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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.

Network190.4.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
190.4.0.0
Broadcast address
190.4.255.255
First usable
190.4.0.1
Last usable
190.4.255.254
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 BE040000 · Integer 3187933184 to 3187998719
Reverse DNS zone
4.190.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111110.00000100..00000000.00000000190.4.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network10111110.00000100..00000000.00000000190.4.0.0
Broadcast10111110.00000100..11111111.11111111190.4.255.255
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)

190.4.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1190.4.0.0/23190.4.0.1 to 190.4.1.254190.4.1.255510
2190.4.2.0/23190.4.2.1 to 190.4.3.254190.4.3.255510
3190.4.4.0/23190.4.4.1 to 190.4.5.254190.4.5.255510
4190.4.6.0/23190.4.6.1 to 190.4.7.254190.4.7.255510
5190.4.8.0/23190.4.8.1 to 190.4.9.254190.4.9.255510
6190.4.10.0/23190.4.10.1 to 190.4.11.254190.4.11.255510
7190.4.12.0/23190.4.12.1 to 190.4.13.254190.4.13.255510
8190.4.14.0/23190.4.14.1 to 190.4.15.254190.4.15.255510
9190.4.16.0/23190.4.16.1 to 190.4.17.254190.4.17.255510
10190.4.18.0/23190.4.18.1 to 190.4.19.254190.4.19.255510
11190.4.20.0/23190.4.20.1 to 190.4.21.254190.4.21.255510
12190.4.22.0/23190.4.22.1 to 190.4.23.254190.4.23.255510
13190.4.24.0/23190.4.24.1 to 190.4.25.254190.4.25.255510
14190.4.26.0/23190.4.26.1 to 190.4.27.254190.4.27.255510
15190.4.28.0/23190.4.28.1 to 190.4.29.254190.4.29.255510
16190.4.30.0/23190.4.30.1 to 190.4.31.254190.4.31.255510
17190.4.32.0/23190.4.32.1 to 190.4.33.254190.4.33.255510
18190.4.34.0/23190.4.34.1 to 190.4.35.254190.4.35.255510
19190.4.36.0/23190.4.36.1 to 190.4.37.254190.4.37.255510
20190.4.38.0/23190.4.38.1 to 190.4.39.254190.4.39.255510
21190.4.40.0/23190.4.40.1 to 190.4.41.254190.4.41.255510
22190.4.42.0/23190.4.42.1 to 190.4.43.254190.4.43.255510
23190.4.44.0/23190.4.44.1 to 190.4.45.254190.4.45.255510
24190.4.46.0/23190.4.46.1 to 190.4.47.254190.4.47.255510
25190.4.48.0/23190.4.48.1 to 190.4.49.254190.4.49.255510
26190.4.50.0/23190.4.50.1 to 190.4.51.254190.4.51.255510
27190.4.52.0/23190.4.52.1 to 190.4.53.254190.4.53.255510
28190.4.54.0/23190.4.54.1 to 190.4.55.254190.4.55.255510
29190.4.56.0/23190.4.56.1 to 190.4.57.254190.4.57.255510
30190.4.58.0/23190.4.58.1 to 190.4.59.254190.4.59.255510
31190.4.60.0/23190.4.60.1 to 190.4.61.254190.4.61.255510
32190.4.62.0/23190.4.62.1 to 190.4.63.254190.4.63.255510
33190.4.64.0/23190.4.64.1 to 190.4.65.254190.4.65.255510
34190.4.66.0/23190.4.66.1 to 190.4.67.254190.4.67.255510
35190.4.68.0/23190.4.68.1 to 190.4.69.254190.4.69.255510
36190.4.70.0/23190.4.70.1 to 190.4.71.254190.4.71.255510
37190.4.72.0/23190.4.72.1 to 190.4.73.254190.4.73.255510
38190.4.74.0/23190.4.74.1 to 190.4.75.254190.4.75.255510
39190.4.76.0/23190.4.76.1 to 190.4.77.254190.4.77.255510
40190.4.78.0/23190.4.78.1 to 190.4.79.254190.4.79.255510
41190.4.80.0/23190.4.80.1 to 190.4.81.254190.4.81.255510
42190.4.82.0/23190.4.82.1 to 190.4.83.254190.4.83.255510
43190.4.84.0/23190.4.84.1 to 190.4.85.254190.4.85.255510
44190.4.86.0/23190.4.86.1 to 190.4.87.254190.4.87.255510
45190.4.88.0/23190.4.88.1 to 190.4.89.254190.4.89.255510
46190.4.90.0/23190.4.90.1 to 190.4.91.254190.4.91.255510
47190.4.92.0/23190.4.92.1 to 190.4.93.254190.4.93.255510
48190.4.94.0/23190.4.94.1 to 190.4.95.254190.4.95.255510
49190.4.96.0/23190.4.96.1 to 190.4.97.254190.4.97.255510
50190.4.98.0/23190.4.98.1 to 190.4.99.254190.4.99.255510
51190.4.100.0/23190.4.100.1 to 190.4.101.254190.4.101.255510
52190.4.102.0/23190.4.102.1 to 190.4.103.254190.4.103.255510
53190.4.104.0/23190.4.104.1 to 190.4.105.254190.4.105.255510
54190.4.106.0/23190.4.106.1 to 190.4.107.254190.4.107.255510
55190.4.108.0/23190.4.108.1 to 190.4.109.254190.4.109.255510
56190.4.110.0/23190.4.110.1 to 190.4.111.254190.4.111.255510
57190.4.112.0/23190.4.112.1 to 190.4.113.254190.4.113.255510
58190.4.114.0/23190.4.114.1 to 190.4.115.254190.4.115.255510
59190.4.116.0/23190.4.116.1 to 190.4.117.254190.4.117.255510
60190.4.118.0/23190.4.118.1 to 190.4.119.254190.4.119.255510
61190.4.120.0/23190.4.120.1 to 190.4.121.254190.4.121.255510
62190.4.122.0/23190.4.122.1 to 190.4.123.254190.4.123.255510
63190.4.124.0/23190.4.124.1 to 190.4.125.254190.4.125.255510
64190.4.126.0/23190.4.126.1 to 190.4.127.254190.4.127.255510
65190.4.128.0/23190.4.128.1 to 190.4.129.254190.4.129.255510
66190.4.130.0/23190.4.130.1 to 190.4.131.254190.4.131.255510
67190.4.132.0/23190.4.132.1 to 190.4.133.254190.4.133.255510
68190.4.134.0/23190.4.134.1 to 190.4.135.254190.4.135.255510
69190.4.136.0/23190.4.136.1 to 190.4.137.254190.4.137.255510
70190.4.138.0/23190.4.138.1 to 190.4.139.254190.4.139.255510
71190.4.140.0/23190.4.140.1 to 190.4.141.254190.4.141.255510
72190.4.142.0/23190.4.142.1 to 190.4.143.254190.4.143.255510
73190.4.144.0/23190.4.144.1 to 190.4.145.254190.4.145.255510
74190.4.146.0/23190.4.146.1 to 190.4.147.254190.4.147.255510
75190.4.148.0/23190.4.148.1 to 190.4.149.254190.4.149.255510
76190.4.150.0/23190.4.150.1 to 190.4.151.254190.4.151.255510
77190.4.152.0/23190.4.152.1 to 190.4.153.254190.4.153.255510
78190.4.154.0/23190.4.154.1 to 190.4.155.254190.4.155.255510
79190.4.156.0/23190.4.156.1 to 190.4.157.254190.4.157.255510
80190.4.158.0/23190.4.158.1 to 190.4.159.254190.4.159.255510
81190.4.160.0/23190.4.160.1 to 190.4.161.254190.4.161.255510
82190.4.162.0/23190.4.162.1 to 190.4.163.254190.4.163.255510
83190.4.164.0/23190.4.164.1 to 190.4.165.254190.4.165.255510
84190.4.166.0/23190.4.166.1 to 190.4.167.254190.4.167.255510
85190.4.168.0/23190.4.168.1 to 190.4.169.254190.4.169.255510
86190.4.170.0/23190.4.170.1 to 190.4.171.254190.4.171.255510
87190.4.172.0/23190.4.172.1 to 190.4.173.254190.4.173.255510
88190.4.174.0/23190.4.174.1 to 190.4.175.254190.4.175.255510
89190.4.176.0/23190.4.176.1 to 190.4.177.254190.4.177.255510
90190.4.178.0/23190.4.178.1 to 190.4.179.254190.4.179.255510
91190.4.180.0/23190.4.180.1 to 190.4.181.254190.4.181.255510
92190.4.182.0/23190.4.182.1 to 190.4.183.254190.4.183.255510
93190.4.184.0/23190.4.184.1 to 190.4.185.254190.4.185.255510
94190.4.186.0/23190.4.186.1 to 190.4.187.254190.4.187.255510
95190.4.188.0/23190.4.188.1 to 190.4.189.254190.4.189.255510
96190.4.190.0/23190.4.190.1 to 190.4.191.254190.4.191.255510
97190.4.192.0/23190.4.192.1 to 190.4.193.254190.4.193.255510
98190.4.194.0/23190.4.194.1 to 190.4.195.254190.4.195.255510
99190.4.196.0/23190.4.196.1 to 190.4.197.254190.4.197.255510
100190.4.198.0/23190.4.198.1 to 190.4.199.254190.4.199.255510
101190.4.200.0/23190.4.200.1 to 190.4.201.254190.4.201.255510
102190.4.202.0/23190.4.202.1 to 190.4.203.254190.4.203.255510
103190.4.204.0/23190.4.204.1 to 190.4.205.254190.4.205.255510
104190.4.206.0/23190.4.206.1 to 190.4.207.254190.4.207.255510
105190.4.208.0/23190.4.208.1 to 190.4.209.254190.4.209.255510
106190.4.210.0/23190.4.210.1 to 190.4.211.254190.4.211.255510
107190.4.212.0/23190.4.212.1 to 190.4.213.254190.4.213.255510
108190.4.214.0/23190.4.214.1 to 190.4.215.254190.4.215.255510
109190.4.216.0/23190.4.216.1 to 190.4.217.254190.4.217.255510
110190.4.218.0/23190.4.218.1 to 190.4.219.254190.4.219.255510
111190.4.220.0/23190.4.220.1 to 190.4.221.254190.4.221.255510
112190.4.222.0/23190.4.222.1 to 190.4.223.254190.4.223.255510
113190.4.224.0/23190.4.224.1 to 190.4.225.254190.4.225.255510
114190.4.226.0/23190.4.226.1 to 190.4.227.254190.4.227.255510
115190.4.228.0/23190.4.228.1 to 190.4.229.254190.4.229.255510
116190.4.230.0/23190.4.230.1 to 190.4.231.254190.4.231.255510
117190.4.232.0/23190.4.232.1 to 190.4.233.254190.4.233.255510
118190.4.234.0/23190.4.234.1 to 190.4.235.254190.4.235.255510
119190.4.236.0/23190.4.236.1 to 190.4.237.254190.4.237.255510
120190.4.238.0/23190.4.238.1 to 190.4.239.254190.4.239.255510
121190.4.240.0/23190.4.240.1 to 190.4.241.254190.4.241.255510
122190.4.242.0/23190.4.242.1 to 190.4.243.254190.4.243.255510
123190.4.244.0/23190.4.244.1 to 190.4.245.254190.4.245.255510
124190.4.246.0/23190.4.246.1 to 190.4.247.254190.4.247.255510
125190.4.248.0/23190.4.248.1 to 190.4.249.254190.4.249.255510
126190.4.250.0/23190.4.250.1 to 190.4.251.254190.4.251.255510
127190.4.252.0/23190.4.252.1 to 190.4.253.254190.4.253.255510
128190.4.254.0/23190.4.254.1 to 190.4.255.254190.4.255.255510

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.