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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.

Network0.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
0.0.0.0
Broadcast address
0.255.255.255
First usable
0.0.0.1
Last usable
0.255.255.254
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
This network 0.0.0.0/8
Not routed; 0.0.0.0 means "any address" in settings
Old class
A (default /8)
As numbers
Hex 00000000 · Integer 0 to 16777215
Reverse DNS zone
0.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000000..00000000.00000000.000000000.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00000000..00000000.00000000.000000000.0.0.0
Broadcast00000000..11111111.11111111.111111110.255.255.255
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)

0.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
10.0.0.0/150.0.0.1 to 0.1.255.2540.1.255.255131,070
20.2.0.0/150.2.0.1 to 0.3.255.2540.3.255.255131,070
30.4.0.0/150.4.0.1 to 0.5.255.2540.5.255.255131,070
40.6.0.0/150.6.0.1 to 0.7.255.2540.7.255.255131,070
50.8.0.0/150.8.0.1 to 0.9.255.2540.9.255.255131,070
60.10.0.0/150.10.0.1 to 0.11.255.2540.11.255.255131,070
70.12.0.0/150.12.0.1 to 0.13.255.2540.13.255.255131,070
80.14.0.0/150.14.0.1 to 0.15.255.2540.15.255.255131,070
90.16.0.0/150.16.0.1 to 0.17.255.2540.17.255.255131,070
100.18.0.0/150.18.0.1 to 0.19.255.2540.19.255.255131,070
110.20.0.0/150.20.0.1 to 0.21.255.2540.21.255.255131,070
120.22.0.0/150.22.0.1 to 0.23.255.2540.23.255.255131,070
130.24.0.0/150.24.0.1 to 0.25.255.2540.25.255.255131,070
140.26.0.0/150.26.0.1 to 0.27.255.2540.27.255.255131,070
150.28.0.0/150.28.0.1 to 0.29.255.2540.29.255.255131,070
160.30.0.0/150.30.0.1 to 0.31.255.2540.31.255.255131,070
170.32.0.0/150.32.0.1 to 0.33.255.2540.33.255.255131,070
180.34.0.0/150.34.0.1 to 0.35.255.2540.35.255.255131,070
190.36.0.0/150.36.0.1 to 0.37.255.2540.37.255.255131,070
200.38.0.0/150.38.0.1 to 0.39.255.2540.39.255.255131,070
210.40.0.0/150.40.0.1 to 0.41.255.2540.41.255.255131,070
220.42.0.0/150.42.0.1 to 0.43.255.2540.43.255.255131,070
230.44.0.0/150.44.0.1 to 0.45.255.2540.45.255.255131,070
240.46.0.0/150.46.0.1 to 0.47.255.2540.47.255.255131,070
250.48.0.0/150.48.0.1 to 0.49.255.2540.49.255.255131,070
260.50.0.0/150.50.0.1 to 0.51.255.2540.51.255.255131,070
270.52.0.0/150.52.0.1 to 0.53.255.2540.53.255.255131,070
280.54.0.0/150.54.0.1 to 0.55.255.2540.55.255.255131,070
290.56.0.0/150.56.0.1 to 0.57.255.2540.57.255.255131,070
300.58.0.0/150.58.0.1 to 0.59.255.2540.59.255.255131,070
310.60.0.0/150.60.0.1 to 0.61.255.2540.61.255.255131,070
320.62.0.0/150.62.0.1 to 0.63.255.2540.63.255.255131,070
330.64.0.0/150.64.0.1 to 0.65.255.2540.65.255.255131,070
340.66.0.0/150.66.0.1 to 0.67.255.2540.67.255.255131,070
350.68.0.0/150.68.0.1 to 0.69.255.2540.69.255.255131,070
360.70.0.0/150.70.0.1 to 0.71.255.2540.71.255.255131,070
370.72.0.0/150.72.0.1 to 0.73.255.2540.73.255.255131,070
380.74.0.0/150.74.0.1 to 0.75.255.2540.75.255.255131,070
390.76.0.0/150.76.0.1 to 0.77.255.2540.77.255.255131,070
400.78.0.0/150.78.0.1 to 0.79.255.2540.79.255.255131,070
410.80.0.0/150.80.0.1 to 0.81.255.2540.81.255.255131,070
420.82.0.0/150.82.0.1 to 0.83.255.2540.83.255.255131,070
430.84.0.0/150.84.0.1 to 0.85.255.2540.85.255.255131,070
440.86.0.0/150.86.0.1 to 0.87.255.2540.87.255.255131,070
450.88.0.0/150.88.0.1 to 0.89.255.2540.89.255.255131,070
460.90.0.0/150.90.0.1 to 0.91.255.2540.91.255.255131,070
470.92.0.0/150.92.0.1 to 0.93.255.2540.93.255.255131,070
480.94.0.0/150.94.0.1 to 0.95.255.2540.95.255.255131,070
490.96.0.0/150.96.0.1 to 0.97.255.2540.97.255.255131,070
500.98.0.0/150.98.0.1 to 0.99.255.2540.99.255.255131,070
510.100.0.0/150.100.0.1 to 0.101.255.2540.101.255.255131,070
520.102.0.0/150.102.0.1 to 0.103.255.2540.103.255.255131,070
530.104.0.0/150.104.0.1 to 0.105.255.2540.105.255.255131,070
540.106.0.0/150.106.0.1 to 0.107.255.2540.107.255.255131,070
550.108.0.0/150.108.0.1 to 0.109.255.2540.109.255.255131,070
560.110.0.0/150.110.0.1 to 0.111.255.2540.111.255.255131,070
570.112.0.0/150.112.0.1 to 0.113.255.2540.113.255.255131,070
580.114.0.0/150.114.0.1 to 0.115.255.2540.115.255.255131,070
590.116.0.0/150.116.0.1 to 0.117.255.2540.117.255.255131,070
600.118.0.0/150.118.0.1 to 0.119.255.2540.119.255.255131,070
610.120.0.0/150.120.0.1 to 0.121.255.2540.121.255.255131,070
620.122.0.0/150.122.0.1 to 0.123.255.2540.123.255.255131,070
630.124.0.0/150.124.0.1 to 0.125.255.2540.125.255.255131,070
640.126.0.0/150.126.0.1 to 0.127.255.2540.127.255.255131,070
650.128.0.0/150.128.0.1 to 0.129.255.2540.129.255.255131,070
660.130.0.0/150.130.0.1 to 0.131.255.2540.131.255.255131,070
670.132.0.0/150.132.0.1 to 0.133.255.2540.133.255.255131,070
680.134.0.0/150.134.0.1 to 0.135.255.2540.135.255.255131,070
690.136.0.0/150.136.0.1 to 0.137.255.2540.137.255.255131,070
700.138.0.0/150.138.0.1 to 0.139.255.2540.139.255.255131,070
710.140.0.0/150.140.0.1 to 0.141.255.2540.141.255.255131,070
720.142.0.0/150.142.0.1 to 0.143.255.2540.143.255.255131,070
730.144.0.0/150.144.0.1 to 0.145.255.2540.145.255.255131,070
740.146.0.0/150.146.0.1 to 0.147.255.2540.147.255.255131,070
750.148.0.0/150.148.0.1 to 0.149.255.2540.149.255.255131,070
760.150.0.0/150.150.0.1 to 0.151.255.2540.151.255.255131,070
770.152.0.0/150.152.0.1 to 0.153.255.2540.153.255.255131,070
780.154.0.0/150.154.0.1 to 0.155.255.2540.155.255.255131,070
790.156.0.0/150.156.0.1 to 0.157.255.2540.157.255.255131,070
800.158.0.0/150.158.0.1 to 0.159.255.2540.159.255.255131,070
810.160.0.0/150.160.0.1 to 0.161.255.2540.161.255.255131,070
820.162.0.0/150.162.0.1 to 0.163.255.2540.163.255.255131,070
830.164.0.0/150.164.0.1 to 0.165.255.2540.165.255.255131,070
840.166.0.0/150.166.0.1 to 0.167.255.2540.167.255.255131,070
850.168.0.0/150.168.0.1 to 0.169.255.2540.169.255.255131,070
860.170.0.0/150.170.0.1 to 0.171.255.2540.171.255.255131,070
870.172.0.0/150.172.0.1 to 0.173.255.2540.173.255.255131,070
880.174.0.0/150.174.0.1 to 0.175.255.2540.175.255.255131,070
890.176.0.0/150.176.0.1 to 0.177.255.2540.177.255.255131,070
900.178.0.0/150.178.0.1 to 0.179.255.2540.179.255.255131,070
910.180.0.0/150.180.0.1 to 0.181.255.2540.181.255.255131,070
920.182.0.0/150.182.0.1 to 0.183.255.2540.183.255.255131,070
930.184.0.0/150.184.0.1 to 0.185.255.2540.185.255.255131,070
940.186.0.0/150.186.0.1 to 0.187.255.2540.187.255.255131,070
950.188.0.0/150.188.0.1 to 0.189.255.2540.189.255.255131,070
960.190.0.0/150.190.0.1 to 0.191.255.2540.191.255.255131,070
970.192.0.0/150.192.0.1 to 0.193.255.2540.193.255.255131,070
980.194.0.0/150.194.0.1 to 0.195.255.2540.195.255.255131,070
990.196.0.0/150.196.0.1 to 0.197.255.2540.197.255.255131,070
1000.198.0.0/150.198.0.1 to 0.199.255.2540.199.255.255131,070
1010.200.0.0/150.200.0.1 to 0.201.255.2540.201.255.255131,070
1020.202.0.0/150.202.0.1 to 0.203.255.2540.203.255.255131,070
1030.204.0.0/150.204.0.1 to 0.205.255.2540.205.255.255131,070
1040.206.0.0/150.206.0.1 to 0.207.255.2540.207.255.255131,070
1050.208.0.0/150.208.0.1 to 0.209.255.2540.209.255.255131,070
1060.210.0.0/150.210.0.1 to 0.211.255.2540.211.255.255131,070
1070.212.0.0/150.212.0.1 to 0.213.255.2540.213.255.255131,070
1080.214.0.0/150.214.0.1 to 0.215.255.2540.215.255.255131,070
1090.216.0.0/150.216.0.1 to 0.217.255.2540.217.255.255131,070
1100.218.0.0/150.218.0.1 to 0.219.255.2540.219.255.255131,070
1110.220.0.0/150.220.0.1 to 0.221.255.2540.221.255.255131,070
1120.222.0.0/150.222.0.1 to 0.223.255.2540.223.255.255131,070
1130.224.0.0/150.224.0.1 to 0.225.255.2540.225.255.255131,070
1140.226.0.0/150.226.0.1 to 0.227.255.2540.227.255.255131,070
1150.228.0.0/150.228.0.1 to 0.229.255.2540.229.255.255131,070
1160.230.0.0/150.230.0.1 to 0.231.255.2540.231.255.255131,070
1170.232.0.0/150.232.0.1 to 0.233.255.2540.233.255.255131,070
1180.234.0.0/150.234.0.1 to 0.235.255.2540.235.255.255131,070
1190.236.0.0/150.236.0.1 to 0.237.255.2540.237.255.255131,070
1200.238.0.0/150.238.0.1 to 0.239.255.2540.239.255.255131,070
1210.240.0.0/150.240.0.1 to 0.241.255.2540.241.255.255131,070
1220.242.0.0/150.242.0.1 to 0.243.255.2540.243.255.255131,070
1230.244.0.0/150.244.0.1 to 0.245.255.2540.245.255.255131,070
1240.246.0.0/150.246.0.1 to 0.247.255.2540.247.255.255131,070
1250.248.0.0/150.248.0.1 to 0.249.255.2540.249.255.255131,070
1260.250.0.0/150.250.0.1 to 0.251.255.2540.251.255.255131,070
1270.252.0.0/150.252.0.1 to 0.253.255.2540.253.255.255131,070
1280.254.0.0/150.254.0.1 to 0.255.255.2540.255.255.255131,070

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.