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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.

Network192.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
192.0.0.0
Broadcast address
193.255.255.255
First usable
192.0.0.1
Last usable
193.255.255.254
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 C0000000 · Integer 3221225472 to 3254779903
Reverse DNS zones
192.in-addr.arpa
193.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
Address11000000.00000000.00000000.00000000192.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11000000.00000000.00000000.00000000192.0.0.0
Broadcast11000001.11111111.11111111.11111111193.255.255.255
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)

192.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1192.0.0.0/14192.0.0.1 to 192.3.255.254192.3.255.255262,142
2192.4.0.0/14192.4.0.1 to 192.7.255.254192.7.255.255262,142
3192.8.0.0/14192.8.0.1 to 192.11.255.254192.11.255.255262,142
4192.12.0.0/14192.12.0.1 to 192.15.255.254192.15.255.255262,142
5192.16.0.0/14192.16.0.1 to 192.19.255.254192.19.255.255262,142
6192.20.0.0/14192.20.0.1 to 192.23.255.254192.23.255.255262,142
7192.24.0.0/14192.24.0.1 to 192.27.255.254192.27.255.255262,142
8192.28.0.0/14192.28.0.1 to 192.31.255.254192.31.255.255262,142
9192.32.0.0/14192.32.0.1 to 192.35.255.254192.35.255.255262,142
10192.36.0.0/14192.36.0.1 to 192.39.255.254192.39.255.255262,142
11192.40.0.0/14192.40.0.1 to 192.43.255.254192.43.255.255262,142
12192.44.0.0/14192.44.0.1 to 192.47.255.254192.47.255.255262,142
13192.48.0.0/14192.48.0.1 to 192.51.255.254192.51.255.255262,142
14192.52.0.0/14192.52.0.1 to 192.55.255.254192.55.255.255262,142
15192.56.0.0/14192.56.0.1 to 192.59.255.254192.59.255.255262,142
16192.60.0.0/14192.60.0.1 to 192.63.255.254192.63.255.255262,142
17192.64.0.0/14192.64.0.1 to 192.67.255.254192.67.255.255262,142
18192.68.0.0/14192.68.0.1 to 192.71.255.254192.71.255.255262,142
19192.72.0.0/14192.72.0.1 to 192.75.255.254192.75.255.255262,142
20192.76.0.0/14192.76.0.1 to 192.79.255.254192.79.255.255262,142
21192.80.0.0/14192.80.0.1 to 192.83.255.254192.83.255.255262,142
22192.84.0.0/14192.84.0.1 to 192.87.255.254192.87.255.255262,142
23192.88.0.0/14192.88.0.1 to 192.91.255.254192.91.255.255262,142
24192.92.0.0/14192.92.0.1 to 192.95.255.254192.95.255.255262,142
25192.96.0.0/14192.96.0.1 to 192.99.255.254192.99.255.255262,142
26192.100.0.0/14192.100.0.1 to 192.103.255.254192.103.255.255262,142
27192.104.0.0/14192.104.0.1 to 192.107.255.254192.107.255.255262,142
28192.108.0.0/14192.108.0.1 to 192.111.255.254192.111.255.255262,142
29192.112.0.0/14192.112.0.1 to 192.115.255.254192.115.255.255262,142
30192.116.0.0/14192.116.0.1 to 192.119.255.254192.119.255.255262,142
31192.120.0.0/14192.120.0.1 to 192.123.255.254192.123.255.255262,142
32192.124.0.0/14192.124.0.1 to 192.127.255.254192.127.255.255262,142
33192.128.0.0/14192.128.0.1 to 192.131.255.254192.131.255.255262,142
34192.132.0.0/14192.132.0.1 to 192.135.255.254192.135.255.255262,142
35192.136.0.0/14192.136.0.1 to 192.139.255.254192.139.255.255262,142
36192.140.0.0/14192.140.0.1 to 192.143.255.254192.143.255.255262,142
37192.144.0.0/14192.144.0.1 to 192.147.255.254192.147.255.255262,142
38192.148.0.0/14192.148.0.1 to 192.151.255.254192.151.255.255262,142
39192.152.0.0/14192.152.0.1 to 192.155.255.254192.155.255.255262,142
40192.156.0.0/14192.156.0.1 to 192.159.255.254192.159.255.255262,142
41192.160.0.0/14192.160.0.1 to 192.163.255.254192.163.255.255262,142
42192.164.0.0/14192.164.0.1 to 192.167.255.254192.167.255.255262,142
43192.168.0.0/14192.168.0.1 to 192.171.255.254192.171.255.255262,142
44192.172.0.0/14192.172.0.1 to 192.175.255.254192.175.255.255262,142
45192.176.0.0/14192.176.0.1 to 192.179.255.254192.179.255.255262,142
46192.180.0.0/14192.180.0.1 to 192.183.255.254192.183.255.255262,142
47192.184.0.0/14192.184.0.1 to 192.187.255.254192.187.255.255262,142
48192.188.0.0/14192.188.0.1 to 192.191.255.254192.191.255.255262,142
49192.192.0.0/14192.192.0.1 to 192.195.255.254192.195.255.255262,142
50192.196.0.0/14192.196.0.1 to 192.199.255.254192.199.255.255262,142
51192.200.0.0/14192.200.0.1 to 192.203.255.254192.203.255.255262,142
52192.204.0.0/14192.204.0.1 to 192.207.255.254192.207.255.255262,142
53192.208.0.0/14192.208.0.1 to 192.211.255.254192.211.255.255262,142
54192.212.0.0/14192.212.0.1 to 192.215.255.254192.215.255.255262,142
55192.216.0.0/14192.216.0.1 to 192.219.255.254192.219.255.255262,142
56192.220.0.0/14192.220.0.1 to 192.223.255.254192.223.255.255262,142
57192.224.0.0/14192.224.0.1 to 192.227.255.254192.227.255.255262,142
58192.228.0.0/14192.228.0.1 to 192.231.255.254192.231.255.255262,142
59192.232.0.0/14192.232.0.1 to 192.235.255.254192.235.255.255262,142
60192.236.0.0/14192.236.0.1 to 192.239.255.254192.239.255.255262,142
61192.240.0.0/14192.240.0.1 to 192.243.255.254192.243.255.255262,142
62192.244.0.0/14192.244.0.1 to 192.247.255.254192.247.255.255262,142
63192.248.0.0/14192.248.0.1 to 192.251.255.254192.251.255.255262,142
64192.252.0.0/14192.252.0.1 to 192.255.255.254192.255.255.255262,142
65193.0.0.0/14193.0.0.1 to 193.3.255.254193.3.255.255262,142
66193.4.0.0/14193.4.0.1 to 193.7.255.254193.7.255.255262,142
67193.8.0.0/14193.8.0.1 to 193.11.255.254193.11.255.255262,142
68193.12.0.0/14193.12.0.1 to 193.15.255.254193.15.255.255262,142
69193.16.0.0/14193.16.0.1 to 193.19.255.254193.19.255.255262,142
70193.20.0.0/14193.20.0.1 to 193.23.255.254193.23.255.255262,142
71193.24.0.0/14193.24.0.1 to 193.27.255.254193.27.255.255262,142
72193.28.0.0/14193.28.0.1 to 193.31.255.254193.31.255.255262,142
73193.32.0.0/14193.32.0.1 to 193.35.255.254193.35.255.255262,142
74193.36.0.0/14193.36.0.1 to 193.39.255.254193.39.255.255262,142
75193.40.0.0/14193.40.0.1 to 193.43.255.254193.43.255.255262,142
76193.44.0.0/14193.44.0.1 to 193.47.255.254193.47.255.255262,142
77193.48.0.0/14193.48.0.1 to 193.51.255.254193.51.255.255262,142
78193.52.0.0/14193.52.0.1 to 193.55.255.254193.55.255.255262,142
79193.56.0.0/14193.56.0.1 to 193.59.255.254193.59.255.255262,142
80193.60.0.0/14193.60.0.1 to 193.63.255.254193.63.255.255262,142
81193.64.0.0/14193.64.0.1 to 193.67.255.254193.67.255.255262,142
82193.68.0.0/14193.68.0.1 to 193.71.255.254193.71.255.255262,142
83193.72.0.0/14193.72.0.1 to 193.75.255.254193.75.255.255262,142
84193.76.0.0/14193.76.0.1 to 193.79.255.254193.79.255.255262,142
85193.80.0.0/14193.80.0.1 to 193.83.255.254193.83.255.255262,142
86193.84.0.0/14193.84.0.1 to 193.87.255.254193.87.255.255262,142
87193.88.0.0/14193.88.0.1 to 193.91.255.254193.91.255.255262,142
88193.92.0.0/14193.92.0.1 to 193.95.255.254193.95.255.255262,142
89193.96.0.0/14193.96.0.1 to 193.99.255.254193.99.255.255262,142
90193.100.0.0/14193.100.0.1 to 193.103.255.254193.103.255.255262,142
91193.104.0.0/14193.104.0.1 to 193.107.255.254193.107.255.255262,142
92193.108.0.0/14193.108.0.1 to 193.111.255.254193.111.255.255262,142
93193.112.0.0/14193.112.0.1 to 193.115.255.254193.115.255.255262,142
94193.116.0.0/14193.116.0.1 to 193.119.255.254193.119.255.255262,142
95193.120.0.0/14193.120.0.1 to 193.123.255.254193.123.255.255262,142
96193.124.0.0/14193.124.0.1 to 193.127.255.254193.127.255.255262,142
97193.128.0.0/14193.128.0.1 to 193.131.255.254193.131.255.255262,142
98193.132.0.0/14193.132.0.1 to 193.135.255.254193.135.255.255262,142
99193.136.0.0/14193.136.0.1 to 193.139.255.254193.139.255.255262,142
100193.140.0.0/14193.140.0.1 to 193.143.255.254193.143.255.255262,142
101193.144.0.0/14193.144.0.1 to 193.147.255.254193.147.255.255262,142
102193.148.0.0/14193.148.0.1 to 193.151.255.254193.151.255.255262,142
103193.152.0.0/14193.152.0.1 to 193.155.255.254193.155.255.255262,142
104193.156.0.0/14193.156.0.1 to 193.159.255.254193.159.255.255262,142
105193.160.0.0/14193.160.0.1 to 193.163.255.254193.163.255.255262,142
106193.164.0.0/14193.164.0.1 to 193.167.255.254193.167.255.255262,142
107193.168.0.0/14193.168.0.1 to 193.171.255.254193.171.255.255262,142
108193.172.0.0/14193.172.0.1 to 193.175.255.254193.175.255.255262,142
109193.176.0.0/14193.176.0.1 to 193.179.255.254193.179.255.255262,142
110193.180.0.0/14193.180.0.1 to 193.183.255.254193.183.255.255262,142
111193.184.0.0/14193.184.0.1 to 193.187.255.254193.187.255.255262,142
112193.188.0.0/14193.188.0.1 to 193.191.255.254193.191.255.255262,142
113193.192.0.0/14193.192.0.1 to 193.195.255.254193.195.255.255262,142
114193.196.0.0/14193.196.0.1 to 193.199.255.254193.199.255.255262,142
115193.200.0.0/14193.200.0.1 to 193.203.255.254193.203.255.255262,142
116193.204.0.0/14193.204.0.1 to 193.207.255.254193.207.255.255262,142
117193.208.0.0/14193.208.0.1 to 193.211.255.254193.211.255.255262,142
118193.212.0.0/14193.212.0.1 to 193.215.255.254193.215.255.255262,142
119193.216.0.0/14193.216.0.1 to 193.219.255.254193.219.255.255262,142
120193.220.0.0/14193.220.0.1 to 193.223.255.254193.223.255.255262,142
121193.224.0.0/14193.224.0.1 to 193.227.255.254193.227.255.255262,142
122193.228.0.0/14193.228.0.1 to 193.231.255.254193.231.255.255262,142
123193.232.0.0/14193.232.0.1 to 193.235.255.254193.235.255.255262,142
124193.236.0.0/14193.236.0.1 to 193.239.255.254193.239.255.255262,142
125193.240.0.0/14193.240.0.1 to 193.243.255.254193.243.255.255262,142
126193.244.0.0/14193.244.0.1 to 193.247.255.254193.247.255.255262,142
127193.248.0.0/14193.248.0.1 to 193.251.255.254193.251.255.255262,142
128193.252.0.0/14193.252.0.1 to 193.255.255.254193.255.255.255262,142

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.