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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.

Network178.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
178.0.0.0
Broadcast address
179.255.255.255
First usable
178.0.0.1
Last usable
179.255.255.254
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 B2000000 · Integer 2986344448 to 3019898879
Reverse DNS zones
178.in-addr.arpa
179.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
Address10110010.00000000.00000000.00000000178.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10110010.00000000.00000000.00000000178.0.0.0
Broadcast10110011.11111111.11111111.11111111179.255.255.255
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)

178.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1178.0.0.0/14178.0.0.1 to 178.3.255.254178.3.255.255262,142
2178.4.0.0/14178.4.0.1 to 178.7.255.254178.7.255.255262,142
3178.8.0.0/14178.8.0.1 to 178.11.255.254178.11.255.255262,142
4178.12.0.0/14178.12.0.1 to 178.15.255.254178.15.255.255262,142
5178.16.0.0/14178.16.0.1 to 178.19.255.254178.19.255.255262,142
6178.20.0.0/14178.20.0.1 to 178.23.255.254178.23.255.255262,142
7178.24.0.0/14178.24.0.1 to 178.27.255.254178.27.255.255262,142
8178.28.0.0/14178.28.0.1 to 178.31.255.254178.31.255.255262,142
9178.32.0.0/14178.32.0.1 to 178.35.255.254178.35.255.255262,142
10178.36.0.0/14178.36.0.1 to 178.39.255.254178.39.255.255262,142
11178.40.0.0/14178.40.0.1 to 178.43.255.254178.43.255.255262,142
12178.44.0.0/14178.44.0.1 to 178.47.255.254178.47.255.255262,142
13178.48.0.0/14178.48.0.1 to 178.51.255.254178.51.255.255262,142
14178.52.0.0/14178.52.0.1 to 178.55.255.254178.55.255.255262,142
15178.56.0.0/14178.56.0.1 to 178.59.255.254178.59.255.255262,142
16178.60.0.0/14178.60.0.1 to 178.63.255.254178.63.255.255262,142
17178.64.0.0/14178.64.0.1 to 178.67.255.254178.67.255.255262,142
18178.68.0.0/14178.68.0.1 to 178.71.255.254178.71.255.255262,142
19178.72.0.0/14178.72.0.1 to 178.75.255.254178.75.255.255262,142
20178.76.0.0/14178.76.0.1 to 178.79.255.254178.79.255.255262,142
21178.80.0.0/14178.80.0.1 to 178.83.255.254178.83.255.255262,142
22178.84.0.0/14178.84.0.1 to 178.87.255.254178.87.255.255262,142
23178.88.0.0/14178.88.0.1 to 178.91.255.254178.91.255.255262,142
24178.92.0.0/14178.92.0.1 to 178.95.255.254178.95.255.255262,142
25178.96.0.0/14178.96.0.1 to 178.99.255.254178.99.255.255262,142
26178.100.0.0/14178.100.0.1 to 178.103.255.254178.103.255.255262,142
27178.104.0.0/14178.104.0.1 to 178.107.255.254178.107.255.255262,142
28178.108.0.0/14178.108.0.1 to 178.111.255.254178.111.255.255262,142
29178.112.0.0/14178.112.0.1 to 178.115.255.254178.115.255.255262,142
30178.116.0.0/14178.116.0.1 to 178.119.255.254178.119.255.255262,142
31178.120.0.0/14178.120.0.1 to 178.123.255.254178.123.255.255262,142
32178.124.0.0/14178.124.0.1 to 178.127.255.254178.127.255.255262,142
33178.128.0.0/14178.128.0.1 to 178.131.255.254178.131.255.255262,142
34178.132.0.0/14178.132.0.1 to 178.135.255.254178.135.255.255262,142
35178.136.0.0/14178.136.0.1 to 178.139.255.254178.139.255.255262,142
36178.140.0.0/14178.140.0.1 to 178.143.255.254178.143.255.255262,142
37178.144.0.0/14178.144.0.1 to 178.147.255.254178.147.255.255262,142
38178.148.0.0/14178.148.0.1 to 178.151.255.254178.151.255.255262,142
39178.152.0.0/14178.152.0.1 to 178.155.255.254178.155.255.255262,142
40178.156.0.0/14178.156.0.1 to 178.159.255.254178.159.255.255262,142
41178.160.0.0/14178.160.0.1 to 178.163.255.254178.163.255.255262,142
42178.164.0.0/14178.164.0.1 to 178.167.255.254178.167.255.255262,142
43178.168.0.0/14178.168.0.1 to 178.171.255.254178.171.255.255262,142
44178.172.0.0/14178.172.0.1 to 178.175.255.254178.175.255.255262,142
45178.176.0.0/14178.176.0.1 to 178.179.255.254178.179.255.255262,142
46178.180.0.0/14178.180.0.1 to 178.183.255.254178.183.255.255262,142
47178.184.0.0/14178.184.0.1 to 178.187.255.254178.187.255.255262,142
48178.188.0.0/14178.188.0.1 to 178.191.255.254178.191.255.255262,142
49178.192.0.0/14178.192.0.1 to 178.195.255.254178.195.255.255262,142
50178.196.0.0/14178.196.0.1 to 178.199.255.254178.199.255.255262,142
51178.200.0.0/14178.200.0.1 to 178.203.255.254178.203.255.255262,142
52178.204.0.0/14178.204.0.1 to 178.207.255.254178.207.255.255262,142
53178.208.0.0/14178.208.0.1 to 178.211.255.254178.211.255.255262,142
54178.212.0.0/14178.212.0.1 to 178.215.255.254178.215.255.255262,142
55178.216.0.0/14178.216.0.1 to 178.219.255.254178.219.255.255262,142
56178.220.0.0/14178.220.0.1 to 178.223.255.254178.223.255.255262,142
57178.224.0.0/14178.224.0.1 to 178.227.255.254178.227.255.255262,142
58178.228.0.0/14178.228.0.1 to 178.231.255.254178.231.255.255262,142
59178.232.0.0/14178.232.0.1 to 178.235.255.254178.235.255.255262,142
60178.236.0.0/14178.236.0.1 to 178.239.255.254178.239.255.255262,142
61178.240.0.0/14178.240.0.1 to 178.243.255.254178.243.255.255262,142
62178.244.0.0/14178.244.0.1 to 178.247.255.254178.247.255.255262,142
63178.248.0.0/14178.248.0.1 to 178.251.255.254178.251.255.255262,142
64178.252.0.0/14178.252.0.1 to 178.255.255.254178.255.255.255262,142
65179.0.0.0/14179.0.0.1 to 179.3.255.254179.3.255.255262,142
66179.4.0.0/14179.4.0.1 to 179.7.255.254179.7.255.255262,142
67179.8.0.0/14179.8.0.1 to 179.11.255.254179.11.255.255262,142
68179.12.0.0/14179.12.0.1 to 179.15.255.254179.15.255.255262,142
69179.16.0.0/14179.16.0.1 to 179.19.255.254179.19.255.255262,142
70179.20.0.0/14179.20.0.1 to 179.23.255.254179.23.255.255262,142
71179.24.0.0/14179.24.0.1 to 179.27.255.254179.27.255.255262,142
72179.28.0.0/14179.28.0.1 to 179.31.255.254179.31.255.255262,142
73179.32.0.0/14179.32.0.1 to 179.35.255.254179.35.255.255262,142
74179.36.0.0/14179.36.0.1 to 179.39.255.254179.39.255.255262,142
75179.40.0.0/14179.40.0.1 to 179.43.255.254179.43.255.255262,142
76179.44.0.0/14179.44.0.1 to 179.47.255.254179.47.255.255262,142
77179.48.0.0/14179.48.0.1 to 179.51.255.254179.51.255.255262,142
78179.52.0.0/14179.52.0.1 to 179.55.255.254179.55.255.255262,142
79179.56.0.0/14179.56.0.1 to 179.59.255.254179.59.255.255262,142
80179.60.0.0/14179.60.0.1 to 179.63.255.254179.63.255.255262,142
81179.64.0.0/14179.64.0.1 to 179.67.255.254179.67.255.255262,142
82179.68.0.0/14179.68.0.1 to 179.71.255.254179.71.255.255262,142
83179.72.0.0/14179.72.0.1 to 179.75.255.254179.75.255.255262,142
84179.76.0.0/14179.76.0.1 to 179.79.255.254179.79.255.255262,142
85179.80.0.0/14179.80.0.1 to 179.83.255.254179.83.255.255262,142
86179.84.0.0/14179.84.0.1 to 179.87.255.254179.87.255.255262,142
87179.88.0.0/14179.88.0.1 to 179.91.255.254179.91.255.255262,142
88179.92.0.0/14179.92.0.1 to 179.95.255.254179.95.255.255262,142
89179.96.0.0/14179.96.0.1 to 179.99.255.254179.99.255.255262,142
90179.100.0.0/14179.100.0.1 to 179.103.255.254179.103.255.255262,142
91179.104.0.0/14179.104.0.1 to 179.107.255.254179.107.255.255262,142
92179.108.0.0/14179.108.0.1 to 179.111.255.254179.111.255.255262,142
93179.112.0.0/14179.112.0.1 to 179.115.255.254179.115.255.255262,142
94179.116.0.0/14179.116.0.1 to 179.119.255.254179.119.255.255262,142
95179.120.0.0/14179.120.0.1 to 179.123.255.254179.123.255.255262,142
96179.124.0.0/14179.124.0.1 to 179.127.255.254179.127.255.255262,142
97179.128.0.0/14179.128.0.1 to 179.131.255.254179.131.255.255262,142
98179.132.0.0/14179.132.0.1 to 179.135.255.254179.135.255.255262,142
99179.136.0.0/14179.136.0.1 to 179.139.255.254179.139.255.255262,142
100179.140.0.0/14179.140.0.1 to 179.143.255.254179.143.255.255262,142
101179.144.0.0/14179.144.0.1 to 179.147.255.254179.147.255.255262,142
102179.148.0.0/14179.148.0.1 to 179.151.255.254179.151.255.255262,142
103179.152.0.0/14179.152.0.1 to 179.155.255.254179.155.255.255262,142
104179.156.0.0/14179.156.0.1 to 179.159.255.254179.159.255.255262,142
105179.160.0.0/14179.160.0.1 to 179.163.255.254179.163.255.255262,142
106179.164.0.0/14179.164.0.1 to 179.167.255.254179.167.255.255262,142
107179.168.0.0/14179.168.0.1 to 179.171.255.254179.171.255.255262,142
108179.172.0.0/14179.172.0.1 to 179.175.255.254179.175.255.255262,142
109179.176.0.0/14179.176.0.1 to 179.179.255.254179.179.255.255262,142
110179.180.0.0/14179.180.0.1 to 179.183.255.254179.183.255.255262,142
111179.184.0.0/14179.184.0.1 to 179.187.255.254179.187.255.255262,142
112179.188.0.0/14179.188.0.1 to 179.191.255.254179.191.255.255262,142
113179.192.0.0/14179.192.0.1 to 179.195.255.254179.195.255.255262,142
114179.196.0.0/14179.196.0.1 to 179.199.255.254179.199.255.255262,142
115179.200.0.0/14179.200.0.1 to 179.203.255.254179.203.255.255262,142
116179.204.0.0/14179.204.0.1 to 179.207.255.254179.207.255.255262,142
117179.208.0.0/14179.208.0.1 to 179.211.255.254179.211.255.255262,142
118179.212.0.0/14179.212.0.1 to 179.215.255.254179.215.255.255262,142
119179.216.0.0/14179.216.0.1 to 179.219.255.254179.219.255.255262,142
120179.220.0.0/14179.220.0.1 to 179.223.255.254179.223.255.255262,142
121179.224.0.0/14179.224.0.1 to 179.227.255.254179.227.255.255262,142
122179.228.0.0/14179.228.0.1 to 179.231.255.254179.231.255.255262,142
123179.232.0.0/14179.232.0.1 to 179.235.255.254179.235.255.255262,142
124179.236.0.0/14179.236.0.1 to 179.239.255.254179.239.255.255262,142
125179.240.0.0/14179.240.0.1 to 179.243.255.254179.243.255.255262,142
126179.244.0.0/14179.244.0.1 to 179.247.255.254179.247.255.255262,142
127179.248.0.0/14179.248.0.1 to 179.251.255.254179.251.255.255262,142
128179.252.0.0/14179.252.0.1 to 179.255.255.254179.255.255.255262,142

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.