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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.

Network230.192.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
230.192.0.0
Broadcast address
230.207.255.255
First usable
230.192.0.1
Last usable
230.207.255.254
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 E6C00000 · Integer 3871342592 to 3872391167
Reverse DNS zones
192.230.in-addr.arpa
193.230.in-addr.arpa
194.230.in-addr.arpa
195.230.in-addr.arpa
196.230.in-addr.arpa
197.230.in-addr.arpa
198.230.in-addr.arpa
199.230.in-addr.arpa
200.230.in-addr.arpa
201.230.in-addr.arpa
202.230.in-addr.arpa
203.230.in-addr.arpa
204.230.in-addr.arpa
205.230.in-addr.arpa
206.230.in-addr.arpa
207.230.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
Address11100110.11000000.00000000.00000000230.192.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11100110.11000000.00000000.00000000230.192.0.0
Broadcast11100110.11001111.11111111.11111111230.207.255.255
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)

230.192.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1230.192.0.0/19230.192.0.1 to 230.192.31.254230.192.31.2558,190
2230.192.32.0/19230.192.32.1 to 230.192.63.254230.192.63.2558,190
3230.192.64.0/19230.192.64.1 to 230.192.95.254230.192.95.2558,190
4230.192.96.0/19230.192.96.1 to 230.192.127.254230.192.127.2558,190
5230.192.128.0/19230.192.128.1 to 230.192.159.254230.192.159.2558,190
6230.192.160.0/19230.192.160.1 to 230.192.191.254230.192.191.2558,190
7230.192.192.0/19230.192.192.1 to 230.192.223.254230.192.223.2558,190
8230.192.224.0/19230.192.224.1 to 230.192.255.254230.192.255.2558,190
9230.193.0.0/19230.193.0.1 to 230.193.31.254230.193.31.2558,190
10230.193.32.0/19230.193.32.1 to 230.193.63.254230.193.63.2558,190
11230.193.64.0/19230.193.64.1 to 230.193.95.254230.193.95.2558,190
12230.193.96.0/19230.193.96.1 to 230.193.127.254230.193.127.2558,190
13230.193.128.0/19230.193.128.1 to 230.193.159.254230.193.159.2558,190
14230.193.160.0/19230.193.160.1 to 230.193.191.254230.193.191.2558,190
15230.193.192.0/19230.193.192.1 to 230.193.223.254230.193.223.2558,190
16230.193.224.0/19230.193.224.1 to 230.193.255.254230.193.255.2558,190
17230.194.0.0/19230.194.0.1 to 230.194.31.254230.194.31.2558,190
18230.194.32.0/19230.194.32.1 to 230.194.63.254230.194.63.2558,190
19230.194.64.0/19230.194.64.1 to 230.194.95.254230.194.95.2558,190
20230.194.96.0/19230.194.96.1 to 230.194.127.254230.194.127.2558,190
21230.194.128.0/19230.194.128.1 to 230.194.159.254230.194.159.2558,190
22230.194.160.0/19230.194.160.1 to 230.194.191.254230.194.191.2558,190
23230.194.192.0/19230.194.192.1 to 230.194.223.254230.194.223.2558,190
24230.194.224.0/19230.194.224.1 to 230.194.255.254230.194.255.2558,190
25230.195.0.0/19230.195.0.1 to 230.195.31.254230.195.31.2558,190
26230.195.32.0/19230.195.32.1 to 230.195.63.254230.195.63.2558,190
27230.195.64.0/19230.195.64.1 to 230.195.95.254230.195.95.2558,190
28230.195.96.0/19230.195.96.1 to 230.195.127.254230.195.127.2558,190
29230.195.128.0/19230.195.128.1 to 230.195.159.254230.195.159.2558,190
30230.195.160.0/19230.195.160.1 to 230.195.191.254230.195.191.2558,190
31230.195.192.0/19230.195.192.1 to 230.195.223.254230.195.223.2558,190
32230.195.224.0/19230.195.224.1 to 230.195.255.254230.195.255.2558,190
33230.196.0.0/19230.196.0.1 to 230.196.31.254230.196.31.2558,190
34230.196.32.0/19230.196.32.1 to 230.196.63.254230.196.63.2558,190
35230.196.64.0/19230.196.64.1 to 230.196.95.254230.196.95.2558,190
36230.196.96.0/19230.196.96.1 to 230.196.127.254230.196.127.2558,190
37230.196.128.0/19230.196.128.1 to 230.196.159.254230.196.159.2558,190
38230.196.160.0/19230.196.160.1 to 230.196.191.254230.196.191.2558,190
39230.196.192.0/19230.196.192.1 to 230.196.223.254230.196.223.2558,190
40230.196.224.0/19230.196.224.1 to 230.196.255.254230.196.255.2558,190
41230.197.0.0/19230.197.0.1 to 230.197.31.254230.197.31.2558,190
42230.197.32.0/19230.197.32.1 to 230.197.63.254230.197.63.2558,190
43230.197.64.0/19230.197.64.1 to 230.197.95.254230.197.95.2558,190
44230.197.96.0/19230.197.96.1 to 230.197.127.254230.197.127.2558,190
45230.197.128.0/19230.197.128.1 to 230.197.159.254230.197.159.2558,190
46230.197.160.0/19230.197.160.1 to 230.197.191.254230.197.191.2558,190
47230.197.192.0/19230.197.192.1 to 230.197.223.254230.197.223.2558,190
48230.197.224.0/19230.197.224.1 to 230.197.255.254230.197.255.2558,190
49230.198.0.0/19230.198.0.1 to 230.198.31.254230.198.31.2558,190
50230.198.32.0/19230.198.32.1 to 230.198.63.254230.198.63.2558,190
51230.198.64.0/19230.198.64.1 to 230.198.95.254230.198.95.2558,190
52230.198.96.0/19230.198.96.1 to 230.198.127.254230.198.127.2558,190
53230.198.128.0/19230.198.128.1 to 230.198.159.254230.198.159.2558,190
54230.198.160.0/19230.198.160.1 to 230.198.191.254230.198.191.2558,190
55230.198.192.0/19230.198.192.1 to 230.198.223.254230.198.223.2558,190
56230.198.224.0/19230.198.224.1 to 230.198.255.254230.198.255.2558,190
57230.199.0.0/19230.199.0.1 to 230.199.31.254230.199.31.2558,190
58230.199.32.0/19230.199.32.1 to 230.199.63.254230.199.63.2558,190
59230.199.64.0/19230.199.64.1 to 230.199.95.254230.199.95.2558,190
60230.199.96.0/19230.199.96.1 to 230.199.127.254230.199.127.2558,190
61230.199.128.0/19230.199.128.1 to 230.199.159.254230.199.159.2558,190
62230.199.160.0/19230.199.160.1 to 230.199.191.254230.199.191.2558,190
63230.199.192.0/19230.199.192.1 to 230.199.223.254230.199.223.2558,190
64230.199.224.0/19230.199.224.1 to 230.199.255.254230.199.255.2558,190
65230.200.0.0/19230.200.0.1 to 230.200.31.254230.200.31.2558,190
66230.200.32.0/19230.200.32.1 to 230.200.63.254230.200.63.2558,190
67230.200.64.0/19230.200.64.1 to 230.200.95.254230.200.95.2558,190
68230.200.96.0/19230.200.96.1 to 230.200.127.254230.200.127.2558,190
69230.200.128.0/19230.200.128.1 to 230.200.159.254230.200.159.2558,190
70230.200.160.0/19230.200.160.1 to 230.200.191.254230.200.191.2558,190
71230.200.192.0/19230.200.192.1 to 230.200.223.254230.200.223.2558,190
72230.200.224.0/19230.200.224.1 to 230.200.255.254230.200.255.2558,190
73230.201.0.0/19230.201.0.1 to 230.201.31.254230.201.31.2558,190
74230.201.32.0/19230.201.32.1 to 230.201.63.254230.201.63.2558,190
75230.201.64.0/19230.201.64.1 to 230.201.95.254230.201.95.2558,190
76230.201.96.0/19230.201.96.1 to 230.201.127.254230.201.127.2558,190
77230.201.128.0/19230.201.128.1 to 230.201.159.254230.201.159.2558,190
78230.201.160.0/19230.201.160.1 to 230.201.191.254230.201.191.2558,190
79230.201.192.0/19230.201.192.1 to 230.201.223.254230.201.223.2558,190
80230.201.224.0/19230.201.224.1 to 230.201.255.254230.201.255.2558,190
81230.202.0.0/19230.202.0.1 to 230.202.31.254230.202.31.2558,190
82230.202.32.0/19230.202.32.1 to 230.202.63.254230.202.63.2558,190
83230.202.64.0/19230.202.64.1 to 230.202.95.254230.202.95.2558,190
84230.202.96.0/19230.202.96.1 to 230.202.127.254230.202.127.2558,190
85230.202.128.0/19230.202.128.1 to 230.202.159.254230.202.159.2558,190
86230.202.160.0/19230.202.160.1 to 230.202.191.254230.202.191.2558,190
87230.202.192.0/19230.202.192.1 to 230.202.223.254230.202.223.2558,190
88230.202.224.0/19230.202.224.1 to 230.202.255.254230.202.255.2558,190
89230.203.0.0/19230.203.0.1 to 230.203.31.254230.203.31.2558,190
90230.203.32.0/19230.203.32.1 to 230.203.63.254230.203.63.2558,190
91230.203.64.0/19230.203.64.1 to 230.203.95.254230.203.95.2558,190
92230.203.96.0/19230.203.96.1 to 230.203.127.254230.203.127.2558,190
93230.203.128.0/19230.203.128.1 to 230.203.159.254230.203.159.2558,190
94230.203.160.0/19230.203.160.1 to 230.203.191.254230.203.191.2558,190
95230.203.192.0/19230.203.192.1 to 230.203.223.254230.203.223.2558,190
96230.203.224.0/19230.203.224.1 to 230.203.255.254230.203.255.2558,190
97230.204.0.0/19230.204.0.1 to 230.204.31.254230.204.31.2558,190
98230.204.32.0/19230.204.32.1 to 230.204.63.254230.204.63.2558,190
99230.204.64.0/19230.204.64.1 to 230.204.95.254230.204.95.2558,190
100230.204.96.0/19230.204.96.1 to 230.204.127.254230.204.127.2558,190
101230.204.128.0/19230.204.128.1 to 230.204.159.254230.204.159.2558,190
102230.204.160.0/19230.204.160.1 to 230.204.191.254230.204.191.2558,190
103230.204.192.0/19230.204.192.1 to 230.204.223.254230.204.223.2558,190
104230.204.224.0/19230.204.224.1 to 230.204.255.254230.204.255.2558,190
105230.205.0.0/19230.205.0.1 to 230.205.31.254230.205.31.2558,190
106230.205.32.0/19230.205.32.1 to 230.205.63.254230.205.63.2558,190
107230.205.64.0/19230.205.64.1 to 230.205.95.254230.205.95.2558,190
108230.205.96.0/19230.205.96.1 to 230.205.127.254230.205.127.2558,190
109230.205.128.0/19230.205.128.1 to 230.205.159.254230.205.159.2558,190
110230.205.160.0/19230.205.160.1 to 230.205.191.254230.205.191.2558,190
111230.205.192.0/19230.205.192.1 to 230.205.223.254230.205.223.2558,190
112230.205.224.0/19230.205.224.1 to 230.205.255.254230.205.255.2558,190
113230.206.0.0/19230.206.0.1 to 230.206.31.254230.206.31.2558,190
114230.206.32.0/19230.206.32.1 to 230.206.63.254230.206.63.2558,190
115230.206.64.0/19230.206.64.1 to 230.206.95.254230.206.95.2558,190
116230.206.96.0/19230.206.96.1 to 230.206.127.254230.206.127.2558,190
117230.206.128.0/19230.206.128.1 to 230.206.159.254230.206.159.2558,190
118230.206.160.0/19230.206.160.1 to 230.206.191.254230.206.191.2558,190
119230.206.192.0/19230.206.192.1 to 230.206.223.254230.206.223.2558,190
120230.206.224.0/19230.206.224.1 to 230.206.255.254230.206.255.2558,190
121230.207.0.0/19230.207.0.1 to 230.207.31.254230.207.31.2558,190
122230.207.32.0/19230.207.32.1 to 230.207.63.254230.207.63.2558,190
123230.207.64.0/19230.207.64.1 to 230.207.95.254230.207.95.2558,190
124230.207.96.0/19230.207.96.1 to 230.207.127.254230.207.127.2558,190
125230.207.128.0/19230.207.128.1 to 230.207.159.254230.207.159.2558,190
126230.207.160.0/19230.207.160.1 to 230.207.191.254230.207.191.2558,190
127230.207.192.0/19230.207.192.1 to 230.207.223.254230.207.223.2558,190
128230.207.224.0/19230.207.224.1 to 230.207.255.254230.207.255.2558,190

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.