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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.

Network191.232.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
191.232.0.0
Broadcast address
191.239.255.255
First usable
191.232.0.1
Last usable
191.239.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
B (default /16)
As numbers
Hex BFE80000 · Integer 3219652608 to 3220176895
Reverse DNS zones
232.191.in-addr.arpa
233.191.in-addr.arpa
234.191.in-addr.arpa
235.191.in-addr.arpa
236.191.in-addr.arpa
237.191.in-addr.arpa
238.191.in-addr.arpa
239.191.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111111.11101000.00000000.00000000191.232.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network10111111.11101000.00000000.00000000191.232.0.0
Broadcast10111111.11101111.11111111.11111111191.239.255.255
Split into smaller subnets/20
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

191.232.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1191.232.0.0/20191.232.0.1 to 191.232.15.254191.232.15.2554,094
2191.232.16.0/20191.232.16.1 to 191.232.31.254191.232.31.2554,094
3191.232.32.0/20191.232.32.1 to 191.232.47.254191.232.47.2554,094
4191.232.48.0/20191.232.48.1 to 191.232.63.254191.232.63.2554,094
5191.232.64.0/20191.232.64.1 to 191.232.79.254191.232.79.2554,094
6191.232.80.0/20191.232.80.1 to 191.232.95.254191.232.95.2554,094
7191.232.96.0/20191.232.96.1 to 191.232.111.254191.232.111.2554,094
8191.232.112.0/20191.232.112.1 to 191.232.127.254191.232.127.2554,094
9191.232.128.0/20191.232.128.1 to 191.232.143.254191.232.143.2554,094
10191.232.144.0/20191.232.144.1 to 191.232.159.254191.232.159.2554,094
11191.232.160.0/20191.232.160.1 to 191.232.175.254191.232.175.2554,094
12191.232.176.0/20191.232.176.1 to 191.232.191.254191.232.191.2554,094
13191.232.192.0/20191.232.192.1 to 191.232.207.254191.232.207.2554,094
14191.232.208.0/20191.232.208.1 to 191.232.223.254191.232.223.2554,094
15191.232.224.0/20191.232.224.1 to 191.232.239.254191.232.239.2554,094
16191.232.240.0/20191.232.240.1 to 191.232.255.254191.232.255.2554,094
17191.233.0.0/20191.233.0.1 to 191.233.15.254191.233.15.2554,094
18191.233.16.0/20191.233.16.1 to 191.233.31.254191.233.31.2554,094
19191.233.32.0/20191.233.32.1 to 191.233.47.254191.233.47.2554,094
20191.233.48.0/20191.233.48.1 to 191.233.63.254191.233.63.2554,094
21191.233.64.0/20191.233.64.1 to 191.233.79.254191.233.79.2554,094
22191.233.80.0/20191.233.80.1 to 191.233.95.254191.233.95.2554,094
23191.233.96.0/20191.233.96.1 to 191.233.111.254191.233.111.2554,094
24191.233.112.0/20191.233.112.1 to 191.233.127.254191.233.127.2554,094
25191.233.128.0/20191.233.128.1 to 191.233.143.254191.233.143.2554,094
26191.233.144.0/20191.233.144.1 to 191.233.159.254191.233.159.2554,094
27191.233.160.0/20191.233.160.1 to 191.233.175.254191.233.175.2554,094
28191.233.176.0/20191.233.176.1 to 191.233.191.254191.233.191.2554,094
29191.233.192.0/20191.233.192.1 to 191.233.207.254191.233.207.2554,094
30191.233.208.0/20191.233.208.1 to 191.233.223.254191.233.223.2554,094
31191.233.224.0/20191.233.224.1 to 191.233.239.254191.233.239.2554,094
32191.233.240.0/20191.233.240.1 to 191.233.255.254191.233.255.2554,094
33191.234.0.0/20191.234.0.1 to 191.234.15.254191.234.15.2554,094
34191.234.16.0/20191.234.16.1 to 191.234.31.254191.234.31.2554,094
35191.234.32.0/20191.234.32.1 to 191.234.47.254191.234.47.2554,094
36191.234.48.0/20191.234.48.1 to 191.234.63.254191.234.63.2554,094
37191.234.64.0/20191.234.64.1 to 191.234.79.254191.234.79.2554,094
38191.234.80.0/20191.234.80.1 to 191.234.95.254191.234.95.2554,094
39191.234.96.0/20191.234.96.1 to 191.234.111.254191.234.111.2554,094
40191.234.112.0/20191.234.112.1 to 191.234.127.254191.234.127.2554,094
41191.234.128.0/20191.234.128.1 to 191.234.143.254191.234.143.2554,094
42191.234.144.0/20191.234.144.1 to 191.234.159.254191.234.159.2554,094
43191.234.160.0/20191.234.160.1 to 191.234.175.254191.234.175.2554,094
44191.234.176.0/20191.234.176.1 to 191.234.191.254191.234.191.2554,094
45191.234.192.0/20191.234.192.1 to 191.234.207.254191.234.207.2554,094
46191.234.208.0/20191.234.208.1 to 191.234.223.254191.234.223.2554,094
47191.234.224.0/20191.234.224.1 to 191.234.239.254191.234.239.2554,094
48191.234.240.0/20191.234.240.1 to 191.234.255.254191.234.255.2554,094
49191.235.0.0/20191.235.0.1 to 191.235.15.254191.235.15.2554,094
50191.235.16.0/20191.235.16.1 to 191.235.31.254191.235.31.2554,094
51191.235.32.0/20191.235.32.1 to 191.235.47.254191.235.47.2554,094
52191.235.48.0/20191.235.48.1 to 191.235.63.254191.235.63.2554,094
53191.235.64.0/20191.235.64.1 to 191.235.79.254191.235.79.2554,094
54191.235.80.0/20191.235.80.1 to 191.235.95.254191.235.95.2554,094
55191.235.96.0/20191.235.96.1 to 191.235.111.254191.235.111.2554,094
56191.235.112.0/20191.235.112.1 to 191.235.127.254191.235.127.2554,094
57191.235.128.0/20191.235.128.1 to 191.235.143.254191.235.143.2554,094
58191.235.144.0/20191.235.144.1 to 191.235.159.254191.235.159.2554,094
59191.235.160.0/20191.235.160.1 to 191.235.175.254191.235.175.2554,094
60191.235.176.0/20191.235.176.1 to 191.235.191.254191.235.191.2554,094
61191.235.192.0/20191.235.192.1 to 191.235.207.254191.235.207.2554,094
62191.235.208.0/20191.235.208.1 to 191.235.223.254191.235.223.2554,094
63191.235.224.0/20191.235.224.1 to 191.235.239.254191.235.239.2554,094
64191.235.240.0/20191.235.240.1 to 191.235.255.254191.235.255.2554,094
65191.236.0.0/20191.236.0.1 to 191.236.15.254191.236.15.2554,094
66191.236.16.0/20191.236.16.1 to 191.236.31.254191.236.31.2554,094
67191.236.32.0/20191.236.32.1 to 191.236.47.254191.236.47.2554,094
68191.236.48.0/20191.236.48.1 to 191.236.63.254191.236.63.2554,094
69191.236.64.0/20191.236.64.1 to 191.236.79.254191.236.79.2554,094
70191.236.80.0/20191.236.80.1 to 191.236.95.254191.236.95.2554,094
71191.236.96.0/20191.236.96.1 to 191.236.111.254191.236.111.2554,094
72191.236.112.0/20191.236.112.1 to 191.236.127.254191.236.127.2554,094
73191.236.128.0/20191.236.128.1 to 191.236.143.254191.236.143.2554,094
74191.236.144.0/20191.236.144.1 to 191.236.159.254191.236.159.2554,094
75191.236.160.0/20191.236.160.1 to 191.236.175.254191.236.175.2554,094
76191.236.176.0/20191.236.176.1 to 191.236.191.254191.236.191.2554,094
77191.236.192.0/20191.236.192.1 to 191.236.207.254191.236.207.2554,094
78191.236.208.0/20191.236.208.1 to 191.236.223.254191.236.223.2554,094
79191.236.224.0/20191.236.224.1 to 191.236.239.254191.236.239.2554,094
80191.236.240.0/20191.236.240.1 to 191.236.255.254191.236.255.2554,094
81191.237.0.0/20191.237.0.1 to 191.237.15.254191.237.15.2554,094
82191.237.16.0/20191.237.16.1 to 191.237.31.254191.237.31.2554,094
83191.237.32.0/20191.237.32.1 to 191.237.47.254191.237.47.2554,094
84191.237.48.0/20191.237.48.1 to 191.237.63.254191.237.63.2554,094
85191.237.64.0/20191.237.64.1 to 191.237.79.254191.237.79.2554,094
86191.237.80.0/20191.237.80.1 to 191.237.95.254191.237.95.2554,094
87191.237.96.0/20191.237.96.1 to 191.237.111.254191.237.111.2554,094
88191.237.112.0/20191.237.112.1 to 191.237.127.254191.237.127.2554,094
89191.237.128.0/20191.237.128.1 to 191.237.143.254191.237.143.2554,094
90191.237.144.0/20191.237.144.1 to 191.237.159.254191.237.159.2554,094
91191.237.160.0/20191.237.160.1 to 191.237.175.254191.237.175.2554,094
92191.237.176.0/20191.237.176.1 to 191.237.191.254191.237.191.2554,094
93191.237.192.0/20191.237.192.1 to 191.237.207.254191.237.207.2554,094
94191.237.208.0/20191.237.208.1 to 191.237.223.254191.237.223.2554,094
95191.237.224.0/20191.237.224.1 to 191.237.239.254191.237.239.2554,094
96191.237.240.0/20191.237.240.1 to 191.237.255.254191.237.255.2554,094
97191.238.0.0/20191.238.0.1 to 191.238.15.254191.238.15.2554,094
98191.238.16.0/20191.238.16.1 to 191.238.31.254191.238.31.2554,094
99191.238.32.0/20191.238.32.1 to 191.238.47.254191.238.47.2554,094
100191.238.48.0/20191.238.48.1 to 191.238.63.254191.238.63.2554,094
101191.238.64.0/20191.238.64.1 to 191.238.79.254191.238.79.2554,094
102191.238.80.0/20191.238.80.1 to 191.238.95.254191.238.95.2554,094
103191.238.96.0/20191.238.96.1 to 191.238.111.254191.238.111.2554,094
104191.238.112.0/20191.238.112.1 to 191.238.127.254191.238.127.2554,094
105191.238.128.0/20191.238.128.1 to 191.238.143.254191.238.143.2554,094
106191.238.144.0/20191.238.144.1 to 191.238.159.254191.238.159.2554,094
107191.238.160.0/20191.238.160.1 to 191.238.175.254191.238.175.2554,094
108191.238.176.0/20191.238.176.1 to 191.238.191.254191.238.191.2554,094
109191.238.192.0/20191.238.192.1 to 191.238.207.254191.238.207.2554,094
110191.238.208.0/20191.238.208.1 to 191.238.223.254191.238.223.2554,094
111191.238.224.0/20191.238.224.1 to 191.238.239.254191.238.239.2554,094
112191.238.240.0/20191.238.240.1 to 191.238.255.254191.238.255.2554,094
113191.239.0.0/20191.239.0.1 to 191.239.15.254191.239.15.2554,094
114191.239.16.0/20191.239.16.1 to 191.239.31.254191.239.31.2554,094
115191.239.32.0/20191.239.32.1 to 191.239.47.254191.239.47.2554,094
116191.239.48.0/20191.239.48.1 to 191.239.63.254191.239.63.2554,094
117191.239.64.0/20191.239.64.1 to 191.239.79.254191.239.79.2554,094
118191.239.80.0/20191.239.80.1 to 191.239.95.254191.239.95.2554,094
119191.239.96.0/20191.239.96.1 to 191.239.111.254191.239.111.2554,094
120191.239.112.0/20191.239.112.1 to 191.239.127.254191.239.127.2554,094
121191.239.128.0/20191.239.128.1 to 191.239.143.254191.239.143.2554,094
122191.239.144.0/20191.239.144.1 to 191.239.159.254191.239.159.2554,094
123191.239.160.0/20191.239.160.1 to 191.239.175.254191.239.175.2554,094
124191.239.176.0/20191.239.176.1 to 191.239.191.254191.239.191.2554,094
125191.239.192.0/20191.239.192.1 to 191.239.207.254191.239.207.2554,094
126191.239.208.0/20191.239.208.1 to 191.239.223.254191.239.223.2554,094
127191.239.224.0/20191.239.224.1 to 191.239.239.254191.239.239.2554,094
128191.239.240.0/20191.239.240.1 to 191.239.255.254191.239.255.2554,094

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.