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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.

Network190.128.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
190.128.0.0
Broadcast address
190.143.255.255
First usable
190.128.0.1
Last usable
190.143.255.254
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
Public public
Old class
B (default /16)
As numbers
Hex BE800000 · Integer 3196059648 to 3197108223
Reverse DNS zones
128.190.in-addr.arpa
129.190.in-addr.arpa
130.190.in-addr.arpa
131.190.in-addr.arpa
132.190.in-addr.arpa
133.190.in-addr.arpa
134.190.in-addr.arpa
135.190.in-addr.arpa
136.190.in-addr.arpa
137.190.in-addr.arpa
138.190.in-addr.arpa
139.190.in-addr.arpa
140.190.in-addr.arpa
141.190.in-addr.arpa
142.190.in-addr.arpa
143.190.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
Address10111110.10000000.00000000.00000000190.128.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10111110.10000000.00000000.00000000190.128.0.0
Broadcast10111110.10001111.11111111.11111111190.143.255.255
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)

190.128.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1190.128.0.0/19190.128.0.1 to 190.128.31.254190.128.31.2558,190
2190.128.32.0/19190.128.32.1 to 190.128.63.254190.128.63.2558,190
3190.128.64.0/19190.128.64.1 to 190.128.95.254190.128.95.2558,190
4190.128.96.0/19190.128.96.1 to 190.128.127.254190.128.127.2558,190
5190.128.128.0/19190.128.128.1 to 190.128.159.254190.128.159.2558,190
6190.128.160.0/19190.128.160.1 to 190.128.191.254190.128.191.2558,190
7190.128.192.0/19190.128.192.1 to 190.128.223.254190.128.223.2558,190
8190.128.224.0/19190.128.224.1 to 190.128.255.254190.128.255.2558,190
9190.129.0.0/19190.129.0.1 to 190.129.31.254190.129.31.2558,190
10190.129.32.0/19190.129.32.1 to 190.129.63.254190.129.63.2558,190
11190.129.64.0/19190.129.64.1 to 190.129.95.254190.129.95.2558,190
12190.129.96.0/19190.129.96.1 to 190.129.127.254190.129.127.2558,190
13190.129.128.0/19190.129.128.1 to 190.129.159.254190.129.159.2558,190
14190.129.160.0/19190.129.160.1 to 190.129.191.254190.129.191.2558,190
15190.129.192.0/19190.129.192.1 to 190.129.223.254190.129.223.2558,190
16190.129.224.0/19190.129.224.1 to 190.129.255.254190.129.255.2558,190
17190.130.0.0/19190.130.0.1 to 190.130.31.254190.130.31.2558,190
18190.130.32.0/19190.130.32.1 to 190.130.63.254190.130.63.2558,190
19190.130.64.0/19190.130.64.1 to 190.130.95.254190.130.95.2558,190
20190.130.96.0/19190.130.96.1 to 190.130.127.254190.130.127.2558,190
21190.130.128.0/19190.130.128.1 to 190.130.159.254190.130.159.2558,190
22190.130.160.0/19190.130.160.1 to 190.130.191.254190.130.191.2558,190
23190.130.192.0/19190.130.192.1 to 190.130.223.254190.130.223.2558,190
24190.130.224.0/19190.130.224.1 to 190.130.255.254190.130.255.2558,190
25190.131.0.0/19190.131.0.1 to 190.131.31.254190.131.31.2558,190
26190.131.32.0/19190.131.32.1 to 190.131.63.254190.131.63.2558,190
27190.131.64.0/19190.131.64.1 to 190.131.95.254190.131.95.2558,190
28190.131.96.0/19190.131.96.1 to 190.131.127.254190.131.127.2558,190
29190.131.128.0/19190.131.128.1 to 190.131.159.254190.131.159.2558,190
30190.131.160.0/19190.131.160.1 to 190.131.191.254190.131.191.2558,190
31190.131.192.0/19190.131.192.1 to 190.131.223.254190.131.223.2558,190
32190.131.224.0/19190.131.224.1 to 190.131.255.254190.131.255.2558,190
33190.132.0.0/19190.132.0.1 to 190.132.31.254190.132.31.2558,190
34190.132.32.0/19190.132.32.1 to 190.132.63.254190.132.63.2558,190
35190.132.64.0/19190.132.64.1 to 190.132.95.254190.132.95.2558,190
36190.132.96.0/19190.132.96.1 to 190.132.127.254190.132.127.2558,190
37190.132.128.0/19190.132.128.1 to 190.132.159.254190.132.159.2558,190
38190.132.160.0/19190.132.160.1 to 190.132.191.254190.132.191.2558,190
39190.132.192.0/19190.132.192.1 to 190.132.223.254190.132.223.2558,190
40190.132.224.0/19190.132.224.1 to 190.132.255.254190.132.255.2558,190
41190.133.0.0/19190.133.0.1 to 190.133.31.254190.133.31.2558,190
42190.133.32.0/19190.133.32.1 to 190.133.63.254190.133.63.2558,190
43190.133.64.0/19190.133.64.1 to 190.133.95.254190.133.95.2558,190
44190.133.96.0/19190.133.96.1 to 190.133.127.254190.133.127.2558,190
45190.133.128.0/19190.133.128.1 to 190.133.159.254190.133.159.2558,190
46190.133.160.0/19190.133.160.1 to 190.133.191.254190.133.191.2558,190
47190.133.192.0/19190.133.192.1 to 190.133.223.254190.133.223.2558,190
48190.133.224.0/19190.133.224.1 to 190.133.255.254190.133.255.2558,190
49190.134.0.0/19190.134.0.1 to 190.134.31.254190.134.31.2558,190
50190.134.32.0/19190.134.32.1 to 190.134.63.254190.134.63.2558,190
51190.134.64.0/19190.134.64.1 to 190.134.95.254190.134.95.2558,190
52190.134.96.0/19190.134.96.1 to 190.134.127.254190.134.127.2558,190
53190.134.128.0/19190.134.128.1 to 190.134.159.254190.134.159.2558,190
54190.134.160.0/19190.134.160.1 to 190.134.191.254190.134.191.2558,190
55190.134.192.0/19190.134.192.1 to 190.134.223.254190.134.223.2558,190
56190.134.224.0/19190.134.224.1 to 190.134.255.254190.134.255.2558,190
57190.135.0.0/19190.135.0.1 to 190.135.31.254190.135.31.2558,190
58190.135.32.0/19190.135.32.1 to 190.135.63.254190.135.63.2558,190
59190.135.64.0/19190.135.64.1 to 190.135.95.254190.135.95.2558,190
60190.135.96.0/19190.135.96.1 to 190.135.127.254190.135.127.2558,190
61190.135.128.0/19190.135.128.1 to 190.135.159.254190.135.159.2558,190
62190.135.160.0/19190.135.160.1 to 190.135.191.254190.135.191.2558,190
63190.135.192.0/19190.135.192.1 to 190.135.223.254190.135.223.2558,190
64190.135.224.0/19190.135.224.1 to 190.135.255.254190.135.255.2558,190
65190.136.0.0/19190.136.0.1 to 190.136.31.254190.136.31.2558,190
66190.136.32.0/19190.136.32.1 to 190.136.63.254190.136.63.2558,190
67190.136.64.0/19190.136.64.1 to 190.136.95.254190.136.95.2558,190
68190.136.96.0/19190.136.96.1 to 190.136.127.254190.136.127.2558,190
69190.136.128.0/19190.136.128.1 to 190.136.159.254190.136.159.2558,190
70190.136.160.0/19190.136.160.1 to 190.136.191.254190.136.191.2558,190
71190.136.192.0/19190.136.192.1 to 190.136.223.254190.136.223.2558,190
72190.136.224.0/19190.136.224.1 to 190.136.255.254190.136.255.2558,190
73190.137.0.0/19190.137.0.1 to 190.137.31.254190.137.31.2558,190
74190.137.32.0/19190.137.32.1 to 190.137.63.254190.137.63.2558,190
75190.137.64.0/19190.137.64.1 to 190.137.95.254190.137.95.2558,190
76190.137.96.0/19190.137.96.1 to 190.137.127.254190.137.127.2558,190
77190.137.128.0/19190.137.128.1 to 190.137.159.254190.137.159.2558,190
78190.137.160.0/19190.137.160.1 to 190.137.191.254190.137.191.2558,190
79190.137.192.0/19190.137.192.1 to 190.137.223.254190.137.223.2558,190
80190.137.224.0/19190.137.224.1 to 190.137.255.254190.137.255.2558,190
81190.138.0.0/19190.138.0.1 to 190.138.31.254190.138.31.2558,190
82190.138.32.0/19190.138.32.1 to 190.138.63.254190.138.63.2558,190
83190.138.64.0/19190.138.64.1 to 190.138.95.254190.138.95.2558,190
84190.138.96.0/19190.138.96.1 to 190.138.127.254190.138.127.2558,190
85190.138.128.0/19190.138.128.1 to 190.138.159.254190.138.159.2558,190
86190.138.160.0/19190.138.160.1 to 190.138.191.254190.138.191.2558,190
87190.138.192.0/19190.138.192.1 to 190.138.223.254190.138.223.2558,190
88190.138.224.0/19190.138.224.1 to 190.138.255.254190.138.255.2558,190
89190.139.0.0/19190.139.0.1 to 190.139.31.254190.139.31.2558,190
90190.139.32.0/19190.139.32.1 to 190.139.63.254190.139.63.2558,190
91190.139.64.0/19190.139.64.1 to 190.139.95.254190.139.95.2558,190
92190.139.96.0/19190.139.96.1 to 190.139.127.254190.139.127.2558,190
93190.139.128.0/19190.139.128.1 to 190.139.159.254190.139.159.2558,190
94190.139.160.0/19190.139.160.1 to 190.139.191.254190.139.191.2558,190
95190.139.192.0/19190.139.192.1 to 190.139.223.254190.139.223.2558,190
96190.139.224.0/19190.139.224.1 to 190.139.255.254190.139.255.2558,190
97190.140.0.0/19190.140.0.1 to 190.140.31.254190.140.31.2558,190
98190.140.32.0/19190.140.32.1 to 190.140.63.254190.140.63.2558,190
99190.140.64.0/19190.140.64.1 to 190.140.95.254190.140.95.2558,190
100190.140.96.0/19190.140.96.1 to 190.140.127.254190.140.127.2558,190
101190.140.128.0/19190.140.128.1 to 190.140.159.254190.140.159.2558,190
102190.140.160.0/19190.140.160.1 to 190.140.191.254190.140.191.2558,190
103190.140.192.0/19190.140.192.1 to 190.140.223.254190.140.223.2558,190
104190.140.224.0/19190.140.224.1 to 190.140.255.254190.140.255.2558,190
105190.141.0.0/19190.141.0.1 to 190.141.31.254190.141.31.2558,190
106190.141.32.0/19190.141.32.1 to 190.141.63.254190.141.63.2558,190
107190.141.64.0/19190.141.64.1 to 190.141.95.254190.141.95.2558,190
108190.141.96.0/19190.141.96.1 to 190.141.127.254190.141.127.2558,190
109190.141.128.0/19190.141.128.1 to 190.141.159.254190.141.159.2558,190
110190.141.160.0/19190.141.160.1 to 190.141.191.254190.141.191.2558,190
111190.141.192.0/19190.141.192.1 to 190.141.223.254190.141.223.2558,190
112190.141.224.0/19190.141.224.1 to 190.141.255.254190.141.255.2558,190
113190.142.0.0/19190.142.0.1 to 190.142.31.254190.142.31.2558,190
114190.142.32.0/19190.142.32.1 to 190.142.63.254190.142.63.2558,190
115190.142.64.0/19190.142.64.1 to 190.142.95.254190.142.95.2558,190
116190.142.96.0/19190.142.96.1 to 190.142.127.254190.142.127.2558,190
117190.142.128.0/19190.142.128.1 to 190.142.159.254190.142.159.2558,190
118190.142.160.0/19190.142.160.1 to 190.142.191.254190.142.191.2558,190
119190.142.192.0/19190.142.192.1 to 190.142.223.254190.142.223.2558,190
120190.142.224.0/19190.142.224.1 to 190.142.255.254190.142.255.2558,190
121190.143.0.0/19190.143.0.1 to 190.143.31.254190.143.31.2558,190
122190.143.32.0/19190.143.32.1 to 190.143.63.254190.143.63.2558,190
123190.143.64.0/19190.143.64.1 to 190.143.95.254190.143.95.2558,190
124190.143.96.0/19190.143.96.1 to 190.143.127.254190.143.127.2558,190
125190.143.128.0/19190.143.128.1 to 190.143.159.254190.143.159.2558,190
126190.143.160.0/19190.143.160.1 to 190.143.191.254190.143.191.2558,190
127190.143.192.0/19190.143.192.1 to 190.143.223.254190.143.223.2558,190
128190.143.224.0/19190.143.224.1 to 190.143.255.254190.143.255.2558,190

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.