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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.

Network212.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
212.0.0.0
Broadcast address
213.255.255.255
First usable
212.0.0.1
Last usable
213.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
C (default /24)
As numbers
Hex D4000000 · Integer 3556769792 to 3590324223
Reverse DNS zones
212.in-addr.arpa
213.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010100.00000000.00000000.00000000212.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11010100.00000000.00000000.00000000212.0.0.0
Broadcast11010101.11111111.11111111.11111111213.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

212.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1212.0.0.0/14212.0.0.1 to 212.3.255.254212.3.255.255262,142
2212.4.0.0/14212.4.0.1 to 212.7.255.254212.7.255.255262,142
3212.8.0.0/14212.8.0.1 to 212.11.255.254212.11.255.255262,142
4212.12.0.0/14212.12.0.1 to 212.15.255.254212.15.255.255262,142
5212.16.0.0/14212.16.0.1 to 212.19.255.254212.19.255.255262,142
6212.20.0.0/14212.20.0.1 to 212.23.255.254212.23.255.255262,142
7212.24.0.0/14212.24.0.1 to 212.27.255.254212.27.255.255262,142
8212.28.0.0/14212.28.0.1 to 212.31.255.254212.31.255.255262,142
9212.32.0.0/14212.32.0.1 to 212.35.255.254212.35.255.255262,142
10212.36.0.0/14212.36.0.1 to 212.39.255.254212.39.255.255262,142
11212.40.0.0/14212.40.0.1 to 212.43.255.254212.43.255.255262,142
12212.44.0.0/14212.44.0.1 to 212.47.255.254212.47.255.255262,142
13212.48.0.0/14212.48.0.1 to 212.51.255.254212.51.255.255262,142
14212.52.0.0/14212.52.0.1 to 212.55.255.254212.55.255.255262,142
15212.56.0.0/14212.56.0.1 to 212.59.255.254212.59.255.255262,142
16212.60.0.0/14212.60.0.1 to 212.63.255.254212.63.255.255262,142
17212.64.0.0/14212.64.0.1 to 212.67.255.254212.67.255.255262,142
18212.68.0.0/14212.68.0.1 to 212.71.255.254212.71.255.255262,142
19212.72.0.0/14212.72.0.1 to 212.75.255.254212.75.255.255262,142
20212.76.0.0/14212.76.0.1 to 212.79.255.254212.79.255.255262,142
21212.80.0.0/14212.80.0.1 to 212.83.255.254212.83.255.255262,142
22212.84.0.0/14212.84.0.1 to 212.87.255.254212.87.255.255262,142
23212.88.0.0/14212.88.0.1 to 212.91.255.254212.91.255.255262,142
24212.92.0.0/14212.92.0.1 to 212.95.255.254212.95.255.255262,142
25212.96.0.0/14212.96.0.1 to 212.99.255.254212.99.255.255262,142
26212.100.0.0/14212.100.0.1 to 212.103.255.254212.103.255.255262,142
27212.104.0.0/14212.104.0.1 to 212.107.255.254212.107.255.255262,142
28212.108.0.0/14212.108.0.1 to 212.111.255.254212.111.255.255262,142
29212.112.0.0/14212.112.0.1 to 212.115.255.254212.115.255.255262,142
30212.116.0.0/14212.116.0.1 to 212.119.255.254212.119.255.255262,142
31212.120.0.0/14212.120.0.1 to 212.123.255.254212.123.255.255262,142
32212.124.0.0/14212.124.0.1 to 212.127.255.254212.127.255.255262,142
33212.128.0.0/14212.128.0.1 to 212.131.255.254212.131.255.255262,142
34212.132.0.0/14212.132.0.1 to 212.135.255.254212.135.255.255262,142
35212.136.0.0/14212.136.0.1 to 212.139.255.254212.139.255.255262,142
36212.140.0.0/14212.140.0.1 to 212.143.255.254212.143.255.255262,142
37212.144.0.0/14212.144.0.1 to 212.147.255.254212.147.255.255262,142
38212.148.0.0/14212.148.0.1 to 212.151.255.254212.151.255.255262,142
39212.152.0.0/14212.152.0.1 to 212.155.255.254212.155.255.255262,142
40212.156.0.0/14212.156.0.1 to 212.159.255.254212.159.255.255262,142
41212.160.0.0/14212.160.0.1 to 212.163.255.254212.163.255.255262,142
42212.164.0.0/14212.164.0.1 to 212.167.255.254212.167.255.255262,142
43212.168.0.0/14212.168.0.1 to 212.171.255.254212.171.255.255262,142
44212.172.0.0/14212.172.0.1 to 212.175.255.254212.175.255.255262,142
45212.176.0.0/14212.176.0.1 to 212.179.255.254212.179.255.255262,142
46212.180.0.0/14212.180.0.1 to 212.183.255.254212.183.255.255262,142
47212.184.0.0/14212.184.0.1 to 212.187.255.254212.187.255.255262,142
48212.188.0.0/14212.188.0.1 to 212.191.255.254212.191.255.255262,142
49212.192.0.0/14212.192.0.1 to 212.195.255.254212.195.255.255262,142
50212.196.0.0/14212.196.0.1 to 212.199.255.254212.199.255.255262,142
51212.200.0.0/14212.200.0.1 to 212.203.255.254212.203.255.255262,142
52212.204.0.0/14212.204.0.1 to 212.207.255.254212.207.255.255262,142
53212.208.0.0/14212.208.0.1 to 212.211.255.254212.211.255.255262,142
54212.212.0.0/14212.212.0.1 to 212.215.255.254212.215.255.255262,142
55212.216.0.0/14212.216.0.1 to 212.219.255.254212.219.255.255262,142
56212.220.0.0/14212.220.0.1 to 212.223.255.254212.223.255.255262,142
57212.224.0.0/14212.224.0.1 to 212.227.255.254212.227.255.255262,142
58212.228.0.0/14212.228.0.1 to 212.231.255.254212.231.255.255262,142
59212.232.0.0/14212.232.0.1 to 212.235.255.254212.235.255.255262,142
60212.236.0.0/14212.236.0.1 to 212.239.255.254212.239.255.255262,142
61212.240.0.0/14212.240.0.1 to 212.243.255.254212.243.255.255262,142
62212.244.0.0/14212.244.0.1 to 212.247.255.254212.247.255.255262,142
63212.248.0.0/14212.248.0.1 to 212.251.255.254212.251.255.255262,142
64212.252.0.0/14212.252.0.1 to 212.255.255.254212.255.255.255262,142
65213.0.0.0/14213.0.0.1 to 213.3.255.254213.3.255.255262,142
66213.4.0.0/14213.4.0.1 to 213.7.255.254213.7.255.255262,142
67213.8.0.0/14213.8.0.1 to 213.11.255.254213.11.255.255262,142
68213.12.0.0/14213.12.0.1 to 213.15.255.254213.15.255.255262,142
69213.16.0.0/14213.16.0.1 to 213.19.255.254213.19.255.255262,142
70213.20.0.0/14213.20.0.1 to 213.23.255.254213.23.255.255262,142
71213.24.0.0/14213.24.0.1 to 213.27.255.254213.27.255.255262,142
72213.28.0.0/14213.28.0.1 to 213.31.255.254213.31.255.255262,142
73213.32.0.0/14213.32.0.1 to 213.35.255.254213.35.255.255262,142
74213.36.0.0/14213.36.0.1 to 213.39.255.254213.39.255.255262,142
75213.40.0.0/14213.40.0.1 to 213.43.255.254213.43.255.255262,142
76213.44.0.0/14213.44.0.1 to 213.47.255.254213.47.255.255262,142
77213.48.0.0/14213.48.0.1 to 213.51.255.254213.51.255.255262,142
78213.52.0.0/14213.52.0.1 to 213.55.255.254213.55.255.255262,142
79213.56.0.0/14213.56.0.1 to 213.59.255.254213.59.255.255262,142
80213.60.0.0/14213.60.0.1 to 213.63.255.254213.63.255.255262,142
81213.64.0.0/14213.64.0.1 to 213.67.255.254213.67.255.255262,142
82213.68.0.0/14213.68.0.1 to 213.71.255.254213.71.255.255262,142
83213.72.0.0/14213.72.0.1 to 213.75.255.254213.75.255.255262,142
84213.76.0.0/14213.76.0.1 to 213.79.255.254213.79.255.255262,142
85213.80.0.0/14213.80.0.1 to 213.83.255.254213.83.255.255262,142
86213.84.0.0/14213.84.0.1 to 213.87.255.254213.87.255.255262,142
87213.88.0.0/14213.88.0.1 to 213.91.255.254213.91.255.255262,142
88213.92.0.0/14213.92.0.1 to 213.95.255.254213.95.255.255262,142
89213.96.0.0/14213.96.0.1 to 213.99.255.254213.99.255.255262,142
90213.100.0.0/14213.100.0.1 to 213.103.255.254213.103.255.255262,142
91213.104.0.0/14213.104.0.1 to 213.107.255.254213.107.255.255262,142
92213.108.0.0/14213.108.0.1 to 213.111.255.254213.111.255.255262,142
93213.112.0.0/14213.112.0.1 to 213.115.255.254213.115.255.255262,142
94213.116.0.0/14213.116.0.1 to 213.119.255.254213.119.255.255262,142
95213.120.0.0/14213.120.0.1 to 213.123.255.254213.123.255.255262,142
96213.124.0.0/14213.124.0.1 to 213.127.255.254213.127.255.255262,142
97213.128.0.0/14213.128.0.1 to 213.131.255.254213.131.255.255262,142
98213.132.0.0/14213.132.0.1 to 213.135.255.254213.135.255.255262,142
99213.136.0.0/14213.136.0.1 to 213.139.255.254213.139.255.255262,142
100213.140.0.0/14213.140.0.1 to 213.143.255.254213.143.255.255262,142
101213.144.0.0/14213.144.0.1 to 213.147.255.254213.147.255.255262,142
102213.148.0.0/14213.148.0.1 to 213.151.255.254213.151.255.255262,142
103213.152.0.0/14213.152.0.1 to 213.155.255.254213.155.255.255262,142
104213.156.0.0/14213.156.0.1 to 213.159.255.254213.159.255.255262,142
105213.160.0.0/14213.160.0.1 to 213.163.255.254213.163.255.255262,142
106213.164.0.0/14213.164.0.1 to 213.167.255.254213.167.255.255262,142
107213.168.0.0/14213.168.0.1 to 213.171.255.254213.171.255.255262,142
108213.172.0.0/14213.172.0.1 to 213.175.255.254213.175.255.255262,142
109213.176.0.0/14213.176.0.1 to 213.179.255.254213.179.255.255262,142
110213.180.0.0/14213.180.0.1 to 213.183.255.254213.183.255.255262,142
111213.184.0.0/14213.184.0.1 to 213.187.255.254213.187.255.255262,142
112213.188.0.0/14213.188.0.1 to 213.191.255.254213.191.255.255262,142
113213.192.0.0/14213.192.0.1 to 213.195.255.254213.195.255.255262,142
114213.196.0.0/14213.196.0.1 to 213.199.255.254213.199.255.255262,142
115213.200.0.0/14213.200.0.1 to 213.203.255.254213.203.255.255262,142
116213.204.0.0/14213.204.0.1 to 213.207.255.254213.207.255.255262,142
117213.208.0.0/14213.208.0.1 to 213.211.255.254213.211.255.255262,142
118213.212.0.0/14213.212.0.1 to 213.215.255.254213.215.255.255262,142
119213.216.0.0/14213.216.0.1 to 213.219.255.254213.219.255.255262,142
120213.220.0.0/14213.220.0.1 to 213.223.255.254213.223.255.255262,142
121213.224.0.0/14213.224.0.1 to 213.227.255.254213.227.255.255262,142
122213.228.0.0/14213.228.0.1 to 213.231.255.254213.231.255.255262,142
123213.232.0.0/14213.232.0.1 to 213.235.255.254213.235.255.255262,142
124213.236.0.0/14213.236.0.1 to 213.239.255.254213.239.255.255262,142
125213.240.0.0/14213.240.0.1 to 213.243.255.254213.243.255.255262,142
126213.244.0.0/14213.244.0.1 to 213.247.255.254213.247.255.255262,142
127213.248.0.0/14213.248.0.1 to 213.251.255.254213.251.255.255262,142
128213.252.0.0/14213.252.0.1 to 213.255.255.254213.255.255.255262,142

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.