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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.

Network234.224.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
234.224.0.0
Broadcast address
234.239.255.255
First usable
234.224.0.1
Last usable
234.239.255.254
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 EAE00000 · Integer 3940548608 to 3941597183
Reverse DNS zones
224.234.in-addr.arpa
225.234.in-addr.arpa
226.234.in-addr.arpa
227.234.in-addr.arpa
228.234.in-addr.arpa
229.234.in-addr.arpa
230.234.in-addr.arpa
231.234.in-addr.arpa
232.234.in-addr.arpa
233.234.in-addr.arpa
234.234.in-addr.arpa
235.234.in-addr.arpa
236.234.in-addr.arpa
237.234.in-addr.arpa
238.234.in-addr.arpa
239.234.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
Address11101010.11100000.00000000.00000000234.224.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11101010.11100000.00000000.00000000234.224.0.0
Broadcast11101010.11101111.11111111.11111111234.239.255.255
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)

234.224.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1234.224.0.0/19234.224.0.1 to 234.224.31.254234.224.31.2558,190
2234.224.32.0/19234.224.32.1 to 234.224.63.254234.224.63.2558,190
3234.224.64.0/19234.224.64.1 to 234.224.95.254234.224.95.2558,190
4234.224.96.0/19234.224.96.1 to 234.224.127.254234.224.127.2558,190
5234.224.128.0/19234.224.128.1 to 234.224.159.254234.224.159.2558,190
6234.224.160.0/19234.224.160.1 to 234.224.191.254234.224.191.2558,190
7234.224.192.0/19234.224.192.1 to 234.224.223.254234.224.223.2558,190
8234.224.224.0/19234.224.224.1 to 234.224.255.254234.224.255.2558,190
9234.225.0.0/19234.225.0.1 to 234.225.31.254234.225.31.2558,190
10234.225.32.0/19234.225.32.1 to 234.225.63.254234.225.63.2558,190
11234.225.64.0/19234.225.64.1 to 234.225.95.254234.225.95.2558,190
12234.225.96.0/19234.225.96.1 to 234.225.127.254234.225.127.2558,190
13234.225.128.0/19234.225.128.1 to 234.225.159.254234.225.159.2558,190
14234.225.160.0/19234.225.160.1 to 234.225.191.254234.225.191.2558,190
15234.225.192.0/19234.225.192.1 to 234.225.223.254234.225.223.2558,190
16234.225.224.0/19234.225.224.1 to 234.225.255.254234.225.255.2558,190
17234.226.0.0/19234.226.0.1 to 234.226.31.254234.226.31.2558,190
18234.226.32.0/19234.226.32.1 to 234.226.63.254234.226.63.2558,190
19234.226.64.0/19234.226.64.1 to 234.226.95.254234.226.95.2558,190
20234.226.96.0/19234.226.96.1 to 234.226.127.254234.226.127.2558,190
21234.226.128.0/19234.226.128.1 to 234.226.159.254234.226.159.2558,190
22234.226.160.0/19234.226.160.1 to 234.226.191.254234.226.191.2558,190
23234.226.192.0/19234.226.192.1 to 234.226.223.254234.226.223.2558,190
24234.226.224.0/19234.226.224.1 to 234.226.255.254234.226.255.2558,190
25234.227.0.0/19234.227.0.1 to 234.227.31.254234.227.31.2558,190
26234.227.32.0/19234.227.32.1 to 234.227.63.254234.227.63.2558,190
27234.227.64.0/19234.227.64.1 to 234.227.95.254234.227.95.2558,190
28234.227.96.0/19234.227.96.1 to 234.227.127.254234.227.127.2558,190
29234.227.128.0/19234.227.128.1 to 234.227.159.254234.227.159.2558,190
30234.227.160.0/19234.227.160.1 to 234.227.191.254234.227.191.2558,190
31234.227.192.0/19234.227.192.1 to 234.227.223.254234.227.223.2558,190
32234.227.224.0/19234.227.224.1 to 234.227.255.254234.227.255.2558,190
33234.228.0.0/19234.228.0.1 to 234.228.31.254234.228.31.2558,190
34234.228.32.0/19234.228.32.1 to 234.228.63.254234.228.63.2558,190
35234.228.64.0/19234.228.64.1 to 234.228.95.254234.228.95.2558,190
36234.228.96.0/19234.228.96.1 to 234.228.127.254234.228.127.2558,190
37234.228.128.0/19234.228.128.1 to 234.228.159.254234.228.159.2558,190
38234.228.160.0/19234.228.160.1 to 234.228.191.254234.228.191.2558,190
39234.228.192.0/19234.228.192.1 to 234.228.223.254234.228.223.2558,190
40234.228.224.0/19234.228.224.1 to 234.228.255.254234.228.255.2558,190
41234.229.0.0/19234.229.0.1 to 234.229.31.254234.229.31.2558,190
42234.229.32.0/19234.229.32.1 to 234.229.63.254234.229.63.2558,190
43234.229.64.0/19234.229.64.1 to 234.229.95.254234.229.95.2558,190
44234.229.96.0/19234.229.96.1 to 234.229.127.254234.229.127.2558,190
45234.229.128.0/19234.229.128.1 to 234.229.159.254234.229.159.2558,190
46234.229.160.0/19234.229.160.1 to 234.229.191.254234.229.191.2558,190
47234.229.192.0/19234.229.192.1 to 234.229.223.254234.229.223.2558,190
48234.229.224.0/19234.229.224.1 to 234.229.255.254234.229.255.2558,190
49234.230.0.0/19234.230.0.1 to 234.230.31.254234.230.31.2558,190
50234.230.32.0/19234.230.32.1 to 234.230.63.254234.230.63.2558,190
51234.230.64.0/19234.230.64.1 to 234.230.95.254234.230.95.2558,190
52234.230.96.0/19234.230.96.1 to 234.230.127.254234.230.127.2558,190
53234.230.128.0/19234.230.128.1 to 234.230.159.254234.230.159.2558,190
54234.230.160.0/19234.230.160.1 to 234.230.191.254234.230.191.2558,190
55234.230.192.0/19234.230.192.1 to 234.230.223.254234.230.223.2558,190
56234.230.224.0/19234.230.224.1 to 234.230.255.254234.230.255.2558,190
57234.231.0.0/19234.231.0.1 to 234.231.31.254234.231.31.2558,190
58234.231.32.0/19234.231.32.1 to 234.231.63.254234.231.63.2558,190
59234.231.64.0/19234.231.64.1 to 234.231.95.254234.231.95.2558,190
60234.231.96.0/19234.231.96.1 to 234.231.127.254234.231.127.2558,190
61234.231.128.0/19234.231.128.1 to 234.231.159.254234.231.159.2558,190
62234.231.160.0/19234.231.160.1 to 234.231.191.254234.231.191.2558,190
63234.231.192.0/19234.231.192.1 to 234.231.223.254234.231.223.2558,190
64234.231.224.0/19234.231.224.1 to 234.231.255.254234.231.255.2558,190
65234.232.0.0/19234.232.0.1 to 234.232.31.254234.232.31.2558,190
66234.232.32.0/19234.232.32.1 to 234.232.63.254234.232.63.2558,190
67234.232.64.0/19234.232.64.1 to 234.232.95.254234.232.95.2558,190
68234.232.96.0/19234.232.96.1 to 234.232.127.254234.232.127.2558,190
69234.232.128.0/19234.232.128.1 to 234.232.159.254234.232.159.2558,190
70234.232.160.0/19234.232.160.1 to 234.232.191.254234.232.191.2558,190
71234.232.192.0/19234.232.192.1 to 234.232.223.254234.232.223.2558,190
72234.232.224.0/19234.232.224.1 to 234.232.255.254234.232.255.2558,190
73234.233.0.0/19234.233.0.1 to 234.233.31.254234.233.31.2558,190
74234.233.32.0/19234.233.32.1 to 234.233.63.254234.233.63.2558,190
75234.233.64.0/19234.233.64.1 to 234.233.95.254234.233.95.2558,190
76234.233.96.0/19234.233.96.1 to 234.233.127.254234.233.127.2558,190
77234.233.128.0/19234.233.128.1 to 234.233.159.254234.233.159.2558,190
78234.233.160.0/19234.233.160.1 to 234.233.191.254234.233.191.2558,190
79234.233.192.0/19234.233.192.1 to 234.233.223.254234.233.223.2558,190
80234.233.224.0/19234.233.224.1 to 234.233.255.254234.233.255.2558,190
81234.234.0.0/19234.234.0.1 to 234.234.31.254234.234.31.2558,190
82234.234.32.0/19234.234.32.1 to 234.234.63.254234.234.63.2558,190
83234.234.64.0/19234.234.64.1 to 234.234.95.254234.234.95.2558,190
84234.234.96.0/19234.234.96.1 to 234.234.127.254234.234.127.2558,190
85234.234.128.0/19234.234.128.1 to 234.234.159.254234.234.159.2558,190
86234.234.160.0/19234.234.160.1 to 234.234.191.254234.234.191.2558,190
87234.234.192.0/19234.234.192.1 to 234.234.223.254234.234.223.2558,190
88234.234.224.0/19234.234.224.1 to 234.234.255.254234.234.255.2558,190
89234.235.0.0/19234.235.0.1 to 234.235.31.254234.235.31.2558,190
90234.235.32.0/19234.235.32.1 to 234.235.63.254234.235.63.2558,190
91234.235.64.0/19234.235.64.1 to 234.235.95.254234.235.95.2558,190
92234.235.96.0/19234.235.96.1 to 234.235.127.254234.235.127.2558,190
93234.235.128.0/19234.235.128.1 to 234.235.159.254234.235.159.2558,190
94234.235.160.0/19234.235.160.1 to 234.235.191.254234.235.191.2558,190
95234.235.192.0/19234.235.192.1 to 234.235.223.254234.235.223.2558,190
96234.235.224.0/19234.235.224.1 to 234.235.255.254234.235.255.2558,190
97234.236.0.0/19234.236.0.1 to 234.236.31.254234.236.31.2558,190
98234.236.32.0/19234.236.32.1 to 234.236.63.254234.236.63.2558,190
99234.236.64.0/19234.236.64.1 to 234.236.95.254234.236.95.2558,190
100234.236.96.0/19234.236.96.1 to 234.236.127.254234.236.127.2558,190
101234.236.128.0/19234.236.128.1 to 234.236.159.254234.236.159.2558,190
102234.236.160.0/19234.236.160.1 to 234.236.191.254234.236.191.2558,190
103234.236.192.0/19234.236.192.1 to 234.236.223.254234.236.223.2558,190
104234.236.224.0/19234.236.224.1 to 234.236.255.254234.236.255.2558,190
105234.237.0.0/19234.237.0.1 to 234.237.31.254234.237.31.2558,190
106234.237.32.0/19234.237.32.1 to 234.237.63.254234.237.63.2558,190
107234.237.64.0/19234.237.64.1 to 234.237.95.254234.237.95.2558,190
108234.237.96.0/19234.237.96.1 to 234.237.127.254234.237.127.2558,190
109234.237.128.0/19234.237.128.1 to 234.237.159.254234.237.159.2558,190
110234.237.160.0/19234.237.160.1 to 234.237.191.254234.237.191.2558,190
111234.237.192.0/19234.237.192.1 to 234.237.223.254234.237.223.2558,190
112234.237.224.0/19234.237.224.1 to 234.237.255.254234.237.255.2558,190
113234.238.0.0/19234.238.0.1 to 234.238.31.254234.238.31.2558,190
114234.238.32.0/19234.238.32.1 to 234.238.63.254234.238.63.2558,190
115234.238.64.0/19234.238.64.1 to 234.238.95.254234.238.95.2558,190
116234.238.96.0/19234.238.96.1 to 234.238.127.254234.238.127.2558,190
117234.238.128.0/19234.238.128.1 to 234.238.159.254234.238.159.2558,190
118234.238.160.0/19234.238.160.1 to 234.238.191.254234.238.191.2558,190
119234.238.192.0/19234.238.192.1 to 234.238.223.254234.238.223.2558,190
120234.238.224.0/19234.238.224.1 to 234.238.255.254234.238.255.2558,190
121234.239.0.0/19234.239.0.1 to 234.239.31.254234.239.31.2558,190
122234.239.32.0/19234.239.32.1 to 234.239.63.254234.239.63.2558,190
123234.239.64.0/19234.239.64.1 to 234.239.95.254234.239.95.2558,190
124234.239.96.0/19234.239.96.1 to 234.239.127.254234.239.127.2558,190
125234.239.128.0/19234.239.128.1 to 234.239.159.254234.239.159.2558,190
126234.239.160.0/19234.239.160.1 to 234.239.191.254234.239.191.2558,190
127234.239.192.0/19234.239.192.1 to 234.239.223.254234.239.223.2558,190
128234.239.224.0/19234.239.224.1 to 234.239.255.254234.239.255.2558,190

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.