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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.

Network6.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
6.0.0.0
Broadcast address
7.255.255.255
First usable
6.0.0.1
Last usable
7.255.255.254
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 06000000 · Integer 100663296 to 134217727
Reverse DNS zones
6.in-addr.arpa
7.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
Address00000110.00000000.00000000.000000006.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network00000110.00000000.00000000.000000006.0.0.0
Broadcast00000111.11111111.11111111.111111117.255.255.255
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)

6.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
16.0.0.0/146.0.0.1 to 6.3.255.2546.3.255.255262,142
26.4.0.0/146.4.0.1 to 6.7.255.2546.7.255.255262,142
36.8.0.0/146.8.0.1 to 6.11.255.2546.11.255.255262,142
46.12.0.0/146.12.0.1 to 6.15.255.2546.15.255.255262,142
56.16.0.0/146.16.0.1 to 6.19.255.2546.19.255.255262,142
66.20.0.0/146.20.0.1 to 6.23.255.2546.23.255.255262,142
76.24.0.0/146.24.0.1 to 6.27.255.2546.27.255.255262,142
86.28.0.0/146.28.0.1 to 6.31.255.2546.31.255.255262,142
96.32.0.0/146.32.0.1 to 6.35.255.2546.35.255.255262,142
106.36.0.0/146.36.0.1 to 6.39.255.2546.39.255.255262,142
116.40.0.0/146.40.0.1 to 6.43.255.2546.43.255.255262,142
126.44.0.0/146.44.0.1 to 6.47.255.2546.47.255.255262,142
136.48.0.0/146.48.0.1 to 6.51.255.2546.51.255.255262,142
146.52.0.0/146.52.0.1 to 6.55.255.2546.55.255.255262,142
156.56.0.0/146.56.0.1 to 6.59.255.2546.59.255.255262,142
166.60.0.0/146.60.0.1 to 6.63.255.2546.63.255.255262,142
176.64.0.0/146.64.0.1 to 6.67.255.2546.67.255.255262,142
186.68.0.0/146.68.0.1 to 6.71.255.2546.71.255.255262,142
196.72.0.0/146.72.0.1 to 6.75.255.2546.75.255.255262,142
206.76.0.0/146.76.0.1 to 6.79.255.2546.79.255.255262,142
216.80.0.0/146.80.0.1 to 6.83.255.2546.83.255.255262,142
226.84.0.0/146.84.0.1 to 6.87.255.2546.87.255.255262,142
236.88.0.0/146.88.0.1 to 6.91.255.2546.91.255.255262,142
246.92.0.0/146.92.0.1 to 6.95.255.2546.95.255.255262,142
256.96.0.0/146.96.0.1 to 6.99.255.2546.99.255.255262,142
266.100.0.0/146.100.0.1 to 6.103.255.2546.103.255.255262,142
276.104.0.0/146.104.0.1 to 6.107.255.2546.107.255.255262,142
286.108.0.0/146.108.0.1 to 6.111.255.2546.111.255.255262,142
296.112.0.0/146.112.0.1 to 6.115.255.2546.115.255.255262,142
306.116.0.0/146.116.0.1 to 6.119.255.2546.119.255.255262,142
316.120.0.0/146.120.0.1 to 6.123.255.2546.123.255.255262,142
326.124.0.0/146.124.0.1 to 6.127.255.2546.127.255.255262,142
336.128.0.0/146.128.0.1 to 6.131.255.2546.131.255.255262,142
346.132.0.0/146.132.0.1 to 6.135.255.2546.135.255.255262,142
356.136.0.0/146.136.0.1 to 6.139.255.2546.139.255.255262,142
366.140.0.0/146.140.0.1 to 6.143.255.2546.143.255.255262,142
376.144.0.0/146.144.0.1 to 6.147.255.2546.147.255.255262,142
386.148.0.0/146.148.0.1 to 6.151.255.2546.151.255.255262,142
396.152.0.0/146.152.0.1 to 6.155.255.2546.155.255.255262,142
406.156.0.0/146.156.0.1 to 6.159.255.2546.159.255.255262,142
416.160.0.0/146.160.0.1 to 6.163.255.2546.163.255.255262,142
426.164.0.0/146.164.0.1 to 6.167.255.2546.167.255.255262,142
436.168.0.0/146.168.0.1 to 6.171.255.2546.171.255.255262,142
446.172.0.0/146.172.0.1 to 6.175.255.2546.175.255.255262,142
456.176.0.0/146.176.0.1 to 6.179.255.2546.179.255.255262,142
466.180.0.0/146.180.0.1 to 6.183.255.2546.183.255.255262,142
476.184.0.0/146.184.0.1 to 6.187.255.2546.187.255.255262,142
486.188.0.0/146.188.0.1 to 6.191.255.2546.191.255.255262,142
496.192.0.0/146.192.0.1 to 6.195.255.2546.195.255.255262,142
506.196.0.0/146.196.0.1 to 6.199.255.2546.199.255.255262,142
516.200.0.0/146.200.0.1 to 6.203.255.2546.203.255.255262,142
526.204.0.0/146.204.0.1 to 6.207.255.2546.207.255.255262,142
536.208.0.0/146.208.0.1 to 6.211.255.2546.211.255.255262,142
546.212.0.0/146.212.0.1 to 6.215.255.2546.215.255.255262,142
556.216.0.0/146.216.0.1 to 6.219.255.2546.219.255.255262,142
566.220.0.0/146.220.0.1 to 6.223.255.2546.223.255.255262,142
576.224.0.0/146.224.0.1 to 6.227.255.2546.227.255.255262,142
586.228.0.0/146.228.0.1 to 6.231.255.2546.231.255.255262,142
596.232.0.0/146.232.0.1 to 6.235.255.2546.235.255.255262,142
606.236.0.0/146.236.0.1 to 6.239.255.2546.239.255.255262,142
616.240.0.0/146.240.0.1 to 6.243.255.2546.243.255.255262,142
626.244.0.0/146.244.0.1 to 6.247.255.2546.247.255.255262,142
636.248.0.0/146.248.0.1 to 6.251.255.2546.251.255.255262,142
646.252.0.0/146.252.0.1 to 6.255.255.2546.255.255.255262,142
657.0.0.0/147.0.0.1 to 7.3.255.2547.3.255.255262,142
667.4.0.0/147.4.0.1 to 7.7.255.2547.7.255.255262,142
677.8.0.0/147.8.0.1 to 7.11.255.2547.11.255.255262,142
687.12.0.0/147.12.0.1 to 7.15.255.2547.15.255.255262,142
697.16.0.0/147.16.0.1 to 7.19.255.2547.19.255.255262,142
707.20.0.0/147.20.0.1 to 7.23.255.2547.23.255.255262,142
717.24.0.0/147.24.0.1 to 7.27.255.2547.27.255.255262,142
727.28.0.0/147.28.0.1 to 7.31.255.2547.31.255.255262,142
737.32.0.0/147.32.0.1 to 7.35.255.2547.35.255.255262,142
747.36.0.0/147.36.0.1 to 7.39.255.2547.39.255.255262,142
757.40.0.0/147.40.0.1 to 7.43.255.2547.43.255.255262,142
767.44.0.0/147.44.0.1 to 7.47.255.2547.47.255.255262,142
777.48.0.0/147.48.0.1 to 7.51.255.2547.51.255.255262,142
787.52.0.0/147.52.0.1 to 7.55.255.2547.55.255.255262,142
797.56.0.0/147.56.0.1 to 7.59.255.2547.59.255.255262,142
807.60.0.0/147.60.0.1 to 7.63.255.2547.63.255.255262,142
817.64.0.0/147.64.0.1 to 7.67.255.2547.67.255.255262,142
827.68.0.0/147.68.0.1 to 7.71.255.2547.71.255.255262,142
837.72.0.0/147.72.0.1 to 7.75.255.2547.75.255.255262,142
847.76.0.0/147.76.0.1 to 7.79.255.2547.79.255.255262,142
857.80.0.0/147.80.0.1 to 7.83.255.2547.83.255.255262,142
867.84.0.0/147.84.0.1 to 7.87.255.2547.87.255.255262,142
877.88.0.0/147.88.0.1 to 7.91.255.2547.91.255.255262,142
887.92.0.0/147.92.0.1 to 7.95.255.2547.95.255.255262,142
897.96.0.0/147.96.0.1 to 7.99.255.2547.99.255.255262,142
907.100.0.0/147.100.0.1 to 7.103.255.2547.103.255.255262,142
917.104.0.0/147.104.0.1 to 7.107.255.2547.107.255.255262,142
927.108.0.0/147.108.0.1 to 7.111.255.2547.111.255.255262,142
937.112.0.0/147.112.0.1 to 7.115.255.2547.115.255.255262,142
947.116.0.0/147.116.0.1 to 7.119.255.2547.119.255.255262,142
957.120.0.0/147.120.0.1 to 7.123.255.2547.123.255.255262,142
967.124.0.0/147.124.0.1 to 7.127.255.2547.127.255.255262,142
977.128.0.0/147.128.0.1 to 7.131.255.2547.131.255.255262,142
987.132.0.0/147.132.0.1 to 7.135.255.2547.135.255.255262,142
997.136.0.0/147.136.0.1 to 7.139.255.2547.139.255.255262,142
1007.140.0.0/147.140.0.1 to 7.143.255.2547.143.255.255262,142
1017.144.0.0/147.144.0.1 to 7.147.255.2547.147.255.255262,142
1027.148.0.0/147.148.0.1 to 7.151.255.2547.151.255.255262,142
1037.152.0.0/147.152.0.1 to 7.155.255.2547.155.255.255262,142
1047.156.0.0/147.156.0.1 to 7.159.255.2547.159.255.255262,142
1057.160.0.0/147.160.0.1 to 7.163.255.2547.163.255.255262,142
1067.164.0.0/147.164.0.1 to 7.167.255.2547.167.255.255262,142
1077.168.0.0/147.168.0.1 to 7.171.255.2547.171.255.255262,142
1087.172.0.0/147.172.0.1 to 7.175.255.2547.175.255.255262,142
1097.176.0.0/147.176.0.1 to 7.179.255.2547.179.255.255262,142
1107.180.0.0/147.180.0.1 to 7.183.255.2547.183.255.255262,142
1117.184.0.0/147.184.0.1 to 7.187.255.2547.187.255.255262,142
1127.188.0.0/147.188.0.1 to 7.191.255.2547.191.255.255262,142
1137.192.0.0/147.192.0.1 to 7.195.255.2547.195.255.255262,142
1147.196.0.0/147.196.0.1 to 7.199.255.2547.199.255.255262,142
1157.200.0.0/147.200.0.1 to 7.203.255.2547.203.255.255262,142
1167.204.0.0/147.204.0.1 to 7.207.255.2547.207.255.255262,142
1177.208.0.0/147.208.0.1 to 7.211.255.2547.211.255.255262,142
1187.212.0.0/147.212.0.1 to 7.215.255.2547.215.255.255262,142
1197.216.0.0/147.216.0.1 to 7.219.255.2547.219.255.255262,142
1207.220.0.0/147.220.0.1 to 7.223.255.2547.223.255.255262,142
1217.224.0.0/147.224.0.1 to 7.227.255.2547.227.255.255262,142
1227.228.0.0/147.228.0.1 to 7.231.255.2547.231.255.255262,142
1237.232.0.0/147.232.0.1 to 7.235.255.2547.235.255.255262,142
1247.236.0.0/147.236.0.1 to 7.239.255.2547.239.255.255262,142
1257.240.0.0/147.240.0.1 to 7.243.255.2547.243.255.255262,142
1267.244.0.0/147.244.0.1 to 7.247.255.2547.247.255.255262,142
1277.248.0.0/147.248.0.1 to 7.251.255.2547.251.255.255262,142
1287.252.0.0/147.252.0.1 to 7.255.255.2547.255.255.255262,142

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.