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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.

Network228.28.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
228.28.0.0
Broadcast address
228.28.255.255
First usable
228.28.0.1
Last usable
228.28.255.254
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 E41C0000 · Integer 3827040256 to 3827105791
Reverse DNS zone
28.228.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11100100.00011100..00000000.00000000228.28.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network11100100.00011100..00000000.00000000228.28.0.0
Broadcast11100100.00011100..11111111.11111111228.28.255.255
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)

228.28.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1228.28.0.0/23228.28.0.1 to 228.28.1.254228.28.1.255510
2228.28.2.0/23228.28.2.1 to 228.28.3.254228.28.3.255510
3228.28.4.0/23228.28.4.1 to 228.28.5.254228.28.5.255510
4228.28.6.0/23228.28.6.1 to 228.28.7.254228.28.7.255510
5228.28.8.0/23228.28.8.1 to 228.28.9.254228.28.9.255510
6228.28.10.0/23228.28.10.1 to 228.28.11.254228.28.11.255510
7228.28.12.0/23228.28.12.1 to 228.28.13.254228.28.13.255510
8228.28.14.0/23228.28.14.1 to 228.28.15.254228.28.15.255510
9228.28.16.0/23228.28.16.1 to 228.28.17.254228.28.17.255510
10228.28.18.0/23228.28.18.1 to 228.28.19.254228.28.19.255510
11228.28.20.0/23228.28.20.1 to 228.28.21.254228.28.21.255510
12228.28.22.0/23228.28.22.1 to 228.28.23.254228.28.23.255510
13228.28.24.0/23228.28.24.1 to 228.28.25.254228.28.25.255510
14228.28.26.0/23228.28.26.1 to 228.28.27.254228.28.27.255510
15228.28.28.0/23228.28.28.1 to 228.28.29.254228.28.29.255510
16228.28.30.0/23228.28.30.1 to 228.28.31.254228.28.31.255510
17228.28.32.0/23228.28.32.1 to 228.28.33.254228.28.33.255510
18228.28.34.0/23228.28.34.1 to 228.28.35.254228.28.35.255510
19228.28.36.0/23228.28.36.1 to 228.28.37.254228.28.37.255510
20228.28.38.0/23228.28.38.1 to 228.28.39.254228.28.39.255510
21228.28.40.0/23228.28.40.1 to 228.28.41.254228.28.41.255510
22228.28.42.0/23228.28.42.1 to 228.28.43.254228.28.43.255510
23228.28.44.0/23228.28.44.1 to 228.28.45.254228.28.45.255510
24228.28.46.0/23228.28.46.1 to 228.28.47.254228.28.47.255510
25228.28.48.0/23228.28.48.1 to 228.28.49.254228.28.49.255510
26228.28.50.0/23228.28.50.1 to 228.28.51.254228.28.51.255510
27228.28.52.0/23228.28.52.1 to 228.28.53.254228.28.53.255510
28228.28.54.0/23228.28.54.1 to 228.28.55.254228.28.55.255510
29228.28.56.0/23228.28.56.1 to 228.28.57.254228.28.57.255510
30228.28.58.0/23228.28.58.1 to 228.28.59.254228.28.59.255510
31228.28.60.0/23228.28.60.1 to 228.28.61.254228.28.61.255510
32228.28.62.0/23228.28.62.1 to 228.28.63.254228.28.63.255510
33228.28.64.0/23228.28.64.1 to 228.28.65.254228.28.65.255510
34228.28.66.0/23228.28.66.1 to 228.28.67.254228.28.67.255510
35228.28.68.0/23228.28.68.1 to 228.28.69.254228.28.69.255510
36228.28.70.0/23228.28.70.1 to 228.28.71.254228.28.71.255510
37228.28.72.0/23228.28.72.1 to 228.28.73.254228.28.73.255510
38228.28.74.0/23228.28.74.1 to 228.28.75.254228.28.75.255510
39228.28.76.0/23228.28.76.1 to 228.28.77.254228.28.77.255510
40228.28.78.0/23228.28.78.1 to 228.28.79.254228.28.79.255510
41228.28.80.0/23228.28.80.1 to 228.28.81.254228.28.81.255510
42228.28.82.0/23228.28.82.1 to 228.28.83.254228.28.83.255510
43228.28.84.0/23228.28.84.1 to 228.28.85.254228.28.85.255510
44228.28.86.0/23228.28.86.1 to 228.28.87.254228.28.87.255510
45228.28.88.0/23228.28.88.1 to 228.28.89.254228.28.89.255510
46228.28.90.0/23228.28.90.1 to 228.28.91.254228.28.91.255510
47228.28.92.0/23228.28.92.1 to 228.28.93.254228.28.93.255510
48228.28.94.0/23228.28.94.1 to 228.28.95.254228.28.95.255510
49228.28.96.0/23228.28.96.1 to 228.28.97.254228.28.97.255510
50228.28.98.0/23228.28.98.1 to 228.28.99.254228.28.99.255510
51228.28.100.0/23228.28.100.1 to 228.28.101.254228.28.101.255510
52228.28.102.0/23228.28.102.1 to 228.28.103.254228.28.103.255510
53228.28.104.0/23228.28.104.1 to 228.28.105.254228.28.105.255510
54228.28.106.0/23228.28.106.1 to 228.28.107.254228.28.107.255510
55228.28.108.0/23228.28.108.1 to 228.28.109.254228.28.109.255510
56228.28.110.0/23228.28.110.1 to 228.28.111.254228.28.111.255510
57228.28.112.0/23228.28.112.1 to 228.28.113.254228.28.113.255510
58228.28.114.0/23228.28.114.1 to 228.28.115.254228.28.115.255510
59228.28.116.0/23228.28.116.1 to 228.28.117.254228.28.117.255510
60228.28.118.0/23228.28.118.1 to 228.28.119.254228.28.119.255510
61228.28.120.0/23228.28.120.1 to 228.28.121.254228.28.121.255510
62228.28.122.0/23228.28.122.1 to 228.28.123.254228.28.123.255510
63228.28.124.0/23228.28.124.1 to 228.28.125.254228.28.125.255510
64228.28.126.0/23228.28.126.1 to 228.28.127.254228.28.127.255510
65228.28.128.0/23228.28.128.1 to 228.28.129.254228.28.129.255510
66228.28.130.0/23228.28.130.1 to 228.28.131.254228.28.131.255510
67228.28.132.0/23228.28.132.1 to 228.28.133.254228.28.133.255510
68228.28.134.0/23228.28.134.1 to 228.28.135.254228.28.135.255510
69228.28.136.0/23228.28.136.1 to 228.28.137.254228.28.137.255510
70228.28.138.0/23228.28.138.1 to 228.28.139.254228.28.139.255510
71228.28.140.0/23228.28.140.1 to 228.28.141.254228.28.141.255510
72228.28.142.0/23228.28.142.1 to 228.28.143.254228.28.143.255510
73228.28.144.0/23228.28.144.1 to 228.28.145.254228.28.145.255510
74228.28.146.0/23228.28.146.1 to 228.28.147.254228.28.147.255510
75228.28.148.0/23228.28.148.1 to 228.28.149.254228.28.149.255510
76228.28.150.0/23228.28.150.1 to 228.28.151.254228.28.151.255510
77228.28.152.0/23228.28.152.1 to 228.28.153.254228.28.153.255510
78228.28.154.0/23228.28.154.1 to 228.28.155.254228.28.155.255510
79228.28.156.0/23228.28.156.1 to 228.28.157.254228.28.157.255510
80228.28.158.0/23228.28.158.1 to 228.28.159.254228.28.159.255510
81228.28.160.0/23228.28.160.1 to 228.28.161.254228.28.161.255510
82228.28.162.0/23228.28.162.1 to 228.28.163.254228.28.163.255510
83228.28.164.0/23228.28.164.1 to 228.28.165.254228.28.165.255510
84228.28.166.0/23228.28.166.1 to 228.28.167.254228.28.167.255510
85228.28.168.0/23228.28.168.1 to 228.28.169.254228.28.169.255510
86228.28.170.0/23228.28.170.1 to 228.28.171.254228.28.171.255510
87228.28.172.0/23228.28.172.1 to 228.28.173.254228.28.173.255510
88228.28.174.0/23228.28.174.1 to 228.28.175.254228.28.175.255510
89228.28.176.0/23228.28.176.1 to 228.28.177.254228.28.177.255510
90228.28.178.0/23228.28.178.1 to 228.28.179.254228.28.179.255510
91228.28.180.0/23228.28.180.1 to 228.28.181.254228.28.181.255510
92228.28.182.0/23228.28.182.1 to 228.28.183.254228.28.183.255510
93228.28.184.0/23228.28.184.1 to 228.28.185.254228.28.185.255510
94228.28.186.0/23228.28.186.1 to 228.28.187.254228.28.187.255510
95228.28.188.0/23228.28.188.1 to 228.28.189.254228.28.189.255510
96228.28.190.0/23228.28.190.1 to 228.28.191.254228.28.191.255510
97228.28.192.0/23228.28.192.1 to 228.28.193.254228.28.193.255510
98228.28.194.0/23228.28.194.1 to 228.28.195.254228.28.195.255510
99228.28.196.0/23228.28.196.1 to 228.28.197.254228.28.197.255510
100228.28.198.0/23228.28.198.1 to 228.28.199.254228.28.199.255510
101228.28.200.0/23228.28.200.1 to 228.28.201.254228.28.201.255510
102228.28.202.0/23228.28.202.1 to 228.28.203.254228.28.203.255510
103228.28.204.0/23228.28.204.1 to 228.28.205.254228.28.205.255510
104228.28.206.0/23228.28.206.1 to 228.28.207.254228.28.207.255510
105228.28.208.0/23228.28.208.1 to 228.28.209.254228.28.209.255510
106228.28.210.0/23228.28.210.1 to 228.28.211.254228.28.211.255510
107228.28.212.0/23228.28.212.1 to 228.28.213.254228.28.213.255510
108228.28.214.0/23228.28.214.1 to 228.28.215.254228.28.215.255510
109228.28.216.0/23228.28.216.1 to 228.28.217.254228.28.217.255510
110228.28.218.0/23228.28.218.1 to 228.28.219.254228.28.219.255510
111228.28.220.0/23228.28.220.1 to 228.28.221.254228.28.221.255510
112228.28.222.0/23228.28.222.1 to 228.28.223.254228.28.223.255510
113228.28.224.0/23228.28.224.1 to 228.28.225.254228.28.225.255510
114228.28.226.0/23228.28.226.1 to 228.28.227.254228.28.227.255510
115228.28.228.0/23228.28.228.1 to 228.28.229.254228.28.229.255510
116228.28.230.0/23228.28.230.1 to 228.28.231.254228.28.231.255510
117228.28.232.0/23228.28.232.1 to 228.28.233.254228.28.233.255510
118228.28.234.0/23228.28.234.1 to 228.28.235.254228.28.235.255510
119228.28.236.0/23228.28.236.1 to 228.28.237.254228.28.237.255510
120228.28.238.0/23228.28.238.1 to 228.28.239.254228.28.239.255510
121228.28.240.0/23228.28.240.1 to 228.28.241.254228.28.241.255510
122228.28.242.0/23228.28.242.1 to 228.28.243.254228.28.243.255510
123228.28.244.0/23228.28.244.1 to 228.28.245.254228.28.245.255510
124228.28.246.0/23228.28.246.1 to 228.28.247.254228.28.247.255510
125228.28.248.0/23228.28.248.1 to 228.28.249.254228.28.249.255510
126228.28.250.0/23228.28.250.1 to 228.28.251.254228.28.251.255510
127228.28.252.0/23228.28.252.1 to 228.28.253.254228.28.253.255510
128228.28.254.0/23228.28.254.1 to 228.28.255.254228.28.255.255510

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.