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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.

Network104.63.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
104.63.0.0
Broadcast address
104.63.255.255
First usable
104.63.0.1
Last usable
104.63.255.254
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
A (default /8)
As numbers
Hex 683F0000 · Integer 1748959232 to 1749024767
Reverse DNS zone
63.104.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01101000.00111111..00000000.00000000104.63.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network01101000.00111111..00000000.00000000104.63.0.0
Broadcast01101000.00111111..11111111.11111111104.63.255.255
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)

104.63.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1104.63.0.0/23104.63.0.1 to 104.63.1.254104.63.1.255510
2104.63.2.0/23104.63.2.1 to 104.63.3.254104.63.3.255510
3104.63.4.0/23104.63.4.1 to 104.63.5.254104.63.5.255510
4104.63.6.0/23104.63.6.1 to 104.63.7.254104.63.7.255510
5104.63.8.0/23104.63.8.1 to 104.63.9.254104.63.9.255510
6104.63.10.0/23104.63.10.1 to 104.63.11.254104.63.11.255510
7104.63.12.0/23104.63.12.1 to 104.63.13.254104.63.13.255510
8104.63.14.0/23104.63.14.1 to 104.63.15.254104.63.15.255510
9104.63.16.0/23104.63.16.1 to 104.63.17.254104.63.17.255510
10104.63.18.0/23104.63.18.1 to 104.63.19.254104.63.19.255510
11104.63.20.0/23104.63.20.1 to 104.63.21.254104.63.21.255510
12104.63.22.0/23104.63.22.1 to 104.63.23.254104.63.23.255510
13104.63.24.0/23104.63.24.1 to 104.63.25.254104.63.25.255510
14104.63.26.0/23104.63.26.1 to 104.63.27.254104.63.27.255510
15104.63.28.0/23104.63.28.1 to 104.63.29.254104.63.29.255510
16104.63.30.0/23104.63.30.1 to 104.63.31.254104.63.31.255510
17104.63.32.0/23104.63.32.1 to 104.63.33.254104.63.33.255510
18104.63.34.0/23104.63.34.1 to 104.63.35.254104.63.35.255510
19104.63.36.0/23104.63.36.1 to 104.63.37.254104.63.37.255510
20104.63.38.0/23104.63.38.1 to 104.63.39.254104.63.39.255510
21104.63.40.0/23104.63.40.1 to 104.63.41.254104.63.41.255510
22104.63.42.0/23104.63.42.1 to 104.63.43.254104.63.43.255510
23104.63.44.0/23104.63.44.1 to 104.63.45.254104.63.45.255510
24104.63.46.0/23104.63.46.1 to 104.63.47.254104.63.47.255510
25104.63.48.0/23104.63.48.1 to 104.63.49.254104.63.49.255510
26104.63.50.0/23104.63.50.1 to 104.63.51.254104.63.51.255510
27104.63.52.0/23104.63.52.1 to 104.63.53.254104.63.53.255510
28104.63.54.0/23104.63.54.1 to 104.63.55.254104.63.55.255510
29104.63.56.0/23104.63.56.1 to 104.63.57.254104.63.57.255510
30104.63.58.0/23104.63.58.1 to 104.63.59.254104.63.59.255510
31104.63.60.0/23104.63.60.1 to 104.63.61.254104.63.61.255510
32104.63.62.0/23104.63.62.1 to 104.63.63.254104.63.63.255510
33104.63.64.0/23104.63.64.1 to 104.63.65.254104.63.65.255510
34104.63.66.0/23104.63.66.1 to 104.63.67.254104.63.67.255510
35104.63.68.0/23104.63.68.1 to 104.63.69.254104.63.69.255510
36104.63.70.0/23104.63.70.1 to 104.63.71.254104.63.71.255510
37104.63.72.0/23104.63.72.1 to 104.63.73.254104.63.73.255510
38104.63.74.0/23104.63.74.1 to 104.63.75.254104.63.75.255510
39104.63.76.0/23104.63.76.1 to 104.63.77.254104.63.77.255510
40104.63.78.0/23104.63.78.1 to 104.63.79.254104.63.79.255510
41104.63.80.0/23104.63.80.1 to 104.63.81.254104.63.81.255510
42104.63.82.0/23104.63.82.1 to 104.63.83.254104.63.83.255510
43104.63.84.0/23104.63.84.1 to 104.63.85.254104.63.85.255510
44104.63.86.0/23104.63.86.1 to 104.63.87.254104.63.87.255510
45104.63.88.0/23104.63.88.1 to 104.63.89.254104.63.89.255510
46104.63.90.0/23104.63.90.1 to 104.63.91.254104.63.91.255510
47104.63.92.0/23104.63.92.1 to 104.63.93.254104.63.93.255510
48104.63.94.0/23104.63.94.1 to 104.63.95.254104.63.95.255510
49104.63.96.0/23104.63.96.1 to 104.63.97.254104.63.97.255510
50104.63.98.0/23104.63.98.1 to 104.63.99.254104.63.99.255510
51104.63.100.0/23104.63.100.1 to 104.63.101.254104.63.101.255510
52104.63.102.0/23104.63.102.1 to 104.63.103.254104.63.103.255510
53104.63.104.0/23104.63.104.1 to 104.63.105.254104.63.105.255510
54104.63.106.0/23104.63.106.1 to 104.63.107.254104.63.107.255510
55104.63.108.0/23104.63.108.1 to 104.63.109.254104.63.109.255510
56104.63.110.0/23104.63.110.1 to 104.63.111.254104.63.111.255510
57104.63.112.0/23104.63.112.1 to 104.63.113.254104.63.113.255510
58104.63.114.0/23104.63.114.1 to 104.63.115.254104.63.115.255510
59104.63.116.0/23104.63.116.1 to 104.63.117.254104.63.117.255510
60104.63.118.0/23104.63.118.1 to 104.63.119.254104.63.119.255510
61104.63.120.0/23104.63.120.1 to 104.63.121.254104.63.121.255510
62104.63.122.0/23104.63.122.1 to 104.63.123.254104.63.123.255510
63104.63.124.0/23104.63.124.1 to 104.63.125.254104.63.125.255510
64104.63.126.0/23104.63.126.1 to 104.63.127.254104.63.127.255510
65104.63.128.0/23104.63.128.1 to 104.63.129.254104.63.129.255510
66104.63.130.0/23104.63.130.1 to 104.63.131.254104.63.131.255510
67104.63.132.0/23104.63.132.1 to 104.63.133.254104.63.133.255510
68104.63.134.0/23104.63.134.1 to 104.63.135.254104.63.135.255510
69104.63.136.0/23104.63.136.1 to 104.63.137.254104.63.137.255510
70104.63.138.0/23104.63.138.1 to 104.63.139.254104.63.139.255510
71104.63.140.0/23104.63.140.1 to 104.63.141.254104.63.141.255510
72104.63.142.0/23104.63.142.1 to 104.63.143.254104.63.143.255510
73104.63.144.0/23104.63.144.1 to 104.63.145.254104.63.145.255510
74104.63.146.0/23104.63.146.1 to 104.63.147.254104.63.147.255510
75104.63.148.0/23104.63.148.1 to 104.63.149.254104.63.149.255510
76104.63.150.0/23104.63.150.1 to 104.63.151.254104.63.151.255510
77104.63.152.0/23104.63.152.1 to 104.63.153.254104.63.153.255510
78104.63.154.0/23104.63.154.1 to 104.63.155.254104.63.155.255510
79104.63.156.0/23104.63.156.1 to 104.63.157.254104.63.157.255510
80104.63.158.0/23104.63.158.1 to 104.63.159.254104.63.159.255510
81104.63.160.0/23104.63.160.1 to 104.63.161.254104.63.161.255510
82104.63.162.0/23104.63.162.1 to 104.63.163.254104.63.163.255510
83104.63.164.0/23104.63.164.1 to 104.63.165.254104.63.165.255510
84104.63.166.0/23104.63.166.1 to 104.63.167.254104.63.167.255510
85104.63.168.0/23104.63.168.1 to 104.63.169.254104.63.169.255510
86104.63.170.0/23104.63.170.1 to 104.63.171.254104.63.171.255510
87104.63.172.0/23104.63.172.1 to 104.63.173.254104.63.173.255510
88104.63.174.0/23104.63.174.1 to 104.63.175.254104.63.175.255510
89104.63.176.0/23104.63.176.1 to 104.63.177.254104.63.177.255510
90104.63.178.0/23104.63.178.1 to 104.63.179.254104.63.179.255510
91104.63.180.0/23104.63.180.1 to 104.63.181.254104.63.181.255510
92104.63.182.0/23104.63.182.1 to 104.63.183.254104.63.183.255510
93104.63.184.0/23104.63.184.1 to 104.63.185.254104.63.185.255510
94104.63.186.0/23104.63.186.1 to 104.63.187.254104.63.187.255510
95104.63.188.0/23104.63.188.1 to 104.63.189.254104.63.189.255510
96104.63.190.0/23104.63.190.1 to 104.63.191.254104.63.191.255510
97104.63.192.0/23104.63.192.1 to 104.63.193.254104.63.193.255510
98104.63.194.0/23104.63.194.1 to 104.63.195.254104.63.195.255510
99104.63.196.0/23104.63.196.1 to 104.63.197.254104.63.197.255510
100104.63.198.0/23104.63.198.1 to 104.63.199.254104.63.199.255510
101104.63.200.0/23104.63.200.1 to 104.63.201.254104.63.201.255510
102104.63.202.0/23104.63.202.1 to 104.63.203.254104.63.203.255510
103104.63.204.0/23104.63.204.1 to 104.63.205.254104.63.205.255510
104104.63.206.0/23104.63.206.1 to 104.63.207.254104.63.207.255510
105104.63.208.0/23104.63.208.1 to 104.63.209.254104.63.209.255510
106104.63.210.0/23104.63.210.1 to 104.63.211.254104.63.211.255510
107104.63.212.0/23104.63.212.1 to 104.63.213.254104.63.213.255510
108104.63.214.0/23104.63.214.1 to 104.63.215.254104.63.215.255510
109104.63.216.0/23104.63.216.1 to 104.63.217.254104.63.217.255510
110104.63.218.0/23104.63.218.1 to 104.63.219.254104.63.219.255510
111104.63.220.0/23104.63.220.1 to 104.63.221.254104.63.221.255510
112104.63.222.0/23104.63.222.1 to 104.63.223.254104.63.223.255510
113104.63.224.0/23104.63.224.1 to 104.63.225.254104.63.225.255510
114104.63.226.0/23104.63.226.1 to 104.63.227.254104.63.227.255510
115104.63.228.0/23104.63.228.1 to 104.63.229.254104.63.229.255510
116104.63.230.0/23104.63.230.1 to 104.63.231.254104.63.231.255510
117104.63.232.0/23104.63.232.1 to 104.63.233.254104.63.233.255510
118104.63.234.0/23104.63.234.1 to 104.63.235.254104.63.235.255510
119104.63.236.0/23104.63.236.1 to 104.63.237.254104.63.237.255510
120104.63.238.0/23104.63.238.1 to 104.63.239.254104.63.239.255510
121104.63.240.0/23104.63.240.1 to 104.63.241.254104.63.241.255510
122104.63.242.0/23104.63.242.1 to 104.63.243.254104.63.243.255510
123104.63.244.0/23104.63.244.1 to 104.63.245.254104.63.245.255510
124104.63.246.0/23104.63.246.1 to 104.63.247.254104.63.247.255510
125104.63.248.0/23104.63.248.1 to 104.63.249.254104.63.249.255510
126104.63.250.0/23104.63.250.1 to 104.63.251.254104.63.251.255510
127104.63.252.0/23104.63.252.1 to 104.63.253.254104.63.253.255510
128104.63.254.0/23104.63.254.1 to 104.63.255.254104.63.255.255510

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.