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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.

Network228.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
228.0.0.0
Broadcast address
228.255.255.255
First usable
228.0.0.1
Last usable
228.255.255.254
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 E4000000 · Integer 3825205248 to 3841982463
Reverse DNS zone
228.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11100100..00000000.00000000.00000000228.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11100100..00000000.00000000.00000000228.0.0.0
Broadcast11100100..11111111.11111111.11111111228.255.255.255
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)

228.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1228.0.0.0/15228.0.0.1 to 228.1.255.254228.1.255.255131,070
2228.2.0.0/15228.2.0.1 to 228.3.255.254228.3.255.255131,070
3228.4.0.0/15228.4.0.1 to 228.5.255.254228.5.255.255131,070
4228.6.0.0/15228.6.0.1 to 228.7.255.254228.7.255.255131,070
5228.8.0.0/15228.8.0.1 to 228.9.255.254228.9.255.255131,070
6228.10.0.0/15228.10.0.1 to 228.11.255.254228.11.255.255131,070
7228.12.0.0/15228.12.0.1 to 228.13.255.254228.13.255.255131,070
8228.14.0.0/15228.14.0.1 to 228.15.255.254228.15.255.255131,070
9228.16.0.0/15228.16.0.1 to 228.17.255.254228.17.255.255131,070
10228.18.0.0/15228.18.0.1 to 228.19.255.254228.19.255.255131,070
11228.20.0.0/15228.20.0.1 to 228.21.255.254228.21.255.255131,070
12228.22.0.0/15228.22.0.1 to 228.23.255.254228.23.255.255131,070
13228.24.0.0/15228.24.0.1 to 228.25.255.254228.25.255.255131,070
14228.26.0.0/15228.26.0.1 to 228.27.255.254228.27.255.255131,070
15228.28.0.0/15228.28.0.1 to 228.29.255.254228.29.255.255131,070
16228.30.0.0/15228.30.0.1 to 228.31.255.254228.31.255.255131,070
17228.32.0.0/15228.32.0.1 to 228.33.255.254228.33.255.255131,070
18228.34.0.0/15228.34.0.1 to 228.35.255.254228.35.255.255131,070
19228.36.0.0/15228.36.0.1 to 228.37.255.254228.37.255.255131,070
20228.38.0.0/15228.38.0.1 to 228.39.255.254228.39.255.255131,070
21228.40.0.0/15228.40.0.1 to 228.41.255.254228.41.255.255131,070
22228.42.0.0/15228.42.0.1 to 228.43.255.254228.43.255.255131,070
23228.44.0.0/15228.44.0.1 to 228.45.255.254228.45.255.255131,070
24228.46.0.0/15228.46.0.1 to 228.47.255.254228.47.255.255131,070
25228.48.0.0/15228.48.0.1 to 228.49.255.254228.49.255.255131,070
26228.50.0.0/15228.50.0.1 to 228.51.255.254228.51.255.255131,070
27228.52.0.0/15228.52.0.1 to 228.53.255.254228.53.255.255131,070
28228.54.0.0/15228.54.0.1 to 228.55.255.254228.55.255.255131,070
29228.56.0.0/15228.56.0.1 to 228.57.255.254228.57.255.255131,070
30228.58.0.0/15228.58.0.1 to 228.59.255.254228.59.255.255131,070
31228.60.0.0/15228.60.0.1 to 228.61.255.254228.61.255.255131,070
32228.62.0.0/15228.62.0.1 to 228.63.255.254228.63.255.255131,070
33228.64.0.0/15228.64.0.1 to 228.65.255.254228.65.255.255131,070
34228.66.0.0/15228.66.0.1 to 228.67.255.254228.67.255.255131,070
35228.68.0.0/15228.68.0.1 to 228.69.255.254228.69.255.255131,070
36228.70.0.0/15228.70.0.1 to 228.71.255.254228.71.255.255131,070
37228.72.0.0/15228.72.0.1 to 228.73.255.254228.73.255.255131,070
38228.74.0.0/15228.74.0.1 to 228.75.255.254228.75.255.255131,070
39228.76.0.0/15228.76.0.1 to 228.77.255.254228.77.255.255131,070
40228.78.0.0/15228.78.0.1 to 228.79.255.254228.79.255.255131,070
41228.80.0.0/15228.80.0.1 to 228.81.255.254228.81.255.255131,070
42228.82.0.0/15228.82.0.1 to 228.83.255.254228.83.255.255131,070
43228.84.0.0/15228.84.0.1 to 228.85.255.254228.85.255.255131,070
44228.86.0.0/15228.86.0.1 to 228.87.255.254228.87.255.255131,070
45228.88.0.0/15228.88.0.1 to 228.89.255.254228.89.255.255131,070
46228.90.0.0/15228.90.0.1 to 228.91.255.254228.91.255.255131,070
47228.92.0.0/15228.92.0.1 to 228.93.255.254228.93.255.255131,070
48228.94.0.0/15228.94.0.1 to 228.95.255.254228.95.255.255131,070
49228.96.0.0/15228.96.0.1 to 228.97.255.254228.97.255.255131,070
50228.98.0.0/15228.98.0.1 to 228.99.255.254228.99.255.255131,070
51228.100.0.0/15228.100.0.1 to 228.101.255.254228.101.255.255131,070
52228.102.0.0/15228.102.0.1 to 228.103.255.254228.103.255.255131,070
53228.104.0.0/15228.104.0.1 to 228.105.255.254228.105.255.255131,070
54228.106.0.0/15228.106.0.1 to 228.107.255.254228.107.255.255131,070
55228.108.0.0/15228.108.0.1 to 228.109.255.254228.109.255.255131,070
56228.110.0.0/15228.110.0.1 to 228.111.255.254228.111.255.255131,070
57228.112.0.0/15228.112.0.1 to 228.113.255.254228.113.255.255131,070
58228.114.0.0/15228.114.0.1 to 228.115.255.254228.115.255.255131,070
59228.116.0.0/15228.116.0.1 to 228.117.255.254228.117.255.255131,070
60228.118.0.0/15228.118.0.1 to 228.119.255.254228.119.255.255131,070
61228.120.0.0/15228.120.0.1 to 228.121.255.254228.121.255.255131,070
62228.122.0.0/15228.122.0.1 to 228.123.255.254228.123.255.255131,070
63228.124.0.0/15228.124.0.1 to 228.125.255.254228.125.255.255131,070
64228.126.0.0/15228.126.0.1 to 228.127.255.254228.127.255.255131,070
65228.128.0.0/15228.128.0.1 to 228.129.255.254228.129.255.255131,070
66228.130.0.0/15228.130.0.1 to 228.131.255.254228.131.255.255131,070
67228.132.0.0/15228.132.0.1 to 228.133.255.254228.133.255.255131,070
68228.134.0.0/15228.134.0.1 to 228.135.255.254228.135.255.255131,070
69228.136.0.0/15228.136.0.1 to 228.137.255.254228.137.255.255131,070
70228.138.0.0/15228.138.0.1 to 228.139.255.254228.139.255.255131,070
71228.140.0.0/15228.140.0.1 to 228.141.255.254228.141.255.255131,070
72228.142.0.0/15228.142.0.1 to 228.143.255.254228.143.255.255131,070
73228.144.0.0/15228.144.0.1 to 228.145.255.254228.145.255.255131,070
74228.146.0.0/15228.146.0.1 to 228.147.255.254228.147.255.255131,070
75228.148.0.0/15228.148.0.1 to 228.149.255.254228.149.255.255131,070
76228.150.0.0/15228.150.0.1 to 228.151.255.254228.151.255.255131,070
77228.152.0.0/15228.152.0.1 to 228.153.255.254228.153.255.255131,070
78228.154.0.0/15228.154.0.1 to 228.155.255.254228.155.255.255131,070
79228.156.0.0/15228.156.0.1 to 228.157.255.254228.157.255.255131,070
80228.158.0.0/15228.158.0.1 to 228.159.255.254228.159.255.255131,070
81228.160.0.0/15228.160.0.1 to 228.161.255.254228.161.255.255131,070
82228.162.0.0/15228.162.0.1 to 228.163.255.254228.163.255.255131,070
83228.164.0.0/15228.164.0.1 to 228.165.255.254228.165.255.255131,070
84228.166.0.0/15228.166.0.1 to 228.167.255.254228.167.255.255131,070
85228.168.0.0/15228.168.0.1 to 228.169.255.254228.169.255.255131,070
86228.170.0.0/15228.170.0.1 to 228.171.255.254228.171.255.255131,070
87228.172.0.0/15228.172.0.1 to 228.173.255.254228.173.255.255131,070
88228.174.0.0/15228.174.0.1 to 228.175.255.254228.175.255.255131,070
89228.176.0.0/15228.176.0.1 to 228.177.255.254228.177.255.255131,070
90228.178.0.0/15228.178.0.1 to 228.179.255.254228.179.255.255131,070
91228.180.0.0/15228.180.0.1 to 228.181.255.254228.181.255.255131,070
92228.182.0.0/15228.182.0.1 to 228.183.255.254228.183.255.255131,070
93228.184.0.0/15228.184.0.1 to 228.185.255.254228.185.255.255131,070
94228.186.0.0/15228.186.0.1 to 228.187.255.254228.187.255.255131,070
95228.188.0.0/15228.188.0.1 to 228.189.255.254228.189.255.255131,070
96228.190.0.0/15228.190.0.1 to 228.191.255.254228.191.255.255131,070
97228.192.0.0/15228.192.0.1 to 228.193.255.254228.193.255.255131,070
98228.194.0.0/15228.194.0.1 to 228.195.255.254228.195.255.255131,070
99228.196.0.0/15228.196.0.1 to 228.197.255.254228.197.255.255131,070
100228.198.0.0/15228.198.0.1 to 228.199.255.254228.199.255.255131,070
101228.200.0.0/15228.200.0.1 to 228.201.255.254228.201.255.255131,070
102228.202.0.0/15228.202.0.1 to 228.203.255.254228.203.255.255131,070
103228.204.0.0/15228.204.0.1 to 228.205.255.254228.205.255.255131,070
104228.206.0.0/15228.206.0.1 to 228.207.255.254228.207.255.255131,070
105228.208.0.0/15228.208.0.1 to 228.209.255.254228.209.255.255131,070
106228.210.0.0/15228.210.0.1 to 228.211.255.254228.211.255.255131,070
107228.212.0.0/15228.212.0.1 to 228.213.255.254228.213.255.255131,070
108228.214.0.0/15228.214.0.1 to 228.215.255.254228.215.255.255131,070
109228.216.0.0/15228.216.0.1 to 228.217.255.254228.217.255.255131,070
110228.218.0.0/15228.218.0.1 to 228.219.255.254228.219.255.255131,070
111228.220.0.0/15228.220.0.1 to 228.221.255.254228.221.255.255131,070
112228.222.0.0/15228.222.0.1 to 228.223.255.254228.223.255.255131,070
113228.224.0.0/15228.224.0.1 to 228.225.255.254228.225.255.255131,070
114228.226.0.0/15228.226.0.1 to 228.227.255.254228.227.255.255131,070
115228.228.0.0/15228.228.0.1 to 228.229.255.254228.229.255.255131,070
116228.230.0.0/15228.230.0.1 to 228.231.255.254228.231.255.255131,070
117228.232.0.0/15228.232.0.1 to 228.233.255.254228.233.255.255131,070
118228.234.0.0/15228.234.0.1 to 228.235.255.254228.235.255.255131,070
119228.236.0.0/15228.236.0.1 to 228.237.255.254228.237.255.255131,070
120228.238.0.0/15228.238.0.1 to 228.239.255.254228.239.255.255131,070
121228.240.0.0/15228.240.0.1 to 228.241.255.254228.241.255.255131,070
122228.242.0.0/15228.242.0.1 to 228.243.255.254228.243.255.255131,070
123228.244.0.0/15228.244.0.1 to 228.245.255.254228.245.255.255131,070
124228.246.0.0/15228.246.0.1 to 228.247.255.254228.247.255.255131,070
125228.248.0.0/15228.248.0.1 to 228.249.255.254228.249.255.255131,070
126228.250.0.0/15228.250.0.1 to 228.251.255.254228.251.255.255131,070
127228.252.0.0/15228.252.0.1 to 228.253.255.254228.253.255.255131,070
128228.254.0.0/15228.254.0.1 to 228.255.255.254228.255.255.255131,070

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.