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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.

Network192.168.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
192.168.0.0
Broadcast address
192.168.255.255
First usable
192.168.0.1
Last usable
192.168.255.254
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
Private (RFC 1918) 192.168.0.0/16
Office and home networks; not routed on the internet
Old class
C (default /24)
As numbers
Hex C0A80000 · Integer 3232235520 to 3232301055
Reverse DNS zone
168.192.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000000.10101000..00000000.00000000192.168.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network11000000.10101000..00000000.00000000192.168.0.0
Broadcast11000000.10101000..11111111.11111111192.168.255.255
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)

192.168.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1192.168.0.0/23192.168.0.1 to 192.168.1.254192.168.1.255510
2192.168.2.0/23192.168.2.1 to 192.168.3.254192.168.3.255510
3192.168.4.0/23192.168.4.1 to 192.168.5.254192.168.5.255510
4192.168.6.0/23192.168.6.1 to 192.168.7.254192.168.7.255510
5192.168.8.0/23192.168.8.1 to 192.168.9.254192.168.9.255510
6192.168.10.0/23192.168.10.1 to 192.168.11.254192.168.11.255510
7192.168.12.0/23192.168.12.1 to 192.168.13.254192.168.13.255510
8192.168.14.0/23192.168.14.1 to 192.168.15.254192.168.15.255510
9192.168.16.0/23192.168.16.1 to 192.168.17.254192.168.17.255510
10192.168.18.0/23192.168.18.1 to 192.168.19.254192.168.19.255510
11192.168.20.0/23192.168.20.1 to 192.168.21.254192.168.21.255510
12192.168.22.0/23192.168.22.1 to 192.168.23.254192.168.23.255510
13192.168.24.0/23192.168.24.1 to 192.168.25.254192.168.25.255510
14192.168.26.0/23192.168.26.1 to 192.168.27.254192.168.27.255510
15192.168.28.0/23192.168.28.1 to 192.168.29.254192.168.29.255510
16192.168.30.0/23192.168.30.1 to 192.168.31.254192.168.31.255510
17192.168.32.0/23192.168.32.1 to 192.168.33.254192.168.33.255510
18192.168.34.0/23192.168.34.1 to 192.168.35.254192.168.35.255510
19192.168.36.0/23192.168.36.1 to 192.168.37.254192.168.37.255510
20192.168.38.0/23192.168.38.1 to 192.168.39.254192.168.39.255510
21192.168.40.0/23192.168.40.1 to 192.168.41.254192.168.41.255510
22192.168.42.0/23192.168.42.1 to 192.168.43.254192.168.43.255510
23192.168.44.0/23192.168.44.1 to 192.168.45.254192.168.45.255510
24192.168.46.0/23192.168.46.1 to 192.168.47.254192.168.47.255510
25192.168.48.0/23192.168.48.1 to 192.168.49.254192.168.49.255510
26192.168.50.0/23192.168.50.1 to 192.168.51.254192.168.51.255510
27192.168.52.0/23192.168.52.1 to 192.168.53.254192.168.53.255510
28192.168.54.0/23192.168.54.1 to 192.168.55.254192.168.55.255510
29192.168.56.0/23192.168.56.1 to 192.168.57.254192.168.57.255510
30192.168.58.0/23192.168.58.1 to 192.168.59.254192.168.59.255510
31192.168.60.0/23192.168.60.1 to 192.168.61.254192.168.61.255510
32192.168.62.0/23192.168.62.1 to 192.168.63.254192.168.63.255510
33192.168.64.0/23192.168.64.1 to 192.168.65.254192.168.65.255510
34192.168.66.0/23192.168.66.1 to 192.168.67.254192.168.67.255510
35192.168.68.0/23192.168.68.1 to 192.168.69.254192.168.69.255510
36192.168.70.0/23192.168.70.1 to 192.168.71.254192.168.71.255510
37192.168.72.0/23192.168.72.1 to 192.168.73.254192.168.73.255510
38192.168.74.0/23192.168.74.1 to 192.168.75.254192.168.75.255510
39192.168.76.0/23192.168.76.1 to 192.168.77.254192.168.77.255510
40192.168.78.0/23192.168.78.1 to 192.168.79.254192.168.79.255510
41192.168.80.0/23192.168.80.1 to 192.168.81.254192.168.81.255510
42192.168.82.0/23192.168.82.1 to 192.168.83.254192.168.83.255510
43192.168.84.0/23192.168.84.1 to 192.168.85.254192.168.85.255510
44192.168.86.0/23192.168.86.1 to 192.168.87.254192.168.87.255510
45192.168.88.0/23192.168.88.1 to 192.168.89.254192.168.89.255510
46192.168.90.0/23192.168.90.1 to 192.168.91.254192.168.91.255510
47192.168.92.0/23192.168.92.1 to 192.168.93.254192.168.93.255510
48192.168.94.0/23192.168.94.1 to 192.168.95.254192.168.95.255510
49192.168.96.0/23192.168.96.1 to 192.168.97.254192.168.97.255510
50192.168.98.0/23192.168.98.1 to 192.168.99.254192.168.99.255510
51192.168.100.0/23192.168.100.1 to 192.168.101.254192.168.101.255510
52192.168.102.0/23192.168.102.1 to 192.168.103.254192.168.103.255510
53192.168.104.0/23192.168.104.1 to 192.168.105.254192.168.105.255510
54192.168.106.0/23192.168.106.1 to 192.168.107.254192.168.107.255510
55192.168.108.0/23192.168.108.1 to 192.168.109.254192.168.109.255510
56192.168.110.0/23192.168.110.1 to 192.168.111.254192.168.111.255510
57192.168.112.0/23192.168.112.1 to 192.168.113.254192.168.113.255510
58192.168.114.0/23192.168.114.1 to 192.168.115.254192.168.115.255510
59192.168.116.0/23192.168.116.1 to 192.168.117.254192.168.117.255510
60192.168.118.0/23192.168.118.1 to 192.168.119.254192.168.119.255510
61192.168.120.0/23192.168.120.1 to 192.168.121.254192.168.121.255510
62192.168.122.0/23192.168.122.1 to 192.168.123.254192.168.123.255510
63192.168.124.0/23192.168.124.1 to 192.168.125.254192.168.125.255510
64192.168.126.0/23192.168.126.1 to 192.168.127.254192.168.127.255510
65192.168.128.0/23192.168.128.1 to 192.168.129.254192.168.129.255510
66192.168.130.0/23192.168.130.1 to 192.168.131.254192.168.131.255510
67192.168.132.0/23192.168.132.1 to 192.168.133.254192.168.133.255510
68192.168.134.0/23192.168.134.1 to 192.168.135.254192.168.135.255510
69192.168.136.0/23192.168.136.1 to 192.168.137.254192.168.137.255510
70192.168.138.0/23192.168.138.1 to 192.168.139.254192.168.139.255510
71192.168.140.0/23192.168.140.1 to 192.168.141.254192.168.141.255510
72192.168.142.0/23192.168.142.1 to 192.168.143.254192.168.143.255510
73192.168.144.0/23192.168.144.1 to 192.168.145.254192.168.145.255510
74192.168.146.0/23192.168.146.1 to 192.168.147.254192.168.147.255510
75192.168.148.0/23192.168.148.1 to 192.168.149.254192.168.149.255510
76192.168.150.0/23192.168.150.1 to 192.168.151.254192.168.151.255510
77192.168.152.0/23192.168.152.1 to 192.168.153.254192.168.153.255510
78192.168.154.0/23192.168.154.1 to 192.168.155.254192.168.155.255510
79192.168.156.0/23192.168.156.1 to 192.168.157.254192.168.157.255510
80192.168.158.0/23192.168.158.1 to 192.168.159.254192.168.159.255510
81192.168.160.0/23192.168.160.1 to 192.168.161.254192.168.161.255510
82192.168.162.0/23192.168.162.1 to 192.168.163.254192.168.163.255510
83192.168.164.0/23192.168.164.1 to 192.168.165.254192.168.165.255510
84192.168.166.0/23192.168.166.1 to 192.168.167.254192.168.167.255510
85192.168.168.0/23192.168.168.1 to 192.168.169.254192.168.169.255510
86192.168.170.0/23192.168.170.1 to 192.168.171.254192.168.171.255510
87192.168.172.0/23192.168.172.1 to 192.168.173.254192.168.173.255510
88192.168.174.0/23192.168.174.1 to 192.168.175.254192.168.175.255510
89192.168.176.0/23192.168.176.1 to 192.168.177.254192.168.177.255510
90192.168.178.0/23192.168.178.1 to 192.168.179.254192.168.179.255510
91192.168.180.0/23192.168.180.1 to 192.168.181.254192.168.181.255510
92192.168.182.0/23192.168.182.1 to 192.168.183.254192.168.183.255510
93192.168.184.0/23192.168.184.1 to 192.168.185.254192.168.185.255510
94192.168.186.0/23192.168.186.1 to 192.168.187.254192.168.187.255510
95192.168.188.0/23192.168.188.1 to 192.168.189.254192.168.189.255510
96192.168.190.0/23192.168.190.1 to 192.168.191.254192.168.191.255510
97192.168.192.0/23192.168.192.1 to 192.168.193.254192.168.193.255510
98192.168.194.0/23192.168.194.1 to 192.168.195.254192.168.195.255510
99192.168.196.0/23192.168.196.1 to 192.168.197.254192.168.197.255510
100192.168.198.0/23192.168.198.1 to 192.168.199.254192.168.199.255510
101192.168.200.0/23192.168.200.1 to 192.168.201.254192.168.201.255510
102192.168.202.0/23192.168.202.1 to 192.168.203.254192.168.203.255510
103192.168.204.0/23192.168.204.1 to 192.168.205.254192.168.205.255510
104192.168.206.0/23192.168.206.1 to 192.168.207.254192.168.207.255510
105192.168.208.0/23192.168.208.1 to 192.168.209.254192.168.209.255510
106192.168.210.0/23192.168.210.1 to 192.168.211.254192.168.211.255510
107192.168.212.0/23192.168.212.1 to 192.168.213.254192.168.213.255510
108192.168.214.0/23192.168.214.1 to 192.168.215.254192.168.215.255510
109192.168.216.0/23192.168.216.1 to 192.168.217.254192.168.217.255510
110192.168.218.0/23192.168.218.1 to 192.168.219.254192.168.219.255510
111192.168.220.0/23192.168.220.1 to 192.168.221.254192.168.221.255510
112192.168.222.0/23192.168.222.1 to 192.168.223.254192.168.223.255510
113192.168.224.0/23192.168.224.1 to 192.168.225.254192.168.225.255510
114192.168.226.0/23192.168.226.1 to 192.168.227.254192.168.227.255510
115192.168.228.0/23192.168.228.1 to 192.168.229.254192.168.229.255510
116192.168.230.0/23192.168.230.1 to 192.168.231.254192.168.231.255510
117192.168.232.0/23192.168.232.1 to 192.168.233.254192.168.233.255510
118192.168.234.0/23192.168.234.1 to 192.168.235.254192.168.235.255510
119192.168.236.0/23192.168.236.1 to 192.168.237.254192.168.237.255510
120192.168.238.0/23192.168.238.1 to 192.168.239.254192.168.239.255510
121192.168.240.0/23192.168.240.1 to 192.168.241.254192.168.241.255510
122192.168.242.0/23192.168.242.1 to 192.168.243.254192.168.243.255510
123192.168.244.0/23192.168.244.1 to 192.168.245.254192.168.245.255510
124192.168.246.0/23192.168.246.1 to 192.168.247.254192.168.247.255510
125192.168.248.0/23192.168.248.1 to 192.168.249.254192.168.249.255510
126192.168.250.0/23192.168.250.1 to 192.168.251.254192.168.251.255510
127192.168.252.0/23192.168.252.1 to 192.168.253.254192.168.253.255510
128192.168.254.0/23192.168.254.1 to 192.168.255.254192.168.255.255510

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.