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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.

Network143.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
143.0.0.0
Broadcast address
143.255.255.255
First usable
143.0.0.1
Last usable
143.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex 8F000000 · Integer 2399141888 to 2415919103
Reverse DNS zone
143.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001111..00000000.00000000.00000000143.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10001111..00000000.00000000.00000000143.0.0.0
Broadcast10001111..11111111.11111111.11111111143.255.255.255
Split into smaller subnets/15
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

143.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1143.0.0.0/15143.0.0.1 to 143.1.255.254143.1.255.255131,070
2143.2.0.0/15143.2.0.1 to 143.3.255.254143.3.255.255131,070
3143.4.0.0/15143.4.0.1 to 143.5.255.254143.5.255.255131,070
4143.6.0.0/15143.6.0.1 to 143.7.255.254143.7.255.255131,070
5143.8.0.0/15143.8.0.1 to 143.9.255.254143.9.255.255131,070
6143.10.0.0/15143.10.0.1 to 143.11.255.254143.11.255.255131,070
7143.12.0.0/15143.12.0.1 to 143.13.255.254143.13.255.255131,070
8143.14.0.0/15143.14.0.1 to 143.15.255.254143.15.255.255131,070
9143.16.0.0/15143.16.0.1 to 143.17.255.254143.17.255.255131,070
10143.18.0.0/15143.18.0.1 to 143.19.255.254143.19.255.255131,070
11143.20.0.0/15143.20.0.1 to 143.21.255.254143.21.255.255131,070
12143.22.0.0/15143.22.0.1 to 143.23.255.254143.23.255.255131,070
13143.24.0.0/15143.24.0.1 to 143.25.255.254143.25.255.255131,070
14143.26.0.0/15143.26.0.1 to 143.27.255.254143.27.255.255131,070
15143.28.0.0/15143.28.0.1 to 143.29.255.254143.29.255.255131,070
16143.30.0.0/15143.30.0.1 to 143.31.255.254143.31.255.255131,070
17143.32.0.0/15143.32.0.1 to 143.33.255.254143.33.255.255131,070
18143.34.0.0/15143.34.0.1 to 143.35.255.254143.35.255.255131,070
19143.36.0.0/15143.36.0.1 to 143.37.255.254143.37.255.255131,070
20143.38.0.0/15143.38.0.1 to 143.39.255.254143.39.255.255131,070
21143.40.0.0/15143.40.0.1 to 143.41.255.254143.41.255.255131,070
22143.42.0.0/15143.42.0.1 to 143.43.255.254143.43.255.255131,070
23143.44.0.0/15143.44.0.1 to 143.45.255.254143.45.255.255131,070
24143.46.0.0/15143.46.0.1 to 143.47.255.254143.47.255.255131,070
25143.48.0.0/15143.48.0.1 to 143.49.255.254143.49.255.255131,070
26143.50.0.0/15143.50.0.1 to 143.51.255.254143.51.255.255131,070
27143.52.0.0/15143.52.0.1 to 143.53.255.254143.53.255.255131,070
28143.54.0.0/15143.54.0.1 to 143.55.255.254143.55.255.255131,070
29143.56.0.0/15143.56.0.1 to 143.57.255.254143.57.255.255131,070
30143.58.0.0/15143.58.0.1 to 143.59.255.254143.59.255.255131,070
31143.60.0.0/15143.60.0.1 to 143.61.255.254143.61.255.255131,070
32143.62.0.0/15143.62.0.1 to 143.63.255.254143.63.255.255131,070
33143.64.0.0/15143.64.0.1 to 143.65.255.254143.65.255.255131,070
34143.66.0.0/15143.66.0.1 to 143.67.255.254143.67.255.255131,070
35143.68.0.0/15143.68.0.1 to 143.69.255.254143.69.255.255131,070
36143.70.0.0/15143.70.0.1 to 143.71.255.254143.71.255.255131,070
37143.72.0.0/15143.72.0.1 to 143.73.255.254143.73.255.255131,070
38143.74.0.0/15143.74.0.1 to 143.75.255.254143.75.255.255131,070
39143.76.0.0/15143.76.0.1 to 143.77.255.254143.77.255.255131,070
40143.78.0.0/15143.78.0.1 to 143.79.255.254143.79.255.255131,070
41143.80.0.0/15143.80.0.1 to 143.81.255.254143.81.255.255131,070
42143.82.0.0/15143.82.0.1 to 143.83.255.254143.83.255.255131,070
43143.84.0.0/15143.84.0.1 to 143.85.255.254143.85.255.255131,070
44143.86.0.0/15143.86.0.1 to 143.87.255.254143.87.255.255131,070
45143.88.0.0/15143.88.0.1 to 143.89.255.254143.89.255.255131,070
46143.90.0.0/15143.90.0.1 to 143.91.255.254143.91.255.255131,070
47143.92.0.0/15143.92.0.1 to 143.93.255.254143.93.255.255131,070
48143.94.0.0/15143.94.0.1 to 143.95.255.254143.95.255.255131,070
49143.96.0.0/15143.96.0.1 to 143.97.255.254143.97.255.255131,070
50143.98.0.0/15143.98.0.1 to 143.99.255.254143.99.255.255131,070
51143.100.0.0/15143.100.0.1 to 143.101.255.254143.101.255.255131,070
52143.102.0.0/15143.102.0.1 to 143.103.255.254143.103.255.255131,070
53143.104.0.0/15143.104.0.1 to 143.105.255.254143.105.255.255131,070
54143.106.0.0/15143.106.0.1 to 143.107.255.254143.107.255.255131,070
55143.108.0.0/15143.108.0.1 to 143.109.255.254143.109.255.255131,070
56143.110.0.0/15143.110.0.1 to 143.111.255.254143.111.255.255131,070
57143.112.0.0/15143.112.0.1 to 143.113.255.254143.113.255.255131,070
58143.114.0.0/15143.114.0.1 to 143.115.255.254143.115.255.255131,070
59143.116.0.0/15143.116.0.1 to 143.117.255.254143.117.255.255131,070
60143.118.0.0/15143.118.0.1 to 143.119.255.254143.119.255.255131,070
61143.120.0.0/15143.120.0.1 to 143.121.255.254143.121.255.255131,070
62143.122.0.0/15143.122.0.1 to 143.123.255.254143.123.255.255131,070
63143.124.0.0/15143.124.0.1 to 143.125.255.254143.125.255.255131,070
64143.126.0.0/15143.126.0.1 to 143.127.255.254143.127.255.255131,070
65143.128.0.0/15143.128.0.1 to 143.129.255.254143.129.255.255131,070
66143.130.0.0/15143.130.0.1 to 143.131.255.254143.131.255.255131,070
67143.132.0.0/15143.132.0.1 to 143.133.255.254143.133.255.255131,070
68143.134.0.0/15143.134.0.1 to 143.135.255.254143.135.255.255131,070
69143.136.0.0/15143.136.0.1 to 143.137.255.254143.137.255.255131,070
70143.138.0.0/15143.138.0.1 to 143.139.255.254143.139.255.255131,070
71143.140.0.0/15143.140.0.1 to 143.141.255.254143.141.255.255131,070
72143.142.0.0/15143.142.0.1 to 143.143.255.254143.143.255.255131,070
73143.144.0.0/15143.144.0.1 to 143.145.255.254143.145.255.255131,070
74143.146.0.0/15143.146.0.1 to 143.147.255.254143.147.255.255131,070
75143.148.0.0/15143.148.0.1 to 143.149.255.254143.149.255.255131,070
76143.150.0.0/15143.150.0.1 to 143.151.255.254143.151.255.255131,070
77143.152.0.0/15143.152.0.1 to 143.153.255.254143.153.255.255131,070
78143.154.0.0/15143.154.0.1 to 143.155.255.254143.155.255.255131,070
79143.156.0.0/15143.156.0.1 to 143.157.255.254143.157.255.255131,070
80143.158.0.0/15143.158.0.1 to 143.159.255.254143.159.255.255131,070
81143.160.0.0/15143.160.0.1 to 143.161.255.254143.161.255.255131,070
82143.162.0.0/15143.162.0.1 to 143.163.255.254143.163.255.255131,070
83143.164.0.0/15143.164.0.1 to 143.165.255.254143.165.255.255131,070
84143.166.0.0/15143.166.0.1 to 143.167.255.254143.167.255.255131,070
85143.168.0.0/15143.168.0.1 to 143.169.255.254143.169.255.255131,070
86143.170.0.0/15143.170.0.1 to 143.171.255.254143.171.255.255131,070
87143.172.0.0/15143.172.0.1 to 143.173.255.254143.173.255.255131,070
88143.174.0.0/15143.174.0.1 to 143.175.255.254143.175.255.255131,070
89143.176.0.0/15143.176.0.1 to 143.177.255.254143.177.255.255131,070
90143.178.0.0/15143.178.0.1 to 143.179.255.254143.179.255.255131,070
91143.180.0.0/15143.180.0.1 to 143.181.255.254143.181.255.255131,070
92143.182.0.0/15143.182.0.1 to 143.183.255.254143.183.255.255131,070
93143.184.0.0/15143.184.0.1 to 143.185.255.254143.185.255.255131,070
94143.186.0.0/15143.186.0.1 to 143.187.255.254143.187.255.255131,070
95143.188.0.0/15143.188.0.1 to 143.189.255.254143.189.255.255131,070
96143.190.0.0/15143.190.0.1 to 143.191.255.254143.191.255.255131,070
97143.192.0.0/15143.192.0.1 to 143.193.255.254143.193.255.255131,070
98143.194.0.0/15143.194.0.1 to 143.195.255.254143.195.255.255131,070
99143.196.0.0/15143.196.0.1 to 143.197.255.254143.197.255.255131,070
100143.198.0.0/15143.198.0.1 to 143.199.255.254143.199.255.255131,070
101143.200.0.0/15143.200.0.1 to 143.201.255.254143.201.255.255131,070
102143.202.0.0/15143.202.0.1 to 143.203.255.254143.203.255.255131,070
103143.204.0.0/15143.204.0.1 to 143.205.255.254143.205.255.255131,070
104143.206.0.0/15143.206.0.1 to 143.207.255.254143.207.255.255131,070
105143.208.0.0/15143.208.0.1 to 143.209.255.254143.209.255.255131,070
106143.210.0.0/15143.210.0.1 to 143.211.255.254143.211.255.255131,070
107143.212.0.0/15143.212.0.1 to 143.213.255.254143.213.255.255131,070
108143.214.0.0/15143.214.0.1 to 143.215.255.254143.215.255.255131,070
109143.216.0.0/15143.216.0.1 to 143.217.255.254143.217.255.255131,070
110143.218.0.0/15143.218.0.1 to 143.219.255.254143.219.255.255131,070
111143.220.0.0/15143.220.0.1 to 143.221.255.254143.221.255.255131,070
112143.222.0.0/15143.222.0.1 to 143.223.255.254143.223.255.255131,070
113143.224.0.0/15143.224.0.1 to 143.225.255.254143.225.255.255131,070
114143.226.0.0/15143.226.0.1 to 143.227.255.254143.227.255.255131,070
115143.228.0.0/15143.228.0.1 to 143.229.255.254143.229.255.255131,070
116143.230.0.0/15143.230.0.1 to 143.231.255.254143.231.255.255131,070
117143.232.0.0/15143.232.0.1 to 143.233.255.254143.233.255.255131,070
118143.234.0.0/15143.234.0.1 to 143.235.255.254143.235.255.255131,070
119143.236.0.0/15143.236.0.1 to 143.237.255.254143.237.255.255131,070
120143.238.0.0/15143.238.0.1 to 143.239.255.254143.239.255.255131,070
121143.240.0.0/15143.240.0.1 to 143.241.255.254143.241.255.255131,070
122143.242.0.0/15143.242.0.1 to 143.243.255.254143.243.255.255131,070
123143.244.0.0/15143.244.0.1 to 143.245.255.254143.245.255.255131,070
124143.246.0.0/15143.246.0.1 to 143.247.255.254143.247.255.255131,070
125143.248.0.0/15143.248.0.1 to 143.249.255.254143.249.255.255131,070
126143.250.0.0/15143.250.0.1 to 143.251.255.254143.251.255.255131,070
127143.252.0.0/15143.252.0.1 to 143.253.255.254143.253.255.255131,070
128143.254.0.0/15143.254.0.1 to 143.255.255.254143.255.255.255131,070

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.