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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.

Network254.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
254.0.0.0
Broadcast address
255.255.255.255
First usable
254.0.0.1
Last usable
255.255.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FE000000 · Integer 4261412864 to 4294967295
Reverse DNS zones
254.in-addr.arpa
255.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
Address11111110.00000000.00000000.00000000254.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11111110.00000000.00000000.00000000254.0.0.0
Broadcast11111111.11111111.11111111.11111111255.255.255.255
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)

254.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1254.0.0.0/14254.0.0.1 to 254.3.255.254254.3.255.255262,142
2254.4.0.0/14254.4.0.1 to 254.7.255.254254.7.255.255262,142
3254.8.0.0/14254.8.0.1 to 254.11.255.254254.11.255.255262,142
4254.12.0.0/14254.12.0.1 to 254.15.255.254254.15.255.255262,142
5254.16.0.0/14254.16.0.1 to 254.19.255.254254.19.255.255262,142
6254.20.0.0/14254.20.0.1 to 254.23.255.254254.23.255.255262,142
7254.24.0.0/14254.24.0.1 to 254.27.255.254254.27.255.255262,142
8254.28.0.0/14254.28.0.1 to 254.31.255.254254.31.255.255262,142
9254.32.0.0/14254.32.0.1 to 254.35.255.254254.35.255.255262,142
10254.36.0.0/14254.36.0.1 to 254.39.255.254254.39.255.255262,142
11254.40.0.0/14254.40.0.1 to 254.43.255.254254.43.255.255262,142
12254.44.0.0/14254.44.0.1 to 254.47.255.254254.47.255.255262,142
13254.48.0.0/14254.48.0.1 to 254.51.255.254254.51.255.255262,142
14254.52.0.0/14254.52.0.1 to 254.55.255.254254.55.255.255262,142
15254.56.0.0/14254.56.0.1 to 254.59.255.254254.59.255.255262,142
16254.60.0.0/14254.60.0.1 to 254.63.255.254254.63.255.255262,142
17254.64.0.0/14254.64.0.1 to 254.67.255.254254.67.255.255262,142
18254.68.0.0/14254.68.0.1 to 254.71.255.254254.71.255.255262,142
19254.72.0.0/14254.72.0.1 to 254.75.255.254254.75.255.255262,142
20254.76.0.0/14254.76.0.1 to 254.79.255.254254.79.255.255262,142
21254.80.0.0/14254.80.0.1 to 254.83.255.254254.83.255.255262,142
22254.84.0.0/14254.84.0.1 to 254.87.255.254254.87.255.255262,142
23254.88.0.0/14254.88.0.1 to 254.91.255.254254.91.255.255262,142
24254.92.0.0/14254.92.0.1 to 254.95.255.254254.95.255.255262,142
25254.96.0.0/14254.96.0.1 to 254.99.255.254254.99.255.255262,142
26254.100.0.0/14254.100.0.1 to 254.103.255.254254.103.255.255262,142
27254.104.0.0/14254.104.0.1 to 254.107.255.254254.107.255.255262,142
28254.108.0.0/14254.108.0.1 to 254.111.255.254254.111.255.255262,142
29254.112.0.0/14254.112.0.1 to 254.115.255.254254.115.255.255262,142
30254.116.0.0/14254.116.0.1 to 254.119.255.254254.119.255.255262,142
31254.120.0.0/14254.120.0.1 to 254.123.255.254254.123.255.255262,142
32254.124.0.0/14254.124.0.1 to 254.127.255.254254.127.255.255262,142
33254.128.0.0/14254.128.0.1 to 254.131.255.254254.131.255.255262,142
34254.132.0.0/14254.132.0.1 to 254.135.255.254254.135.255.255262,142
35254.136.0.0/14254.136.0.1 to 254.139.255.254254.139.255.255262,142
36254.140.0.0/14254.140.0.1 to 254.143.255.254254.143.255.255262,142
37254.144.0.0/14254.144.0.1 to 254.147.255.254254.147.255.255262,142
38254.148.0.0/14254.148.0.1 to 254.151.255.254254.151.255.255262,142
39254.152.0.0/14254.152.0.1 to 254.155.255.254254.155.255.255262,142
40254.156.0.0/14254.156.0.1 to 254.159.255.254254.159.255.255262,142
41254.160.0.0/14254.160.0.1 to 254.163.255.254254.163.255.255262,142
42254.164.0.0/14254.164.0.1 to 254.167.255.254254.167.255.255262,142
43254.168.0.0/14254.168.0.1 to 254.171.255.254254.171.255.255262,142
44254.172.0.0/14254.172.0.1 to 254.175.255.254254.175.255.255262,142
45254.176.0.0/14254.176.0.1 to 254.179.255.254254.179.255.255262,142
46254.180.0.0/14254.180.0.1 to 254.183.255.254254.183.255.255262,142
47254.184.0.0/14254.184.0.1 to 254.187.255.254254.187.255.255262,142
48254.188.0.0/14254.188.0.1 to 254.191.255.254254.191.255.255262,142
49254.192.0.0/14254.192.0.1 to 254.195.255.254254.195.255.255262,142
50254.196.0.0/14254.196.0.1 to 254.199.255.254254.199.255.255262,142
51254.200.0.0/14254.200.0.1 to 254.203.255.254254.203.255.255262,142
52254.204.0.0/14254.204.0.1 to 254.207.255.254254.207.255.255262,142
53254.208.0.0/14254.208.0.1 to 254.211.255.254254.211.255.255262,142
54254.212.0.0/14254.212.0.1 to 254.215.255.254254.215.255.255262,142
55254.216.0.0/14254.216.0.1 to 254.219.255.254254.219.255.255262,142
56254.220.0.0/14254.220.0.1 to 254.223.255.254254.223.255.255262,142
57254.224.0.0/14254.224.0.1 to 254.227.255.254254.227.255.255262,142
58254.228.0.0/14254.228.0.1 to 254.231.255.254254.231.255.255262,142
59254.232.0.0/14254.232.0.1 to 254.235.255.254254.235.255.255262,142
60254.236.0.0/14254.236.0.1 to 254.239.255.254254.239.255.255262,142
61254.240.0.0/14254.240.0.1 to 254.243.255.254254.243.255.255262,142
62254.244.0.0/14254.244.0.1 to 254.247.255.254254.247.255.255262,142
63254.248.0.0/14254.248.0.1 to 254.251.255.254254.251.255.255262,142
64254.252.0.0/14254.252.0.1 to 254.255.255.254254.255.255.255262,142
65255.0.0.0/14255.0.0.1 to 255.3.255.254255.3.255.255262,142
66255.4.0.0/14255.4.0.1 to 255.7.255.254255.7.255.255262,142
67255.8.0.0/14255.8.0.1 to 255.11.255.254255.11.255.255262,142
68255.12.0.0/14255.12.0.1 to 255.15.255.254255.15.255.255262,142
69255.16.0.0/14255.16.0.1 to 255.19.255.254255.19.255.255262,142
70255.20.0.0/14255.20.0.1 to 255.23.255.254255.23.255.255262,142
71255.24.0.0/14255.24.0.1 to 255.27.255.254255.27.255.255262,142
72255.28.0.0/14255.28.0.1 to 255.31.255.254255.31.255.255262,142
73255.32.0.0/14255.32.0.1 to 255.35.255.254255.35.255.255262,142
74255.36.0.0/14255.36.0.1 to 255.39.255.254255.39.255.255262,142
75255.40.0.0/14255.40.0.1 to 255.43.255.254255.43.255.255262,142
76255.44.0.0/14255.44.0.1 to 255.47.255.254255.47.255.255262,142
77255.48.0.0/14255.48.0.1 to 255.51.255.254255.51.255.255262,142
78255.52.0.0/14255.52.0.1 to 255.55.255.254255.55.255.255262,142
79255.56.0.0/14255.56.0.1 to 255.59.255.254255.59.255.255262,142
80255.60.0.0/14255.60.0.1 to 255.63.255.254255.63.255.255262,142
81255.64.0.0/14255.64.0.1 to 255.67.255.254255.67.255.255262,142
82255.68.0.0/14255.68.0.1 to 255.71.255.254255.71.255.255262,142
83255.72.0.0/14255.72.0.1 to 255.75.255.254255.75.255.255262,142
84255.76.0.0/14255.76.0.1 to 255.79.255.254255.79.255.255262,142
85255.80.0.0/14255.80.0.1 to 255.83.255.254255.83.255.255262,142
86255.84.0.0/14255.84.0.1 to 255.87.255.254255.87.255.255262,142
87255.88.0.0/14255.88.0.1 to 255.91.255.254255.91.255.255262,142
88255.92.0.0/14255.92.0.1 to 255.95.255.254255.95.255.255262,142
89255.96.0.0/14255.96.0.1 to 255.99.255.254255.99.255.255262,142
90255.100.0.0/14255.100.0.1 to 255.103.255.254255.103.255.255262,142
91255.104.0.0/14255.104.0.1 to 255.107.255.254255.107.255.255262,142
92255.108.0.0/14255.108.0.1 to 255.111.255.254255.111.255.255262,142
93255.112.0.0/14255.112.0.1 to 255.115.255.254255.115.255.255262,142
94255.116.0.0/14255.116.0.1 to 255.119.255.254255.119.255.255262,142
95255.120.0.0/14255.120.0.1 to 255.123.255.254255.123.255.255262,142
96255.124.0.0/14255.124.0.1 to 255.127.255.254255.127.255.255262,142
97255.128.0.0/14255.128.0.1 to 255.131.255.254255.131.255.255262,142
98255.132.0.0/14255.132.0.1 to 255.135.255.254255.135.255.255262,142
99255.136.0.0/14255.136.0.1 to 255.139.255.254255.139.255.255262,142
100255.140.0.0/14255.140.0.1 to 255.143.255.254255.143.255.255262,142
101255.144.0.0/14255.144.0.1 to 255.147.255.254255.147.255.255262,142
102255.148.0.0/14255.148.0.1 to 255.151.255.254255.151.255.255262,142
103255.152.0.0/14255.152.0.1 to 255.155.255.254255.155.255.255262,142
104255.156.0.0/14255.156.0.1 to 255.159.255.254255.159.255.255262,142
105255.160.0.0/14255.160.0.1 to 255.163.255.254255.163.255.255262,142
106255.164.0.0/14255.164.0.1 to 255.167.255.254255.167.255.255262,142
107255.168.0.0/14255.168.0.1 to 255.171.255.254255.171.255.255262,142
108255.172.0.0/14255.172.0.1 to 255.175.255.254255.175.255.255262,142
109255.176.0.0/14255.176.0.1 to 255.179.255.254255.179.255.255262,142
110255.180.0.0/14255.180.0.1 to 255.183.255.254255.183.255.255262,142
111255.184.0.0/14255.184.0.1 to 255.187.255.254255.187.255.255262,142
112255.188.0.0/14255.188.0.1 to 255.191.255.254255.191.255.255262,142
113255.192.0.0/14255.192.0.1 to 255.195.255.254255.195.255.255262,142
114255.196.0.0/14255.196.0.1 to 255.199.255.254255.199.255.255262,142
115255.200.0.0/14255.200.0.1 to 255.203.255.254255.203.255.255262,142
116255.204.0.0/14255.204.0.1 to 255.207.255.254255.207.255.255262,142
117255.208.0.0/14255.208.0.1 to 255.211.255.254255.211.255.255262,142
118255.212.0.0/14255.212.0.1 to 255.215.255.254255.215.255.255262,142
119255.216.0.0/14255.216.0.1 to 255.219.255.254255.219.255.255262,142
120255.220.0.0/14255.220.0.1 to 255.223.255.254255.223.255.255262,142
121255.224.0.0/14255.224.0.1 to 255.227.255.254255.227.255.255262,142
122255.228.0.0/14255.228.0.1 to 255.231.255.254255.231.255.255262,142
123255.232.0.0/14255.232.0.1 to 255.235.255.254255.235.255.255262,142
124255.236.0.0/14255.236.0.1 to 255.239.255.254255.239.255.255262,142
125255.240.0.0/14255.240.0.1 to 255.243.255.254255.243.255.255262,142
126255.244.0.0/14255.244.0.1 to 255.247.255.254255.247.255.255262,142
127255.248.0.0/14255.248.0.1 to 255.251.255.254255.251.255.255262,142
128255.252.0.0/14255.252.0.1 to 255.255.255.254255.255.255.255262,142

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.