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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.

Network238.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
238.0.0.0
Broadcast address
238.255.255.255
First usable
238.0.0.1
Last usable
238.255.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EE000000 · Integer 3992977408 to 4009754623
Reverse DNS zone
238.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11101110..00000000.00000000.00000000238.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11101110..00000000.00000000.00000000238.0.0.0
Broadcast11101110..11111111.11111111.11111111238.255.255.255
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)

238.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1238.0.0.0/15238.0.0.1 to 238.1.255.254238.1.255.255131,070
2238.2.0.0/15238.2.0.1 to 238.3.255.254238.3.255.255131,070
3238.4.0.0/15238.4.0.1 to 238.5.255.254238.5.255.255131,070
4238.6.0.0/15238.6.0.1 to 238.7.255.254238.7.255.255131,070
5238.8.0.0/15238.8.0.1 to 238.9.255.254238.9.255.255131,070
6238.10.0.0/15238.10.0.1 to 238.11.255.254238.11.255.255131,070
7238.12.0.0/15238.12.0.1 to 238.13.255.254238.13.255.255131,070
8238.14.0.0/15238.14.0.1 to 238.15.255.254238.15.255.255131,070
9238.16.0.0/15238.16.0.1 to 238.17.255.254238.17.255.255131,070
10238.18.0.0/15238.18.0.1 to 238.19.255.254238.19.255.255131,070
11238.20.0.0/15238.20.0.1 to 238.21.255.254238.21.255.255131,070
12238.22.0.0/15238.22.0.1 to 238.23.255.254238.23.255.255131,070
13238.24.0.0/15238.24.0.1 to 238.25.255.254238.25.255.255131,070
14238.26.0.0/15238.26.0.1 to 238.27.255.254238.27.255.255131,070
15238.28.0.0/15238.28.0.1 to 238.29.255.254238.29.255.255131,070
16238.30.0.0/15238.30.0.1 to 238.31.255.254238.31.255.255131,070
17238.32.0.0/15238.32.0.1 to 238.33.255.254238.33.255.255131,070
18238.34.0.0/15238.34.0.1 to 238.35.255.254238.35.255.255131,070
19238.36.0.0/15238.36.0.1 to 238.37.255.254238.37.255.255131,070
20238.38.0.0/15238.38.0.1 to 238.39.255.254238.39.255.255131,070
21238.40.0.0/15238.40.0.1 to 238.41.255.254238.41.255.255131,070
22238.42.0.0/15238.42.0.1 to 238.43.255.254238.43.255.255131,070
23238.44.0.0/15238.44.0.1 to 238.45.255.254238.45.255.255131,070
24238.46.0.0/15238.46.0.1 to 238.47.255.254238.47.255.255131,070
25238.48.0.0/15238.48.0.1 to 238.49.255.254238.49.255.255131,070
26238.50.0.0/15238.50.0.1 to 238.51.255.254238.51.255.255131,070
27238.52.0.0/15238.52.0.1 to 238.53.255.254238.53.255.255131,070
28238.54.0.0/15238.54.0.1 to 238.55.255.254238.55.255.255131,070
29238.56.0.0/15238.56.0.1 to 238.57.255.254238.57.255.255131,070
30238.58.0.0/15238.58.0.1 to 238.59.255.254238.59.255.255131,070
31238.60.0.0/15238.60.0.1 to 238.61.255.254238.61.255.255131,070
32238.62.0.0/15238.62.0.1 to 238.63.255.254238.63.255.255131,070
33238.64.0.0/15238.64.0.1 to 238.65.255.254238.65.255.255131,070
34238.66.0.0/15238.66.0.1 to 238.67.255.254238.67.255.255131,070
35238.68.0.0/15238.68.0.1 to 238.69.255.254238.69.255.255131,070
36238.70.0.0/15238.70.0.1 to 238.71.255.254238.71.255.255131,070
37238.72.0.0/15238.72.0.1 to 238.73.255.254238.73.255.255131,070
38238.74.0.0/15238.74.0.1 to 238.75.255.254238.75.255.255131,070
39238.76.0.0/15238.76.0.1 to 238.77.255.254238.77.255.255131,070
40238.78.0.0/15238.78.0.1 to 238.79.255.254238.79.255.255131,070
41238.80.0.0/15238.80.0.1 to 238.81.255.254238.81.255.255131,070
42238.82.0.0/15238.82.0.1 to 238.83.255.254238.83.255.255131,070
43238.84.0.0/15238.84.0.1 to 238.85.255.254238.85.255.255131,070
44238.86.0.0/15238.86.0.1 to 238.87.255.254238.87.255.255131,070
45238.88.0.0/15238.88.0.1 to 238.89.255.254238.89.255.255131,070
46238.90.0.0/15238.90.0.1 to 238.91.255.254238.91.255.255131,070
47238.92.0.0/15238.92.0.1 to 238.93.255.254238.93.255.255131,070
48238.94.0.0/15238.94.0.1 to 238.95.255.254238.95.255.255131,070
49238.96.0.0/15238.96.0.1 to 238.97.255.254238.97.255.255131,070
50238.98.0.0/15238.98.0.1 to 238.99.255.254238.99.255.255131,070
51238.100.0.0/15238.100.0.1 to 238.101.255.254238.101.255.255131,070
52238.102.0.0/15238.102.0.1 to 238.103.255.254238.103.255.255131,070
53238.104.0.0/15238.104.0.1 to 238.105.255.254238.105.255.255131,070
54238.106.0.0/15238.106.0.1 to 238.107.255.254238.107.255.255131,070
55238.108.0.0/15238.108.0.1 to 238.109.255.254238.109.255.255131,070
56238.110.0.0/15238.110.0.1 to 238.111.255.254238.111.255.255131,070
57238.112.0.0/15238.112.0.1 to 238.113.255.254238.113.255.255131,070
58238.114.0.0/15238.114.0.1 to 238.115.255.254238.115.255.255131,070
59238.116.0.0/15238.116.0.1 to 238.117.255.254238.117.255.255131,070
60238.118.0.0/15238.118.0.1 to 238.119.255.254238.119.255.255131,070
61238.120.0.0/15238.120.0.1 to 238.121.255.254238.121.255.255131,070
62238.122.0.0/15238.122.0.1 to 238.123.255.254238.123.255.255131,070
63238.124.0.0/15238.124.0.1 to 238.125.255.254238.125.255.255131,070
64238.126.0.0/15238.126.0.1 to 238.127.255.254238.127.255.255131,070
65238.128.0.0/15238.128.0.1 to 238.129.255.254238.129.255.255131,070
66238.130.0.0/15238.130.0.1 to 238.131.255.254238.131.255.255131,070
67238.132.0.0/15238.132.0.1 to 238.133.255.254238.133.255.255131,070
68238.134.0.0/15238.134.0.1 to 238.135.255.254238.135.255.255131,070
69238.136.0.0/15238.136.0.1 to 238.137.255.254238.137.255.255131,070
70238.138.0.0/15238.138.0.1 to 238.139.255.254238.139.255.255131,070
71238.140.0.0/15238.140.0.1 to 238.141.255.254238.141.255.255131,070
72238.142.0.0/15238.142.0.1 to 238.143.255.254238.143.255.255131,070
73238.144.0.0/15238.144.0.1 to 238.145.255.254238.145.255.255131,070
74238.146.0.0/15238.146.0.1 to 238.147.255.254238.147.255.255131,070
75238.148.0.0/15238.148.0.1 to 238.149.255.254238.149.255.255131,070
76238.150.0.0/15238.150.0.1 to 238.151.255.254238.151.255.255131,070
77238.152.0.0/15238.152.0.1 to 238.153.255.254238.153.255.255131,070
78238.154.0.0/15238.154.0.1 to 238.155.255.254238.155.255.255131,070
79238.156.0.0/15238.156.0.1 to 238.157.255.254238.157.255.255131,070
80238.158.0.0/15238.158.0.1 to 238.159.255.254238.159.255.255131,070
81238.160.0.0/15238.160.0.1 to 238.161.255.254238.161.255.255131,070
82238.162.0.0/15238.162.0.1 to 238.163.255.254238.163.255.255131,070
83238.164.0.0/15238.164.0.1 to 238.165.255.254238.165.255.255131,070
84238.166.0.0/15238.166.0.1 to 238.167.255.254238.167.255.255131,070
85238.168.0.0/15238.168.0.1 to 238.169.255.254238.169.255.255131,070
86238.170.0.0/15238.170.0.1 to 238.171.255.254238.171.255.255131,070
87238.172.0.0/15238.172.0.1 to 238.173.255.254238.173.255.255131,070
88238.174.0.0/15238.174.0.1 to 238.175.255.254238.175.255.255131,070
89238.176.0.0/15238.176.0.1 to 238.177.255.254238.177.255.255131,070
90238.178.0.0/15238.178.0.1 to 238.179.255.254238.179.255.255131,070
91238.180.0.0/15238.180.0.1 to 238.181.255.254238.181.255.255131,070
92238.182.0.0/15238.182.0.1 to 238.183.255.254238.183.255.255131,070
93238.184.0.0/15238.184.0.1 to 238.185.255.254238.185.255.255131,070
94238.186.0.0/15238.186.0.1 to 238.187.255.254238.187.255.255131,070
95238.188.0.0/15238.188.0.1 to 238.189.255.254238.189.255.255131,070
96238.190.0.0/15238.190.0.1 to 238.191.255.254238.191.255.255131,070
97238.192.0.0/15238.192.0.1 to 238.193.255.254238.193.255.255131,070
98238.194.0.0/15238.194.0.1 to 238.195.255.254238.195.255.255131,070
99238.196.0.0/15238.196.0.1 to 238.197.255.254238.197.255.255131,070
100238.198.0.0/15238.198.0.1 to 238.199.255.254238.199.255.255131,070
101238.200.0.0/15238.200.0.1 to 238.201.255.254238.201.255.255131,070
102238.202.0.0/15238.202.0.1 to 238.203.255.254238.203.255.255131,070
103238.204.0.0/15238.204.0.1 to 238.205.255.254238.205.255.255131,070
104238.206.0.0/15238.206.0.1 to 238.207.255.254238.207.255.255131,070
105238.208.0.0/15238.208.0.1 to 238.209.255.254238.209.255.255131,070
106238.210.0.0/15238.210.0.1 to 238.211.255.254238.211.255.255131,070
107238.212.0.0/15238.212.0.1 to 238.213.255.254238.213.255.255131,070
108238.214.0.0/15238.214.0.1 to 238.215.255.254238.215.255.255131,070
109238.216.0.0/15238.216.0.1 to 238.217.255.254238.217.255.255131,070
110238.218.0.0/15238.218.0.1 to 238.219.255.254238.219.255.255131,070
111238.220.0.0/15238.220.0.1 to 238.221.255.254238.221.255.255131,070
112238.222.0.0/15238.222.0.1 to 238.223.255.254238.223.255.255131,070
113238.224.0.0/15238.224.0.1 to 238.225.255.254238.225.255.255131,070
114238.226.0.0/15238.226.0.1 to 238.227.255.254238.227.255.255131,070
115238.228.0.0/15238.228.0.1 to 238.229.255.254238.229.255.255131,070
116238.230.0.0/15238.230.0.1 to 238.231.255.254238.231.255.255131,070
117238.232.0.0/15238.232.0.1 to 238.233.255.254238.233.255.255131,070
118238.234.0.0/15238.234.0.1 to 238.235.255.254238.235.255.255131,070
119238.236.0.0/15238.236.0.1 to 238.237.255.254238.237.255.255131,070
120238.238.0.0/15238.238.0.1 to 238.239.255.254238.239.255.255131,070
121238.240.0.0/15238.240.0.1 to 238.241.255.254238.241.255.255131,070
122238.242.0.0/15238.242.0.1 to 238.243.255.254238.243.255.255131,070
123238.244.0.0/15238.244.0.1 to 238.245.255.254238.245.255.255131,070
124238.246.0.0/15238.246.0.1 to 238.247.255.254238.247.255.255131,070
125238.248.0.0/15238.248.0.1 to 238.249.255.254238.249.255.255131,070
126238.250.0.0/15238.250.0.1 to 238.251.255.254238.251.255.255131,070
127238.252.0.0/15238.252.0.1 to 238.253.255.254238.253.255.255131,070
128238.254.0.0/15238.254.0.1 to 238.255.255.254238.255.255.255131,070

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.