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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.

Network180.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
180.0.0.0
Broadcast address
181.255.255.255
First usable
180.0.0.1
Last usable
181.255.255.254
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
B (default /16)
As numbers
Hex B4000000 · Integer 3019898880 to 3053453311
Reverse DNS zones
180.in-addr.arpa
181.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
Address10110100.00000000.00000000.00000000180.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10110100.00000000.00000000.00000000180.0.0.0
Broadcast10110101.11111111.11111111.11111111181.255.255.255
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)

180.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1180.0.0.0/14180.0.0.1 to 180.3.255.254180.3.255.255262,142
2180.4.0.0/14180.4.0.1 to 180.7.255.254180.7.255.255262,142
3180.8.0.0/14180.8.0.1 to 180.11.255.254180.11.255.255262,142
4180.12.0.0/14180.12.0.1 to 180.15.255.254180.15.255.255262,142
5180.16.0.0/14180.16.0.1 to 180.19.255.254180.19.255.255262,142
6180.20.0.0/14180.20.0.1 to 180.23.255.254180.23.255.255262,142
7180.24.0.0/14180.24.0.1 to 180.27.255.254180.27.255.255262,142
8180.28.0.0/14180.28.0.1 to 180.31.255.254180.31.255.255262,142
9180.32.0.0/14180.32.0.1 to 180.35.255.254180.35.255.255262,142
10180.36.0.0/14180.36.0.1 to 180.39.255.254180.39.255.255262,142
11180.40.0.0/14180.40.0.1 to 180.43.255.254180.43.255.255262,142
12180.44.0.0/14180.44.0.1 to 180.47.255.254180.47.255.255262,142
13180.48.0.0/14180.48.0.1 to 180.51.255.254180.51.255.255262,142
14180.52.0.0/14180.52.0.1 to 180.55.255.254180.55.255.255262,142
15180.56.0.0/14180.56.0.1 to 180.59.255.254180.59.255.255262,142
16180.60.0.0/14180.60.0.1 to 180.63.255.254180.63.255.255262,142
17180.64.0.0/14180.64.0.1 to 180.67.255.254180.67.255.255262,142
18180.68.0.0/14180.68.0.1 to 180.71.255.254180.71.255.255262,142
19180.72.0.0/14180.72.0.1 to 180.75.255.254180.75.255.255262,142
20180.76.0.0/14180.76.0.1 to 180.79.255.254180.79.255.255262,142
21180.80.0.0/14180.80.0.1 to 180.83.255.254180.83.255.255262,142
22180.84.0.0/14180.84.0.1 to 180.87.255.254180.87.255.255262,142
23180.88.0.0/14180.88.0.1 to 180.91.255.254180.91.255.255262,142
24180.92.0.0/14180.92.0.1 to 180.95.255.254180.95.255.255262,142
25180.96.0.0/14180.96.0.1 to 180.99.255.254180.99.255.255262,142
26180.100.0.0/14180.100.0.1 to 180.103.255.254180.103.255.255262,142
27180.104.0.0/14180.104.0.1 to 180.107.255.254180.107.255.255262,142
28180.108.0.0/14180.108.0.1 to 180.111.255.254180.111.255.255262,142
29180.112.0.0/14180.112.0.1 to 180.115.255.254180.115.255.255262,142
30180.116.0.0/14180.116.0.1 to 180.119.255.254180.119.255.255262,142
31180.120.0.0/14180.120.0.1 to 180.123.255.254180.123.255.255262,142
32180.124.0.0/14180.124.0.1 to 180.127.255.254180.127.255.255262,142
33180.128.0.0/14180.128.0.1 to 180.131.255.254180.131.255.255262,142
34180.132.0.0/14180.132.0.1 to 180.135.255.254180.135.255.255262,142
35180.136.0.0/14180.136.0.1 to 180.139.255.254180.139.255.255262,142
36180.140.0.0/14180.140.0.1 to 180.143.255.254180.143.255.255262,142
37180.144.0.0/14180.144.0.1 to 180.147.255.254180.147.255.255262,142
38180.148.0.0/14180.148.0.1 to 180.151.255.254180.151.255.255262,142
39180.152.0.0/14180.152.0.1 to 180.155.255.254180.155.255.255262,142
40180.156.0.0/14180.156.0.1 to 180.159.255.254180.159.255.255262,142
41180.160.0.0/14180.160.0.1 to 180.163.255.254180.163.255.255262,142
42180.164.0.0/14180.164.0.1 to 180.167.255.254180.167.255.255262,142
43180.168.0.0/14180.168.0.1 to 180.171.255.254180.171.255.255262,142
44180.172.0.0/14180.172.0.1 to 180.175.255.254180.175.255.255262,142
45180.176.0.0/14180.176.0.1 to 180.179.255.254180.179.255.255262,142
46180.180.0.0/14180.180.0.1 to 180.183.255.254180.183.255.255262,142
47180.184.0.0/14180.184.0.1 to 180.187.255.254180.187.255.255262,142
48180.188.0.0/14180.188.0.1 to 180.191.255.254180.191.255.255262,142
49180.192.0.0/14180.192.0.1 to 180.195.255.254180.195.255.255262,142
50180.196.0.0/14180.196.0.1 to 180.199.255.254180.199.255.255262,142
51180.200.0.0/14180.200.0.1 to 180.203.255.254180.203.255.255262,142
52180.204.0.0/14180.204.0.1 to 180.207.255.254180.207.255.255262,142
53180.208.0.0/14180.208.0.1 to 180.211.255.254180.211.255.255262,142
54180.212.0.0/14180.212.0.1 to 180.215.255.254180.215.255.255262,142
55180.216.0.0/14180.216.0.1 to 180.219.255.254180.219.255.255262,142
56180.220.0.0/14180.220.0.1 to 180.223.255.254180.223.255.255262,142
57180.224.0.0/14180.224.0.1 to 180.227.255.254180.227.255.255262,142
58180.228.0.0/14180.228.0.1 to 180.231.255.254180.231.255.255262,142
59180.232.0.0/14180.232.0.1 to 180.235.255.254180.235.255.255262,142
60180.236.0.0/14180.236.0.1 to 180.239.255.254180.239.255.255262,142
61180.240.0.0/14180.240.0.1 to 180.243.255.254180.243.255.255262,142
62180.244.0.0/14180.244.0.1 to 180.247.255.254180.247.255.255262,142
63180.248.0.0/14180.248.0.1 to 180.251.255.254180.251.255.255262,142
64180.252.0.0/14180.252.0.1 to 180.255.255.254180.255.255.255262,142
65181.0.0.0/14181.0.0.1 to 181.3.255.254181.3.255.255262,142
66181.4.0.0/14181.4.0.1 to 181.7.255.254181.7.255.255262,142
67181.8.0.0/14181.8.0.1 to 181.11.255.254181.11.255.255262,142
68181.12.0.0/14181.12.0.1 to 181.15.255.254181.15.255.255262,142
69181.16.0.0/14181.16.0.1 to 181.19.255.254181.19.255.255262,142
70181.20.0.0/14181.20.0.1 to 181.23.255.254181.23.255.255262,142
71181.24.0.0/14181.24.0.1 to 181.27.255.254181.27.255.255262,142
72181.28.0.0/14181.28.0.1 to 181.31.255.254181.31.255.255262,142
73181.32.0.0/14181.32.0.1 to 181.35.255.254181.35.255.255262,142
74181.36.0.0/14181.36.0.1 to 181.39.255.254181.39.255.255262,142
75181.40.0.0/14181.40.0.1 to 181.43.255.254181.43.255.255262,142
76181.44.0.0/14181.44.0.1 to 181.47.255.254181.47.255.255262,142
77181.48.0.0/14181.48.0.1 to 181.51.255.254181.51.255.255262,142
78181.52.0.0/14181.52.0.1 to 181.55.255.254181.55.255.255262,142
79181.56.0.0/14181.56.0.1 to 181.59.255.254181.59.255.255262,142
80181.60.0.0/14181.60.0.1 to 181.63.255.254181.63.255.255262,142
81181.64.0.0/14181.64.0.1 to 181.67.255.254181.67.255.255262,142
82181.68.0.0/14181.68.0.1 to 181.71.255.254181.71.255.255262,142
83181.72.0.0/14181.72.0.1 to 181.75.255.254181.75.255.255262,142
84181.76.0.0/14181.76.0.1 to 181.79.255.254181.79.255.255262,142
85181.80.0.0/14181.80.0.1 to 181.83.255.254181.83.255.255262,142
86181.84.0.0/14181.84.0.1 to 181.87.255.254181.87.255.255262,142
87181.88.0.0/14181.88.0.1 to 181.91.255.254181.91.255.255262,142
88181.92.0.0/14181.92.0.1 to 181.95.255.254181.95.255.255262,142
89181.96.0.0/14181.96.0.1 to 181.99.255.254181.99.255.255262,142
90181.100.0.0/14181.100.0.1 to 181.103.255.254181.103.255.255262,142
91181.104.0.0/14181.104.0.1 to 181.107.255.254181.107.255.255262,142
92181.108.0.0/14181.108.0.1 to 181.111.255.254181.111.255.255262,142
93181.112.0.0/14181.112.0.1 to 181.115.255.254181.115.255.255262,142
94181.116.0.0/14181.116.0.1 to 181.119.255.254181.119.255.255262,142
95181.120.0.0/14181.120.0.1 to 181.123.255.254181.123.255.255262,142
96181.124.0.0/14181.124.0.1 to 181.127.255.254181.127.255.255262,142
97181.128.0.0/14181.128.0.1 to 181.131.255.254181.131.255.255262,142
98181.132.0.0/14181.132.0.1 to 181.135.255.254181.135.255.255262,142
99181.136.0.0/14181.136.0.1 to 181.139.255.254181.139.255.255262,142
100181.140.0.0/14181.140.0.1 to 181.143.255.254181.143.255.255262,142
101181.144.0.0/14181.144.0.1 to 181.147.255.254181.147.255.255262,142
102181.148.0.0/14181.148.0.1 to 181.151.255.254181.151.255.255262,142
103181.152.0.0/14181.152.0.1 to 181.155.255.254181.155.255.255262,142
104181.156.0.0/14181.156.0.1 to 181.159.255.254181.159.255.255262,142
105181.160.0.0/14181.160.0.1 to 181.163.255.254181.163.255.255262,142
106181.164.0.0/14181.164.0.1 to 181.167.255.254181.167.255.255262,142
107181.168.0.0/14181.168.0.1 to 181.171.255.254181.171.255.255262,142
108181.172.0.0/14181.172.0.1 to 181.175.255.254181.175.255.255262,142
109181.176.0.0/14181.176.0.1 to 181.179.255.254181.179.255.255262,142
110181.180.0.0/14181.180.0.1 to 181.183.255.254181.183.255.255262,142
111181.184.0.0/14181.184.0.1 to 181.187.255.254181.187.255.255262,142
112181.188.0.0/14181.188.0.1 to 181.191.255.254181.191.255.255262,142
113181.192.0.0/14181.192.0.1 to 181.195.255.254181.195.255.255262,142
114181.196.0.0/14181.196.0.1 to 181.199.255.254181.199.255.255262,142
115181.200.0.0/14181.200.0.1 to 181.203.255.254181.203.255.255262,142
116181.204.0.0/14181.204.0.1 to 181.207.255.254181.207.255.255262,142
117181.208.0.0/14181.208.0.1 to 181.211.255.254181.211.255.255262,142
118181.212.0.0/14181.212.0.1 to 181.215.255.254181.215.255.255262,142
119181.216.0.0/14181.216.0.1 to 181.219.255.254181.219.255.255262,142
120181.220.0.0/14181.220.0.1 to 181.223.255.254181.223.255.255262,142
121181.224.0.0/14181.224.0.1 to 181.227.255.254181.227.255.255262,142
122181.228.0.0/14181.228.0.1 to 181.231.255.254181.231.255.255262,142
123181.232.0.0/14181.232.0.1 to 181.235.255.254181.235.255.255262,142
124181.236.0.0/14181.236.0.1 to 181.239.255.254181.239.255.255262,142
125181.240.0.0/14181.240.0.1 to 181.243.255.254181.243.255.255262,142
126181.244.0.0/14181.244.0.1 to 181.247.255.254181.247.255.255262,142
127181.248.0.0/14181.248.0.1 to 181.251.255.254181.251.255.255262,142
128181.252.0.0/14181.252.0.1 to 181.255.255.254181.255.255.255262,142

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.