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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.

Network232.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
232.0.0.0
Broadcast address
232.255.255.255
First usable
232.0.0.1
Last usable
232.255.255.254
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 E8000000 · Integer 3892314112 to 3909091327
Reverse DNS zone
232.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11101000..00000000.00000000.00000000232.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11101000..00000000.00000000.00000000232.0.0.0
Broadcast11101000..11111111.11111111.11111111232.255.255.255
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)

232.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1232.0.0.0/15232.0.0.1 to 232.1.255.254232.1.255.255131,070
2232.2.0.0/15232.2.0.1 to 232.3.255.254232.3.255.255131,070
3232.4.0.0/15232.4.0.1 to 232.5.255.254232.5.255.255131,070
4232.6.0.0/15232.6.0.1 to 232.7.255.254232.7.255.255131,070
5232.8.0.0/15232.8.0.1 to 232.9.255.254232.9.255.255131,070
6232.10.0.0/15232.10.0.1 to 232.11.255.254232.11.255.255131,070
7232.12.0.0/15232.12.0.1 to 232.13.255.254232.13.255.255131,070
8232.14.0.0/15232.14.0.1 to 232.15.255.254232.15.255.255131,070
9232.16.0.0/15232.16.0.1 to 232.17.255.254232.17.255.255131,070
10232.18.0.0/15232.18.0.1 to 232.19.255.254232.19.255.255131,070
11232.20.0.0/15232.20.0.1 to 232.21.255.254232.21.255.255131,070
12232.22.0.0/15232.22.0.1 to 232.23.255.254232.23.255.255131,070
13232.24.0.0/15232.24.0.1 to 232.25.255.254232.25.255.255131,070
14232.26.0.0/15232.26.0.1 to 232.27.255.254232.27.255.255131,070
15232.28.0.0/15232.28.0.1 to 232.29.255.254232.29.255.255131,070
16232.30.0.0/15232.30.0.1 to 232.31.255.254232.31.255.255131,070
17232.32.0.0/15232.32.0.1 to 232.33.255.254232.33.255.255131,070
18232.34.0.0/15232.34.0.1 to 232.35.255.254232.35.255.255131,070
19232.36.0.0/15232.36.0.1 to 232.37.255.254232.37.255.255131,070
20232.38.0.0/15232.38.0.1 to 232.39.255.254232.39.255.255131,070
21232.40.0.0/15232.40.0.1 to 232.41.255.254232.41.255.255131,070
22232.42.0.0/15232.42.0.1 to 232.43.255.254232.43.255.255131,070
23232.44.0.0/15232.44.0.1 to 232.45.255.254232.45.255.255131,070
24232.46.0.0/15232.46.0.1 to 232.47.255.254232.47.255.255131,070
25232.48.0.0/15232.48.0.1 to 232.49.255.254232.49.255.255131,070
26232.50.0.0/15232.50.0.1 to 232.51.255.254232.51.255.255131,070
27232.52.0.0/15232.52.0.1 to 232.53.255.254232.53.255.255131,070
28232.54.0.0/15232.54.0.1 to 232.55.255.254232.55.255.255131,070
29232.56.0.0/15232.56.0.1 to 232.57.255.254232.57.255.255131,070
30232.58.0.0/15232.58.0.1 to 232.59.255.254232.59.255.255131,070
31232.60.0.0/15232.60.0.1 to 232.61.255.254232.61.255.255131,070
32232.62.0.0/15232.62.0.1 to 232.63.255.254232.63.255.255131,070
33232.64.0.0/15232.64.0.1 to 232.65.255.254232.65.255.255131,070
34232.66.0.0/15232.66.0.1 to 232.67.255.254232.67.255.255131,070
35232.68.0.0/15232.68.0.1 to 232.69.255.254232.69.255.255131,070
36232.70.0.0/15232.70.0.1 to 232.71.255.254232.71.255.255131,070
37232.72.0.0/15232.72.0.1 to 232.73.255.254232.73.255.255131,070
38232.74.0.0/15232.74.0.1 to 232.75.255.254232.75.255.255131,070
39232.76.0.0/15232.76.0.1 to 232.77.255.254232.77.255.255131,070
40232.78.0.0/15232.78.0.1 to 232.79.255.254232.79.255.255131,070
41232.80.0.0/15232.80.0.1 to 232.81.255.254232.81.255.255131,070
42232.82.0.0/15232.82.0.1 to 232.83.255.254232.83.255.255131,070
43232.84.0.0/15232.84.0.1 to 232.85.255.254232.85.255.255131,070
44232.86.0.0/15232.86.0.1 to 232.87.255.254232.87.255.255131,070
45232.88.0.0/15232.88.0.1 to 232.89.255.254232.89.255.255131,070
46232.90.0.0/15232.90.0.1 to 232.91.255.254232.91.255.255131,070
47232.92.0.0/15232.92.0.1 to 232.93.255.254232.93.255.255131,070
48232.94.0.0/15232.94.0.1 to 232.95.255.254232.95.255.255131,070
49232.96.0.0/15232.96.0.1 to 232.97.255.254232.97.255.255131,070
50232.98.0.0/15232.98.0.1 to 232.99.255.254232.99.255.255131,070
51232.100.0.0/15232.100.0.1 to 232.101.255.254232.101.255.255131,070
52232.102.0.0/15232.102.0.1 to 232.103.255.254232.103.255.255131,070
53232.104.0.0/15232.104.0.1 to 232.105.255.254232.105.255.255131,070
54232.106.0.0/15232.106.0.1 to 232.107.255.254232.107.255.255131,070
55232.108.0.0/15232.108.0.1 to 232.109.255.254232.109.255.255131,070
56232.110.0.0/15232.110.0.1 to 232.111.255.254232.111.255.255131,070
57232.112.0.0/15232.112.0.1 to 232.113.255.254232.113.255.255131,070
58232.114.0.0/15232.114.0.1 to 232.115.255.254232.115.255.255131,070
59232.116.0.0/15232.116.0.1 to 232.117.255.254232.117.255.255131,070
60232.118.0.0/15232.118.0.1 to 232.119.255.254232.119.255.255131,070
61232.120.0.0/15232.120.0.1 to 232.121.255.254232.121.255.255131,070
62232.122.0.0/15232.122.0.1 to 232.123.255.254232.123.255.255131,070
63232.124.0.0/15232.124.0.1 to 232.125.255.254232.125.255.255131,070
64232.126.0.0/15232.126.0.1 to 232.127.255.254232.127.255.255131,070
65232.128.0.0/15232.128.0.1 to 232.129.255.254232.129.255.255131,070
66232.130.0.0/15232.130.0.1 to 232.131.255.254232.131.255.255131,070
67232.132.0.0/15232.132.0.1 to 232.133.255.254232.133.255.255131,070
68232.134.0.0/15232.134.0.1 to 232.135.255.254232.135.255.255131,070
69232.136.0.0/15232.136.0.1 to 232.137.255.254232.137.255.255131,070
70232.138.0.0/15232.138.0.1 to 232.139.255.254232.139.255.255131,070
71232.140.0.0/15232.140.0.1 to 232.141.255.254232.141.255.255131,070
72232.142.0.0/15232.142.0.1 to 232.143.255.254232.143.255.255131,070
73232.144.0.0/15232.144.0.1 to 232.145.255.254232.145.255.255131,070
74232.146.0.0/15232.146.0.1 to 232.147.255.254232.147.255.255131,070
75232.148.0.0/15232.148.0.1 to 232.149.255.254232.149.255.255131,070
76232.150.0.0/15232.150.0.1 to 232.151.255.254232.151.255.255131,070
77232.152.0.0/15232.152.0.1 to 232.153.255.254232.153.255.255131,070
78232.154.0.0/15232.154.0.1 to 232.155.255.254232.155.255.255131,070
79232.156.0.0/15232.156.0.1 to 232.157.255.254232.157.255.255131,070
80232.158.0.0/15232.158.0.1 to 232.159.255.254232.159.255.255131,070
81232.160.0.0/15232.160.0.1 to 232.161.255.254232.161.255.255131,070
82232.162.0.0/15232.162.0.1 to 232.163.255.254232.163.255.255131,070
83232.164.0.0/15232.164.0.1 to 232.165.255.254232.165.255.255131,070
84232.166.0.0/15232.166.0.1 to 232.167.255.254232.167.255.255131,070
85232.168.0.0/15232.168.0.1 to 232.169.255.254232.169.255.255131,070
86232.170.0.0/15232.170.0.1 to 232.171.255.254232.171.255.255131,070
87232.172.0.0/15232.172.0.1 to 232.173.255.254232.173.255.255131,070
88232.174.0.0/15232.174.0.1 to 232.175.255.254232.175.255.255131,070
89232.176.0.0/15232.176.0.1 to 232.177.255.254232.177.255.255131,070
90232.178.0.0/15232.178.0.1 to 232.179.255.254232.179.255.255131,070
91232.180.0.0/15232.180.0.1 to 232.181.255.254232.181.255.255131,070
92232.182.0.0/15232.182.0.1 to 232.183.255.254232.183.255.255131,070
93232.184.0.0/15232.184.0.1 to 232.185.255.254232.185.255.255131,070
94232.186.0.0/15232.186.0.1 to 232.187.255.254232.187.255.255131,070
95232.188.0.0/15232.188.0.1 to 232.189.255.254232.189.255.255131,070
96232.190.0.0/15232.190.0.1 to 232.191.255.254232.191.255.255131,070
97232.192.0.0/15232.192.0.1 to 232.193.255.254232.193.255.255131,070
98232.194.0.0/15232.194.0.1 to 232.195.255.254232.195.255.255131,070
99232.196.0.0/15232.196.0.1 to 232.197.255.254232.197.255.255131,070
100232.198.0.0/15232.198.0.1 to 232.199.255.254232.199.255.255131,070
101232.200.0.0/15232.200.0.1 to 232.201.255.254232.201.255.255131,070
102232.202.0.0/15232.202.0.1 to 232.203.255.254232.203.255.255131,070
103232.204.0.0/15232.204.0.1 to 232.205.255.254232.205.255.255131,070
104232.206.0.0/15232.206.0.1 to 232.207.255.254232.207.255.255131,070
105232.208.0.0/15232.208.0.1 to 232.209.255.254232.209.255.255131,070
106232.210.0.0/15232.210.0.1 to 232.211.255.254232.211.255.255131,070
107232.212.0.0/15232.212.0.1 to 232.213.255.254232.213.255.255131,070
108232.214.0.0/15232.214.0.1 to 232.215.255.254232.215.255.255131,070
109232.216.0.0/15232.216.0.1 to 232.217.255.254232.217.255.255131,070
110232.218.0.0/15232.218.0.1 to 232.219.255.254232.219.255.255131,070
111232.220.0.0/15232.220.0.1 to 232.221.255.254232.221.255.255131,070
112232.222.0.0/15232.222.0.1 to 232.223.255.254232.223.255.255131,070
113232.224.0.0/15232.224.0.1 to 232.225.255.254232.225.255.255131,070
114232.226.0.0/15232.226.0.1 to 232.227.255.254232.227.255.255131,070
115232.228.0.0/15232.228.0.1 to 232.229.255.254232.229.255.255131,070
116232.230.0.0/15232.230.0.1 to 232.231.255.254232.231.255.255131,070
117232.232.0.0/15232.232.0.1 to 232.233.255.254232.233.255.255131,070
118232.234.0.0/15232.234.0.1 to 232.235.255.254232.235.255.255131,070
119232.236.0.0/15232.236.0.1 to 232.237.255.254232.237.255.255131,070
120232.238.0.0/15232.238.0.1 to 232.239.255.254232.239.255.255131,070
121232.240.0.0/15232.240.0.1 to 232.241.255.254232.241.255.255131,070
122232.242.0.0/15232.242.0.1 to 232.243.255.254232.243.255.255131,070
123232.244.0.0/15232.244.0.1 to 232.245.255.254232.245.255.255131,070
124232.246.0.0/15232.246.0.1 to 232.247.255.254232.247.255.255131,070
125232.248.0.0/15232.248.0.1 to 232.249.255.254232.249.255.255131,070
126232.250.0.0/15232.250.0.1 to 232.251.255.254232.251.255.255131,070
127232.252.0.0/15232.252.0.1 to 232.253.255.254232.253.255.255131,070
128232.254.0.0/15232.254.0.1 to 232.255.255.254232.255.255.255131,070

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.