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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.

Network145.167.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
145.167.0.0
Broadcast address
145.167.255.255
First usable
145.167.0.1
Last usable
145.167.255.254
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 91A70000 · Integer 2443640832 to 2443706367
Reverse DNS zone
167.145.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010001.10100111..00000000.00000000145.167.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network10010001.10100111..00000000.00000000145.167.0.0
Broadcast10010001.10100111..11111111.11111111145.167.255.255
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)

145.167.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1145.167.0.0/23145.167.0.1 to 145.167.1.254145.167.1.255510
2145.167.2.0/23145.167.2.1 to 145.167.3.254145.167.3.255510
3145.167.4.0/23145.167.4.1 to 145.167.5.254145.167.5.255510
4145.167.6.0/23145.167.6.1 to 145.167.7.254145.167.7.255510
5145.167.8.0/23145.167.8.1 to 145.167.9.254145.167.9.255510
6145.167.10.0/23145.167.10.1 to 145.167.11.254145.167.11.255510
7145.167.12.0/23145.167.12.1 to 145.167.13.254145.167.13.255510
8145.167.14.0/23145.167.14.1 to 145.167.15.254145.167.15.255510
9145.167.16.0/23145.167.16.1 to 145.167.17.254145.167.17.255510
10145.167.18.0/23145.167.18.1 to 145.167.19.254145.167.19.255510
11145.167.20.0/23145.167.20.1 to 145.167.21.254145.167.21.255510
12145.167.22.0/23145.167.22.1 to 145.167.23.254145.167.23.255510
13145.167.24.0/23145.167.24.1 to 145.167.25.254145.167.25.255510
14145.167.26.0/23145.167.26.1 to 145.167.27.254145.167.27.255510
15145.167.28.0/23145.167.28.1 to 145.167.29.254145.167.29.255510
16145.167.30.0/23145.167.30.1 to 145.167.31.254145.167.31.255510
17145.167.32.0/23145.167.32.1 to 145.167.33.254145.167.33.255510
18145.167.34.0/23145.167.34.1 to 145.167.35.254145.167.35.255510
19145.167.36.0/23145.167.36.1 to 145.167.37.254145.167.37.255510
20145.167.38.0/23145.167.38.1 to 145.167.39.254145.167.39.255510
21145.167.40.0/23145.167.40.1 to 145.167.41.254145.167.41.255510
22145.167.42.0/23145.167.42.1 to 145.167.43.254145.167.43.255510
23145.167.44.0/23145.167.44.1 to 145.167.45.254145.167.45.255510
24145.167.46.0/23145.167.46.1 to 145.167.47.254145.167.47.255510
25145.167.48.0/23145.167.48.1 to 145.167.49.254145.167.49.255510
26145.167.50.0/23145.167.50.1 to 145.167.51.254145.167.51.255510
27145.167.52.0/23145.167.52.1 to 145.167.53.254145.167.53.255510
28145.167.54.0/23145.167.54.1 to 145.167.55.254145.167.55.255510
29145.167.56.0/23145.167.56.1 to 145.167.57.254145.167.57.255510
30145.167.58.0/23145.167.58.1 to 145.167.59.254145.167.59.255510
31145.167.60.0/23145.167.60.1 to 145.167.61.254145.167.61.255510
32145.167.62.0/23145.167.62.1 to 145.167.63.254145.167.63.255510
33145.167.64.0/23145.167.64.1 to 145.167.65.254145.167.65.255510
34145.167.66.0/23145.167.66.1 to 145.167.67.254145.167.67.255510
35145.167.68.0/23145.167.68.1 to 145.167.69.254145.167.69.255510
36145.167.70.0/23145.167.70.1 to 145.167.71.254145.167.71.255510
37145.167.72.0/23145.167.72.1 to 145.167.73.254145.167.73.255510
38145.167.74.0/23145.167.74.1 to 145.167.75.254145.167.75.255510
39145.167.76.0/23145.167.76.1 to 145.167.77.254145.167.77.255510
40145.167.78.0/23145.167.78.1 to 145.167.79.254145.167.79.255510
41145.167.80.0/23145.167.80.1 to 145.167.81.254145.167.81.255510
42145.167.82.0/23145.167.82.1 to 145.167.83.254145.167.83.255510
43145.167.84.0/23145.167.84.1 to 145.167.85.254145.167.85.255510
44145.167.86.0/23145.167.86.1 to 145.167.87.254145.167.87.255510
45145.167.88.0/23145.167.88.1 to 145.167.89.254145.167.89.255510
46145.167.90.0/23145.167.90.1 to 145.167.91.254145.167.91.255510
47145.167.92.0/23145.167.92.1 to 145.167.93.254145.167.93.255510
48145.167.94.0/23145.167.94.1 to 145.167.95.254145.167.95.255510
49145.167.96.0/23145.167.96.1 to 145.167.97.254145.167.97.255510
50145.167.98.0/23145.167.98.1 to 145.167.99.254145.167.99.255510
51145.167.100.0/23145.167.100.1 to 145.167.101.254145.167.101.255510
52145.167.102.0/23145.167.102.1 to 145.167.103.254145.167.103.255510
53145.167.104.0/23145.167.104.1 to 145.167.105.254145.167.105.255510
54145.167.106.0/23145.167.106.1 to 145.167.107.254145.167.107.255510
55145.167.108.0/23145.167.108.1 to 145.167.109.254145.167.109.255510
56145.167.110.0/23145.167.110.1 to 145.167.111.254145.167.111.255510
57145.167.112.0/23145.167.112.1 to 145.167.113.254145.167.113.255510
58145.167.114.0/23145.167.114.1 to 145.167.115.254145.167.115.255510
59145.167.116.0/23145.167.116.1 to 145.167.117.254145.167.117.255510
60145.167.118.0/23145.167.118.1 to 145.167.119.254145.167.119.255510
61145.167.120.0/23145.167.120.1 to 145.167.121.254145.167.121.255510
62145.167.122.0/23145.167.122.1 to 145.167.123.254145.167.123.255510
63145.167.124.0/23145.167.124.1 to 145.167.125.254145.167.125.255510
64145.167.126.0/23145.167.126.1 to 145.167.127.254145.167.127.255510
65145.167.128.0/23145.167.128.1 to 145.167.129.254145.167.129.255510
66145.167.130.0/23145.167.130.1 to 145.167.131.254145.167.131.255510
67145.167.132.0/23145.167.132.1 to 145.167.133.254145.167.133.255510
68145.167.134.0/23145.167.134.1 to 145.167.135.254145.167.135.255510
69145.167.136.0/23145.167.136.1 to 145.167.137.254145.167.137.255510
70145.167.138.0/23145.167.138.1 to 145.167.139.254145.167.139.255510
71145.167.140.0/23145.167.140.1 to 145.167.141.254145.167.141.255510
72145.167.142.0/23145.167.142.1 to 145.167.143.254145.167.143.255510
73145.167.144.0/23145.167.144.1 to 145.167.145.254145.167.145.255510
74145.167.146.0/23145.167.146.1 to 145.167.147.254145.167.147.255510
75145.167.148.0/23145.167.148.1 to 145.167.149.254145.167.149.255510
76145.167.150.0/23145.167.150.1 to 145.167.151.254145.167.151.255510
77145.167.152.0/23145.167.152.1 to 145.167.153.254145.167.153.255510
78145.167.154.0/23145.167.154.1 to 145.167.155.254145.167.155.255510
79145.167.156.0/23145.167.156.1 to 145.167.157.254145.167.157.255510
80145.167.158.0/23145.167.158.1 to 145.167.159.254145.167.159.255510
81145.167.160.0/23145.167.160.1 to 145.167.161.254145.167.161.255510
82145.167.162.0/23145.167.162.1 to 145.167.163.254145.167.163.255510
83145.167.164.0/23145.167.164.1 to 145.167.165.254145.167.165.255510
84145.167.166.0/23145.167.166.1 to 145.167.167.254145.167.167.255510
85145.167.168.0/23145.167.168.1 to 145.167.169.254145.167.169.255510
86145.167.170.0/23145.167.170.1 to 145.167.171.254145.167.171.255510
87145.167.172.0/23145.167.172.1 to 145.167.173.254145.167.173.255510
88145.167.174.0/23145.167.174.1 to 145.167.175.254145.167.175.255510
89145.167.176.0/23145.167.176.1 to 145.167.177.254145.167.177.255510
90145.167.178.0/23145.167.178.1 to 145.167.179.254145.167.179.255510
91145.167.180.0/23145.167.180.1 to 145.167.181.254145.167.181.255510
92145.167.182.0/23145.167.182.1 to 145.167.183.254145.167.183.255510
93145.167.184.0/23145.167.184.1 to 145.167.185.254145.167.185.255510
94145.167.186.0/23145.167.186.1 to 145.167.187.254145.167.187.255510
95145.167.188.0/23145.167.188.1 to 145.167.189.254145.167.189.255510
96145.167.190.0/23145.167.190.1 to 145.167.191.254145.167.191.255510
97145.167.192.0/23145.167.192.1 to 145.167.193.254145.167.193.255510
98145.167.194.0/23145.167.194.1 to 145.167.195.254145.167.195.255510
99145.167.196.0/23145.167.196.1 to 145.167.197.254145.167.197.255510
100145.167.198.0/23145.167.198.1 to 145.167.199.254145.167.199.255510
101145.167.200.0/23145.167.200.1 to 145.167.201.254145.167.201.255510
102145.167.202.0/23145.167.202.1 to 145.167.203.254145.167.203.255510
103145.167.204.0/23145.167.204.1 to 145.167.205.254145.167.205.255510
104145.167.206.0/23145.167.206.1 to 145.167.207.254145.167.207.255510
105145.167.208.0/23145.167.208.1 to 145.167.209.254145.167.209.255510
106145.167.210.0/23145.167.210.1 to 145.167.211.254145.167.211.255510
107145.167.212.0/23145.167.212.1 to 145.167.213.254145.167.213.255510
108145.167.214.0/23145.167.214.1 to 145.167.215.254145.167.215.255510
109145.167.216.0/23145.167.216.1 to 145.167.217.254145.167.217.255510
110145.167.218.0/23145.167.218.1 to 145.167.219.254145.167.219.255510
111145.167.220.0/23145.167.220.1 to 145.167.221.254145.167.221.255510
112145.167.222.0/23145.167.222.1 to 145.167.223.254145.167.223.255510
113145.167.224.0/23145.167.224.1 to 145.167.225.254145.167.225.255510
114145.167.226.0/23145.167.226.1 to 145.167.227.254145.167.227.255510
115145.167.228.0/23145.167.228.1 to 145.167.229.254145.167.229.255510
116145.167.230.0/23145.167.230.1 to 145.167.231.254145.167.231.255510
117145.167.232.0/23145.167.232.1 to 145.167.233.254145.167.233.255510
118145.167.234.0/23145.167.234.1 to 145.167.235.254145.167.235.255510
119145.167.236.0/23145.167.236.1 to 145.167.237.254145.167.237.255510
120145.167.238.0/23145.167.238.1 to 145.167.239.254145.167.239.255510
121145.167.240.0/23145.167.240.1 to 145.167.241.254145.167.241.255510
122145.167.242.0/23145.167.242.1 to 145.167.243.254145.167.243.255510
123145.167.244.0/23145.167.244.1 to 145.167.245.254145.167.245.255510
124145.167.246.0/23145.167.246.1 to 145.167.247.254145.167.247.255510
125145.167.248.0/23145.167.248.1 to 145.167.249.254145.167.249.255510
126145.167.250.0/23145.167.250.1 to 145.167.251.254145.167.251.255510
127145.167.252.0/23145.167.252.1 to 145.167.253.254145.167.253.255510
128145.167.254.0/23145.167.254.1 to 145.167.255.254145.167.255.255510

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.