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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.

Network28.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
28.0.0.0
Broadcast address
29.255.255.255
First usable
28.0.0.1
Last usable
29.255.255.254
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
A (default /8)
As numbers
Hex 1C000000 · Integer 469762048 to 503316479
Reverse DNS zones
28.in-addr.arpa
29.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
Address00011100.00000000.00000000.0000000028.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network00011100.00000000.00000000.0000000028.0.0.0
Broadcast00011101.11111111.11111111.1111111129.255.255.255
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)

28.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
128.0.0.0/1428.0.0.1 to 28.3.255.25428.3.255.255262,142
228.4.0.0/1428.4.0.1 to 28.7.255.25428.7.255.255262,142
328.8.0.0/1428.8.0.1 to 28.11.255.25428.11.255.255262,142
428.12.0.0/1428.12.0.1 to 28.15.255.25428.15.255.255262,142
528.16.0.0/1428.16.0.1 to 28.19.255.25428.19.255.255262,142
628.20.0.0/1428.20.0.1 to 28.23.255.25428.23.255.255262,142
728.24.0.0/1428.24.0.1 to 28.27.255.25428.27.255.255262,142
828.28.0.0/1428.28.0.1 to 28.31.255.25428.31.255.255262,142
928.32.0.0/1428.32.0.1 to 28.35.255.25428.35.255.255262,142
1028.36.0.0/1428.36.0.1 to 28.39.255.25428.39.255.255262,142
1128.40.0.0/1428.40.0.1 to 28.43.255.25428.43.255.255262,142
1228.44.0.0/1428.44.0.1 to 28.47.255.25428.47.255.255262,142
1328.48.0.0/1428.48.0.1 to 28.51.255.25428.51.255.255262,142
1428.52.0.0/1428.52.0.1 to 28.55.255.25428.55.255.255262,142
1528.56.0.0/1428.56.0.1 to 28.59.255.25428.59.255.255262,142
1628.60.0.0/1428.60.0.1 to 28.63.255.25428.63.255.255262,142
1728.64.0.0/1428.64.0.1 to 28.67.255.25428.67.255.255262,142
1828.68.0.0/1428.68.0.1 to 28.71.255.25428.71.255.255262,142
1928.72.0.0/1428.72.0.1 to 28.75.255.25428.75.255.255262,142
2028.76.0.0/1428.76.0.1 to 28.79.255.25428.79.255.255262,142
2128.80.0.0/1428.80.0.1 to 28.83.255.25428.83.255.255262,142
2228.84.0.0/1428.84.0.1 to 28.87.255.25428.87.255.255262,142
2328.88.0.0/1428.88.0.1 to 28.91.255.25428.91.255.255262,142
2428.92.0.0/1428.92.0.1 to 28.95.255.25428.95.255.255262,142
2528.96.0.0/1428.96.0.1 to 28.99.255.25428.99.255.255262,142
2628.100.0.0/1428.100.0.1 to 28.103.255.25428.103.255.255262,142
2728.104.0.0/1428.104.0.1 to 28.107.255.25428.107.255.255262,142
2828.108.0.0/1428.108.0.1 to 28.111.255.25428.111.255.255262,142
2928.112.0.0/1428.112.0.1 to 28.115.255.25428.115.255.255262,142
3028.116.0.0/1428.116.0.1 to 28.119.255.25428.119.255.255262,142
3128.120.0.0/1428.120.0.1 to 28.123.255.25428.123.255.255262,142
3228.124.0.0/1428.124.0.1 to 28.127.255.25428.127.255.255262,142
3328.128.0.0/1428.128.0.1 to 28.131.255.25428.131.255.255262,142
3428.132.0.0/1428.132.0.1 to 28.135.255.25428.135.255.255262,142
3528.136.0.0/1428.136.0.1 to 28.139.255.25428.139.255.255262,142
3628.140.0.0/1428.140.0.1 to 28.143.255.25428.143.255.255262,142
3728.144.0.0/1428.144.0.1 to 28.147.255.25428.147.255.255262,142
3828.148.0.0/1428.148.0.1 to 28.151.255.25428.151.255.255262,142
3928.152.0.0/1428.152.0.1 to 28.155.255.25428.155.255.255262,142
4028.156.0.0/1428.156.0.1 to 28.159.255.25428.159.255.255262,142
4128.160.0.0/1428.160.0.1 to 28.163.255.25428.163.255.255262,142
4228.164.0.0/1428.164.0.1 to 28.167.255.25428.167.255.255262,142
4328.168.0.0/1428.168.0.1 to 28.171.255.25428.171.255.255262,142
4428.172.0.0/1428.172.0.1 to 28.175.255.25428.175.255.255262,142
4528.176.0.0/1428.176.0.1 to 28.179.255.25428.179.255.255262,142
4628.180.0.0/1428.180.0.1 to 28.183.255.25428.183.255.255262,142
4728.184.0.0/1428.184.0.1 to 28.187.255.25428.187.255.255262,142
4828.188.0.0/1428.188.0.1 to 28.191.255.25428.191.255.255262,142
4928.192.0.0/1428.192.0.1 to 28.195.255.25428.195.255.255262,142
5028.196.0.0/1428.196.0.1 to 28.199.255.25428.199.255.255262,142
5128.200.0.0/1428.200.0.1 to 28.203.255.25428.203.255.255262,142
5228.204.0.0/1428.204.0.1 to 28.207.255.25428.207.255.255262,142
5328.208.0.0/1428.208.0.1 to 28.211.255.25428.211.255.255262,142
5428.212.0.0/1428.212.0.1 to 28.215.255.25428.215.255.255262,142
5528.216.0.0/1428.216.0.1 to 28.219.255.25428.219.255.255262,142
5628.220.0.0/1428.220.0.1 to 28.223.255.25428.223.255.255262,142
5728.224.0.0/1428.224.0.1 to 28.227.255.25428.227.255.255262,142
5828.228.0.0/1428.228.0.1 to 28.231.255.25428.231.255.255262,142
5928.232.0.0/1428.232.0.1 to 28.235.255.25428.235.255.255262,142
6028.236.0.0/1428.236.0.1 to 28.239.255.25428.239.255.255262,142
6128.240.0.0/1428.240.0.1 to 28.243.255.25428.243.255.255262,142
6228.244.0.0/1428.244.0.1 to 28.247.255.25428.247.255.255262,142
6328.248.0.0/1428.248.0.1 to 28.251.255.25428.251.255.255262,142
6428.252.0.0/1428.252.0.1 to 28.255.255.25428.255.255.255262,142
6529.0.0.0/1429.0.0.1 to 29.3.255.25429.3.255.255262,142
6629.4.0.0/1429.4.0.1 to 29.7.255.25429.7.255.255262,142
6729.8.0.0/1429.8.0.1 to 29.11.255.25429.11.255.255262,142
6829.12.0.0/1429.12.0.1 to 29.15.255.25429.15.255.255262,142
6929.16.0.0/1429.16.0.1 to 29.19.255.25429.19.255.255262,142
7029.20.0.0/1429.20.0.1 to 29.23.255.25429.23.255.255262,142
7129.24.0.0/1429.24.0.1 to 29.27.255.25429.27.255.255262,142
7229.28.0.0/1429.28.0.1 to 29.31.255.25429.31.255.255262,142
7329.32.0.0/1429.32.0.1 to 29.35.255.25429.35.255.255262,142
7429.36.0.0/1429.36.0.1 to 29.39.255.25429.39.255.255262,142
7529.40.0.0/1429.40.0.1 to 29.43.255.25429.43.255.255262,142
7629.44.0.0/1429.44.0.1 to 29.47.255.25429.47.255.255262,142
7729.48.0.0/1429.48.0.1 to 29.51.255.25429.51.255.255262,142
7829.52.0.0/1429.52.0.1 to 29.55.255.25429.55.255.255262,142
7929.56.0.0/1429.56.0.1 to 29.59.255.25429.59.255.255262,142
8029.60.0.0/1429.60.0.1 to 29.63.255.25429.63.255.255262,142
8129.64.0.0/1429.64.0.1 to 29.67.255.25429.67.255.255262,142
8229.68.0.0/1429.68.0.1 to 29.71.255.25429.71.255.255262,142
8329.72.0.0/1429.72.0.1 to 29.75.255.25429.75.255.255262,142
8429.76.0.0/1429.76.0.1 to 29.79.255.25429.79.255.255262,142
8529.80.0.0/1429.80.0.1 to 29.83.255.25429.83.255.255262,142
8629.84.0.0/1429.84.0.1 to 29.87.255.25429.87.255.255262,142
8729.88.0.0/1429.88.0.1 to 29.91.255.25429.91.255.255262,142
8829.92.0.0/1429.92.0.1 to 29.95.255.25429.95.255.255262,142
8929.96.0.0/1429.96.0.1 to 29.99.255.25429.99.255.255262,142
9029.100.0.0/1429.100.0.1 to 29.103.255.25429.103.255.255262,142
9129.104.0.0/1429.104.0.1 to 29.107.255.25429.107.255.255262,142
9229.108.0.0/1429.108.0.1 to 29.111.255.25429.111.255.255262,142
9329.112.0.0/1429.112.0.1 to 29.115.255.25429.115.255.255262,142
9429.116.0.0/1429.116.0.1 to 29.119.255.25429.119.255.255262,142
9529.120.0.0/1429.120.0.1 to 29.123.255.25429.123.255.255262,142
9629.124.0.0/1429.124.0.1 to 29.127.255.25429.127.255.255262,142
9729.128.0.0/1429.128.0.1 to 29.131.255.25429.131.255.255262,142
9829.132.0.0/1429.132.0.1 to 29.135.255.25429.135.255.255262,142
9929.136.0.0/1429.136.0.1 to 29.139.255.25429.139.255.255262,142
10029.140.0.0/1429.140.0.1 to 29.143.255.25429.143.255.255262,142
10129.144.0.0/1429.144.0.1 to 29.147.255.25429.147.255.255262,142
10229.148.0.0/1429.148.0.1 to 29.151.255.25429.151.255.255262,142
10329.152.0.0/1429.152.0.1 to 29.155.255.25429.155.255.255262,142
10429.156.0.0/1429.156.0.1 to 29.159.255.25429.159.255.255262,142
10529.160.0.0/1429.160.0.1 to 29.163.255.25429.163.255.255262,142
10629.164.0.0/1429.164.0.1 to 29.167.255.25429.167.255.255262,142
10729.168.0.0/1429.168.0.1 to 29.171.255.25429.171.255.255262,142
10829.172.0.0/1429.172.0.1 to 29.175.255.25429.175.255.255262,142
10929.176.0.0/1429.176.0.1 to 29.179.255.25429.179.255.255262,142
11029.180.0.0/1429.180.0.1 to 29.183.255.25429.183.255.255262,142
11129.184.0.0/1429.184.0.1 to 29.187.255.25429.187.255.255262,142
11229.188.0.0/1429.188.0.1 to 29.191.255.25429.191.255.255262,142
11329.192.0.0/1429.192.0.1 to 29.195.255.25429.195.255.255262,142
11429.196.0.0/1429.196.0.1 to 29.199.255.25429.199.255.255262,142
11529.200.0.0/1429.200.0.1 to 29.203.255.25429.203.255.255262,142
11629.204.0.0/1429.204.0.1 to 29.207.255.25429.207.255.255262,142
11729.208.0.0/1429.208.0.1 to 29.211.255.25429.211.255.255262,142
11829.212.0.0/1429.212.0.1 to 29.215.255.25429.215.255.255262,142
11929.216.0.0/1429.216.0.1 to 29.219.255.25429.219.255.255262,142
12029.220.0.0/1429.220.0.1 to 29.223.255.25429.223.255.255262,142
12129.224.0.0/1429.224.0.1 to 29.227.255.25429.227.255.255262,142
12229.228.0.0/1429.228.0.1 to 29.231.255.25429.231.255.255262,142
12329.232.0.0/1429.232.0.1 to 29.235.255.25429.235.255.255262,142
12429.236.0.0/1429.236.0.1 to 29.239.255.25429.239.255.255262,142
12529.240.0.0/1429.240.0.1 to 29.243.255.25429.243.255.255262,142
12629.244.0.0/1429.244.0.1 to 29.247.255.25429.247.255.255262,142
12729.248.0.0/1429.248.0.1 to 29.251.255.25429.251.255.255262,142
12829.252.0.0/1429.252.0.1 to 29.255.255.25429.255.255.255262,142

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.