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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.

Network236.69.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
236.69.0.0
Broadcast address
236.69.255.255
First usable
236.69.0.1
Last usable
236.69.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EC450000 · Integer 3963944960 to 3964010495
Reverse DNS zone
69.236.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11101100.01000101..00000000.00000000236.69.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network11101100.01000101..00000000.00000000236.69.0.0
Broadcast11101100.01000101..11111111.11111111236.69.255.255
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)

236.69.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1236.69.0.0/23236.69.0.1 to 236.69.1.254236.69.1.255510
2236.69.2.0/23236.69.2.1 to 236.69.3.254236.69.3.255510
3236.69.4.0/23236.69.4.1 to 236.69.5.254236.69.5.255510
4236.69.6.0/23236.69.6.1 to 236.69.7.254236.69.7.255510
5236.69.8.0/23236.69.8.1 to 236.69.9.254236.69.9.255510
6236.69.10.0/23236.69.10.1 to 236.69.11.254236.69.11.255510
7236.69.12.0/23236.69.12.1 to 236.69.13.254236.69.13.255510
8236.69.14.0/23236.69.14.1 to 236.69.15.254236.69.15.255510
9236.69.16.0/23236.69.16.1 to 236.69.17.254236.69.17.255510
10236.69.18.0/23236.69.18.1 to 236.69.19.254236.69.19.255510
11236.69.20.0/23236.69.20.1 to 236.69.21.254236.69.21.255510
12236.69.22.0/23236.69.22.1 to 236.69.23.254236.69.23.255510
13236.69.24.0/23236.69.24.1 to 236.69.25.254236.69.25.255510
14236.69.26.0/23236.69.26.1 to 236.69.27.254236.69.27.255510
15236.69.28.0/23236.69.28.1 to 236.69.29.254236.69.29.255510
16236.69.30.0/23236.69.30.1 to 236.69.31.254236.69.31.255510
17236.69.32.0/23236.69.32.1 to 236.69.33.254236.69.33.255510
18236.69.34.0/23236.69.34.1 to 236.69.35.254236.69.35.255510
19236.69.36.0/23236.69.36.1 to 236.69.37.254236.69.37.255510
20236.69.38.0/23236.69.38.1 to 236.69.39.254236.69.39.255510
21236.69.40.0/23236.69.40.1 to 236.69.41.254236.69.41.255510
22236.69.42.0/23236.69.42.1 to 236.69.43.254236.69.43.255510
23236.69.44.0/23236.69.44.1 to 236.69.45.254236.69.45.255510
24236.69.46.0/23236.69.46.1 to 236.69.47.254236.69.47.255510
25236.69.48.0/23236.69.48.1 to 236.69.49.254236.69.49.255510
26236.69.50.0/23236.69.50.1 to 236.69.51.254236.69.51.255510
27236.69.52.0/23236.69.52.1 to 236.69.53.254236.69.53.255510
28236.69.54.0/23236.69.54.1 to 236.69.55.254236.69.55.255510
29236.69.56.0/23236.69.56.1 to 236.69.57.254236.69.57.255510
30236.69.58.0/23236.69.58.1 to 236.69.59.254236.69.59.255510
31236.69.60.0/23236.69.60.1 to 236.69.61.254236.69.61.255510
32236.69.62.0/23236.69.62.1 to 236.69.63.254236.69.63.255510
33236.69.64.0/23236.69.64.1 to 236.69.65.254236.69.65.255510
34236.69.66.0/23236.69.66.1 to 236.69.67.254236.69.67.255510
35236.69.68.0/23236.69.68.1 to 236.69.69.254236.69.69.255510
36236.69.70.0/23236.69.70.1 to 236.69.71.254236.69.71.255510
37236.69.72.0/23236.69.72.1 to 236.69.73.254236.69.73.255510
38236.69.74.0/23236.69.74.1 to 236.69.75.254236.69.75.255510
39236.69.76.0/23236.69.76.1 to 236.69.77.254236.69.77.255510
40236.69.78.0/23236.69.78.1 to 236.69.79.254236.69.79.255510
41236.69.80.0/23236.69.80.1 to 236.69.81.254236.69.81.255510
42236.69.82.0/23236.69.82.1 to 236.69.83.254236.69.83.255510
43236.69.84.0/23236.69.84.1 to 236.69.85.254236.69.85.255510
44236.69.86.0/23236.69.86.1 to 236.69.87.254236.69.87.255510
45236.69.88.0/23236.69.88.1 to 236.69.89.254236.69.89.255510
46236.69.90.0/23236.69.90.1 to 236.69.91.254236.69.91.255510
47236.69.92.0/23236.69.92.1 to 236.69.93.254236.69.93.255510
48236.69.94.0/23236.69.94.1 to 236.69.95.254236.69.95.255510
49236.69.96.0/23236.69.96.1 to 236.69.97.254236.69.97.255510
50236.69.98.0/23236.69.98.1 to 236.69.99.254236.69.99.255510
51236.69.100.0/23236.69.100.1 to 236.69.101.254236.69.101.255510
52236.69.102.0/23236.69.102.1 to 236.69.103.254236.69.103.255510
53236.69.104.0/23236.69.104.1 to 236.69.105.254236.69.105.255510
54236.69.106.0/23236.69.106.1 to 236.69.107.254236.69.107.255510
55236.69.108.0/23236.69.108.1 to 236.69.109.254236.69.109.255510
56236.69.110.0/23236.69.110.1 to 236.69.111.254236.69.111.255510
57236.69.112.0/23236.69.112.1 to 236.69.113.254236.69.113.255510
58236.69.114.0/23236.69.114.1 to 236.69.115.254236.69.115.255510
59236.69.116.0/23236.69.116.1 to 236.69.117.254236.69.117.255510
60236.69.118.0/23236.69.118.1 to 236.69.119.254236.69.119.255510
61236.69.120.0/23236.69.120.1 to 236.69.121.254236.69.121.255510
62236.69.122.0/23236.69.122.1 to 236.69.123.254236.69.123.255510
63236.69.124.0/23236.69.124.1 to 236.69.125.254236.69.125.255510
64236.69.126.0/23236.69.126.1 to 236.69.127.254236.69.127.255510
65236.69.128.0/23236.69.128.1 to 236.69.129.254236.69.129.255510
66236.69.130.0/23236.69.130.1 to 236.69.131.254236.69.131.255510
67236.69.132.0/23236.69.132.1 to 236.69.133.254236.69.133.255510
68236.69.134.0/23236.69.134.1 to 236.69.135.254236.69.135.255510
69236.69.136.0/23236.69.136.1 to 236.69.137.254236.69.137.255510
70236.69.138.0/23236.69.138.1 to 236.69.139.254236.69.139.255510
71236.69.140.0/23236.69.140.1 to 236.69.141.254236.69.141.255510
72236.69.142.0/23236.69.142.1 to 236.69.143.254236.69.143.255510
73236.69.144.0/23236.69.144.1 to 236.69.145.254236.69.145.255510
74236.69.146.0/23236.69.146.1 to 236.69.147.254236.69.147.255510
75236.69.148.0/23236.69.148.1 to 236.69.149.254236.69.149.255510
76236.69.150.0/23236.69.150.1 to 236.69.151.254236.69.151.255510
77236.69.152.0/23236.69.152.1 to 236.69.153.254236.69.153.255510
78236.69.154.0/23236.69.154.1 to 236.69.155.254236.69.155.255510
79236.69.156.0/23236.69.156.1 to 236.69.157.254236.69.157.255510
80236.69.158.0/23236.69.158.1 to 236.69.159.254236.69.159.255510
81236.69.160.0/23236.69.160.1 to 236.69.161.254236.69.161.255510
82236.69.162.0/23236.69.162.1 to 236.69.163.254236.69.163.255510
83236.69.164.0/23236.69.164.1 to 236.69.165.254236.69.165.255510
84236.69.166.0/23236.69.166.1 to 236.69.167.254236.69.167.255510
85236.69.168.0/23236.69.168.1 to 236.69.169.254236.69.169.255510
86236.69.170.0/23236.69.170.1 to 236.69.171.254236.69.171.255510
87236.69.172.0/23236.69.172.1 to 236.69.173.254236.69.173.255510
88236.69.174.0/23236.69.174.1 to 236.69.175.254236.69.175.255510
89236.69.176.0/23236.69.176.1 to 236.69.177.254236.69.177.255510
90236.69.178.0/23236.69.178.1 to 236.69.179.254236.69.179.255510
91236.69.180.0/23236.69.180.1 to 236.69.181.254236.69.181.255510
92236.69.182.0/23236.69.182.1 to 236.69.183.254236.69.183.255510
93236.69.184.0/23236.69.184.1 to 236.69.185.254236.69.185.255510
94236.69.186.0/23236.69.186.1 to 236.69.187.254236.69.187.255510
95236.69.188.0/23236.69.188.1 to 236.69.189.254236.69.189.255510
96236.69.190.0/23236.69.190.1 to 236.69.191.254236.69.191.255510
97236.69.192.0/23236.69.192.1 to 236.69.193.254236.69.193.255510
98236.69.194.0/23236.69.194.1 to 236.69.195.254236.69.195.255510
99236.69.196.0/23236.69.196.1 to 236.69.197.254236.69.197.255510
100236.69.198.0/23236.69.198.1 to 236.69.199.254236.69.199.255510
101236.69.200.0/23236.69.200.1 to 236.69.201.254236.69.201.255510
102236.69.202.0/23236.69.202.1 to 236.69.203.254236.69.203.255510
103236.69.204.0/23236.69.204.1 to 236.69.205.254236.69.205.255510
104236.69.206.0/23236.69.206.1 to 236.69.207.254236.69.207.255510
105236.69.208.0/23236.69.208.1 to 236.69.209.254236.69.209.255510
106236.69.210.0/23236.69.210.1 to 236.69.211.254236.69.211.255510
107236.69.212.0/23236.69.212.1 to 236.69.213.254236.69.213.255510
108236.69.214.0/23236.69.214.1 to 236.69.215.254236.69.215.255510
109236.69.216.0/23236.69.216.1 to 236.69.217.254236.69.217.255510
110236.69.218.0/23236.69.218.1 to 236.69.219.254236.69.219.255510
111236.69.220.0/23236.69.220.1 to 236.69.221.254236.69.221.255510
112236.69.222.0/23236.69.222.1 to 236.69.223.254236.69.223.255510
113236.69.224.0/23236.69.224.1 to 236.69.225.254236.69.225.255510
114236.69.226.0/23236.69.226.1 to 236.69.227.254236.69.227.255510
115236.69.228.0/23236.69.228.1 to 236.69.229.254236.69.229.255510
116236.69.230.0/23236.69.230.1 to 236.69.231.254236.69.231.255510
117236.69.232.0/23236.69.232.1 to 236.69.233.254236.69.233.255510
118236.69.234.0/23236.69.234.1 to 236.69.235.254236.69.235.255510
119236.69.236.0/23236.69.236.1 to 236.69.237.254236.69.237.255510
120236.69.238.0/23236.69.238.1 to 236.69.239.254236.69.239.255510
121236.69.240.0/23236.69.240.1 to 236.69.241.254236.69.241.255510
122236.69.242.0/23236.69.242.1 to 236.69.243.254236.69.243.255510
123236.69.244.0/23236.69.244.1 to 236.69.245.254236.69.245.255510
124236.69.246.0/23236.69.246.1 to 236.69.247.254236.69.247.255510
125236.69.248.0/23236.69.248.1 to 236.69.249.254236.69.249.255510
126236.69.250.0/23236.69.250.1 to 236.69.251.254236.69.251.255510
127236.69.252.0/23236.69.252.1 to 236.69.253.254236.69.253.255510
128236.69.254.0/23236.69.254.1 to 236.69.255.254236.69.255.255510

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.