
126255.250.0.0/15255.250.0.1 to 255.251.255.254255.251.255.255131,070
127255.252.0.0/15255.252.0.1 to 255.253.255.254255.253.255.255131,070
128255.254.0.0/15255.254.0.1 to 255.255.255.254255.255.255.255131,070

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.