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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.

Network232.0.0.0/5
Usable hosts134,217,726
Subnet mask248.0.0.0
Addresses134,217,728
Network address
232.0.0.0
Broadcast address
239.255.255.255
First usable
232.0.0.1
Last usable
239.255.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E8000000 · Integer 3892314112 to 4026531839
Reverse DNS zones
232.in-addr.arpa
233.in-addr.arpa
234.in-addr.arpa
235.in-addr.arpa
236.in-addr.arpa
237.in-addr.arpa
238.in-addr.arpa
239.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
Address11101000.00000000.00000000.00000000232.0.0.0
Subnet mask11111000.00000000.00000000.00000000248.0.0.0
Network11101000.00000000.00000000.00000000232.0.0.0
Broadcast11101111.11111111.11111111.11111111239.255.255.255
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)

232.0.0.0/5 makes 128 subnets of /12.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1232.0.0.0/12232.0.0.1 to 232.15.255.254232.15.255.2551,048,574
2232.16.0.0/12232.16.0.1 to 232.31.255.254232.31.255.2551,048,574
3232.32.0.0/12232.32.0.1 to 232.47.255.254232.47.255.2551,048,574
4232.48.0.0/12232.48.0.1 to 232.63.255.254232.63.255.2551,048,574
5232.64.0.0/12232.64.0.1 to 232.79.255.254232.79.255.2551,048,574
6232.80.0.0/12232.80.0.1 to 232.95.255.254232.95.255.2551,048,574
7232.96.0.0/12232.96.0.1 to 232.111.255.254232.111.255.2551,048,574
8232.112.0.0/12232.112.0.1 to 232.127.255.254232.127.255.2551,048,574
9232.128.0.0/12232.128.0.1 to 232.143.255.254232.143.255.2551,048,574
10232.144.0.0/12232.144.0.1 to 232.159.255.254232.159.255.2551,048,574
11232.160.0.0/12232.160.0.1 to 232.175.255.254232.175.255.2551,048,574
12232.176.0.0/12232.176.0.1 to 232.191.255.254232.191.255.2551,048,574
13232.192.0.0/12232.192.0.1 to 232.207.255.254232.207.255.2551,048,574
14232.208.0.0/12232.208.0.1 to 232.223.255.254232.223.255.2551,048,574
15232.224.0.0/12232.224.0.1 to 232.239.255.254232.239.255.2551,048,574
16232.240.0.0/12232.240.0.1 to 232.255.255.254232.255.255.2551,048,574
17233.0.0.0/12233.0.0.1 to 233.15.255.254233.15.255.2551,048,574
18233.16.0.0/12233.16.0.1 to 233.31.255.254233.31.255.2551,048,574
19233.32.0.0/12233.32.0.1 to 233.47.255.254233.47.255.2551,048,574
20233.48.0.0/12233.48.0.1 to 233.63.255.254233.63.255.2551,048,574
21233.64.0.0/12233.64.0.1 to 233.79.255.254233.79.255.2551,048,574
22233.80.0.0/12233.80.0.1 to 233.95.255.254233.95.255.2551,048,574
23233.96.0.0/12233.96.0.1 to 233.111.255.254233.111.255.2551,048,574
24233.112.0.0/12233.112.0.1 to 233.127.255.254233.127.255.2551,048,574
25233.128.0.0/12233.128.0.1 to 233.143.255.254233.143.255.2551,048,574
26233.144.0.0/12233.144.0.1 to 233.159.255.254233.159.255.2551,048,574
27233.160.0.0/12233.160.0.1 to 233.175.255.254233.175.255.2551,048,574
28233.176.0.0/12233.176.0.1 to 233.191.255.254233.191.255.2551,048,574
29233.192.0.0/12233.192.0.1 to 233.207.255.254233.207.255.2551,048,574
30233.208.0.0/12233.208.0.1 to 233.223.255.254233.223.255.2551,048,574
31233.224.0.0/12233.224.0.1 to 233.239.255.254233.239.255.2551,048,574
32233.240.0.0/12233.240.0.1 to 233.255.255.254233.255.255.2551,048,574
33234.0.0.0/12234.0.0.1 to 234.15.255.254234.15.255.2551,048,574
34234.16.0.0/12234.16.0.1 to 234.31.255.254234.31.255.2551,048,574
35234.32.0.0/12234.32.0.1 to 234.47.255.254234.47.255.2551,048,574
36234.48.0.0/12234.48.0.1 to 234.63.255.254234.63.255.2551,048,574
37234.64.0.0/12234.64.0.1 to 234.79.255.254234.79.255.2551,048,574
38234.80.0.0/12234.80.0.1 to 234.95.255.254234.95.255.2551,048,574
39234.96.0.0/12234.96.0.1 to 234.111.255.254234.111.255.2551,048,574
40234.112.0.0/12234.112.0.1 to 234.127.255.254234.127.255.2551,048,574
41234.128.0.0/12234.128.0.1 to 234.143.255.254234.143.255.2551,048,574
42234.144.0.0/12234.144.0.1 to 234.159.255.254234.159.255.2551,048,574
43234.160.0.0/12234.160.0.1 to 234.175.255.254234.175.255.2551,048,574
44234.176.0.0/12234.176.0.1 to 234.191.255.254234.191.255.2551,048,574
45234.192.0.0/12234.192.0.1 to 234.207.255.254234.207.255.2551,048,574
46234.208.0.0/12234.208.0.1 to 234.223.255.254234.223.255.2551,048,574
47234.224.0.0/12234.224.0.1 to 234.239.255.254234.239.255.2551,048,574
48234.240.0.0/12234.240.0.1 to 234.255.255.254234.255.255.2551,048,574
49235.0.0.0/12235.0.0.1 to 235.15.255.254235.15.255.2551,048,574
50235.16.0.0/12235.16.0.1 to 235.31.255.254235.31.255.2551,048,574
51235.32.0.0/12235.32.0.1 to 235.47.255.254235.47.255.2551,048,574
52235.48.0.0/12235.48.0.1 to 235.63.255.254235.63.255.2551,048,574
53235.64.0.0/12235.64.0.1 to 235.79.255.254235.79.255.2551,048,574
54235.80.0.0/12235.80.0.1 to 235.95.255.254235.95.255.2551,048,574
55235.96.0.0/12235.96.0.1 to 235.111.255.254235.111.255.2551,048,574
56235.112.0.0/12235.112.0.1 to 235.127.255.254235.127.255.2551,048,574
57235.128.0.0/12235.128.0.1 to 235.143.255.254235.143.255.2551,048,574
58235.144.0.0/12235.144.0.1 to 235.159.255.254235.159.255.2551,048,574
59235.160.0.0/12235.160.0.1 to 235.175.255.254235.175.255.2551,048,574
60235.176.0.0/12235.176.0.1 to 235.191.255.254235.191.255.2551,048,574
61235.192.0.0/12235.192.0.1 to 235.207.255.254235.207.255.2551,048,574
62235.208.0.0/12235.208.0.1 to 235.223.255.254235.223.255.2551,048,574
63235.224.0.0/12235.224.0.1 to 235.239.255.254235.239.255.2551,048,574
64235.240.0.0/12235.240.0.1 to 235.255.255.254235.255.255.2551,048,574
65236.0.0.0/12236.0.0.1 to 236.15.255.254236.15.255.2551,048,574
66236.16.0.0/12236.16.0.1 to 236.31.255.254236.31.255.2551,048,574
67236.32.0.0/12236.32.0.1 to 236.47.255.254236.47.255.2551,048,574
68236.48.0.0/12236.48.0.1 to 236.63.255.254236.63.255.2551,048,574
69236.64.0.0/12236.64.0.1 to 236.79.255.254236.79.255.2551,048,574
70236.80.0.0/12236.80.0.1 to 236.95.255.254236.95.255.2551,048,574
71236.96.0.0/12236.96.0.1 to 236.111.255.254236.111.255.2551,048,574
72236.112.0.0/12236.112.0.1 to 236.127.255.254236.127.255.2551,048,574
73236.128.0.0/12236.128.0.1 to 236.143.255.254236.143.255.2551,048,574
74236.144.0.0/12236.144.0.1 to 236.159.255.254236.159.255.2551,048,574
75236.160.0.0/12236.160.0.1 to 236.175.255.254236.175.255.2551,048,574
76236.176.0.0/12236.176.0.1 to 236.191.255.254236.191.255.2551,048,574
77236.192.0.0/12236.192.0.1 to 236.207.255.254236.207.255.2551,048,574
78236.208.0.0/12236.208.0.1 to 236.223.255.254236.223.255.2551,048,574
79236.224.0.0/12236.224.0.1 to 236.239.255.254236.239.255.2551,048,574
80236.240.0.0/12236.240.0.1 to 236.255.255.254236.255.255.2551,048,574
81237.0.0.0/12237.0.0.1 to 237.15.255.254237.15.255.2551,048,574
82237.16.0.0/12237.16.0.1 to 237.31.255.254237.31.255.2551,048,574
83237.32.0.0/12237.32.0.1 to 237.47.255.254237.47.255.2551,048,574
84237.48.0.0/12237.48.0.1 to 237.63.255.254237.63.255.2551,048,574
85237.64.0.0/12237.64.0.1 to 237.79.255.254237.79.255.2551,048,574
86237.80.0.0/12237.80.0.1 to 237.95.255.254237.95.255.2551,048,574
87237.96.0.0/12237.96.0.1 to 237.111.255.254237.111.255.2551,048,574
88237.112.0.0/12237.112.0.1 to 237.127.255.254237.127.255.2551,048,574
89237.128.0.0/12237.128.0.1 to 237.143.255.254237.143.255.2551,048,574
90237.144.0.0/12237.144.0.1 to 237.159.255.254237.159.255.2551,048,574
91237.160.0.0/12237.160.0.1 to 237.175.255.254237.175.255.2551,048,574
92237.176.0.0/12237.176.0.1 to 237.191.255.254237.191.255.2551,048,574
93237.192.0.0/12237.192.0.1 to 237.207.255.254237.207.255.2551,048,574
94237.208.0.0/12237.208.0.1 to 237.223.255.254237.223.255.2551,048,574
95237.224.0.0/12237.224.0.1 to 237.239.255.254237.239.255.2551,048,574
96237.240.0.0/12237.240.0.1 to 237.255.255.254237.255.255.2551,048,574
97238.0.0.0/12238.0.0.1 to 238.15.255.254238.15.255.2551,048,574
98238.16.0.0/12238.16.0.1 to 238.31.255.254238.31.255.2551,048,574
99238.32.0.0/12238.32.0.1 to 238.47.255.254238.47.255.2551,048,574
100238.48.0.0/12238.48.0.1 to 238.63.255.254238.63.255.2551,048,574
101238.64.0.0/12238.64.0.1 to 238.79.255.254238.79.255.2551,048,574
102238.80.0.0/12238.80.0.1 to 238.95.255.254238.95.255.2551,048,574
103238.96.0.0/12238.96.0.1 to 238.111.255.254238.111.255.2551,048,574
104238.112.0.0/12238.112.0.1 to 238.127.255.254238.127.255.2551,048,574
105238.128.0.0/12238.128.0.1 to 238.143.255.254238.143.255.2551,048,574
106238.144.0.0/12238.144.0.1 to 238.159.255.254238.159.255.2551,048,574
107238.160.0.0/12238.160.0.1 to 238.175.255.254238.175.255.2551,048,574
108238.176.0.0/12238.176.0.1 to 238.191.255.254238.191.255.2551,048,574
109238.192.0.0/12238.192.0.1 to 238.207.255.254238.207.255.2551,048,574
110238.208.0.0/12238.208.0.1 to 238.223.255.254238.223.255.2551,048,574
111238.224.0.0/12238.224.0.1 to 238.239.255.254238.239.255.2551,048,574
112238.240.0.0/12238.240.0.1 to 238.255.255.254238.255.255.2551,048,574
113239.0.0.0/12239.0.0.1 to 239.15.255.254239.15.255.2551,048,574
114239.16.0.0/12239.16.0.1 to 239.31.255.254239.31.255.2551,048,574
115239.32.0.0/12239.32.0.1 to 239.47.255.254239.47.255.2551,048,574
116239.48.0.0/12239.48.0.1 to 239.63.255.254239.63.255.2551,048,574
117239.64.0.0/12239.64.0.1 to 239.79.255.254239.79.255.2551,048,574
118239.80.0.0/12239.80.0.1 to 239.95.255.254239.95.255.2551,048,574
119239.96.0.0/12239.96.0.1 to 239.111.255.254239.111.255.2551,048,574
120239.112.0.0/12239.112.0.1 to 239.127.255.254239.127.255.2551,048,574
121239.128.0.0/12239.128.0.1 to 239.143.255.254239.143.255.2551,048,574
122239.144.0.0/12239.144.0.1 to 239.159.255.254239.159.255.2551,048,574
123239.160.0.0/12239.160.0.1 to 239.175.255.254239.175.255.2551,048,574
124239.176.0.0/12239.176.0.1 to 239.191.255.254239.191.255.2551,048,574
125239.192.0.0/12239.192.0.1 to 239.207.255.254239.207.255.2551,048,574
126239.208.0.0/12239.208.0.1 to 239.223.255.254239.223.255.2551,048,574
127239.224.0.0/12239.224.0.1 to 239.239.255.254239.239.255.2551,048,574
128239.240.0.0/12239.240.0.1 to 239.255.255.254239.255.255.2551,048,574

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.