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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.

Network8.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
8.0.0.0
Broadcast address
8.255.255.255
First usable
8.0.0.1
Last usable
8.255.255.254
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 08000000 · Integer 134217728 to 150994943
Reverse DNS zone
8.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001000..00000000.00000000.000000008.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00001000..00000000.00000000.000000008.0.0.0
Broadcast00001000..11111111.11111111.111111118.255.255.255
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)

8.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
18.0.0.0/158.0.0.1 to 8.1.255.2548.1.255.255131,070
28.2.0.0/158.2.0.1 to 8.3.255.2548.3.255.255131,070
38.4.0.0/158.4.0.1 to 8.5.255.2548.5.255.255131,070
48.6.0.0/158.6.0.1 to 8.7.255.2548.7.255.255131,070
58.8.0.0/158.8.0.1 to 8.9.255.2548.9.255.255131,070
68.10.0.0/158.10.0.1 to 8.11.255.2548.11.255.255131,070
78.12.0.0/158.12.0.1 to 8.13.255.2548.13.255.255131,070
88.14.0.0/158.14.0.1 to 8.15.255.2548.15.255.255131,070
98.16.0.0/158.16.0.1 to 8.17.255.2548.17.255.255131,070
108.18.0.0/158.18.0.1 to 8.19.255.2548.19.255.255131,070
118.20.0.0/158.20.0.1 to 8.21.255.2548.21.255.255131,070
128.22.0.0/158.22.0.1 to 8.23.255.2548.23.255.255131,070
138.24.0.0/158.24.0.1 to 8.25.255.2548.25.255.255131,070
148.26.0.0/158.26.0.1 to 8.27.255.2548.27.255.255131,070
158.28.0.0/158.28.0.1 to 8.29.255.2548.29.255.255131,070
168.30.0.0/158.30.0.1 to 8.31.255.2548.31.255.255131,070
178.32.0.0/158.32.0.1 to 8.33.255.2548.33.255.255131,070
188.34.0.0/158.34.0.1 to 8.35.255.2548.35.255.255131,070
198.36.0.0/158.36.0.1 to 8.37.255.2548.37.255.255131,070
208.38.0.0/158.38.0.1 to 8.39.255.2548.39.255.255131,070
218.40.0.0/158.40.0.1 to 8.41.255.2548.41.255.255131,070
228.42.0.0/158.42.0.1 to 8.43.255.2548.43.255.255131,070
238.44.0.0/158.44.0.1 to 8.45.255.2548.45.255.255131,070
248.46.0.0/158.46.0.1 to 8.47.255.2548.47.255.255131,070
258.48.0.0/158.48.0.1 to 8.49.255.2548.49.255.255131,070
268.50.0.0/158.50.0.1 to 8.51.255.2548.51.255.255131,070
278.52.0.0/158.52.0.1 to 8.53.255.2548.53.255.255131,070
288.54.0.0/158.54.0.1 to 8.55.255.2548.55.255.255131,070
298.56.0.0/158.56.0.1 to 8.57.255.2548.57.255.255131,070
308.58.0.0/158.58.0.1 to 8.59.255.2548.59.255.255131,070
318.60.0.0/158.60.0.1 to 8.61.255.2548.61.255.255131,070
328.62.0.0/158.62.0.1 to 8.63.255.2548.63.255.255131,070
338.64.0.0/158.64.0.1 to 8.65.255.2548.65.255.255131,070
348.66.0.0/158.66.0.1 to 8.67.255.2548.67.255.255131,070
358.68.0.0/158.68.0.1 to 8.69.255.2548.69.255.255131,070
368.70.0.0/158.70.0.1 to 8.71.255.2548.71.255.255131,070
378.72.0.0/158.72.0.1 to 8.73.255.2548.73.255.255131,070
388.74.0.0/158.74.0.1 to 8.75.255.2548.75.255.255131,070
398.76.0.0/158.76.0.1 to 8.77.255.2548.77.255.255131,070
408.78.0.0/158.78.0.1 to 8.79.255.2548.79.255.255131,070
418.80.0.0/158.80.0.1 to 8.81.255.2548.81.255.255131,070
428.82.0.0/158.82.0.1 to 8.83.255.2548.83.255.255131,070
438.84.0.0/158.84.0.1 to 8.85.255.2548.85.255.255131,070
448.86.0.0/158.86.0.1 to 8.87.255.2548.87.255.255131,070
458.88.0.0/158.88.0.1 to 8.89.255.2548.89.255.255131,070
468.90.0.0/158.90.0.1 to 8.91.255.2548.91.255.255131,070
478.92.0.0/158.92.0.1 to 8.93.255.2548.93.255.255131,070
488.94.0.0/158.94.0.1 to 8.95.255.2548.95.255.255131,070
498.96.0.0/158.96.0.1 to 8.97.255.2548.97.255.255131,070
508.98.0.0/158.98.0.1 to 8.99.255.2548.99.255.255131,070
518.100.0.0/158.100.0.1 to 8.101.255.2548.101.255.255131,070
528.102.0.0/158.102.0.1 to 8.103.255.2548.103.255.255131,070
538.104.0.0/158.104.0.1 to 8.105.255.2548.105.255.255131,070
548.106.0.0/158.106.0.1 to 8.107.255.2548.107.255.255131,070
558.108.0.0/158.108.0.1 to 8.109.255.2548.109.255.255131,070
568.110.0.0/158.110.0.1 to 8.111.255.2548.111.255.255131,070
578.112.0.0/158.112.0.1 to 8.113.255.2548.113.255.255131,070
588.114.0.0/158.114.0.1 to 8.115.255.2548.115.255.255131,070
598.116.0.0/158.116.0.1 to 8.117.255.2548.117.255.255131,070
608.118.0.0/158.118.0.1 to 8.119.255.2548.119.255.255131,070
618.120.0.0/158.120.0.1 to 8.121.255.2548.121.255.255131,070
628.122.0.0/158.122.0.1 to 8.123.255.2548.123.255.255131,070
638.124.0.0/158.124.0.1 to 8.125.255.2548.125.255.255131,070
648.126.0.0/158.126.0.1 to 8.127.255.2548.127.255.255131,070
658.128.0.0/158.128.0.1 to 8.129.255.2548.129.255.255131,070
668.130.0.0/158.130.0.1 to 8.131.255.2548.131.255.255131,070
678.132.0.0/158.132.0.1 to 8.133.255.2548.133.255.255131,070
688.134.0.0/158.134.0.1 to 8.135.255.2548.135.255.255131,070
698.136.0.0/158.136.0.1 to 8.137.255.2548.137.255.255131,070
708.138.0.0/158.138.0.1 to 8.139.255.2548.139.255.255131,070
718.140.0.0/158.140.0.1 to 8.141.255.2548.141.255.255131,070
728.142.0.0/158.142.0.1 to 8.143.255.2548.143.255.255131,070
738.144.0.0/158.144.0.1 to 8.145.255.2548.145.255.255131,070
748.146.0.0/158.146.0.1 to 8.147.255.2548.147.255.255131,070
758.148.0.0/158.148.0.1 to 8.149.255.2548.149.255.255131,070
768.150.0.0/158.150.0.1 to 8.151.255.2548.151.255.255131,070
778.152.0.0/158.152.0.1 to 8.153.255.2548.153.255.255131,070
788.154.0.0/158.154.0.1 to 8.155.255.2548.155.255.255131,070
798.156.0.0/158.156.0.1 to 8.157.255.2548.157.255.255131,070
808.158.0.0/158.158.0.1 to 8.159.255.2548.159.255.255131,070
818.160.0.0/158.160.0.1 to 8.161.255.2548.161.255.255131,070
828.162.0.0/158.162.0.1 to 8.163.255.2548.163.255.255131,070
838.164.0.0/158.164.0.1 to 8.165.255.2548.165.255.255131,070
848.166.0.0/158.166.0.1 to 8.167.255.2548.167.255.255131,070
858.168.0.0/158.168.0.1 to 8.169.255.2548.169.255.255131,070
868.170.0.0/158.170.0.1 to 8.171.255.2548.171.255.255131,070
878.172.0.0/158.172.0.1 to 8.173.255.2548.173.255.255131,070
888.174.0.0/158.174.0.1 to 8.175.255.2548.175.255.255131,070
898.176.0.0/158.176.0.1 to 8.177.255.2548.177.255.255131,070
908.178.0.0/158.178.0.1 to 8.179.255.2548.179.255.255131,070
918.180.0.0/158.180.0.1 to 8.181.255.2548.181.255.255131,070
928.182.0.0/158.182.0.1 to 8.183.255.2548.183.255.255131,070
938.184.0.0/158.184.0.1 to 8.185.255.2548.185.255.255131,070
948.186.0.0/158.186.0.1 to 8.187.255.2548.187.255.255131,070
958.188.0.0/158.188.0.1 to 8.189.255.2548.189.255.255131,070
968.190.0.0/158.190.0.1 to 8.191.255.2548.191.255.255131,070
978.192.0.0/158.192.0.1 to 8.193.255.2548.193.255.255131,070
988.194.0.0/158.194.0.1 to 8.195.255.2548.195.255.255131,070
998.196.0.0/158.196.0.1 to 8.197.255.2548.197.255.255131,070
1008.198.0.0/158.198.0.1 to 8.199.255.2548.199.255.255131,070
1018.200.0.0/158.200.0.1 to 8.201.255.2548.201.255.255131,070
1028.202.0.0/158.202.0.1 to 8.203.255.2548.203.255.255131,070
1038.204.0.0/158.204.0.1 to 8.205.255.2548.205.255.255131,070
1048.206.0.0/158.206.0.1 to 8.207.255.2548.207.255.255131,070
1058.208.0.0/158.208.0.1 to 8.209.255.2548.209.255.255131,070
1068.210.0.0/158.210.0.1 to 8.211.255.2548.211.255.255131,070
1078.212.0.0/158.212.0.1 to 8.213.255.2548.213.255.255131,070
1088.214.0.0/158.214.0.1 to 8.215.255.2548.215.255.255131,070
1098.216.0.0/158.216.0.1 to 8.217.255.2548.217.255.255131,070
1108.218.0.0/158.218.0.1 to 8.219.255.2548.219.255.255131,070
1118.220.0.0/158.220.0.1 to 8.221.255.2548.221.255.255131,070
1128.222.0.0/158.222.0.1 to 8.223.255.2548.223.255.255131,070
1138.224.0.0/158.224.0.1 to 8.225.255.2548.225.255.255131,070
1148.226.0.0/158.226.0.1 to 8.227.255.2548.227.255.255131,070
1158.228.0.0/158.228.0.1 to 8.229.255.2548.229.255.255131,070
1168.230.0.0/158.230.0.1 to 8.231.255.2548.231.255.255131,070
1178.232.0.0/158.232.0.1 to 8.233.255.2548.233.255.255131,070
1188.234.0.0/158.234.0.1 to 8.235.255.2548.235.255.255131,070
1198.236.0.0/158.236.0.1 to 8.237.255.2548.237.255.255131,070
1208.238.0.0/158.238.0.1 to 8.239.255.2548.239.255.255131,070
1218.240.0.0/158.240.0.1 to 8.241.255.2548.241.255.255131,070
1228.242.0.0/158.242.0.1 to 8.243.255.2548.243.255.255131,070
1238.244.0.0/158.244.0.1 to 8.245.255.2548.245.255.255131,070
1248.246.0.0/158.246.0.1 to 8.247.255.2548.247.255.255131,070
1258.248.0.0/158.248.0.1 to 8.249.255.2548.249.255.255131,070
1268.250.0.0/158.250.0.1 to 8.251.255.2548.251.255.255131,070
1278.252.0.0/158.252.0.1 to 8.253.255.2548.253.255.255131,070
1288.254.0.0/158.254.0.1 to 8.255.255.2548.255.255.255131,070

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.