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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.

Network202.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
202.0.0.0
Broadcast address
203.255.255.255
First usable
202.0.0.1
Last usable
203.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
C (default /24)
As numbers
Hex CA000000 · Integer 3388997632 to 3422552063
Reverse DNS zones
202.in-addr.arpa
203.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001010.00000000.00000000.00000000202.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11001010.00000000.00000000.00000000202.0.0.0
Broadcast11001011.11111111.11111111.11111111203.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

202.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1202.0.0.0/14202.0.0.1 to 202.3.255.254202.3.255.255262,142
2202.4.0.0/14202.4.0.1 to 202.7.255.254202.7.255.255262,142
3202.8.0.0/14202.8.0.1 to 202.11.255.254202.11.255.255262,142
4202.12.0.0/14202.12.0.1 to 202.15.255.254202.15.255.255262,142
5202.16.0.0/14202.16.0.1 to 202.19.255.254202.19.255.255262,142
6202.20.0.0/14202.20.0.1 to 202.23.255.254202.23.255.255262,142
7202.24.0.0/14202.24.0.1 to 202.27.255.254202.27.255.255262,142
8202.28.0.0/14202.28.0.1 to 202.31.255.254202.31.255.255262,142
9202.32.0.0/14202.32.0.1 to 202.35.255.254202.35.255.255262,142
10202.36.0.0/14202.36.0.1 to 202.39.255.254202.39.255.255262,142
11202.40.0.0/14202.40.0.1 to 202.43.255.254202.43.255.255262,142
12202.44.0.0/14202.44.0.1 to 202.47.255.254202.47.255.255262,142
13202.48.0.0/14202.48.0.1 to 202.51.255.254202.51.255.255262,142
14202.52.0.0/14202.52.0.1 to 202.55.255.254202.55.255.255262,142
15202.56.0.0/14202.56.0.1 to 202.59.255.254202.59.255.255262,142
16202.60.0.0/14202.60.0.1 to 202.63.255.254202.63.255.255262,142
17202.64.0.0/14202.64.0.1 to 202.67.255.254202.67.255.255262,142
18202.68.0.0/14202.68.0.1 to 202.71.255.254202.71.255.255262,142
19202.72.0.0/14202.72.0.1 to 202.75.255.254202.75.255.255262,142
20202.76.0.0/14202.76.0.1 to 202.79.255.254202.79.255.255262,142
21202.80.0.0/14202.80.0.1 to 202.83.255.254202.83.255.255262,142
22202.84.0.0/14202.84.0.1 to 202.87.255.254202.87.255.255262,142
23202.88.0.0/14202.88.0.1 to 202.91.255.254202.91.255.255262,142
24202.92.0.0/14202.92.0.1 to 202.95.255.254202.95.255.255262,142
25202.96.0.0/14202.96.0.1 to 202.99.255.254202.99.255.255262,142
26202.100.0.0/14202.100.0.1 to 202.103.255.254202.103.255.255262,142
27202.104.0.0/14202.104.0.1 to 202.107.255.254202.107.255.255262,142
28202.108.0.0/14202.108.0.1 to 202.111.255.254202.111.255.255262,142
29202.112.0.0/14202.112.0.1 to 202.115.255.254202.115.255.255262,142
30202.116.0.0/14202.116.0.1 to 202.119.255.254202.119.255.255262,142
31202.120.0.0/14202.120.0.1 to 202.123.255.254202.123.255.255262,142
32202.124.0.0/14202.124.0.1 to 202.127.255.254202.127.255.255262,142
33202.128.0.0/14202.128.0.1 to 202.131.255.254202.131.255.255262,142
34202.132.0.0/14202.132.0.1 to 202.135.255.254202.135.255.255262,142
35202.136.0.0/14202.136.0.1 to 202.139.255.254202.139.255.255262,142
36202.140.0.0/14202.140.0.1 to 202.143.255.254202.143.255.255262,142
37202.144.0.0/14202.144.0.1 to 202.147.255.254202.147.255.255262,142
38202.148.0.0/14202.148.0.1 to 202.151.255.254202.151.255.255262,142
39202.152.0.0/14202.152.0.1 to 202.155.255.254202.155.255.255262,142
40202.156.0.0/14202.156.0.1 to 202.159.255.254202.159.255.255262,142
41202.160.0.0/14202.160.0.1 to 202.163.255.254202.163.255.255262,142
42202.164.0.0/14202.164.0.1 to 202.167.255.254202.167.255.255262,142
43202.168.0.0/14202.168.0.1 to 202.171.255.254202.171.255.255262,142
44202.172.0.0/14202.172.0.1 to 202.175.255.254202.175.255.255262,142
45202.176.0.0/14202.176.0.1 to 202.179.255.254202.179.255.255262,142
46202.180.0.0/14202.180.0.1 to 202.183.255.254202.183.255.255262,142
47202.184.0.0/14202.184.0.1 to 202.187.255.254202.187.255.255262,142
48202.188.0.0/14202.188.0.1 to 202.191.255.254202.191.255.255262,142
49202.192.0.0/14202.192.0.1 to 202.195.255.254202.195.255.255262,142
50202.196.0.0/14202.196.0.1 to 202.199.255.254202.199.255.255262,142
51202.200.0.0/14202.200.0.1 to 202.203.255.254202.203.255.255262,142
52202.204.0.0/14202.204.0.1 to 202.207.255.254202.207.255.255262,142
53202.208.0.0/14202.208.0.1 to 202.211.255.254202.211.255.255262,142
54202.212.0.0/14202.212.0.1 to 202.215.255.254202.215.255.255262,142
55202.216.0.0/14202.216.0.1 to 202.219.255.254202.219.255.255262,142
56202.220.0.0/14202.220.0.1 to 202.223.255.254202.223.255.255262,142
57202.224.0.0/14202.224.0.1 to 202.227.255.254202.227.255.255262,142
58202.228.0.0/14202.228.0.1 to 202.231.255.254202.231.255.255262,142
59202.232.0.0/14202.232.0.1 to 202.235.255.254202.235.255.255262,142
60202.236.0.0/14202.236.0.1 to 202.239.255.254202.239.255.255262,142
61202.240.0.0/14202.240.0.1 to 202.243.255.254202.243.255.255262,142
62202.244.0.0/14202.244.0.1 to 202.247.255.254202.247.255.255262,142
63202.248.0.0/14202.248.0.1 to 202.251.255.254202.251.255.255262,142
64202.252.0.0/14202.252.0.1 to 202.255.255.254202.255.255.255262,142
65203.0.0.0/14203.0.0.1 to 203.3.255.254203.3.255.255262,142
66203.4.0.0/14203.4.0.1 to 203.7.255.254203.7.255.255262,142
67203.8.0.0/14203.8.0.1 to 203.11.255.254203.11.255.255262,142
68203.12.0.0/14203.12.0.1 to 203.15.255.254203.15.255.255262,142
69203.16.0.0/14203.16.0.1 to 203.19.255.254203.19.255.255262,142
70203.20.0.0/14203.20.0.1 to 203.23.255.254203.23.255.255262,142
71203.24.0.0/14203.24.0.1 to 203.27.255.254203.27.255.255262,142
72203.28.0.0/14203.28.0.1 to 203.31.255.254203.31.255.255262,142
73203.32.0.0/14203.32.0.1 to 203.35.255.254203.35.255.255262,142
74203.36.0.0/14203.36.0.1 to 203.39.255.254203.39.255.255262,142
75203.40.0.0/14203.40.0.1 to 203.43.255.254203.43.255.255262,142
76203.44.0.0/14203.44.0.1 to 203.47.255.254203.47.255.255262,142
77203.48.0.0/14203.48.0.1 to 203.51.255.254203.51.255.255262,142
78203.52.0.0/14203.52.0.1 to 203.55.255.254203.55.255.255262,142
79203.56.0.0/14203.56.0.1 to 203.59.255.254203.59.255.255262,142
80203.60.0.0/14203.60.0.1 to 203.63.255.254203.63.255.255262,142
81203.64.0.0/14203.64.0.1 to 203.67.255.254203.67.255.255262,142
82203.68.0.0/14203.68.0.1 to 203.71.255.254203.71.255.255262,142
83203.72.0.0/14203.72.0.1 to 203.75.255.254203.75.255.255262,142
84203.76.0.0/14203.76.0.1 to 203.79.255.254203.79.255.255262,142
85203.80.0.0/14203.80.0.1 to 203.83.255.254203.83.255.255262,142
86203.84.0.0/14203.84.0.1 to 203.87.255.254203.87.255.255262,142
87203.88.0.0/14203.88.0.1 to 203.91.255.254203.91.255.255262,142
88203.92.0.0/14203.92.0.1 to 203.95.255.254203.95.255.255262,142
89203.96.0.0/14203.96.0.1 to 203.99.255.254203.99.255.255262,142
90203.100.0.0/14203.100.0.1 to 203.103.255.254203.103.255.255262,142
91203.104.0.0/14203.104.0.1 to 203.107.255.254203.107.255.255262,142
92203.108.0.0/14203.108.0.1 to 203.111.255.254203.111.255.255262,142
93203.112.0.0/14203.112.0.1 to 203.115.255.254203.115.255.255262,142
94203.116.0.0/14203.116.0.1 to 203.119.255.254203.119.255.255262,142
95203.120.0.0/14203.120.0.1 to 203.123.255.254203.123.255.255262,142
96203.124.0.0/14203.124.0.1 to 203.127.255.254203.127.255.255262,142
97203.128.0.0/14203.128.0.1 to 203.131.255.254203.131.255.255262,142
98203.132.0.0/14203.132.0.1 to 203.135.255.254203.135.255.255262,142
99203.136.0.0/14203.136.0.1 to 203.139.255.254203.139.255.255262,142
100203.140.0.0/14203.140.0.1 to 203.143.255.254203.143.255.255262,142
101203.144.0.0/14203.144.0.1 to 203.147.255.254203.147.255.255262,142
102203.148.0.0/14203.148.0.1 to 203.151.255.254203.151.255.255262,142
103203.152.0.0/14203.152.0.1 to 203.155.255.254203.155.255.255262,142
104203.156.0.0/14203.156.0.1 to 203.159.255.254203.159.255.255262,142
105203.160.0.0/14203.160.0.1 to 203.163.255.254203.163.255.255262,142
106203.164.0.0/14203.164.0.1 to 203.167.255.254203.167.255.255262,142
107203.168.0.0/14203.168.0.1 to 203.171.255.254203.171.255.255262,142
108203.172.0.0/14203.172.0.1 to 203.175.255.254203.175.255.255262,142
109203.176.0.0/14203.176.0.1 to 203.179.255.254203.179.255.255262,142
110203.180.0.0/14203.180.0.1 to 203.183.255.254203.183.255.255262,142
111203.184.0.0/14203.184.0.1 to 203.187.255.254203.187.255.255262,142
112203.188.0.0/14203.188.0.1 to 203.191.255.254203.191.255.255262,142
113203.192.0.0/14203.192.0.1 to 203.195.255.254203.195.255.255262,142
114203.196.0.0/14203.196.0.1 to 203.199.255.254203.199.255.255262,142
115203.200.0.0/14203.200.0.1 to 203.203.255.254203.203.255.255262,142
116203.204.0.0/14203.204.0.1 to 203.207.255.254203.207.255.255262,142
117203.208.0.0/14203.208.0.1 to 203.211.255.254203.211.255.255262,142
118203.212.0.0/14203.212.0.1 to 203.215.255.254203.215.255.255262,142
119203.216.0.0/14203.216.0.1 to 203.219.255.254203.219.255.255262,142
120203.220.0.0/14203.220.0.1 to 203.223.255.254203.223.255.255262,142
121203.224.0.0/14203.224.0.1 to 203.227.255.254203.227.255.255262,142
122203.228.0.0/14203.228.0.1 to 203.231.255.254203.231.255.255262,142
123203.232.0.0/14203.232.0.1 to 203.235.255.254203.235.255.255262,142
124203.236.0.0/14203.236.0.1 to 203.239.255.254203.239.255.255262,142
125203.240.0.0/14203.240.0.1 to 203.243.255.254203.243.255.255262,142
126203.244.0.0/14203.244.0.1 to 203.247.255.254203.247.255.255262,142
127203.248.0.0/14203.248.0.1 to 203.251.255.254203.251.255.255262,142
128203.252.0.0/14203.252.0.1 to 203.255.255.254203.255.255.255262,142

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.