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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.

Network244.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
244.0.0.0
Broadcast address
244.255.255.255
First usable
244.0.0.1
Last usable
244.255.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F4000000 · Integer 4093640704 to 4110417919
Reverse DNS zone
244.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110100..00000000.00000000.00000000244.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11110100..00000000.00000000.00000000244.0.0.0
Broadcast11110100..11111111.11111111.11111111244.255.255.255
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)

244.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1244.0.0.0/15244.0.0.1 to 244.1.255.254244.1.255.255131,070
2244.2.0.0/15244.2.0.1 to 244.3.255.254244.3.255.255131,070
3244.4.0.0/15244.4.0.1 to 244.5.255.254244.5.255.255131,070
4244.6.0.0/15244.6.0.1 to 244.7.255.254244.7.255.255131,070
5244.8.0.0/15244.8.0.1 to 244.9.255.254244.9.255.255131,070
6244.10.0.0/15244.10.0.1 to 244.11.255.254244.11.255.255131,070
7244.12.0.0/15244.12.0.1 to 244.13.255.254244.13.255.255131,070
8244.14.0.0/15244.14.0.1 to 244.15.255.254244.15.255.255131,070
9244.16.0.0/15244.16.0.1 to 244.17.255.254244.17.255.255131,070
10244.18.0.0/15244.18.0.1 to 244.19.255.254244.19.255.255131,070
11244.20.0.0/15244.20.0.1 to 244.21.255.254244.21.255.255131,070
12244.22.0.0/15244.22.0.1 to 244.23.255.254244.23.255.255131,070
13244.24.0.0/15244.24.0.1 to 244.25.255.254244.25.255.255131,070
14244.26.0.0/15244.26.0.1 to 244.27.255.254244.27.255.255131,070
15244.28.0.0/15244.28.0.1 to 244.29.255.254244.29.255.255131,070
16244.30.0.0/15244.30.0.1 to 244.31.255.254244.31.255.255131,070
17244.32.0.0/15244.32.0.1 to 244.33.255.254244.33.255.255131,070
18244.34.0.0/15244.34.0.1 to 244.35.255.254244.35.255.255131,070
19244.36.0.0/15244.36.0.1 to 244.37.255.254244.37.255.255131,070
20244.38.0.0/15244.38.0.1 to 244.39.255.254244.39.255.255131,070
21244.40.0.0/15244.40.0.1 to 244.41.255.254244.41.255.255131,070
22244.42.0.0/15244.42.0.1 to 244.43.255.254244.43.255.255131,070
23244.44.0.0/15244.44.0.1 to 244.45.255.254244.45.255.255131,070
24244.46.0.0/15244.46.0.1 to 244.47.255.254244.47.255.255131,070
25244.48.0.0/15244.48.0.1 to 244.49.255.254244.49.255.255131,070
26244.50.0.0/15244.50.0.1 to 244.51.255.254244.51.255.255131,070
27244.52.0.0/15244.52.0.1 to 244.53.255.254244.53.255.255131,070
28244.54.0.0/15244.54.0.1 to 244.55.255.254244.55.255.255131,070
29244.56.0.0/15244.56.0.1 to 244.57.255.254244.57.255.255131,070
30244.58.0.0/15244.58.0.1 to 244.59.255.254244.59.255.255131,070
31244.60.0.0/15244.60.0.1 to 244.61.255.254244.61.255.255131,070
32244.62.0.0/15244.62.0.1 to 244.63.255.254244.63.255.255131,070
33244.64.0.0/15244.64.0.1 to 244.65.255.254244.65.255.255131,070
34244.66.0.0/15244.66.0.1 to 244.67.255.254244.67.255.255131,070
35244.68.0.0/15244.68.0.1 to 244.69.255.254244.69.255.255131,070
36244.70.0.0/15244.70.0.1 to 244.71.255.254244.71.255.255131,070
37244.72.0.0/15244.72.0.1 to 244.73.255.254244.73.255.255131,070
38244.74.0.0/15244.74.0.1 to 244.75.255.254244.75.255.255131,070
39244.76.0.0/15244.76.0.1 to 244.77.255.254244.77.255.255131,070
40244.78.0.0/15244.78.0.1 to 244.79.255.254244.79.255.255131,070
41244.80.0.0/15244.80.0.1 to 244.81.255.254244.81.255.255131,070
42244.82.0.0/15244.82.0.1 to 244.83.255.254244.83.255.255131,070
43244.84.0.0/15244.84.0.1 to 244.85.255.254244.85.255.255131,070
44244.86.0.0/15244.86.0.1 to 244.87.255.254244.87.255.255131,070
45244.88.0.0/15244.88.0.1 to 244.89.255.254244.89.255.255131,070
46244.90.0.0/15244.90.0.1 to 244.91.255.254244.91.255.255131,070
47244.92.0.0/15244.92.0.1 to 244.93.255.254244.93.255.255131,070
48244.94.0.0/15244.94.0.1 to 244.95.255.254244.95.255.255131,070
49244.96.0.0/15244.96.0.1 to 244.97.255.254244.97.255.255131,070
50244.98.0.0/15244.98.0.1 to 244.99.255.254244.99.255.255131,070
51244.100.0.0/15244.100.0.1 to 244.101.255.254244.101.255.255131,070
52244.102.0.0/15244.102.0.1 to 244.103.255.254244.103.255.255131,070
53244.104.0.0/15244.104.0.1 to 244.105.255.254244.105.255.255131,070
54244.106.0.0/15244.106.0.1 to 244.107.255.254244.107.255.255131,070
55244.108.0.0/15244.108.0.1 to 244.109.255.254244.109.255.255131,070
56244.110.0.0/15244.110.0.1 to 244.111.255.254244.111.255.255131,070
57244.112.0.0/15244.112.0.1 to 244.113.255.254244.113.255.255131,070
58244.114.0.0/15244.114.0.1 to 244.115.255.254244.115.255.255131,070
59244.116.0.0/15244.116.0.1 to 244.117.255.254244.117.255.255131,070
60244.118.0.0/15244.118.0.1 to 244.119.255.254244.119.255.255131,070
61244.120.0.0/15244.120.0.1 to 244.121.255.254244.121.255.255131,070
62244.122.0.0/15244.122.0.1 to 244.123.255.254244.123.255.255131,070
63244.124.0.0/15244.124.0.1 to 244.125.255.254244.125.255.255131,070
64244.126.0.0/15244.126.0.1 to 244.127.255.254244.127.255.255131,070
65244.128.0.0/15244.128.0.1 to 244.129.255.254244.129.255.255131,070
66244.130.0.0/15244.130.0.1 to 244.131.255.254244.131.255.255131,070
67244.132.0.0/15244.132.0.1 to 244.133.255.254244.133.255.255131,070
68244.134.0.0/15244.134.0.1 to 244.135.255.254244.135.255.255131,070
69244.136.0.0/15244.136.0.1 to 244.137.255.254244.137.255.255131,070
70244.138.0.0/15244.138.0.1 to 244.139.255.254244.139.255.255131,070
71244.140.0.0/15244.140.0.1 to 244.141.255.254244.141.255.255131,070
72244.142.0.0/15244.142.0.1 to 244.143.255.254244.143.255.255131,070
73244.144.0.0/15244.144.0.1 to 244.145.255.254244.145.255.255131,070
74244.146.0.0/15244.146.0.1 to 244.147.255.254244.147.255.255131,070
75244.148.0.0/15244.148.0.1 to 244.149.255.254244.149.255.255131,070
76244.150.0.0/15244.150.0.1 to 244.151.255.254244.151.255.255131,070
77244.152.0.0/15244.152.0.1 to 244.153.255.254244.153.255.255131,070
78244.154.0.0/15244.154.0.1 to 244.155.255.254244.155.255.255131,070
79244.156.0.0/15244.156.0.1 to 244.157.255.254244.157.255.255131,070
80244.158.0.0/15244.158.0.1 to 244.159.255.254244.159.255.255131,070
81244.160.0.0/15244.160.0.1 to 244.161.255.254244.161.255.255131,070
82244.162.0.0/15244.162.0.1 to 244.163.255.254244.163.255.255131,070
83244.164.0.0/15244.164.0.1 to 244.165.255.254244.165.255.255131,070
84244.166.0.0/15244.166.0.1 to 244.167.255.254244.167.255.255131,070
85244.168.0.0/15244.168.0.1 to 244.169.255.254244.169.255.255131,070
86244.170.0.0/15244.170.0.1 to 244.171.255.254244.171.255.255131,070
87244.172.0.0/15244.172.0.1 to 244.173.255.254244.173.255.255131,070
88244.174.0.0/15244.174.0.1 to 244.175.255.254244.175.255.255131,070
89244.176.0.0/15244.176.0.1 to 244.177.255.254244.177.255.255131,070
90244.178.0.0/15244.178.0.1 to 244.179.255.254244.179.255.255131,070
91244.180.0.0/15244.180.0.1 to 244.181.255.254244.181.255.255131,070
92244.182.0.0/15244.182.0.1 to 244.183.255.254244.183.255.255131,070
93244.184.0.0/15244.184.0.1 to 244.185.255.254244.185.255.255131,070
94244.186.0.0/15244.186.0.1 to 244.187.255.254244.187.255.255131,070
95244.188.0.0/15244.188.0.1 to 244.189.255.254244.189.255.255131,070
96244.190.0.0/15244.190.0.1 to 244.191.255.254244.191.255.255131,070
97244.192.0.0/15244.192.0.1 to 244.193.255.254244.193.255.255131,070
98244.194.0.0/15244.194.0.1 to 244.195.255.254244.195.255.255131,070
99244.196.0.0/15244.196.0.1 to 244.197.255.254244.197.255.255131,070
100244.198.0.0/15244.198.0.1 to 244.199.255.254244.199.255.255131,070
101244.200.0.0/15244.200.0.1 to 244.201.255.254244.201.255.255131,070
102244.202.0.0/15244.202.0.1 to 244.203.255.254244.203.255.255131,070
103244.204.0.0/15244.204.0.1 to 244.205.255.254244.205.255.255131,070
104244.206.0.0/15244.206.0.1 to 244.207.255.254244.207.255.255131,070
105244.208.0.0/15244.208.0.1 to 244.209.255.254244.209.255.255131,070
106244.210.0.0/15244.210.0.1 to 244.211.255.254244.211.255.255131,070
107244.212.0.0/15244.212.0.1 to 244.213.255.254244.213.255.255131,070
108244.214.0.0/15244.214.0.1 to 244.215.255.254244.215.255.255131,070
109244.216.0.0/15244.216.0.1 to 244.217.255.254244.217.255.255131,070
110244.218.0.0/15244.218.0.1 to 244.219.255.254244.219.255.255131,070
111244.220.0.0/15244.220.0.1 to 244.221.255.254244.221.255.255131,070
112244.222.0.0/15244.222.0.1 to 244.223.255.254244.223.255.255131,070
113244.224.0.0/15244.224.0.1 to 244.225.255.254244.225.255.255131,070
114244.226.0.0/15244.226.0.1 to 244.227.255.254244.227.255.255131,070
115244.228.0.0/15244.228.0.1 to 244.229.255.254244.229.255.255131,070
116244.230.0.0/15244.230.0.1 to 244.231.255.254244.231.255.255131,070
117244.232.0.0/15244.232.0.1 to 244.233.255.254244.233.255.255131,070
118244.234.0.0/15244.234.0.1 to 244.235.255.254244.235.255.255131,070
119244.236.0.0/15244.236.0.1 to 244.237.255.254244.237.255.255131,070
120244.238.0.0/15244.238.0.1 to 244.239.255.254244.239.255.255131,070
121244.240.0.0/15244.240.0.1 to 244.241.255.254244.241.255.255131,070
122244.242.0.0/15244.242.0.1 to 244.243.255.254244.243.255.255131,070
123244.244.0.0/15244.244.0.1 to 244.245.255.254244.245.255.255131,070
124244.246.0.0/15244.246.0.1 to 244.247.255.254244.247.255.255131,070
125244.248.0.0/15244.248.0.1 to 244.249.255.254244.249.255.255131,070
126244.250.0.0/15244.250.0.1 to 244.251.255.254244.251.255.255131,070
127244.252.0.0/15244.252.0.1 to 244.253.255.254244.253.255.255131,070
128244.254.0.0/15244.254.0.1 to 244.255.255.254244.255.255.255131,070

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.