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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.

Network167.3.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
167.3.0.0
Broadcast address
167.3.63.255
First usable
167.3.0.1
Last usable
167.3.63.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
B (default /16)
As numbers
Hex A7030000 · Integer 2801991680 to 2802008063
Reverse DNS zones
0.3.167.in-addr.arpa
1.3.167.in-addr.arpa
2.3.167.in-addr.arpa
3.3.167.in-addr.arpa
4.3.167.in-addr.arpa
5.3.167.in-addr.arpa
6.3.167.in-addr.arpa
7.3.167.in-addr.arpa
8.3.167.in-addr.arpa
9.3.167.in-addr.arpa
10.3.167.in-addr.arpa
11.3.167.in-addr.arpa
12.3.167.in-addr.arpa
13.3.167.in-addr.arpa
14.3.167.in-addr.arpa
15.3.167.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100111.00000011.00000000.00000000167.3.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network10100111.00000011.00000000.00000000167.3.0.0
Broadcast10100111.00000011.00111111.11111111167.3.63.255
Split into smaller subnets/25
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

167.3.0.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1167.3.0.0/25167.3.0.1 to 167.3.0.126167.3.0.127126
2167.3.0.128/25167.3.0.129 to 167.3.0.254167.3.0.255126
3167.3.1.0/25167.3.1.1 to 167.3.1.126167.3.1.127126
4167.3.1.128/25167.3.1.129 to 167.3.1.254167.3.1.255126
5167.3.2.0/25167.3.2.1 to 167.3.2.126167.3.2.127126
6167.3.2.128/25167.3.2.129 to 167.3.2.254167.3.2.255126
7167.3.3.0/25167.3.3.1 to 167.3.3.126167.3.3.127126
8167.3.3.128/25167.3.3.129 to 167.3.3.254167.3.3.255126
9167.3.4.0/25167.3.4.1 to 167.3.4.126167.3.4.127126
10167.3.4.128/25167.3.4.129 to 167.3.4.254167.3.4.255126
11167.3.5.0/25167.3.5.1 to 167.3.5.126167.3.5.127126
12167.3.5.128/25167.3.5.129 to 167.3.5.254167.3.5.255126
13167.3.6.0/25167.3.6.1 to 167.3.6.126167.3.6.127126
14167.3.6.128/25167.3.6.129 to 167.3.6.254167.3.6.255126
15167.3.7.0/25167.3.7.1 to 167.3.7.126167.3.7.127126
16167.3.7.128/25167.3.7.129 to 167.3.7.254167.3.7.255126
17167.3.8.0/25167.3.8.1 to 167.3.8.126167.3.8.127126
18167.3.8.128/25167.3.8.129 to 167.3.8.254167.3.8.255126
19167.3.9.0/25167.3.9.1 to 167.3.9.126167.3.9.127126
20167.3.9.128/25167.3.9.129 to 167.3.9.254167.3.9.255126
21167.3.10.0/25167.3.10.1 to 167.3.10.126167.3.10.127126
22167.3.10.128/25167.3.10.129 to 167.3.10.254167.3.10.255126
23167.3.11.0/25167.3.11.1 to 167.3.11.126167.3.11.127126
24167.3.11.128/25167.3.11.129 to 167.3.11.254167.3.11.255126
25167.3.12.0/25167.3.12.1 to 167.3.12.126167.3.12.127126
26167.3.12.128/25167.3.12.129 to 167.3.12.254167.3.12.255126
27167.3.13.0/25167.3.13.1 to 167.3.13.126167.3.13.127126
28167.3.13.128/25167.3.13.129 to 167.3.13.254167.3.13.255126
29167.3.14.0/25167.3.14.1 to 167.3.14.126167.3.14.127126
30167.3.14.128/25167.3.14.129 to 167.3.14.254167.3.14.255126
31167.3.15.0/25167.3.15.1 to 167.3.15.126167.3.15.127126
32167.3.15.128/25167.3.15.129 to 167.3.15.254167.3.15.255126
33167.3.16.0/25167.3.16.1 to 167.3.16.126167.3.16.127126
34167.3.16.128/25167.3.16.129 to 167.3.16.254167.3.16.255126
35167.3.17.0/25167.3.17.1 to 167.3.17.126167.3.17.127126
36167.3.17.128/25167.3.17.129 to 167.3.17.254167.3.17.255126
37167.3.18.0/25167.3.18.1 to 167.3.18.126167.3.18.127126
38167.3.18.128/25167.3.18.129 to 167.3.18.254167.3.18.255126
39167.3.19.0/25167.3.19.1 to 167.3.19.126167.3.19.127126
40167.3.19.128/25167.3.19.129 to 167.3.19.254167.3.19.255126
41167.3.20.0/25167.3.20.1 to 167.3.20.126167.3.20.127126
42167.3.20.128/25167.3.20.129 to 167.3.20.254167.3.20.255126
43167.3.21.0/25167.3.21.1 to 167.3.21.126167.3.21.127126
44167.3.21.128/25167.3.21.129 to 167.3.21.254167.3.21.255126
45167.3.22.0/25167.3.22.1 to 167.3.22.126167.3.22.127126
46167.3.22.128/25167.3.22.129 to 167.3.22.254167.3.22.255126
47167.3.23.0/25167.3.23.1 to 167.3.23.126167.3.23.127126
48167.3.23.128/25167.3.23.129 to 167.3.23.254167.3.23.255126
49167.3.24.0/25167.3.24.1 to 167.3.24.126167.3.24.127126
50167.3.24.128/25167.3.24.129 to 167.3.24.254167.3.24.255126
51167.3.25.0/25167.3.25.1 to 167.3.25.126167.3.25.127126
52167.3.25.128/25167.3.25.129 to 167.3.25.254167.3.25.255126
53167.3.26.0/25167.3.26.1 to 167.3.26.126167.3.26.127126
54167.3.26.128/25167.3.26.129 to 167.3.26.254167.3.26.255126
55167.3.27.0/25167.3.27.1 to 167.3.27.126167.3.27.127126
56167.3.27.128/25167.3.27.129 to 167.3.27.254167.3.27.255126
57167.3.28.0/25167.3.28.1 to 167.3.28.126167.3.28.127126
58167.3.28.128/25167.3.28.129 to 167.3.28.254167.3.28.255126
59167.3.29.0/25167.3.29.1 to 167.3.29.126167.3.29.127126
60167.3.29.128/25167.3.29.129 to 167.3.29.254167.3.29.255126
61167.3.30.0/25167.3.30.1 to 167.3.30.126167.3.30.127126
62167.3.30.128/25167.3.30.129 to 167.3.30.254167.3.30.255126
63167.3.31.0/25167.3.31.1 to 167.3.31.126167.3.31.127126
64167.3.31.128/25167.3.31.129 to 167.3.31.254167.3.31.255126
65167.3.32.0/25167.3.32.1 to 167.3.32.126167.3.32.127126
66167.3.32.128/25167.3.32.129 to 167.3.32.254167.3.32.255126
67167.3.33.0/25167.3.33.1 to 167.3.33.126167.3.33.127126
68167.3.33.128/25167.3.33.129 to 167.3.33.254167.3.33.255126
69167.3.34.0/25167.3.34.1 to 167.3.34.126167.3.34.127126
70167.3.34.128/25167.3.34.129 to 167.3.34.254167.3.34.255126
71167.3.35.0/25167.3.35.1 to 167.3.35.126167.3.35.127126
72167.3.35.128/25167.3.35.129 to 167.3.35.254167.3.35.255126
73167.3.36.0/25167.3.36.1 to 167.3.36.126167.3.36.127126
74167.3.36.128/25167.3.36.129 to 167.3.36.254167.3.36.255126
75167.3.37.0/25167.3.37.1 to 167.3.37.126167.3.37.127126
76167.3.37.128/25167.3.37.129 to 167.3.37.254167.3.37.255126
77167.3.38.0/25167.3.38.1 to 167.3.38.126167.3.38.127126
78167.3.38.128/25167.3.38.129 to 167.3.38.254167.3.38.255126
79167.3.39.0/25167.3.39.1 to 167.3.39.126167.3.39.127126
80167.3.39.128/25167.3.39.129 to 167.3.39.254167.3.39.255126
81167.3.40.0/25167.3.40.1 to 167.3.40.126167.3.40.127126
82167.3.40.128/25167.3.40.129 to 167.3.40.254167.3.40.255126
83167.3.41.0/25167.3.41.1 to 167.3.41.126167.3.41.127126
84167.3.41.128/25167.3.41.129 to 167.3.41.254167.3.41.255126
85167.3.42.0/25167.3.42.1 to 167.3.42.126167.3.42.127126
86167.3.42.128/25167.3.42.129 to 167.3.42.254167.3.42.255126
87167.3.43.0/25167.3.43.1 to 167.3.43.126167.3.43.127126
88167.3.43.128/25167.3.43.129 to 167.3.43.254167.3.43.255126
89167.3.44.0/25167.3.44.1 to 167.3.44.126167.3.44.127126
90167.3.44.128/25167.3.44.129 to 167.3.44.254167.3.44.255126
91167.3.45.0/25167.3.45.1 to 167.3.45.126167.3.45.127126
92167.3.45.128/25167.3.45.129 to 167.3.45.254167.3.45.255126
93167.3.46.0/25167.3.46.1 to 167.3.46.126167.3.46.127126
94167.3.46.128/25167.3.46.129 to 167.3.46.254167.3.46.255126
95167.3.47.0/25167.3.47.1 to 167.3.47.126167.3.47.127126
96167.3.47.128/25167.3.47.129 to 167.3.47.254167.3.47.255126
97167.3.48.0/25167.3.48.1 to 167.3.48.126167.3.48.127126
98167.3.48.128/25167.3.48.129 to 167.3.48.254167.3.48.255126
99167.3.49.0/25167.3.49.1 to 167.3.49.126167.3.49.127126
100167.3.49.128/25167.3.49.129 to 167.3.49.254167.3.49.255126
101167.3.50.0/25167.3.50.1 to 167.3.50.126167.3.50.127126
102167.3.50.128/25167.3.50.129 to 167.3.50.254167.3.50.255126
103167.3.51.0/25167.3.51.1 to 167.3.51.126167.3.51.127126
104167.3.51.128/25167.3.51.129 to 167.3.51.254167.3.51.255126
105167.3.52.0/25167.3.52.1 to 167.3.52.126167.3.52.127126
106167.3.52.128/25167.3.52.129 to 167.3.52.254167.3.52.255126
107167.3.53.0/25167.3.53.1 to 167.3.53.126167.3.53.127126
108167.3.53.128/25167.3.53.129 to 167.3.53.254167.3.53.255126
109167.3.54.0/25167.3.54.1 to 167.3.54.126167.3.54.127126
110167.3.54.128/25167.3.54.129 to 167.3.54.254167.3.54.255126
111167.3.55.0/25167.3.55.1 to 167.3.55.126167.3.55.127126
112167.3.55.128/25167.3.55.129 to 167.3.55.254167.3.55.255126
113167.3.56.0/25167.3.56.1 to 167.3.56.126167.3.56.127126
114167.3.56.128/25167.3.56.129 to 167.3.56.254167.3.56.255126
115167.3.57.0/25167.3.57.1 to 167.3.57.126167.3.57.127126
116167.3.57.128/25167.3.57.129 to 167.3.57.254167.3.57.255126
117167.3.58.0/25167.3.58.1 to 167.3.58.126167.3.58.127126
118167.3.58.128/25167.3.58.129 to 167.3.58.254167.3.58.255126
119167.3.59.0/25167.3.59.1 to 167.3.59.126167.3.59.127126
120167.3.59.128/25167.3.59.129 to 167.3.59.254167.3.59.255126
121167.3.60.0/25167.3.60.1 to 167.3.60.126167.3.60.127126
122167.3.60.128/25167.3.60.129 to 167.3.60.254167.3.60.255126
123167.3.61.0/25167.3.61.1 to 167.3.61.126167.3.61.127126
124167.3.61.128/25167.3.61.129 to 167.3.61.254167.3.61.255126
125167.3.62.0/25167.3.62.1 to 167.3.62.126167.3.62.127126
126167.3.62.128/25167.3.62.129 to 167.3.62.254167.3.62.255126
127167.3.63.0/25167.3.63.1 to 167.3.63.126167.3.63.127126
128167.3.63.128/25167.3.63.129 to 167.3.63.254167.3.63.255126

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.