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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.

Network178.158.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
178.158.0.0
Broadcast address
178.158.255.255
First usable
178.158.0.1
Last usable
178.158.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
B (default /16)
As numbers
Hex B29E0000 · Integer 2996699136 to 2996764671
Reverse DNS zone
158.178.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110010.10011110..00000000.00000000178.158.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network10110010.10011110..00000000.00000000178.158.0.0
Broadcast10110010.10011110..11111111.11111111178.158.255.255
Split into smaller subnets/23
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

178.158.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1178.158.0.0/23178.158.0.1 to 178.158.1.254178.158.1.255510
2178.158.2.0/23178.158.2.1 to 178.158.3.254178.158.3.255510
3178.158.4.0/23178.158.4.1 to 178.158.5.254178.158.5.255510
4178.158.6.0/23178.158.6.1 to 178.158.7.254178.158.7.255510
5178.158.8.0/23178.158.8.1 to 178.158.9.254178.158.9.255510
6178.158.10.0/23178.158.10.1 to 178.158.11.254178.158.11.255510
7178.158.12.0/23178.158.12.1 to 178.158.13.254178.158.13.255510
8178.158.14.0/23178.158.14.1 to 178.158.15.254178.158.15.255510
9178.158.16.0/23178.158.16.1 to 178.158.17.254178.158.17.255510
10178.158.18.0/23178.158.18.1 to 178.158.19.254178.158.19.255510
11178.158.20.0/23178.158.20.1 to 178.158.21.254178.158.21.255510
12178.158.22.0/23178.158.22.1 to 178.158.23.254178.158.23.255510
13178.158.24.0/23178.158.24.1 to 178.158.25.254178.158.25.255510
14178.158.26.0/23178.158.26.1 to 178.158.27.254178.158.27.255510
15178.158.28.0/23178.158.28.1 to 178.158.29.254178.158.29.255510
16178.158.30.0/23178.158.30.1 to 178.158.31.254178.158.31.255510
17178.158.32.0/23178.158.32.1 to 178.158.33.254178.158.33.255510
18178.158.34.0/23178.158.34.1 to 178.158.35.254178.158.35.255510
19178.158.36.0/23178.158.36.1 to 178.158.37.254178.158.37.255510
20178.158.38.0/23178.158.38.1 to 178.158.39.254178.158.39.255510
21178.158.40.0/23178.158.40.1 to 178.158.41.254178.158.41.255510
22178.158.42.0/23178.158.42.1 to 178.158.43.254178.158.43.255510
23178.158.44.0/23178.158.44.1 to 178.158.45.254178.158.45.255510
24178.158.46.0/23178.158.46.1 to 178.158.47.254178.158.47.255510
25178.158.48.0/23178.158.48.1 to 178.158.49.254178.158.49.255510
26178.158.50.0/23178.158.50.1 to 178.158.51.254178.158.51.255510
27178.158.52.0/23178.158.52.1 to 178.158.53.254178.158.53.255510
28178.158.54.0/23178.158.54.1 to 178.158.55.254178.158.55.255510
29178.158.56.0/23178.158.56.1 to 178.158.57.254178.158.57.255510
30178.158.58.0/23178.158.58.1 to 178.158.59.254178.158.59.255510
31178.158.60.0/23178.158.60.1 to 178.158.61.254178.158.61.255510
32178.158.62.0/23178.158.62.1 to 178.158.63.254178.158.63.255510
33178.158.64.0/23178.158.64.1 to 178.158.65.254178.158.65.255510
34178.158.66.0/23178.158.66.1 to 178.158.67.254178.158.67.255510
35178.158.68.0/23178.158.68.1 to 178.158.69.254178.158.69.255510
36178.158.70.0/23178.158.70.1 to 178.158.71.254178.158.71.255510
37178.158.72.0/23178.158.72.1 to 178.158.73.254178.158.73.255510
38178.158.74.0/23178.158.74.1 to 178.158.75.254178.158.75.255510
39178.158.76.0/23178.158.76.1 to 178.158.77.254178.158.77.255510
40178.158.78.0/23178.158.78.1 to 178.158.79.254178.158.79.255510
41178.158.80.0/23178.158.80.1 to 178.158.81.254178.158.81.255510
42178.158.82.0/23178.158.82.1 to 178.158.83.254178.158.83.255510
43178.158.84.0/23178.158.84.1 to 178.158.85.254178.158.85.255510
44178.158.86.0/23178.158.86.1 to 178.158.87.254178.158.87.255510
45178.158.88.0/23178.158.88.1 to 178.158.89.254178.158.89.255510
46178.158.90.0/23178.158.90.1 to 178.158.91.254178.158.91.255510
47178.158.92.0/23178.158.92.1 to 178.158.93.254178.158.93.255510
48178.158.94.0/23178.158.94.1 to 178.158.95.254178.158.95.255510
49178.158.96.0/23178.158.96.1 to 178.158.97.254178.158.97.255510
50178.158.98.0/23178.158.98.1 to 178.158.99.254178.158.99.255510
51178.158.100.0/23178.158.100.1 to 178.158.101.254178.158.101.255510
52178.158.102.0/23178.158.102.1 to 178.158.103.254178.158.103.255510
53178.158.104.0/23178.158.104.1 to 178.158.105.254178.158.105.255510
54178.158.106.0/23178.158.106.1 to 178.158.107.254178.158.107.255510
55178.158.108.0/23178.158.108.1 to 178.158.109.254178.158.109.255510
56178.158.110.0/23178.158.110.1 to 178.158.111.254178.158.111.255510
57178.158.112.0/23178.158.112.1 to 178.158.113.254178.158.113.255510
58178.158.114.0/23178.158.114.1 to 178.158.115.254178.158.115.255510
59178.158.116.0/23178.158.116.1 to 178.158.117.254178.158.117.255510
60178.158.118.0/23178.158.118.1 to 178.158.119.254178.158.119.255510
61178.158.120.0/23178.158.120.1 to 178.158.121.254178.158.121.255510
62178.158.122.0/23178.158.122.1 to 178.158.123.254178.158.123.255510
63178.158.124.0/23178.158.124.1 to 178.158.125.254178.158.125.255510
64178.158.126.0/23178.158.126.1 to 178.158.127.254178.158.127.255510
65178.158.128.0/23178.158.128.1 to 178.158.129.254178.158.129.255510
66178.158.130.0/23178.158.130.1 to 178.158.131.254178.158.131.255510
67178.158.132.0/23178.158.132.1 to 178.158.133.254178.158.133.255510
68178.158.134.0/23178.158.134.1 to 178.158.135.254178.158.135.255510
69178.158.136.0/23178.158.136.1 to 178.158.137.254178.158.137.255510
70178.158.138.0/23178.158.138.1 to 178.158.139.254178.158.139.255510
71178.158.140.0/23178.158.140.1 to 178.158.141.254178.158.141.255510
72178.158.142.0/23178.158.142.1 to 178.158.143.254178.158.143.255510
73178.158.144.0/23178.158.144.1 to 178.158.145.254178.158.145.255510
74178.158.146.0/23178.158.146.1 to 178.158.147.254178.158.147.255510
75178.158.148.0/23178.158.148.1 to 178.158.149.254178.158.149.255510
76178.158.150.0/23178.158.150.1 to 178.158.151.254178.158.151.255510
77178.158.152.0/23178.158.152.1 to 178.158.153.254178.158.153.255510
78178.158.154.0/23178.158.154.1 to 178.158.155.254178.158.155.255510
79178.158.156.0/23178.158.156.1 to 178.158.157.254178.158.157.255510
80178.158.158.0/23178.158.158.1 to 178.158.159.254178.158.159.255510
81178.158.160.0/23178.158.160.1 to 178.158.161.254178.158.161.255510
82178.158.162.0/23178.158.162.1 to 178.158.163.254178.158.163.255510
83178.158.164.0/23178.158.164.1 to 178.158.165.254178.158.165.255510
84178.158.166.0/23178.158.166.1 to 178.158.167.254178.158.167.255510
85178.158.168.0/23178.158.168.1 to 178.158.169.254178.158.169.255510
86178.158.170.0/23178.158.170.1 to 178.158.171.254178.158.171.255510
87178.158.172.0/23178.158.172.1 to 178.158.173.254178.158.173.255510
88178.158.174.0/23178.158.174.1 to 178.158.175.254178.158.175.255510
89178.158.176.0/23178.158.176.1 to 178.158.177.254178.158.177.255510
90178.158.178.0/23178.158.178.1 to 178.158.179.254178.158.179.255510
91178.158.180.0/23178.158.180.1 to 178.158.181.254178.158.181.255510
92178.158.182.0/23178.158.182.1 to 178.158.183.254178.158.183.255510
93178.158.184.0/23178.158.184.1 to 178.158.185.254178.158.185.255510
94178.158.186.0/23178.158.186.1 to 178.158.187.254178.158.187.255510
95178.158.188.0/23178.158.188.1 to 178.158.189.254178.158.189.255510
96178.158.190.0/23178.158.190.1 to 178.158.191.254178.158.191.255510
97178.158.192.0/23178.158.192.1 to 178.158.193.254178.158.193.255510
98178.158.194.0/23178.158.194.1 to 178.158.195.254178.158.195.255510
99178.158.196.0/23178.158.196.1 to 178.158.197.254178.158.197.255510
100178.158.198.0/23178.158.198.1 to 178.158.199.254178.158.199.255510
101178.158.200.0/23178.158.200.1 to 178.158.201.254178.158.201.255510
102178.158.202.0/23178.158.202.1 to 178.158.203.254178.158.203.255510
103178.158.204.0/23178.158.204.1 to 178.158.205.254178.158.205.255510
104178.158.206.0/23178.158.206.1 to 178.158.207.254178.158.207.255510
105178.158.208.0/23178.158.208.1 to 178.158.209.254178.158.209.255510
106178.158.210.0/23178.158.210.1 to 178.158.211.254178.158.211.255510
107178.158.212.0/23178.158.212.1 to 178.158.213.254178.158.213.255510
108178.158.214.0/23178.158.214.1 to 178.158.215.254178.158.215.255510
109178.158.216.0/23178.158.216.1 to 178.158.217.254178.158.217.255510
110178.158.218.0/23178.158.218.1 to 178.158.219.254178.158.219.255510
111178.158.220.0/23178.158.220.1 to 178.158.221.254178.158.221.255510
112178.158.222.0/23178.158.222.1 to 178.158.223.254178.158.223.255510
113178.158.224.0/23178.158.224.1 to 178.158.225.254178.158.225.255510
114178.158.226.0/23178.158.226.1 to 178.158.227.254178.158.227.255510
115178.158.228.0/23178.158.228.1 to 178.158.229.254178.158.229.255510
116178.158.230.0/23178.158.230.1 to 178.158.231.254178.158.231.255510
117178.158.232.0/23178.158.232.1 to 178.158.233.254178.158.233.255510
118178.158.234.0/23178.158.234.1 to 178.158.235.254178.158.235.255510
119178.158.236.0/23178.158.236.1 to 178.158.237.254178.158.237.255510
120178.158.238.0/23178.158.238.1 to 178.158.239.254178.158.239.255510
121178.158.240.0/23178.158.240.1 to 178.158.241.254178.158.241.255510
122178.158.242.0/23178.158.242.1 to 178.158.243.254178.158.243.255510
123178.158.244.0/23178.158.244.1 to 178.158.245.254178.158.245.255510
124178.158.246.0/23178.158.246.1 to 178.158.247.254178.158.247.255510
125178.158.248.0/23178.158.248.1 to 178.158.249.254178.158.249.255510
126178.158.250.0/23178.158.250.1 to 178.158.251.254178.158.251.255510
127178.158.252.0/23178.158.252.1 to 178.158.253.254178.158.253.255510
128178.158.254.0/23178.158.254.1 to 178.158.255.254178.158.255.255510

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.