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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.

Network184.0.0.0/5
Usable hosts134,217,726
Subnet mask248.0.0.0
Addresses134,217,728
Network address
184.0.0.0
Broadcast address
191.255.255.255
First usable
184.0.0.1
Last usable
191.255.255.254
Usable hosts
134,217,726 (134,217,728 less the network and broadcast addresses)
Subnet mask
248.0.0.0
Wildcard mask
7.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/5
Type
Public public
Old class
B (default /16)
As numbers
Hex B8000000 · Integer 3087007744 to 3221225471
Reverse DNS zones
184.in-addr.arpa
185.in-addr.arpa
186.in-addr.arpa
187.in-addr.arpa
188.in-addr.arpa
189.in-addr.arpa
190.in-addr.arpa
191.in-addr.arpa
/5 is not on a 8-bit boundary, so it takes 8 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111000.00000000.00000000.00000000184.0.0.0
Subnet mask11111000.00000000.00000000.00000000248.0.0.0
Network10111000.00000000.00000000.00000000184.0.0.0
Broadcast10111111.11111111.11111111.11111111191.255.255.255
Split into smaller subnets/12
/6 (2)/7 (4)/8 (8)/9 (16)/10 (32)/11 (64)/12 (128)/13 (256)/14 (512)/15 (1,024)/16 (2,048)/17 (4,096)

184.0.0.0/5 makes 128 subnets of /12.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1184.0.0.0/12184.0.0.1 to 184.15.255.254184.15.255.2551,048,574
2184.16.0.0/12184.16.0.1 to 184.31.255.254184.31.255.2551,048,574
3184.32.0.0/12184.32.0.1 to 184.47.255.254184.47.255.2551,048,574
4184.48.0.0/12184.48.0.1 to 184.63.255.254184.63.255.2551,048,574
5184.64.0.0/12184.64.0.1 to 184.79.255.254184.79.255.2551,048,574
6184.80.0.0/12184.80.0.1 to 184.95.255.254184.95.255.2551,048,574
7184.96.0.0/12184.96.0.1 to 184.111.255.254184.111.255.2551,048,574
8184.112.0.0/12184.112.0.1 to 184.127.255.254184.127.255.2551,048,574
9184.128.0.0/12184.128.0.1 to 184.143.255.254184.143.255.2551,048,574
10184.144.0.0/12184.144.0.1 to 184.159.255.254184.159.255.2551,048,574
11184.160.0.0/12184.160.0.1 to 184.175.255.254184.175.255.2551,048,574
12184.176.0.0/12184.176.0.1 to 184.191.255.254184.191.255.2551,048,574
13184.192.0.0/12184.192.0.1 to 184.207.255.254184.207.255.2551,048,574
14184.208.0.0/12184.208.0.1 to 184.223.255.254184.223.255.2551,048,574
15184.224.0.0/12184.224.0.1 to 184.239.255.254184.239.255.2551,048,574
16184.240.0.0/12184.240.0.1 to 184.255.255.254184.255.255.2551,048,574
17185.0.0.0/12185.0.0.1 to 185.15.255.254185.15.255.2551,048,574
18185.16.0.0/12185.16.0.1 to 185.31.255.254185.31.255.2551,048,574
19185.32.0.0/12185.32.0.1 to 185.47.255.254185.47.255.2551,048,574
20185.48.0.0/12185.48.0.1 to 185.63.255.254185.63.255.2551,048,574
21185.64.0.0/12185.64.0.1 to 185.79.255.254185.79.255.2551,048,574
22185.80.0.0/12185.80.0.1 to 185.95.255.254185.95.255.2551,048,574
23185.96.0.0/12185.96.0.1 to 185.111.255.254185.111.255.2551,048,574
24185.112.0.0/12185.112.0.1 to 185.127.255.254185.127.255.2551,048,574
25185.128.0.0/12185.128.0.1 to 185.143.255.254185.143.255.2551,048,574
26185.144.0.0/12185.144.0.1 to 185.159.255.254185.159.255.2551,048,574
27185.160.0.0/12185.160.0.1 to 185.175.255.254185.175.255.2551,048,574
28185.176.0.0/12185.176.0.1 to 185.191.255.254185.191.255.2551,048,574
29185.192.0.0/12185.192.0.1 to 185.207.255.254185.207.255.2551,048,574
30185.208.0.0/12185.208.0.1 to 185.223.255.254185.223.255.2551,048,574
31185.224.0.0/12185.224.0.1 to 185.239.255.254185.239.255.2551,048,574
32185.240.0.0/12185.240.0.1 to 185.255.255.254185.255.255.2551,048,574
33186.0.0.0/12186.0.0.1 to 186.15.255.254186.15.255.2551,048,574
34186.16.0.0/12186.16.0.1 to 186.31.255.254186.31.255.2551,048,574
35186.32.0.0/12186.32.0.1 to 186.47.255.254186.47.255.2551,048,574
36186.48.0.0/12186.48.0.1 to 186.63.255.254186.63.255.2551,048,574
37186.64.0.0/12186.64.0.1 to 186.79.255.254186.79.255.2551,048,574
38186.80.0.0/12186.80.0.1 to 186.95.255.254186.95.255.2551,048,574
39186.96.0.0/12186.96.0.1 to 186.111.255.254186.111.255.2551,048,574
40186.112.0.0/12186.112.0.1 to 186.127.255.254186.127.255.2551,048,574
41186.128.0.0/12186.128.0.1 to 186.143.255.254186.143.255.2551,048,574
42186.144.0.0/12186.144.0.1 to 186.159.255.254186.159.255.2551,048,574
43186.160.0.0/12186.160.0.1 to 186.175.255.254186.175.255.2551,048,574
44186.176.0.0/12186.176.0.1 to 186.191.255.254186.191.255.2551,048,574
45186.192.0.0/12186.192.0.1 to 186.207.255.254186.207.255.2551,048,574
46186.208.0.0/12186.208.0.1 to 186.223.255.254186.223.255.2551,048,574
47186.224.0.0/12186.224.0.1 to 186.239.255.254186.239.255.2551,048,574
48186.240.0.0/12186.240.0.1 to 186.255.255.254186.255.255.2551,048,574
49187.0.0.0/12187.0.0.1 to 187.15.255.254187.15.255.2551,048,574
50187.16.0.0/12187.16.0.1 to 187.31.255.254187.31.255.2551,048,574
51187.32.0.0/12187.32.0.1 to 187.47.255.254187.47.255.2551,048,574
52187.48.0.0/12187.48.0.1 to 187.63.255.254187.63.255.2551,048,574
53187.64.0.0/12187.64.0.1 to 187.79.255.254187.79.255.2551,048,574
54187.80.0.0/12187.80.0.1 to 187.95.255.254187.95.255.2551,048,574
55187.96.0.0/12187.96.0.1 to 187.111.255.254187.111.255.2551,048,574
56187.112.0.0/12187.112.0.1 to 187.127.255.254187.127.255.2551,048,574
57187.128.0.0/12187.128.0.1 to 187.143.255.254187.143.255.2551,048,574
58187.144.0.0/12187.144.0.1 to 187.159.255.254187.159.255.2551,048,574
59187.160.0.0/12187.160.0.1 to 187.175.255.254187.175.255.2551,048,574
60187.176.0.0/12187.176.0.1 to 187.191.255.254187.191.255.2551,048,574
61187.192.0.0/12187.192.0.1 to 187.207.255.254187.207.255.2551,048,574
62187.208.0.0/12187.208.0.1 to 187.223.255.254187.223.255.2551,048,574
63187.224.0.0/12187.224.0.1 to 187.239.255.254187.239.255.2551,048,574
64187.240.0.0/12187.240.0.1 to 187.255.255.254187.255.255.2551,048,574
65188.0.0.0/12188.0.0.1 to 188.15.255.254188.15.255.2551,048,574
66188.16.0.0/12188.16.0.1 to 188.31.255.254188.31.255.2551,048,574
67188.32.0.0/12188.32.0.1 to 188.47.255.254188.47.255.2551,048,574
68188.48.0.0/12188.48.0.1 to 188.63.255.254188.63.255.2551,048,574
69188.64.0.0/12188.64.0.1 to 188.79.255.254188.79.255.2551,048,574
70188.80.0.0/12188.80.0.1 to 188.95.255.254188.95.255.2551,048,574
71188.96.0.0/12188.96.0.1 to 188.111.255.254188.111.255.2551,048,574
72188.112.0.0/12188.112.0.1 to 188.127.255.254188.127.255.2551,048,574
73188.128.0.0/12188.128.0.1 to 188.143.255.254188.143.255.2551,048,574
74188.144.0.0/12188.144.0.1 to 188.159.255.254188.159.255.2551,048,574
75188.160.0.0/12188.160.0.1 to 188.175.255.254188.175.255.2551,048,574
76188.176.0.0/12188.176.0.1 to 188.191.255.254188.191.255.2551,048,574
77188.192.0.0/12188.192.0.1 to 188.207.255.254188.207.255.2551,048,574
78188.208.0.0/12188.208.0.1 to 188.223.255.254188.223.255.2551,048,574
79188.224.0.0/12188.224.0.1 to 188.239.255.254188.239.255.2551,048,574
80188.240.0.0/12188.240.0.1 to 188.255.255.254188.255.255.2551,048,574
81189.0.0.0/12189.0.0.1 to 189.15.255.254189.15.255.2551,048,574
82189.16.0.0/12189.16.0.1 to 189.31.255.254189.31.255.2551,048,574
83189.32.0.0/12189.32.0.1 to 189.47.255.254189.47.255.2551,048,574
84189.48.0.0/12189.48.0.1 to 189.63.255.254189.63.255.2551,048,574
85189.64.0.0/12189.64.0.1 to 189.79.255.254189.79.255.2551,048,574
86189.80.0.0/12189.80.0.1 to 189.95.255.254189.95.255.2551,048,574
87189.96.0.0/12189.96.0.1 to 189.111.255.254189.111.255.2551,048,574
88189.112.0.0/12189.112.0.1 to 189.127.255.254189.127.255.2551,048,574
89189.128.0.0/12189.128.0.1 to 189.143.255.254189.143.255.2551,048,574
90189.144.0.0/12189.144.0.1 to 189.159.255.254189.159.255.2551,048,574
91189.160.0.0/12189.160.0.1 to 189.175.255.254189.175.255.2551,048,574
92189.176.0.0/12189.176.0.1 to 189.191.255.254189.191.255.2551,048,574
93189.192.0.0/12189.192.0.1 to 189.207.255.254189.207.255.2551,048,574
94189.208.0.0/12189.208.0.1 to 189.223.255.254189.223.255.2551,048,574
95189.224.0.0/12189.224.0.1 to 189.239.255.254189.239.255.2551,048,574
96189.240.0.0/12189.240.0.1 to 189.255.255.254189.255.255.2551,048,574
97190.0.0.0/12190.0.0.1 to 190.15.255.254190.15.255.2551,048,574
98190.16.0.0/12190.16.0.1 to 190.31.255.254190.31.255.2551,048,574
99190.32.0.0/12190.32.0.1 to 190.47.255.254190.47.255.2551,048,574
100190.48.0.0/12190.48.0.1 to 190.63.255.254190.63.255.2551,048,574
101190.64.0.0/12190.64.0.1 to 190.79.255.254190.79.255.2551,048,574
102190.80.0.0/12190.80.0.1 to 190.95.255.254190.95.255.2551,048,574
103190.96.0.0/12190.96.0.1 to 190.111.255.254190.111.255.2551,048,574
104190.112.0.0/12190.112.0.1 to 190.127.255.254190.127.255.2551,048,574
105190.128.0.0/12190.128.0.1 to 190.143.255.254190.143.255.2551,048,574
106190.144.0.0/12190.144.0.1 to 190.159.255.254190.159.255.2551,048,574
107190.160.0.0/12190.160.0.1 to 190.175.255.254190.175.255.2551,048,574
108190.176.0.0/12190.176.0.1 to 190.191.255.254190.191.255.2551,048,574
109190.192.0.0/12190.192.0.1 to 190.207.255.254190.207.255.2551,048,574
110190.208.0.0/12190.208.0.1 to 190.223.255.254190.223.255.2551,048,574
111190.224.0.0/12190.224.0.1 to 190.239.255.254190.239.255.2551,048,574
112190.240.0.0/12190.240.0.1 to 190.255.255.254190.255.255.2551,048,574
113191.0.0.0/12191.0.0.1 to 191.15.255.254191.15.255.2551,048,574
114191.16.0.0/12191.16.0.1 to 191.31.255.254191.31.255.2551,048,574
115191.32.0.0/12191.32.0.1 to 191.47.255.254191.47.255.2551,048,574
116191.48.0.0/12191.48.0.1 to 191.63.255.254191.63.255.2551,048,574
117191.64.0.0/12191.64.0.1 to 191.79.255.254191.79.255.2551,048,574
118191.80.0.0/12191.80.0.1 to 191.95.255.254191.95.255.2551,048,574
119191.96.0.0/12191.96.0.1 to 191.111.255.254191.111.255.2551,048,574
120191.112.0.0/12191.112.0.1 to 191.127.255.254191.127.255.2551,048,574
121191.128.0.0/12191.128.0.1 to 191.143.255.254191.143.255.2551,048,574
122191.144.0.0/12191.144.0.1 to 191.159.255.254191.159.255.2551,048,574
123191.160.0.0/12191.160.0.1 to 191.175.255.254191.175.255.2551,048,574
124191.176.0.0/12191.176.0.1 to 191.191.255.254191.191.255.2551,048,574
125191.192.0.0/12191.192.0.1 to 191.207.255.254191.207.255.2551,048,574
126191.208.0.0/12191.208.0.1 to 191.223.255.254191.223.255.2551,048,574
127191.224.0.0/12191.224.0.1 to 191.239.255.254191.239.255.2551,048,574
128191.240.0.0/12191.240.0.1 to 191.255.255.254191.255.255.2551,048,574

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.