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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.

Network108.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
108.0.0.0
Broadcast address
108.255.255.255
First usable
108.0.0.1
Last usable
108.255.255.254
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
A (default /8)
As numbers
Hex 6C000000 · Integer 1811939328 to 1828716543
Reverse DNS zone
108.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01101100..00000000.00000000.00000000108.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network01101100..00000000.00000000.00000000108.0.0.0
Broadcast01101100..11111111.11111111.11111111108.255.255.255
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)

108.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1108.0.0.0/15108.0.0.1 to 108.1.255.254108.1.255.255131,070
2108.2.0.0/15108.2.0.1 to 108.3.255.254108.3.255.255131,070
3108.4.0.0/15108.4.0.1 to 108.5.255.254108.5.255.255131,070
4108.6.0.0/15108.6.0.1 to 108.7.255.254108.7.255.255131,070
5108.8.0.0/15108.8.0.1 to 108.9.255.254108.9.255.255131,070
6108.10.0.0/15108.10.0.1 to 108.11.255.254108.11.255.255131,070
7108.12.0.0/15108.12.0.1 to 108.13.255.254108.13.255.255131,070
8108.14.0.0/15108.14.0.1 to 108.15.255.254108.15.255.255131,070
9108.16.0.0/15108.16.0.1 to 108.17.255.254108.17.255.255131,070
10108.18.0.0/15108.18.0.1 to 108.19.255.254108.19.255.255131,070
11108.20.0.0/15108.20.0.1 to 108.21.255.254108.21.255.255131,070
12108.22.0.0/15108.22.0.1 to 108.23.255.254108.23.255.255131,070
13108.24.0.0/15108.24.0.1 to 108.25.255.254108.25.255.255131,070
14108.26.0.0/15108.26.0.1 to 108.27.255.254108.27.255.255131,070
15108.28.0.0/15108.28.0.1 to 108.29.255.254108.29.255.255131,070
16108.30.0.0/15108.30.0.1 to 108.31.255.254108.31.255.255131,070
17108.32.0.0/15108.32.0.1 to 108.33.255.254108.33.255.255131,070
18108.34.0.0/15108.34.0.1 to 108.35.255.254108.35.255.255131,070
19108.36.0.0/15108.36.0.1 to 108.37.255.254108.37.255.255131,070
20108.38.0.0/15108.38.0.1 to 108.39.255.254108.39.255.255131,070
21108.40.0.0/15108.40.0.1 to 108.41.255.254108.41.255.255131,070
22108.42.0.0/15108.42.0.1 to 108.43.255.254108.43.255.255131,070
23108.44.0.0/15108.44.0.1 to 108.45.255.254108.45.255.255131,070
24108.46.0.0/15108.46.0.1 to 108.47.255.254108.47.255.255131,070
25108.48.0.0/15108.48.0.1 to 108.49.255.254108.49.255.255131,070
26108.50.0.0/15108.50.0.1 to 108.51.255.254108.51.255.255131,070
27108.52.0.0/15108.52.0.1 to 108.53.255.254108.53.255.255131,070
28108.54.0.0/15108.54.0.1 to 108.55.255.254108.55.255.255131,070
29108.56.0.0/15108.56.0.1 to 108.57.255.254108.57.255.255131,070
30108.58.0.0/15108.58.0.1 to 108.59.255.254108.59.255.255131,070
31108.60.0.0/15108.60.0.1 to 108.61.255.254108.61.255.255131,070
32108.62.0.0/15108.62.0.1 to 108.63.255.254108.63.255.255131,070
33108.64.0.0/15108.64.0.1 to 108.65.255.254108.65.255.255131,070
34108.66.0.0/15108.66.0.1 to 108.67.255.254108.67.255.255131,070
35108.68.0.0/15108.68.0.1 to 108.69.255.254108.69.255.255131,070
36108.70.0.0/15108.70.0.1 to 108.71.255.254108.71.255.255131,070
37108.72.0.0/15108.72.0.1 to 108.73.255.254108.73.255.255131,070
38108.74.0.0/15108.74.0.1 to 108.75.255.254108.75.255.255131,070
39108.76.0.0/15108.76.0.1 to 108.77.255.254108.77.255.255131,070
40108.78.0.0/15108.78.0.1 to 108.79.255.254108.79.255.255131,070
41108.80.0.0/15108.80.0.1 to 108.81.255.254108.81.255.255131,070
42108.82.0.0/15108.82.0.1 to 108.83.255.254108.83.255.255131,070
43108.84.0.0/15108.84.0.1 to 108.85.255.254108.85.255.255131,070
44108.86.0.0/15108.86.0.1 to 108.87.255.254108.87.255.255131,070
45108.88.0.0/15108.88.0.1 to 108.89.255.254108.89.255.255131,070
46108.90.0.0/15108.90.0.1 to 108.91.255.254108.91.255.255131,070
47108.92.0.0/15108.92.0.1 to 108.93.255.254108.93.255.255131,070
48108.94.0.0/15108.94.0.1 to 108.95.255.254108.95.255.255131,070
49108.96.0.0/15108.96.0.1 to 108.97.255.254108.97.255.255131,070
50108.98.0.0/15108.98.0.1 to 108.99.255.254108.99.255.255131,070
51108.100.0.0/15108.100.0.1 to 108.101.255.254108.101.255.255131,070
52108.102.0.0/15108.102.0.1 to 108.103.255.254108.103.255.255131,070
53108.104.0.0/15108.104.0.1 to 108.105.255.254108.105.255.255131,070
54108.106.0.0/15108.106.0.1 to 108.107.255.254108.107.255.255131,070
55108.108.0.0/15108.108.0.1 to 108.109.255.254108.109.255.255131,070
56108.110.0.0/15108.110.0.1 to 108.111.255.254108.111.255.255131,070
57108.112.0.0/15108.112.0.1 to 108.113.255.254108.113.255.255131,070
58108.114.0.0/15108.114.0.1 to 108.115.255.254108.115.255.255131,070
59108.116.0.0/15108.116.0.1 to 108.117.255.254108.117.255.255131,070
60108.118.0.0/15108.118.0.1 to 108.119.255.254108.119.255.255131,070
61108.120.0.0/15108.120.0.1 to 108.121.255.254108.121.255.255131,070
62108.122.0.0/15108.122.0.1 to 108.123.255.254108.123.255.255131,070
63108.124.0.0/15108.124.0.1 to 108.125.255.254108.125.255.255131,070
64108.126.0.0/15108.126.0.1 to 108.127.255.254108.127.255.255131,070
65108.128.0.0/15108.128.0.1 to 108.129.255.254108.129.255.255131,070
66108.130.0.0/15108.130.0.1 to 108.131.255.254108.131.255.255131,070
67108.132.0.0/15108.132.0.1 to 108.133.255.254108.133.255.255131,070
68108.134.0.0/15108.134.0.1 to 108.135.255.254108.135.255.255131,070
69108.136.0.0/15108.136.0.1 to 108.137.255.254108.137.255.255131,070
70108.138.0.0/15108.138.0.1 to 108.139.255.254108.139.255.255131,070
71108.140.0.0/15108.140.0.1 to 108.141.255.254108.141.255.255131,070
72108.142.0.0/15108.142.0.1 to 108.143.255.254108.143.255.255131,070
73108.144.0.0/15108.144.0.1 to 108.145.255.254108.145.255.255131,070
74108.146.0.0/15108.146.0.1 to 108.147.255.254108.147.255.255131,070
75108.148.0.0/15108.148.0.1 to 108.149.255.254108.149.255.255131,070
76108.150.0.0/15108.150.0.1 to 108.151.255.254108.151.255.255131,070
77108.152.0.0/15108.152.0.1 to 108.153.255.254108.153.255.255131,070
78108.154.0.0/15108.154.0.1 to 108.155.255.254108.155.255.255131,070
79108.156.0.0/15108.156.0.1 to 108.157.255.254108.157.255.255131,070
80108.158.0.0/15108.158.0.1 to 108.159.255.254108.159.255.255131,070
81108.160.0.0/15108.160.0.1 to 108.161.255.254108.161.255.255131,070
82108.162.0.0/15108.162.0.1 to 108.163.255.254108.163.255.255131,070
83108.164.0.0/15108.164.0.1 to 108.165.255.254108.165.255.255131,070
84108.166.0.0/15108.166.0.1 to 108.167.255.254108.167.255.255131,070
85108.168.0.0/15108.168.0.1 to 108.169.255.254108.169.255.255131,070
86108.170.0.0/15108.170.0.1 to 108.171.255.254108.171.255.255131,070
87108.172.0.0/15108.172.0.1 to 108.173.255.254108.173.255.255131,070
88108.174.0.0/15108.174.0.1 to 108.175.255.254108.175.255.255131,070
89108.176.0.0/15108.176.0.1 to 108.177.255.254108.177.255.255131,070
90108.178.0.0/15108.178.0.1 to 108.179.255.254108.179.255.255131,070
91108.180.0.0/15108.180.0.1 to 108.181.255.254108.181.255.255131,070
92108.182.0.0/15108.182.0.1 to 108.183.255.254108.183.255.255131,070
93108.184.0.0/15108.184.0.1 to 108.185.255.254108.185.255.255131,070
94108.186.0.0/15108.186.0.1 to 108.187.255.254108.187.255.255131,070
95108.188.0.0/15108.188.0.1 to 108.189.255.254108.189.255.255131,070
96108.190.0.0/15108.190.0.1 to 108.191.255.254108.191.255.255131,070
97108.192.0.0/15108.192.0.1 to 108.193.255.254108.193.255.255131,070
98108.194.0.0/15108.194.0.1 to 108.195.255.254108.195.255.255131,070
99108.196.0.0/15108.196.0.1 to 108.197.255.254108.197.255.255131,070
100108.198.0.0/15108.198.0.1 to 108.199.255.254108.199.255.255131,070
101108.200.0.0/15108.200.0.1 to 108.201.255.254108.201.255.255131,070
102108.202.0.0/15108.202.0.1 to 108.203.255.254108.203.255.255131,070
103108.204.0.0/15108.204.0.1 to 108.205.255.254108.205.255.255131,070
104108.206.0.0/15108.206.0.1 to 108.207.255.254108.207.255.255131,070
105108.208.0.0/15108.208.0.1 to 108.209.255.254108.209.255.255131,070
106108.210.0.0/15108.210.0.1 to 108.211.255.254108.211.255.255131,070
107108.212.0.0/15108.212.0.1 to 108.213.255.254108.213.255.255131,070
108108.214.0.0/15108.214.0.1 to 108.215.255.254108.215.255.255131,070
109108.216.0.0/15108.216.0.1 to 108.217.255.254108.217.255.255131,070
110108.218.0.0/15108.218.0.1 to 108.219.255.254108.219.255.255131,070
111108.220.0.0/15108.220.0.1 to 108.221.255.254108.221.255.255131,070
112108.222.0.0/15108.222.0.1 to 108.223.255.254108.223.255.255131,070
113108.224.0.0/15108.224.0.1 to 108.225.255.254108.225.255.255131,070
114108.226.0.0/15108.226.0.1 to 108.227.255.254108.227.255.255131,070
115108.228.0.0/15108.228.0.1 to 108.229.255.254108.229.255.255131,070
116108.230.0.0/15108.230.0.1 to 108.231.255.254108.231.255.255131,070
117108.232.0.0/15108.232.0.1 to 108.233.255.254108.233.255.255131,070
118108.234.0.0/15108.234.0.1 to 108.235.255.254108.235.255.255131,070
119108.236.0.0/15108.236.0.1 to 108.237.255.254108.237.255.255131,070
120108.238.0.0/15108.238.0.1 to 108.239.255.254108.239.255.255131,070
121108.240.0.0/15108.240.0.1 to 108.241.255.254108.241.255.255131,070
122108.242.0.0/15108.242.0.1 to 108.243.255.254108.243.255.255131,070
123108.244.0.0/15108.244.0.1 to 108.245.255.254108.245.255.255131,070
124108.246.0.0/15108.246.0.1 to 108.247.255.254108.247.255.255131,070
125108.248.0.0/15108.248.0.1 to 108.249.255.254108.249.255.255131,070
126108.250.0.0/15108.250.0.1 to 108.251.255.254108.251.255.255131,070
127108.252.0.0/15108.252.0.1 to 108.253.255.254108.253.255.255131,070
128108.254.0.0/15108.254.0.1 to 108.255.255.254108.255.255.255131,070

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.