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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.

Network75.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
75.0.0.0
Broadcast address
75.255.255.255
First usable
75.0.0.1
Last usable
75.255.255.254
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
A (default /8)
As numbers
Hex 4B000000 · Integer 1258291200 to 1275068415
Reverse DNS zone
75.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01001011..00000000.00000000.0000000075.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network01001011..00000000.00000000.0000000075.0.0.0
Broadcast01001011..11111111.11111111.1111111175.255.255.255
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)

75.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
175.0.0.0/1575.0.0.1 to 75.1.255.25475.1.255.255131,070
275.2.0.0/1575.2.0.1 to 75.3.255.25475.3.255.255131,070
375.4.0.0/1575.4.0.1 to 75.5.255.25475.5.255.255131,070
475.6.0.0/1575.6.0.1 to 75.7.255.25475.7.255.255131,070
575.8.0.0/1575.8.0.1 to 75.9.255.25475.9.255.255131,070
675.10.0.0/1575.10.0.1 to 75.11.255.25475.11.255.255131,070
775.12.0.0/1575.12.0.1 to 75.13.255.25475.13.255.255131,070
875.14.0.0/1575.14.0.1 to 75.15.255.25475.15.255.255131,070
975.16.0.0/1575.16.0.1 to 75.17.255.25475.17.255.255131,070
1075.18.0.0/1575.18.0.1 to 75.19.255.25475.19.255.255131,070
1175.20.0.0/1575.20.0.1 to 75.21.255.25475.21.255.255131,070
1275.22.0.0/1575.22.0.1 to 75.23.255.25475.23.255.255131,070
1375.24.0.0/1575.24.0.1 to 75.25.255.25475.25.255.255131,070
1475.26.0.0/1575.26.0.1 to 75.27.255.25475.27.255.255131,070
1575.28.0.0/1575.28.0.1 to 75.29.255.25475.29.255.255131,070
1675.30.0.0/1575.30.0.1 to 75.31.255.25475.31.255.255131,070
1775.32.0.0/1575.32.0.1 to 75.33.255.25475.33.255.255131,070
1875.34.0.0/1575.34.0.1 to 75.35.255.25475.35.255.255131,070
1975.36.0.0/1575.36.0.1 to 75.37.255.25475.37.255.255131,070
2075.38.0.0/1575.38.0.1 to 75.39.255.25475.39.255.255131,070
2175.40.0.0/1575.40.0.1 to 75.41.255.25475.41.255.255131,070
2275.42.0.0/1575.42.0.1 to 75.43.255.25475.43.255.255131,070
2375.44.0.0/1575.44.0.1 to 75.45.255.25475.45.255.255131,070
2475.46.0.0/1575.46.0.1 to 75.47.255.25475.47.255.255131,070
2575.48.0.0/1575.48.0.1 to 75.49.255.25475.49.255.255131,070
2675.50.0.0/1575.50.0.1 to 75.51.255.25475.51.255.255131,070
2775.52.0.0/1575.52.0.1 to 75.53.255.25475.53.255.255131,070
2875.54.0.0/1575.54.0.1 to 75.55.255.25475.55.255.255131,070
2975.56.0.0/1575.56.0.1 to 75.57.255.25475.57.255.255131,070
3075.58.0.0/1575.58.0.1 to 75.59.255.25475.59.255.255131,070
3175.60.0.0/1575.60.0.1 to 75.61.255.25475.61.255.255131,070
3275.62.0.0/1575.62.0.1 to 75.63.255.25475.63.255.255131,070
3375.64.0.0/1575.64.0.1 to 75.65.255.25475.65.255.255131,070
3475.66.0.0/1575.66.0.1 to 75.67.255.25475.67.255.255131,070
3575.68.0.0/1575.68.0.1 to 75.69.255.25475.69.255.255131,070
3675.70.0.0/1575.70.0.1 to 75.71.255.25475.71.255.255131,070
3775.72.0.0/1575.72.0.1 to 75.73.255.25475.73.255.255131,070
3875.74.0.0/1575.74.0.1 to 75.75.255.25475.75.255.255131,070
3975.76.0.0/1575.76.0.1 to 75.77.255.25475.77.255.255131,070
4075.78.0.0/1575.78.0.1 to 75.79.255.25475.79.255.255131,070
4175.80.0.0/1575.80.0.1 to 75.81.255.25475.81.255.255131,070
4275.82.0.0/1575.82.0.1 to 75.83.255.25475.83.255.255131,070
4375.84.0.0/1575.84.0.1 to 75.85.255.25475.85.255.255131,070
4475.86.0.0/1575.86.0.1 to 75.87.255.25475.87.255.255131,070
4575.88.0.0/1575.88.0.1 to 75.89.255.25475.89.255.255131,070
4675.90.0.0/1575.90.0.1 to 75.91.255.25475.91.255.255131,070
4775.92.0.0/1575.92.0.1 to 75.93.255.25475.93.255.255131,070
4875.94.0.0/1575.94.0.1 to 75.95.255.25475.95.255.255131,070
4975.96.0.0/1575.96.0.1 to 75.97.255.25475.97.255.255131,070
5075.98.0.0/1575.98.0.1 to 75.99.255.25475.99.255.255131,070
5175.100.0.0/1575.100.0.1 to 75.101.255.25475.101.255.255131,070
5275.102.0.0/1575.102.0.1 to 75.103.255.25475.103.255.255131,070
5375.104.0.0/1575.104.0.1 to 75.105.255.25475.105.255.255131,070
5475.106.0.0/1575.106.0.1 to 75.107.255.25475.107.255.255131,070
5575.108.0.0/1575.108.0.1 to 75.109.255.25475.109.255.255131,070
5675.110.0.0/1575.110.0.1 to 75.111.255.25475.111.255.255131,070
5775.112.0.0/1575.112.0.1 to 75.113.255.25475.113.255.255131,070
5875.114.0.0/1575.114.0.1 to 75.115.255.25475.115.255.255131,070
5975.116.0.0/1575.116.0.1 to 75.117.255.25475.117.255.255131,070
6075.118.0.0/1575.118.0.1 to 75.119.255.25475.119.255.255131,070
6175.120.0.0/1575.120.0.1 to 75.121.255.25475.121.255.255131,070
6275.122.0.0/1575.122.0.1 to 75.123.255.25475.123.255.255131,070
6375.124.0.0/1575.124.0.1 to 75.125.255.25475.125.255.255131,070
6475.126.0.0/1575.126.0.1 to 75.127.255.25475.127.255.255131,070
6575.128.0.0/1575.128.0.1 to 75.129.255.25475.129.255.255131,070
6675.130.0.0/1575.130.0.1 to 75.131.255.25475.131.255.255131,070
6775.132.0.0/1575.132.0.1 to 75.133.255.25475.133.255.255131,070
6875.134.0.0/1575.134.0.1 to 75.135.255.25475.135.255.255131,070
6975.136.0.0/1575.136.0.1 to 75.137.255.25475.137.255.255131,070
7075.138.0.0/1575.138.0.1 to 75.139.255.25475.139.255.255131,070
7175.140.0.0/1575.140.0.1 to 75.141.255.25475.141.255.255131,070
7275.142.0.0/1575.142.0.1 to 75.143.255.25475.143.255.255131,070
7375.144.0.0/1575.144.0.1 to 75.145.255.25475.145.255.255131,070
7475.146.0.0/1575.146.0.1 to 75.147.255.25475.147.255.255131,070
7575.148.0.0/1575.148.0.1 to 75.149.255.25475.149.255.255131,070
7675.150.0.0/1575.150.0.1 to 75.151.255.25475.151.255.255131,070
7775.152.0.0/1575.152.0.1 to 75.153.255.25475.153.255.255131,070
7875.154.0.0/1575.154.0.1 to 75.155.255.25475.155.255.255131,070
7975.156.0.0/1575.156.0.1 to 75.157.255.25475.157.255.255131,070
8075.158.0.0/1575.158.0.1 to 75.159.255.25475.159.255.255131,070
8175.160.0.0/1575.160.0.1 to 75.161.255.25475.161.255.255131,070
8275.162.0.0/1575.162.0.1 to 75.163.255.25475.163.255.255131,070
8375.164.0.0/1575.164.0.1 to 75.165.255.25475.165.255.255131,070
8475.166.0.0/1575.166.0.1 to 75.167.255.25475.167.255.255131,070
8575.168.0.0/1575.168.0.1 to 75.169.255.25475.169.255.255131,070
8675.170.0.0/1575.170.0.1 to 75.171.255.25475.171.255.255131,070
8775.172.0.0/1575.172.0.1 to 75.173.255.25475.173.255.255131,070
8875.174.0.0/1575.174.0.1 to 75.175.255.25475.175.255.255131,070
8975.176.0.0/1575.176.0.1 to 75.177.255.25475.177.255.255131,070
9075.178.0.0/1575.178.0.1 to 75.179.255.25475.179.255.255131,070
9175.180.0.0/1575.180.0.1 to 75.181.255.25475.181.255.255131,070
9275.182.0.0/1575.182.0.1 to 75.183.255.25475.183.255.255131,070
9375.184.0.0/1575.184.0.1 to 75.185.255.25475.185.255.255131,070
9475.186.0.0/1575.186.0.1 to 75.187.255.25475.187.255.255131,070
9575.188.0.0/1575.188.0.1 to 75.189.255.25475.189.255.255131,070
9675.190.0.0/1575.190.0.1 to 75.191.255.25475.191.255.255131,070
9775.192.0.0/1575.192.0.1 to 75.193.255.25475.193.255.255131,070
9875.194.0.0/1575.194.0.1 to 75.195.255.25475.195.255.255131,070
9975.196.0.0/1575.196.0.1 to 75.197.255.25475.197.255.255131,070
10075.198.0.0/1575.198.0.1 to 75.199.255.25475.199.255.255131,070
10175.200.0.0/1575.200.0.1 to 75.201.255.25475.201.255.255131,070
10275.202.0.0/1575.202.0.1 to 75.203.255.25475.203.255.255131,070
10375.204.0.0/1575.204.0.1 to 75.205.255.25475.205.255.255131,070
10475.206.0.0/1575.206.0.1 to 75.207.255.25475.207.255.255131,070
10575.208.0.0/1575.208.0.1 to 75.209.255.25475.209.255.255131,070
10675.210.0.0/1575.210.0.1 to 75.211.255.25475.211.255.255131,070
10775.212.0.0/1575.212.0.1 to 75.213.255.25475.213.255.255131,070
10875.214.0.0/1575.214.0.1 to 75.215.255.25475.215.255.255131,070
10975.216.0.0/1575.216.0.1 to 75.217.255.25475.217.255.255131,070
11075.218.0.0/1575.218.0.1 to 75.219.255.25475.219.255.255131,070
11175.220.0.0/1575.220.0.1 to 75.221.255.25475.221.255.255131,070
11275.222.0.0/1575.222.0.1 to 75.223.255.25475.223.255.255131,070
11375.224.0.0/1575.224.0.1 to 75.225.255.25475.225.255.255131,070
11475.226.0.0/1575.226.0.1 to 75.227.255.25475.227.255.255131,070
11575.228.0.0/1575.228.0.1 to 75.229.255.25475.229.255.255131,070
11675.230.0.0/1575.230.0.1 to 75.231.255.25475.231.255.255131,070
11775.232.0.0/1575.232.0.1 to 75.233.255.25475.233.255.255131,070
11875.234.0.0/1575.234.0.1 to 75.235.255.25475.235.255.255131,070
11975.236.0.0/1575.236.0.1 to 75.237.255.25475.237.255.255131,070
12075.238.0.0/1575.238.0.1 to 75.239.255.25475.239.255.255131,070
12175.240.0.0/1575.240.0.1 to 75.241.255.25475.241.255.255131,070
12275.242.0.0/1575.242.0.1 to 75.243.255.25475.243.255.255131,070
12375.244.0.0/1575.244.0.1 to 75.245.255.25475.245.255.255131,070
12475.246.0.0/1575.246.0.1 to 75.247.255.25475.247.255.255131,070
12575.248.0.0/1575.248.0.1 to 75.249.255.25475.249.255.255131,070
12675.250.0.0/1575.250.0.1 to 75.251.255.25475.251.255.255131,070
12775.252.0.0/1575.252.0.1 to 75.253.255.25475.253.255.255131,070
12875.254.0.0/1575.254.0.1 to 75.255.255.25475.255.255.255131,070

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.