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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.

Network199.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
199.0.0.0
Broadcast address
199.255.255.255
First usable
199.0.0.1
Last usable
199.255.255.254
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
C (default /24)
As numbers
Hex C7000000 · Integer 3338665984 to 3355443199
Reverse DNS zone
199.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000111..00000000.00000000.00000000199.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11000111..00000000.00000000.00000000199.0.0.0
Broadcast11000111..11111111.11111111.11111111199.255.255.255
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)

199.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1199.0.0.0/15199.0.0.1 to 199.1.255.254199.1.255.255131,070
2199.2.0.0/15199.2.0.1 to 199.3.255.254199.3.255.255131,070
3199.4.0.0/15199.4.0.1 to 199.5.255.254199.5.255.255131,070
4199.6.0.0/15199.6.0.1 to 199.7.255.254199.7.255.255131,070
5199.8.0.0/15199.8.0.1 to 199.9.255.254199.9.255.255131,070
6199.10.0.0/15199.10.0.1 to 199.11.255.254199.11.255.255131,070
7199.12.0.0/15199.12.0.1 to 199.13.255.254199.13.255.255131,070
8199.14.0.0/15199.14.0.1 to 199.15.255.254199.15.255.255131,070
9199.16.0.0/15199.16.0.1 to 199.17.255.254199.17.255.255131,070
10199.18.0.0/15199.18.0.1 to 199.19.255.254199.19.255.255131,070
11199.20.0.0/15199.20.0.1 to 199.21.255.254199.21.255.255131,070
12199.22.0.0/15199.22.0.1 to 199.23.255.254199.23.255.255131,070
13199.24.0.0/15199.24.0.1 to 199.25.255.254199.25.255.255131,070
14199.26.0.0/15199.26.0.1 to 199.27.255.254199.27.255.255131,070
15199.28.0.0/15199.28.0.1 to 199.29.255.254199.29.255.255131,070
16199.30.0.0/15199.30.0.1 to 199.31.255.254199.31.255.255131,070
17199.32.0.0/15199.32.0.1 to 199.33.255.254199.33.255.255131,070
18199.34.0.0/15199.34.0.1 to 199.35.255.254199.35.255.255131,070
19199.36.0.0/15199.36.0.1 to 199.37.255.254199.37.255.255131,070
20199.38.0.0/15199.38.0.1 to 199.39.255.254199.39.255.255131,070
21199.40.0.0/15199.40.0.1 to 199.41.255.254199.41.255.255131,070
22199.42.0.0/15199.42.0.1 to 199.43.255.254199.43.255.255131,070
23199.44.0.0/15199.44.0.1 to 199.45.255.254199.45.255.255131,070
24199.46.0.0/15199.46.0.1 to 199.47.255.254199.47.255.255131,070
25199.48.0.0/15199.48.0.1 to 199.49.255.254199.49.255.255131,070
26199.50.0.0/15199.50.0.1 to 199.51.255.254199.51.255.255131,070
27199.52.0.0/15199.52.0.1 to 199.53.255.254199.53.255.255131,070
28199.54.0.0/15199.54.0.1 to 199.55.255.254199.55.255.255131,070
29199.56.0.0/15199.56.0.1 to 199.57.255.254199.57.255.255131,070
30199.58.0.0/15199.58.0.1 to 199.59.255.254199.59.255.255131,070
31199.60.0.0/15199.60.0.1 to 199.61.255.254199.61.255.255131,070
32199.62.0.0/15199.62.0.1 to 199.63.255.254199.63.255.255131,070
33199.64.0.0/15199.64.0.1 to 199.65.255.254199.65.255.255131,070
34199.66.0.0/15199.66.0.1 to 199.67.255.254199.67.255.255131,070
35199.68.0.0/15199.68.0.1 to 199.69.255.254199.69.255.255131,070
36199.70.0.0/15199.70.0.1 to 199.71.255.254199.71.255.255131,070
37199.72.0.0/15199.72.0.1 to 199.73.255.254199.73.255.255131,070
38199.74.0.0/15199.74.0.1 to 199.75.255.254199.75.255.255131,070
39199.76.0.0/15199.76.0.1 to 199.77.255.254199.77.255.255131,070
40199.78.0.0/15199.78.0.1 to 199.79.255.254199.79.255.255131,070
41199.80.0.0/15199.80.0.1 to 199.81.255.254199.81.255.255131,070
42199.82.0.0/15199.82.0.1 to 199.83.255.254199.83.255.255131,070
43199.84.0.0/15199.84.0.1 to 199.85.255.254199.85.255.255131,070
44199.86.0.0/15199.86.0.1 to 199.87.255.254199.87.255.255131,070
45199.88.0.0/15199.88.0.1 to 199.89.255.254199.89.255.255131,070
46199.90.0.0/15199.90.0.1 to 199.91.255.254199.91.255.255131,070
47199.92.0.0/15199.92.0.1 to 199.93.255.254199.93.255.255131,070
48199.94.0.0/15199.94.0.1 to 199.95.255.254199.95.255.255131,070
49199.96.0.0/15199.96.0.1 to 199.97.255.254199.97.255.255131,070
50199.98.0.0/15199.98.0.1 to 199.99.255.254199.99.255.255131,070
51199.100.0.0/15199.100.0.1 to 199.101.255.254199.101.255.255131,070
52199.102.0.0/15199.102.0.1 to 199.103.255.254199.103.255.255131,070
53199.104.0.0/15199.104.0.1 to 199.105.255.254199.105.255.255131,070
54199.106.0.0/15199.106.0.1 to 199.107.255.254199.107.255.255131,070
55199.108.0.0/15199.108.0.1 to 199.109.255.254199.109.255.255131,070
56199.110.0.0/15199.110.0.1 to 199.111.255.254199.111.255.255131,070
57199.112.0.0/15199.112.0.1 to 199.113.255.254199.113.255.255131,070
58199.114.0.0/15199.114.0.1 to 199.115.255.254199.115.255.255131,070
59199.116.0.0/15199.116.0.1 to 199.117.255.254199.117.255.255131,070
60199.118.0.0/15199.118.0.1 to 199.119.255.254199.119.255.255131,070
61199.120.0.0/15199.120.0.1 to 199.121.255.254199.121.255.255131,070
62199.122.0.0/15199.122.0.1 to 199.123.255.254199.123.255.255131,070
63199.124.0.0/15199.124.0.1 to 199.125.255.254199.125.255.255131,070
64199.126.0.0/15199.126.0.1 to 199.127.255.254199.127.255.255131,070
65199.128.0.0/15199.128.0.1 to 199.129.255.254199.129.255.255131,070
66199.130.0.0/15199.130.0.1 to 199.131.255.254199.131.255.255131,070
67199.132.0.0/15199.132.0.1 to 199.133.255.254199.133.255.255131,070
68199.134.0.0/15199.134.0.1 to 199.135.255.254199.135.255.255131,070
69199.136.0.0/15199.136.0.1 to 199.137.255.254199.137.255.255131,070
70199.138.0.0/15199.138.0.1 to 199.139.255.254199.139.255.255131,070
71199.140.0.0/15199.140.0.1 to 199.141.255.254199.141.255.255131,070
72199.142.0.0/15199.142.0.1 to 199.143.255.254199.143.255.255131,070
73199.144.0.0/15199.144.0.1 to 199.145.255.254199.145.255.255131,070
74199.146.0.0/15199.146.0.1 to 199.147.255.254199.147.255.255131,070
75199.148.0.0/15199.148.0.1 to 199.149.255.254199.149.255.255131,070
76199.150.0.0/15199.150.0.1 to 199.151.255.254199.151.255.255131,070
77199.152.0.0/15199.152.0.1 to 199.153.255.254199.153.255.255131,070
78199.154.0.0/15199.154.0.1 to 199.155.255.254199.155.255.255131,070
79199.156.0.0/15199.156.0.1 to 199.157.255.254199.157.255.255131,070
80199.158.0.0/15199.158.0.1 to 199.159.255.254199.159.255.255131,070
81199.160.0.0/15199.160.0.1 to 199.161.255.254199.161.255.255131,070
82199.162.0.0/15199.162.0.1 to 199.163.255.254199.163.255.255131,070
83199.164.0.0/15199.164.0.1 to 199.165.255.254199.165.255.255131,070
84199.166.0.0/15199.166.0.1 to 199.167.255.254199.167.255.255131,070
85199.168.0.0/15199.168.0.1 to 199.169.255.254199.169.255.255131,070
86199.170.0.0/15199.170.0.1 to 199.171.255.254199.171.255.255131,070
87199.172.0.0/15199.172.0.1 to 199.173.255.254199.173.255.255131,070
88199.174.0.0/15199.174.0.1 to 199.175.255.254199.175.255.255131,070
89199.176.0.0/15199.176.0.1 to 199.177.255.254199.177.255.255131,070
90199.178.0.0/15199.178.0.1 to 199.179.255.254199.179.255.255131,070
91199.180.0.0/15199.180.0.1 to 199.181.255.254199.181.255.255131,070
92199.182.0.0/15199.182.0.1 to 199.183.255.254199.183.255.255131,070
93199.184.0.0/15199.184.0.1 to 199.185.255.254199.185.255.255131,070
94199.186.0.0/15199.186.0.1 to 199.187.255.254199.187.255.255131,070
95199.188.0.0/15199.188.0.1 to 199.189.255.254199.189.255.255131,070
96199.190.0.0/15199.190.0.1 to 199.191.255.254199.191.255.255131,070
97199.192.0.0/15199.192.0.1 to 199.193.255.254199.193.255.255131,070
98199.194.0.0/15199.194.0.1 to 199.195.255.254199.195.255.255131,070
99199.196.0.0/15199.196.0.1 to 199.197.255.254199.197.255.255131,070
100199.198.0.0/15199.198.0.1 to 199.199.255.254199.199.255.255131,070
101199.200.0.0/15199.200.0.1 to 199.201.255.254199.201.255.255131,070
102199.202.0.0/15199.202.0.1 to 199.203.255.254199.203.255.255131,070
103199.204.0.0/15199.204.0.1 to 199.205.255.254199.205.255.255131,070
104199.206.0.0/15199.206.0.1 to 199.207.255.254199.207.255.255131,070
105199.208.0.0/15199.208.0.1 to 199.209.255.254199.209.255.255131,070
106199.210.0.0/15199.210.0.1 to 199.211.255.254199.211.255.255131,070
107199.212.0.0/15199.212.0.1 to 199.213.255.254199.213.255.255131,070
108199.214.0.0/15199.214.0.1 to 199.215.255.254199.215.255.255131,070
109199.216.0.0/15199.216.0.1 to 199.217.255.254199.217.255.255131,070
110199.218.0.0/15199.218.0.1 to 199.219.255.254199.219.255.255131,070
111199.220.0.0/15199.220.0.1 to 199.221.255.254199.221.255.255131,070
112199.222.0.0/15199.222.0.1 to 199.223.255.254199.223.255.255131,070
113199.224.0.0/15199.224.0.1 to 199.225.255.254199.225.255.255131,070
114199.226.0.0/15199.226.0.1 to 199.227.255.254199.227.255.255131,070
115199.228.0.0/15199.228.0.1 to 199.229.255.254199.229.255.255131,070
116199.230.0.0/15199.230.0.1 to 199.231.255.254199.231.255.255131,070
117199.232.0.0/15199.232.0.1 to 199.233.255.254199.233.255.255131,070
118199.234.0.0/15199.234.0.1 to 199.235.255.254199.235.255.255131,070
119199.236.0.0/15199.236.0.1 to 199.237.255.254199.237.255.255131,070
120199.238.0.0/15199.238.0.1 to 199.239.255.254199.239.255.255131,070
121199.240.0.0/15199.240.0.1 to 199.241.255.254199.241.255.255131,070
122199.242.0.0/15199.242.0.1 to 199.243.255.254199.243.255.255131,070
123199.244.0.0/15199.244.0.1 to 199.245.255.254199.245.255.255131,070
124199.246.0.0/15199.246.0.1 to 199.247.255.254199.247.255.255131,070
125199.248.0.0/15199.248.0.1 to 199.249.255.254199.249.255.255131,070
126199.250.0.0/15199.250.0.1 to 199.251.255.254199.251.255.255131,070
127199.252.0.0/15199.252.0.1 to 199.253.255.254199.253.255.255131,070
128199.254.0.0/15199.254.0.1 to 199.255.255.254199.255.255.255131,070

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.