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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.

Network244.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
244.0.0.0
Broadcast address
247.255.255.255
First usable
244.0.0.1
Last usable
247.255.255.254
Usable hosts
67,108,862 (67,108,864 less the network and broadcast addresses)
Subnet mask
252.0.0.0
Wildcard mask
3.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/6
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 4160749567
Reverse DNS zones
244.in-addr.arpa
245.in-addr.arpa
246.in-addr.arpa
247.in-addr.arpa
/6 is not on a 8-bit boundary, so it takes 4 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110100.00000000.00000000.00000000244.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network11110100.00000000.00000000.00000000244.0.0.0
Broadcast11110111.11111111.11111111.11111111247.255.255.255
Split into smaller subnets/13
/7 (2)/8 (4)/9 (8)/10 (16)/11 (32)/12 (64)/13 (128)/14 (256)/15 (512)/16 (1,024)/17 (2,048)/18 (4,096)

244.0.0.0/6 makes 128 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1244.0.0.0/13244.0.0.1 to 244.7.255.254244.7.255.255524,286
2244.8.0.0/13244.8.0.1 to 244.15.255.254244.15.255.255524,286
3244.16.0.0/13244.16.0.1 to 244.23.255.254244.23.255.255524,286
4244.24.0.0/13244.24.0.1 to 244.31.255.254244.31.255.255524,286
5244.32.0.0/13244.32.0.1 to 244.39.255.254244.39.255.255524,286
6244.40.0.0/13244.40.0.1 to 244.47.255.254244.47.255.255524,286
7244.48.0.0/13244.48.0.1 to 244.55.255.254244.55.255.255524,286
8244.56.0.0/13244.56.0.1 to 244.63.255.254244.63.255.255524,286
9244.64.0.0/13244.64.0.1 to 244.71.255.254244.71.255.255524,286
10244.72.0.0/13244.72.0.1 to 244.79.255.254244.79.255.255524,286
11244.80.0.0/13244.80.0.1 to 244.87.255.254244.87.255.255524,286
12244.88.0.0/13244.88.0.1 to 244.95.255.254244.95.255.255524,286
13244.96.0.0/13244.96.0.1 to 244.103.255.254244.103.255.255524,286
14244.104.0.0/13244.104.0.1 to 244.111.255.254244.111.255.255524,286
15244.112.0.0/13244.112.0.1 to 244.119.255.254244.119.255.255524,286
16244.120.0.0/13244.120.0.1 to 244.127.255.254244.127.255.255524,286
17244.128.0.0/13244.128.0.1 to 244.135.255.254244.135.255.255524,286
18244.136.0.0/13244.136.0.1 to 244.143.255.254244.143.255.255524,286
19244.144.0.0/13244.144.0.1 to 244.151.255.254244.151.255.255524,286
20244.152.0.0/13244.152.0.1 to 244.159.255.254244.159.255.255524,286
21244.160.0.0/13244.160.0.1 to 244.167.255.254244.167.255.255524,286
22244.168.0.0/13244.168.0.1 to 244.175.255.254244.175.255.255524,286
23244.176.0.0/13244.176.0.1 to 244.183.255.254244.183.255.255524,286
24244.184.0.0/13244.184.0.1 to 244.191.255.254244.191.255.255524,286
25244.192.0.0/13244.192.0.1 to 244.199.255.254244.199.255.255524,286
26244.200.0.0/13244.200.0.1 to 244.207.255.254244.207.255.255524,286
27244.208.0.0/13244.208.0.1 to 244.215.255.254244.215.255.255524,286
28244.216.0.0/13244.216.0.1 to 244.223.255.254244.223.255.255524,286
29244.224.0.0/13244.224.0.1 to 244.231.255.254244.231.255.255524,286
30244.232.0.0/13244.232.0.1 to 244.239.255.254244.239.255.255524,286
31244.240.0.0/13244.240.0.1 to 244.247.255.254244.247.255.255524,286
32244.248.0.0/13244.248.0.1 to 244.255.255.254244.255.255.255524,286
33245.0.0.0/13245.0.0.1 to 245.7.255.254245.7.255.255524,286
34245.8.0.0/13245.8.0.1 to 245.15.255.254245.15.255.255524,286
35245.16.0.0/13245.16.0.1 to 245.23.255.254245.23.255.255524,286
36245.24.0.0/13245.24.0.1 to 245.31.255.254245.31.255.255524,286
37245.32.0.0/13245.32.0.1 to 245.39.255.254245.39.255.255524,286
38245.40.0.0/13245.40.0.1 to 245.47.255.254245.47.255.255524,286
39245.48.0.0/13245.48.0.1 to 245.55.255.254245.55.255.255524,286
40245.56.0.0/13245.56.0.1 to 245.63.255.254245.63.255.255524,286
41245.64.0.0/13245.64.0.1 to 245.71.255.254245.71.255.255524,286
42245.72.0.0/13245.72.0.1 to 245.79.255.254245.79.255.255524,286
43245.80.0.0/13245.80.0.1 to 245.87.255.254245.87.255.255524,286
44245.88.0.0/13245.88.0.1 to 245.95.255.254245.95.255.255524,286
45245.96.0.0/13245.96.0.1 to 245.103.255.254245.103.255.255524,286
46245.104.0.0/13245.104.0.1 to 245.111.255.254245.111.255.255524,286
47245.112.0.0/13245.112.0.1 to 245.119.255.254245.119.255.255524,286
48245.120.0.0/13245.120.0.1 to 245.127.255.254245.127.255.255524,286
49245.128.0.0/13245.128.0.1 to 245.135.255.254245.135.255.255524,286
50245.136.0.0/13245.136.0.1 to 245.143.255.254245.143.255.255524,286
51245.144.0.0/13245.144.0.1 to 245.151.255.254245.151.255.255524,286
52245.152.0.0/13245.152.0.1 to 245.159.255.254245.159.255.255524,286
53245.160.0.0/13245.160.0.1 to 245.167.255.254245.167.255.255524,286
54245.168.0.0/13245.168.0.1 to 245.175.255.254245.175.255.255524,286
55245.176.0.0/13245.176.0.1 to 245.183.255.254245.183.255.255524,286
56245.184.0.0/13245.184.0.1 to 245.191.255.254245.191.255.255524,286
57245.192.0.0/13245.192.0.1 to 245.199.255.254245.199.255.255524,286
58245.200.0.0/13245.200.0.1 to 245.207.255.254245.207.255.255524,286
59245.208.0.0/13245.208.0.1 to 245.215.255.254245.215.255.255524,286
60245.216.0.0/13245.216.0.1 to 245.223.255.254245.223.255.255524,286
61245.224.0.0/13245.224.0.1 to 245.231.255.254245.231.255.255524,286
62245.232.0.0/13245.232.0.1 to 245.239.255.254245.239.255.255524,286
63245.240.0.0/13245.240.0.1 to 245.247.255.254245.247.255.255524,286
64245.248.0.0/13245.248.0.1 to 245.255.255.254245.255.255.255524,286
65246.0.0.0/13246.0.0.1 to 246.7.255.254246.7.255.255524,286
66246.8.0.0/13246.8.0.1 to 246.15.255.254246.15.255.255524,286
67246.16.0.0/13246.16.0.1 to 246.23.255.254246.23.255.255524,286
68246.24.0.0/13246.24.0.1 to 246.31.255.254246.31.255.255524,286
69246.32.0.0/13246.32.0.1 to 246.39.255.254246.39.255.255524,286
70246.40.0.0/13246.40.0.1 to 246.47.255.254246.47.255.255524,286
71246.48.0.0/13246.48.0.1 to 246.55.255.254246.55.255.255524,286
72246.56.0.0/13246.56.0.1 to 246.63.255.254246.63.255.255524,286
73246.64.0.0/13246.64.0.1 to 246.71.255.254246.71.255.255524,286
74246.72.0.0/13246.72.0.1 to 246.79.255.254246.79.255.255524,286
75246.80.0.0/13246.80.0.1 to 246.87.255.254246.87.255.255524,286
76246.88.0.0/13246.88.0.1 to 246.95.255.254246.95.255.255524,286
77246.96.0.0/13246.96.0.1 to 246.103.255.254246.103.255.255524,286
78246.104.0.0/13246.104.0.1 to 246.111.255.254246.111.255.255524,286
79246.112.0.0/13246.112.0.1 to 246.119.255.254246.119.255.255524,286
80246.120.0.0/13246.120.0.1 to 246.127.255.254246.127.255.255524,286
81246.128.0.0/13246.128.0.1 to 246.135.255.254246.135.255.255524,286
82246.136.0.0/13246.136.0.1 to 246.143.255.254246.143.255.255524,286
83246.144.0.0/13246.144.0.1 to 246.151.255.254246.151.255.255524,286
84246.152.0.0/13246.152.0.1 to 246.159.255.254246.159.255.255524,286
85246.160.0.0/13246.160.0.1 to 246.167.255.254246.167.255.255524,286
86246.168.0.0/13246.168.0.1 to 246.175.255.254246.175.255.255524,286
87246.176.0.0/13246.176.0.1 to 246.183.255.254246.183.255.255524,286
88246.184.0.0/13246.184.0.1 to 246.191.255.254246.191.255.255524,286
89246.192.0.0/13246.192.0.1 to 246.199.255.254246.199.255.255524,286
90246.200.0.0/13246.200.0.1 to 246.207.255.254246.207.255.255524,286
91246.208.0.0/13246.208.0.1 to 246.215.255.254246.215.255.255524,286
92246.216.0.0/13246.216.0.1 to 246.223.255.254246.223.255.255524,286
93246.224.0.0/13246.224.0.1 to 246.231.255.254246.231.255.255524,286
94246.232.0.0/13246.232.0.1 to 246.239.255.254246.239.255.255524,286
95246.240.0.0/13246.240.0.1 to 246.247.255.254246.247.255.255524,286
96246.248.0.0/13246.248.0.1 to 246.255.255.254246.255.255.255524,286
97247.0.0.0/13247.0.0.1 to 247.7.255.254247.7.255.255524,286
98247.8.0.0/13247.8.0.1 to 247.15.255.254247.15.255.255524,286
99247.16.0.0/13247.16.0.1 to 247.23.255.254247.23.255.255524,286
100247.24.0.0/13247.24.0.1 to 247.31.255.254247.31.255.255524,286
101247.32.0.0/13247.32.0.1 to 247.39.255.254247.39.255.255524,286
102247.40.0.0/13247.40.0.1 to 247.47.255.254247.47.255.255524,286
103247.48.0.0/13247.48.0.1 to 247.55.255.254247.55.255.255524,286
104247.56.0.0/13247.56.0.1 to 247.63.255.254247.63.255.255524,286
105247.64.0.0/13247.64.0.1 to 247.71.255.254247.71.255.255524,286
106247.72.0.0/13247.72.0.1 to 247.79.255.254247.79.255.255524,286
107247.80.0.0/13247.80.0.1 to 247.87.255.254247.87.255.255524,286
108247.88.0.0/13247.88.0.1 to 247.95.255.254247.95.255.255524,286
109247.96.0.0/13247.96.0.1 to 247.103.255.254247.103.255.255524,286
110247.104.0.0/13247.104.0.1 to 247.111.255.254247.111.255.255524,286
111247.112.0.0/13247.112.0.1 to 247.119.255.254247.119.255.255524,286
112247.120.0.0/13247.120.0.1 to 247.127.255.254247.127.255.255524,286
113247.128.0.0/13247.128.0.1 to 247.135.255.254247.135.255.255524,286
114247.136.0.0/13247.136.0.1 to 247.143.255.254247.143.255.255524,286
115247.144.0.0/13247.144.0.1 to 247.151.255.254247.151.255.255524,286
116247.152.0.0/13247.152.0.1 to 247.159.255.254247.159.255.255524,286
117247.160.0.0/13247.160.0.1 to 247.167.255.254247.167.255.255524,286
118247.168.0.0/13247.168.0.1 to 247.175.255.254247.175.255.255524,286
119247.176.0.0/13247.176.0.1 to 247.183.255.254247.183.255.255524,286
120247.184.0.0/13247.184.0.1 to 247.191.255.254247.191.255.255524,286
121247.192.0.0/13247.192.0.1 to 247.199.255.254247.199.255.255524,286
122247.200.0.0/13247.200.0.1 to 247.207.255.254247.207.255.255524,286
123247.208.0.0/13247.208.0.1 to 247.215.255.254247.215.255.255524,286
124247.216.0.0/13247.216.0.1 to 247.223.255.254247.223.255.255524,286
125247.224.0.0/13247.224.0.1 to 247.231.255.254247.231.255.255524,286
126247.232.0.0/13247.232.0.1 to 247.239.255.254247.239.255.255524,286
127247.240.0.0/13247.240.0.1 to 247.247.255.254247.247.255.255524,286
128247.248.0.0/13247.248.0.1 to 247.255.255.254247.255.255.255524,286

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.