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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.

Network233.48.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
233.48.0.0
Broadcast address
233.63.255.255
First usable
233.48.0.1
Last usable
233.63.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E9300000 · Integer 3912237056 to 3913285631
Reverse DNS zones
48.233.in-addr.arpa
49.233.in-addr.arpa
50.233.in-addr.arpa
51.233.in-addr.arpa
52.233.in-addr.arpa
53.233.in-addr.arpa
54.233.in-addr.arpa
55.233.in-addr.arpa
56.233.in-addr.arpa
57.233.in-addr.arpa
58.233.in-addr.arpa
59.233.in-addr.arpa
60.233.in-addr.arpa
61.233.in-addr.arpa
62.233.in-addr.arpa
63.233.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11101001.00110000.00000000.00000000233.48.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11101001.00110000.00000000.00000000233.48.0.0
Broadcast11101001.00111111.11111111.11111111233.63.255.255
Split into smaller subnets/19
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

233.48.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1233.48.0.0/19233.48.0.1 to 233.48.31.254233.48.31.2558,190
2233.48.32.0/19233.48.32.1 to 233.48.63.254233.48.63.2558,190
3233.48.64.0/19233.48.64.1 to 233.48.95.254233.48.95.2558,190
4233.48.96.0/19233.48.96.1 to 233.48.127.254233.48.127.2558,190
5233.48.128.0/19233.48.128.1 to 233.48.159.254233.48.159.2558,190
6233.48.160.0/19233.48.160.1 to 233.48.191.254233.48.191.2558,190
7233.48.192.0/19233.48.192.1 to 233.48.223.254233.48.223.2558,190
8233.48.224.0/19233.48.224.1 to 233.48.255.254233.48.255.2558,190
9233.49.0.0/19233.49.0.1 to 233.49.31.254233.49.31.2558,190
10233.49.32.0/19233.49.32.1 to 233.49.63.254233.49.63.2558,190
11233.49.64.0/19233.49.64.1 to 233.49.95.254233.49.95.2558,190
12233.49.96.0/19233.49.96.1 to 233.49.127.254233.49.127.2558,190
13233.49.128.0/19233.49.128.1 to 233.49.159.254233.49.159.2558,190
14233.49.160.0/19233.49.160.1 to 233.49.191.254233.49.191.2558,190
15233.49.192.0/19233.49.192.1 to 233.49.223.254233.49.223.2558,190
16233.49.224.0/19233.49.224.1 to 233.49.255.254233.49.255.2558,190
17233.50.0.0/19233.50.0.1 to 233.50.31.254233.50.31.2558,190
18233.50.32.0/19233.50.32.1 to 233.50.63.254233.50.63.2558,190
19233.50.64.0/19233.50.64.1 to 233.50.95.254233.50.95.2558,190
20233.50.96.0/19233.50.96.1 to 233.50.127.254233.50.127.2558,190
21233.50.128.0/19233.50.128.1 to 233.50.159.254233.50.159.2558,190
22233.50.160.0/19233.50.160.1 to 233.50.191.254233.50.191.2558,190
23233.50.192.0/19233.50.192.1 to 233.50.223.254233.50.223.2558,190
24233.50.224.0/19233.50.224.1 to 233.50.255.254233.50.255.2558,190
25233.51.0.0/19233.51.0.1 to 233.51.31.254233.51.31.2558,190
26233.51.32.0/19233.51.32.1 to 233.51.63.254233.51.63.2558,190
27233.51.64.0/19233.51.64.1 to 233.51.95.254233.51.95.2558,190
28233.51.96.0/19233.51.96.1 to 233.51.127.254233.51.127.2558,190
29233.51.128.0/19233.51.128.1 to 233.51.159.254233.51.159.2558,190
30233.51.160.0/19233.51.160.1 to 233.51.191.254233.51.191.2558,190
31233.51.192.0/19233.51.192.1 to 233.51.223.254233.51.223.2558,190
32233.51.224.0/19233.51.224.1 to 233.51.255.254233.51.255.2558,190
33233.52.0.0/19233.52.0.1 to 233.52.31.254233.52.31.2558,190
34233.52.32.0/19233.52.32.1 to 233.52.63.254233.52.63.2558,190
35233.52.64.0/19233.52.64.1 to 233.52.95.254233.52.95.2558,190
36233.52.96.0/19233.52.96.1 to 233.52.127.254233.52.127.2558,190
37233.52.128.0/19233.52.128.1 to 233.52.159.254233.52.159.2558,190
38233.52.160.0/19233.52.160.1 to 233.52.191.254233.52.191.2558,190
39233.52.192.0/19233.52.192.1 to 233.52.223.254233.52.223.2558,190
40233.52.224.0/19233.52.224.1 to 233.52.255.254233.52.255.2558,190
41233.53.0.0/19233.53.0.1 to 233.53.31.254233.53.31.2558,190
42233.53.32.0/19233.53.32.1 to 233.53.63.254233.53.63.2558,190
43233.53.64.0/19233.53.64.1 to 233.53.95.254233.53.95.2558,190
44233.53.96.0/19233.53.96.1 to 233.53.127.254233.53.127.2558,190
45233.53.128.0/19233.53.128.1 to 233.53.159.254233.53.159.2558,190
46233.53.160.0/19233.53.160.1 to 233.53.191.254233.53.191.2558,190
47233.53.192.0/19233.53.192.1 to 233.53.223.254233.53.223.2558,190
48233.53.224.0/19233.53.224.1 to 233.53.255.254233.53.255.2558,190
49233.54.0.0/19233.54.0.1 to 233.54.31.254233.54.31.2558,190
50233.54.32.0/19233.54.32.1 to 233.54.63.254233.54.63.2558,190
51233.54.64.0/19233.54.64.1 to 233.54.95.254233.54.95.2558,190
52233.54.96.0/19233.54.96.1 to 233.54.127.254233.54.127.2558,190
53233.54.128.0/19233.54.128.1 to 233.54.159.254233.54.159.2558,190
54233.54.160.0/19233.54.160.1 to 233.54.191.254233.54.191.2558,190
55233.54.192.0/19233.54.192.1 to 233.54.223.254233.54.223.2558,190
56233.54.224.0/19233.54.224.1 to 233.54.255.254233.54.255.2558,190
57233.55.0.0/19233.55.0.1 to 233.55.31.254233.55.31.2558,190
58233.55.32.0/19233.55.32.1 to 233.55.63.254233.55.63.2558,190
59233.55.64.0/19233.55.64.1 to 233.55.95.254233.55.95.2558,190
60233.55.96.0/19233.55.96.1 to 233.55.127.254233.55.127.2558,190
61233.55.128.0/19233.55.128.1 to 233.55.159.254233.55.159.2558,190
62233.55.160.0/19233.55.160.1 to 233.55.191.254233.55.191.2558,190
63233.55.192.0/19233.55.192.1 to 233.55.223.254233.55.223.2558,190
64233.55.224.0/19233.55.224.1 to 233.55.255.254233.55.255.2558,190
65233.56.0.0/19233.56.0.1 to 233.56.31.254233.56.31.2558,190
66233.56.32.0/19233.56.32.1 to 233.56.63.254233.56.63.2558,190
67233.56.64.0/19233.56.64.1 to 233.56.95.254233.56.95.2558,190
68233.56.96.0/19233.56.96.1 to 233.56.127.254233.56.127.2558,190
69233.56.128.0/19233.56.128.1 to 233.56.159.254233.56.159.2558,190
70233.56.160.0/19233.56.160.1 to 233.56.191.254233.56.191.2558,190
71233.56.192.0/19233.56.192.1 to 233.56.223.254233.56.223.2558,190
72233.56.224.0/19233.56.224.1 to 233.56.255.254233.56.255.2558,190
73233.57.0.0/19233.57.0.1 to 233.57.31.254233.57.31.2558,190
74233.57.32.0/19233.57.32.1 to 233.57.63.254233.57.63.2558,190
75233.57.64.0/19233.57.64.1 to 233.57.95.254233.57.95.2558,190
76233.57.96.0/19233.57.96.1 to 233.57.127.254233.57.127.2558,190
77233.57.128.0/19233.57.128.1 to 233.57.159.254233.57.159.2558,190
78233.57.160.0/19233.57.160.1 to 233.57.191.254233.57.191.2558,190
79233.57.192.0/19233.57.192.1 to 233.57.223.254233.57.223.2558,190
80233.57.224.0/19233.57.224.1 to 233.57.255.254233.57.255.2558,190
81233.58.0.0/19233.58.0.1 to 233.58.31.254233.58.31.2558,190
82233.58.32.0/19233.58.32.1 to 233.58.63.254233.58.63.2558,190
83233.58.64.0/19233.58.64.1 to 233.58.95.254233.58.95.2558,190
84233.58.96.0/19233.58.96.1 to 233.58.127.254233.58.127.2558,190
85233.58.128.0/19233.58.128.1 to 233.58.159.254233.58.159.2558,190
86233.58.160.0/19233.58.160.1 to 233.58.191.254233.58.191.2558,190
87233.58.192.0/19233.58.192.1 to 233.58.223.254233.58.223.2558,190
88233.58.224.0/19233.58.224.1 to 233.58.255.254233.58.255.2558,190
89233.59.0.0/19233.59.0.1 to 233.59.31.254233.59.31.2558,190
90233.59.32.0/19233.59.32.1 to 233.59.63.254233.59.63.2558,190
91233.59.64.0/19233.59.64.1 to 233.59.95.254233.59.95.2558,190
92233.59.96.0/19233.59.96.1 to 233.59.127.254233.59.127.2558,190
93233.59.128.0/19233.59.128.1 to 233.59.159.254233.59.159.2558,190
94233.59.160.0/19233.59.160.1 to 233.59.191.254233.59.191.2558,190
95233.59.192.0/19233.59.192.1 to 233.59.223.254233.59.223.2558,190
96233.59.224.0/19233.59.224.1 to 233.59.255.254233.59.255.2558,190
97233.60.0.0/19233.60.0.1 to 233.60.31.254233.60.31.2558,190
98233.60.32.0/19233.60.32.1 to 233.60.63.254233.60.63.2558,190
99233.60.64.0/19233.60.64.1 to 233.60.95.254233.60.95.2558,190
100233.60.96.0/19233.60.96.1 to 233.60.127.254233.60.127.2558,190
101233.60.128.0/19233.60.128.1 to 233.60.159.254233.60.159.2558,190
102233.60.160.0/19233.60.160.1 to 233.60.191.254233.60.191.2558,190
103233.60.192.0/19233.60.192.1 to 233.60.223.254233.60.223.2558,190
104233.60.224.0/19233.60.224.1 to 233.60.255.254233.60.255.2558,190
105233.61.0.0/19233.61.0.1 to 233.61.31.254233.61.31.2558,190
106233.61.32.0/19233.61.32.1 to 233.61.63.254233.61.63.2558,190
107233.61.64.0/19233.61.64.1 to 233.61.95.254233.61.95.2558,190
108233.61.96.0/19233.61.96.1 to 233.61.127.254233.61.127.2558,190
109233.61.128.0/19233.61.128.1 to 233.61.159.254233.61.159.2558,190
110233.61.160.0/19233.61.160.1 to 233.61.191.254233.61.191.2558,190
111233.61.192.0/19233.61.192.1 to 233.61.223.254233.61.223.2558,190
112233.61.224.0/19233.61.224.1 to 233.61.255.254233.61.255.2558,190
113233.62.0.0/19233.62.0.1 to 233.62.31.254233.62.31.2558,190
114233.62.32.0/19233.62.32.1 to 233.62.63.254233.62.63.2558,190
115233.62.64.0/19233.62.64.1 to 233.62.95.254233.62.95.2558,190
116233.62.96.0/19233.62.96.1 to 233.62.127.254233.62.127.2558,190
117233.62.128.0/19233.62.128.1 to 233.62.159.254233.62.159.2558,190
118233.62.160.0/19233.62.160.1 to 233.62.191.254233.62.191.2558,190
119233.62.192.0/19233.62.192.1 to 233.62.223.254233.62.223.2558,190
120233.62.224.0/19233.62.224.1 to 233.62.255.254233.62.255.2558,190
121233.63.0.0/19233.63.0.1 to 233.63.31.254233.63.31.2558,190
122233.63.32.0/19233.63.32.1 to 233.63.63.254233.63.63.2558,190
123233.63.64.0/19233.63.64.1 to 233.63.95.254233.63.95.2558,190
124233.63.96.0/19233.63.96.1 to 233.63.127.254233.63.127.2558,190
125233.63.128.0/19233.63.128.1 to 233.63.159.254233.63.159.2558,190
126233.63.160.0/19233.63.160.1 to 233.63.191.254233.63.191.2558,190
127233.63.192.0/19233.63.192.1 to 233.63.223.254233.63.223.2558,190
128233.63.224.0/19233.63.224.1 to 233.63.255.254233.63.255.2558,190

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.