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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.

Network212.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
212.0.0.0
Broadcast address
215.255.255.255
First usable
212.0.0.1
Last usable
215.255.255.254
Usable hosts
67,108,862 (67,108,864 less the network and broadcast addresses)
Subnet mask
252.0.0.0
Wildcard mask
3.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/6
Type
Public public
Old class
C (default /24)
As numbers
Hex D4000000 · Integer 3556769792 to 3623878655
Reverse DNS zones
212.in-addr.arpa
213.in-addr.arpa
214.in-addr.arpa
215.in-addr.arpa
/6 is not on a 8-bit boundary, so it takes 4 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010100.00000000.00000000.00000000212.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network11010100.00000000.00000000.00000000212.0.0.0
Broadcast11010111.11111111.11111111.11111111215.255.255.255
Split into smaller subnets/13
/7 (2)/8 (4)/9 (8)/10 (16)/11 (32)/12 (64)/13 (128)/14 (256)/15 (512)/16 (1,024)/17 (2,048)/18 (4,096)

212.0.0.0/6 makes 128 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1212.0.0.0/13212.0.0.1 to 212.7.255.254212.7.255.255524,286
2212.8.0.0/13212.8.0.1 to 212.15.255.254212.15.255.255524,286
3212.16.0.0/13212.16.0.1 to 212.23.255.254212.23.255.255524,286
4212.24.0.0/13212.24.0.1 to 212.31.255.254212.31.255.255524,286
5212.32.0.0/13212.32.0.1 to 212.39.255.254212.39.255.255524,286
6212.40.0.0/13212.40.0.1 to 212.47.255.254212.47.255.255524,286
7212.48.0.0/13212.48.0.1 to 212.55.255.254212.55.255.255524,286
8212.56.0.0/13212.56.0.1 to 212.63.255.254212.63.255.255524,286
9212.64.0.0/13212.64.0.1 to 212.71.255.254212.71.255.255524,286
10212.72.0.0/13212.72.0.1 to 212.79.255.254212.79.255.255524,286
11212.80.0.0/13212.80.0.1 to 212.87.255.254212.87.255.255524,286
12212.88.0.0/13212.88.0.1 to 212.95.255.254212.95.255.255524,286
13212.96.0.0/13212.96.0.1 to 212.103.255.254212.103.255.255524,286
14212.104.0.0/13212.104.0.1 to 212.111.255.254212.111.255.255524,286
15212.112.0.0/13212.112.0.1 to 212.119.255.254212.119.255.255524,286
16212.120.0.0/13212.120.0.1 to 212.127.255.254212.127.255.255524,286
17212.128.0.0/13212.128.0.1 to 212.135.255.254212.135.255.255524,286
18212.136.0.0/13212.136.0.1 to 212.143.255.254212.143.255.255524,286
19212.144.0.0/13212.144.0.1 to 212.151.255.254212.151.255.255524,286
20212.152.0.0/13212.152.0.1 to 212.159.255.254212.159.255.255524,286
21212.160.0.0/13212.160.0.1 to 212.167.255.254212.167.255.255524,286
22212.168.0.0/13212.168.0.1 to 212.175.255.254212.175.255.255524,286
23212.176.0.0/13212.176.0.1 to 212.183.255.254212.183.255.255524,286
24212.184.0.0/13212.184.0.1 to 212.191.255.254212.191.255.255524,286
25212.192.0.0/13212.192.0.1 to 212.199.255.254212.199.255.255524,286
26212.200.0.0/13212.200.0.1 to 212.207.255.254212.207.255.255524,286
27212.208.0.0/13212.208.0.1 to 212.215.255.254212.215.255.255524,286
28212.216.0.0/13212.216.0.1 to 212.223.255.254212.223.255.255524,286
29212.224.0.0/13212.224.0.1 to 212.231.255.254212.231.255.255524,286
30212.232.0.0/13212.232.0.1 to 212.239.255.254212.239.255.255524,286
31212.240.0.0/13212.240.0.1 to 212.247.255.254212.247.255.255524,286
32212.248.0.0/13212.248.0.1 to 212.255.255.254212.255.255.255524,286
33213.0.0.0/13213.0.0.1 to 213.7.255.254213.7.255.255524,286
34213.8.0.0/13213.8.0.1 to 213.15.255.254213.15.255.255524,286
35213.16.0.0/13213.16.0.1 to 213.23.255.254213.23.255.255524,286
36213.24.0.0/13213.24.0.1 to 213.31.255.254213.31.255.255524,286
37213.32.0.0/13213.32.0.1 to 213.39.255.254213.39.255.255524,286
38213.40.0.0/13213.40.0.1 to 213.47.255.254213.47.255.255524,286
39213.48.0.0/13213.48.0.1 to 213.55.255.254213.55.255.255524,286
40213.56.0.0/13213.56.0.1 to 213.63.255.254213.63.255.255524,286
41213.64.0.0/13213.64.0.1 to 213.71.255.254213.71.255.255524,286
42213.72.0.0/13213.72.0.1 to 213.79.255.254213.79.255.255524,286
43213.80.0.0/13213.80.0.1 to 213.87.255.254213.87.255.255524,286
44213.88.0.0/13213.88.0.1 to 213.95.255.254213.95.255.255524,286
45213.96.0.0/13213.96.0.1 to 213.103.255.254213.103.255.255524,286
46213.104.0.0/13213.104.0.1 to 213.111.255.254213.111.255.255524,286
47213.112.0.0/13213.112.0.1 to 213.119.255.254213.119.255.255524,286
48213.120.0.0/13213.120.0.1 to 213.127.255.254213.127.255.255524,286
49213.128.0.0/13213.128.0.1 to 213.135.255.254213.135.255.255524,286
50213.136.0.0/13213.136.0.1 to 213.143.255.254213.143.255.255524,286
51213.144.0.0/13213.144.0.1 to 213.151.255.254213.151.255.255524,286
52213.152.0.0/13213.152.0.1 to 213.159.255.254213.159.255.255524,286
53213.160.0.0/13213.160.0.1 to 213.167.255.254213.167.255.255524,286
54213.168.0.0/13213.168.0.1 to 213.175.255.254213.175.255.255524,286
55213.176.0.0/13213.176.0.1 to 213.183.255.254213.183.255.255524,286
56213.184.0.0/13213.184.0.1 to 213.191.255.254213.191.255.255524,286
57213.192.0.0/13213.192.0.1 to 213.199.255.254213.199.255.255524,286
58213.200.0.0/13213.200.0.1 to 213.207.255.254213.207.255.255524,286
59213.208.0.0/13213.208.0.1 to 213.215.255.254213.215.255.255524,286
60213.216.0.0/13213.216.0.1 to 213.223.255.254213.223.255.255524,286
61213.224.0.0/13213.224.0.1 to 213.231.255.254213.231.255.255524,286
62213.232.0.0/13213.232.0.1 to 213.239.255.254213.239.255.255524,286
63213.240.0.0/13213.240.0.1 to 213.247.255.254213.247.255.255524,286
64213.248.0.0/13213.248.0.1 to 213.255.255.254213.255.255.255524,286
65214.0.0.0/13214.0.0.1 to 214.7.255.254214.7.255.255524,286
66214.8.0.0/13214.8.0.1 to 214.15.255.254214.15.255.255524,286
67214.16.0.0/13214.16.0.1 to 214.23.255.254214.23.255.255524,286
68214.24.0.0/13214.24.0.1 to 214.31.255.254214.31.255.255524,286
69214.32.0.0/13214.32.0.1 to 214.39.255.254214.39.255.255524,286
70214.40.0.0/13214.40.0.1 to 214.47.255.254214.47.255.255524,286
71214.48.0.0/13214.48.0.1 to 214.55.255.254214.55.255.255524,286
72214.56.0.0/13214.56.0.1 to 214.63.255.254214.63.255.255524,286
73214.64.0.0/13214.64.0.1 to 214.71.255.254214.71.255.255524,286
74214.72.0.0/13214.72.0.1 to 214.79.255.254214.79.255.255524,286
75214.80.0.0/13214.80.0.1 to 214.87.255.254214.87.255.255524,286
76214.88.0.0/13214.88.0.1 to 214.95.255.254214.95.255.255524,286
77214.96.0.0/13214.96.0.1 to 214.103.255.254214.103.255.255524,286
78214.104.0.0/13214.104.0.1 to 214.111.255.254214.111.255.255524,286
79214.112.0.0/13214.112.0.1 to 214.119.255.254214.119.255.255524,286
80214.120.0.0/13214.120.0.1 to 214.127.255.254214.127.255.255524,286
81214.128.0.0/13214.128.0.1 to 214.135.255.254214.135.255.255524,286
82214.136.0.0/13214.136.0.1 to 214.143.255.254214.143.255.255524,286
83214.144.0.0/13214.144.0.1 to 214.151.255.254214.151.255.255524,286
84214.152.0.0/13214.152.0.1 to 214.159.255.254214.159.255.255524,286
85214.160.0.0/13214.160.0.1 to 214.167.255.254214.167.255.255524,286
86214.168.0.0/13214.168.0.1 to 214.175.255.254214.175.255.255524,286
87214.176.0.0/13214.176.0.1 to 214.183.255.254214.183.255.255524,286
88214.184.0.0/13214.184.0.1 to 214.191.255.254214.191.255.255524,286
89214.192.0.0/13214.192.0.1 to 214.199.255.254214.199.255.255524,286
90214.200.0.0/13214.200.0.1 to 214.207.255.254214.207.255.255524,286
91214.208.0.0/13214.208.0.1 to 214.215.255.254214.215.255.255524,286
92214.216.0.0/13214.216.0.1 to 214.223.255.254214.223.255.255524,286
93214.224.0.0/13214.224.0.1 to 214.231.255.254214.231.255.255524,286
94214.232.0.0/13214.232.0.1 to 214.239.255.254214.239.255.255524,286
95214.240.0.0/13214.240.0.1 to 214.247.255.254214.247.255.255524,286
96214.248.0.0/13214.248.0.1 to 214.255.255.254214.255.255.255524,286
97215.0.0.0/13215.0.0.1 to 215.7.255.254215.7.255.255524,286
98215.8.0.0/13215.8.0.1 to 215.15.255.254215.15.255.255524,286
99215.16.0.0/13215.16.0.1 to 215.23.255.254215.23.255.255524,286
100215.24.0.0/13215.24.0.1 to 215.31.255.254215.31.255.255524,286
101215.32.0.0/13215.32.0.1 to 215.39.255.254215.39.255.255524,286
102215.40.0.0/13215.40.0.1 to 215.47.255.254215.47.255.255524,286
103215.48.0.0/13215.48.0.1 to 215.55.255.254215.55.255.255524,286
104215.56.0.0/13215.56.0.1 to 215.63.255.254215.63.255.255524,286
105215.64.0.0/13215.64.0.1 to 215.71.255.254215.71.255.255524,286
106215.72.0.0/13215.72.0.1 to 215.79.255.254215.79.255.255524,286
107215.80.0.0/13215.80.0.1 to 215.87.255.254215.87.255.255524,286
108215.88.0.0/13215.88.0.1 to 215.95.255.254215.95.255.255524,286
109215.96.0.0/13215.96.0.1 to 215.103.255.254215.103.255.255524,286
110215.104.0.0/13215.104.0.1 to 215.111.255.254215.111.255.255524,286
111215.112.0.0/13215.112.0.1 to 215.119.255.254215.119.255.255524,286
112215.120.0.0/13215.120.0.1 to 215.127.255.254215.127.255.255524,286
113215.128.0.0/13215.128.0.1 to 215.135.255.254215.135.255.255524,286
114215.136.0.0/13215.136.0.1 to 215.143.255.254215.143.255.255524,286
115215.144.0.0/13215.144.0.1 to 215.151.255.254215.151.255.255524,286
116215.152.0.0/13215.152.0.1 to 215.159.255.254215.159.255.255524,286
117215.160.0.0/13215.160.0.1 to 215.167.255.254215.167.255.255524,286
118215.168.0.0/13215.168.0.1 to 215.175.255.254215.175.255.255524,286
119215.176.0.0/13215.176.0.1 to 215.183.255.254215.183.255.255524,286
120215.184.0.0/13215.184.0.1 to 215.191.255.254215.191.255.255524,286
121215.192.0.0/13215.192.0.1 to 215.199.255.254215.199.255.255524,286
122215.200.0.0/13215.200.0.1 to 215.207.255.254215.207.255.255524,286
123215.208.0.0/13215.208.0.1 to 215.215.255.254215.215.255.255524,286
124215.216.0.0/13215.216.0.1 to 215.223.255.254215.223.255.255524,286
125215.224.0.0/13215.224.0.1 to 215.231.255.254215.231.255.255524,286
126215.232.0.0/13215.232.0.1 to 215.239.255.254215.239.255.255524,286
127215.240.0.0/13215.240.0.1 to 215.247.255.254215.247.255.255524,286
128215.248.0.0/13215.248.0.1 to 215.255.255.254215.255.255.255524,286

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.