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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.

Network227.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
227.0.0.0
Broadcast address
227.255.255.255
First usable
227.0.0.1
Last usable
227.255.255.254
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 E3000000 · Integer 3808428032 to 3825205247
Reverse DNS zone
227.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11100011..00000000.00000000.00000000227.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11100011..00000000.00000000.00000000227.0.0.0
Broadcast11100011..11111111.11111111.11111111227.255.255.255
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)

227.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1227.0.0.0/15227.0.0.1 to 227.1.255.254227.1.255.255131,070
2227.2.0.0/15227.2.0.1 to 227.3.255.254227.3.255.255131,070
3227.4.0.0/15227.4.0.1 to 227.5.255.254227.5.255.255131,070
4227.6.0.0/15227.6.0.1 to 227.7.255.254227.7.255.255131,070
5227.8.0.0/15227.8.0.1 to 227.9.255.254227.9.255.255131,070
6227.10.0.0/15227.10.0.1 to 227.11.255.254227.11.255.255131,070
7227.12.0.0/15227.12.0.1 to 227.13.255.254227.13.255.255131,070
8227.14.0.0/15227.14.0.1 to 227.15.255.254227.15.255.255131,070
9227.16.0.0/15227.16.0.1 to 227.17.255.254227.17.255.255131,070
10227.18.0.0/15227.18.0.1 to 227.19.255.254227.19.255.255131,070
11227.20.0.0/15227.20.0.1 to 227.21.255.254227.21.255.255131,070
12227.22.0.0/15227.22.0.1 to 227.23.255.254227.23.255.255131,070
13227.24.0.0/15227.24.0.1 to 227.25.255.254227.25.255.255131,070
14227.26.0.0/15227.26.0.1 to 227.27.255.254227.27.255.255131,070
15227.28.0.0/15227.28.0.1 to 227.29.255.254227.29.255.255131,070
16227.30.0.0/15227.30.0.1 to 227.31.255.254227.31.255.255131,070
17227.32.0.0/15227.32.0.1 to 227.33.255.254227.33.255.255131,070
18227.34.0.0/15227.34.0.1 to 227.35.255.254227.35.255.255131,070
19227.36.0.0/15227.36.0.1 to 227.37.255.254227.37.255.255131,070
20227.38.0.0/15227.38.0.1 to 227.39.255.254227.39.255.255131,070
21227.40.0.0/15227.40.0.1 to 227.41.255.254227.41.255.255131,070
22227.42.0.0/15227.42.0.1 to 227.43.255.254227.43.255.255131,070
23227.44.0.0/15227.44.0.1 to 227.45.255.254227.45.255.255131,070
24227.46.0.0/15227.46.0.1 to 227.47.255.254227.47.255.255131,070
25227.48.0.0/15227.48.0.1 to 227.49.255.254227.49.255.255131,070
26227.50.0.0/15227.50.0.1 to 227.51.255.254227.51.255.255131,070
27227.52.0.0/15227.52.0.1 to 227.53.255.254227.53.255.255131,070
28227.54.0.0/15227.54.0.1 to 227.55.255.254227.55.255.255131,070
29227.56.0.0/15227.56.0.1 to 227.57.255.254227.57.255.255131,070
30227.58.0.0/15227.58.0.1 to 227.59.255.254227.59.255.255131,070
31227.60.0.0/15227.60.0.1 to 227.61.255.254227.61.255.255131,070
32227.62.0.0/15227.62.0.1 to 227.63.255.254227.63.255.255131,070
33227.64.0.0/15227.64.0.1 to 227.65.255.254227.65.255.255131,070
34227.66.0.0/15227.66.0.1 to 227.67.255.254227.67.255.255131,070
35227.68.0.0/15227.68.0.1 to 227.69.255.254227.69.255.255131,070
36227.70.0.0/15227.70.0.1 to 227.71.255.254227.71.255.255131,070
37227.72.0.0/15227.72.0.1 to 227.73.255.254227.73.255.255131,070
38227.74.0.0/15227.74.0.1 to 227.75.255.254227.75.255.255131,070
39227.76.0.0/15227.76.0.1 to 227.77.255.254227.77.255.255131,070
40227.78.0.0/15227.78.0.1 to 227.79.255.254227.79.255.255131,070
41227.80.0.0/15227.80.0.1 to 227.81.255.254227.81.255.255131,070
42227.82.0.0/15227.82.0.1 to 227.83.255.254227.83.255.255131,070
43227.84.0.0/15227.84.0.1 to 227.85.255.254227.85.255.255131,070
44227.86.0.0/15227.86.0.1 to 227.87.255.254227.87.255.255131,070
45227.88.0.0/15227.88.0.1 to 227.89.255.254227.89.255.255131,070
46227.90.0.0/15227.90.0.1 to 227.91.255.254227.91.255.255131,070
47227.92.0.0/15227.92.0.1 to 227.93.255.254227.93.255.255131,070
48227.94.0.0/15227.94.0.1 to 227.95.255.254227.95.255.255131,070
49227.96.0.0/15227.96.0.1 to 227.97.255.254227.97.255.255131,070
50227.98.0.0/15227.98.0.1 to 227.99.255.254227.99.255.255131,070
51227.100.0.0/15227.100.0.1 to 227.101.255.254227.101.255.255131,070
52227.102.0.0/15227.102.0.1 to 227.103.255.254227.103.255.255131,070
53227.104.0.0/15227.104.0.1 to 227.105.255.254227.105.255.255131,070
54227.106.0.0/15227.106.0.1 to 227.107.255.254227.107.255.255131,070
55227.108.0.0/15227.108.0.1 to 227.109.255.254227.109.255.255131,070
56227.110.0.0/15227.110.0.1 to 227.111.255.254227.111.255.255131,070
57227.112.0.0/15227.112.0.1 to 227.113.255.254227.113.255.255131,070
58227.114.0.0/15227.114.0.1 to 227.115.255.254227.115.255.255131,070
59227.116.0.0/15227.116.0.1 to 227.117.255.254227.117.255.255131,070
60227.118.0.0/15227.118.0.1 to 227.119.255.254227.119.255.255131,070
61227.120.0.0/15227.120.0.1 to 227.121.255.254227.121.255.255131,070
62227.122.0.0/15227.122.0.1 to 227.123.255.254227.123.255.255131,070
63227.124.0.0/15227.124.0.1 to 227.125.255.254227.125.255.255131,070
64227.126.0.0/15227.126.0.1 to 227.127.255.254227.127.255.255131,070
65227.128.0.0/15227.128.0.1 to 227.129.255.254227.129.255.255131,070
66227.130.0.0/15227.130.0.1 to 227.131.255.254227.131.255.255131,070
67227.132.0.0/15227.132.0.1 to 227.133.255.254227.133.255.255131,070
68227.134.0.0/15227.134.0.1 to 227.135.255.254227.135.255.255131,070
69227.136.0.0/15227.136.0.1 to 227.137.255.254227.137.255.255131,070
70227.138.0.0/15227.138.0.1 to 227.139.255.254227.139.255.255131,070
71227.140.0.0/15227.140.0.1 to 227.141.255.254227.141.255.255131,070
72227.142.0.0/15227.142.0.1 to 227.143.255.254227.143.255.255131,070
73227.144.0.0/15227.144.0.1 to 227.145.255.254227.145.255.255131,070
74227.146.0.0/15227.146.0.1 to 227.147.255.254227.147.255.255131,070
75227.148.0.0/15227.148.0.1 to 227.149.255.254227.149.255.255131,070
76227.150.0.0/15227.150.0.1 to 227.151.255.254227.151.255.255131,070
77227.152.0.0/15227.152.0.1 to 227.153.255.254227.153.255.255131,070
78227.154.0.0/15227.154.0.1 to 227.155.255.254227.155.255.255131,070
79227.156.0.0/15227.156.0.1 to 227.157.255.254227.157.255.255131,070
80227.158.0.0/15227.158.0.1 to 227.159.255.254227.159.255.255131,070
81227.160.0.0/15227.160.0.1 to 227.161.255.254227.161.255.255131,070
82227.162.0.0/15227.162.0.1 to 227.163.255.254227.163.255.255131,070
83227.164.0.0/15227.164.0.1 to 227.165.255.254227.165.255.255131,070
84227.166.0.0/15227.166.0.1 to 227.167.255.254227.167.255.255131,070
85227.168.0.0/15227.168.0.1 to 227.169.255.254227.169.255.255131,070
86227.170.0.0/15227.170.0.1 to 227.171.255.254227.171.255.255131,070
87227.172.0.0/15227.172.0.1 to 227.173.255.254227.173.255.255131,070
88227.174.0.0/15227.174.0.1 to 227.175.255.254227.175.255.255131,070
89227.176.0.0/15227.176.0.1 to 227.177.255.254227.177.255.255131,070
90227.178.0.0/15227.178.0.1 to 227.179.255.254227.179.255.255131,070
91227.180.0.0/15227.180.0.1 to 227.181.255.254227.181.255.255131,070
92227.182.0.0/15227.182.0.1 to 227.183.255.254227.183.255.255131,070
93227.184.0.0/15227.184.0.1 to 227.185.255.254227.185.255.255131,070
94227.186.0.0/15227.186.0.1 to 227.187.255.254227.187.255.255131,070
95227.188.0.0/15227.188.0.1 to 227.189.255.254227.189.255.255131,070
96227.190.0.0/15227.190.0.1 to 227.191.255.254227.191.255.255131,070
97227.192.0.0/15227.192.0.1 to 227.193.255.254227.193.255.255131,070
98227.194.0.0/15227.194.0.1 to 227.195.255.254227.195.255.255131,070
99227.196.0.0/15227.196.0.1 to 227.197.255.254227.197.255.255131,070
100227.198.0.0/15227.198.0.1 to 227.199.255.254227.199.255.255131,070
101227.200.0.0/15227.200.0.1 to 227.201.255.254227.201.255.255131,070
102227.202.0.0/15227.202.0.1 to 227.203.255.254227.203.255.255131,070
103227.204.0.0/15227.204.0.1 to 227.205.255.254227.205.255.255131,070
104227.206.0.0/15227.206.0.1 to 227.207.255.254227.207.255.255131,070
105227.208.0.0/15227.208.0.1 to 227.209.255.254227.209.255.255131,070
106227.210.0.0/15227.210.0.1 to 227.211.255.254227.211.255.255131,070
107227.212.0.0/15227.212.0.1 to 227.213.255.254227.213.255.255131,070
108227.214.0.0/15227.214.0.1 to 227.215.255.254227.215.255.255131,070
109227.216.0.0/15227.216.0.1 to 227.217.255.254227.217.255.255131,070
110227.218.0.0/15227.218.0.1 to 227.219.255.254227.219.255.255131,070
111227.220.0.0/15227.220.0.1 to 227.221.255.254227.221.255.255131,070
112227.222.0.0/15227.222.0.1 to 227.223.255.254227.223.255.255131,070
113227.224.0.0/15227.224.0.1 to 227.225.255.254227.225.255.255131,070
114227.226.0.0/15227.226.0.1 to 227.227.255.254227.227.255.255131,070
115227.228.0.0/15227.228.0.1 to 227.229.255.254227.229.255.255131,070
116227.230.0.0/15227.230.0.1 to 227.231.255.254227.231.255.255131,070
117227.232.0.0/15227.232.0.1 to 227.233.255.254227.233.255.255131,070
118227.234.0.0/15227.234.0.1 to 227.235.255.254227.235.255.255131,070
119227.236.0.0/15227.236.0.1 to 227.237.255.254227.237.255.255131,070
120227.238.0.0/15227.238.0.1 to 227.239.255.254227.239.255.255131,070
121227.240.0.0/15227.240.0.1 to 227.241.255.254227.241.255.255131,070
122227.242.0.0/15227.242.0.1 to 227.243.255.254227.243.255.255131,070
123227.244.0.0/15227.244.0.1 to 227.245.255.254227.245.255.255131,070
124227.246.0.0/15227.246.0.1 to 227.247.255.254227.247.255.255131,070
125227.248.0.0/15227.248.0.1 to 227.249.255.254227.249.255.255131,070
126227.250.0.0/15227.250.0.1 to 227.251.255.254227.251.255.255131,070
127227.252.0.0/15227.252.0.1 to 227.253.255.254227.253.255.255131,070
128227.254.0.0/15227.254.0.1 to 227.255.255.254227.255.255.255131,070

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.