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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.

Network4.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
4.0.0.0
Broadcast address
5.255.255.255
First usable
4.0.0.1
Last usable
5.255.255.254
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 04000000 · Integer 67108864 to 100663295
Reverse DNS zones
4.in-addr.arpa
5.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
Address00000100.00000000.00000000.000000004.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network00000100.00000000.00000000.000000004.0.0.0
Broadcast00000101.11111111.11111111.111111115.255.255.255
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)

4.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
14.0.0.0/144.0.0.1 to 4.3.255.2544.3.255.255262,142
24.4.0.0/144.4.0.1 to 4.7.255.2544.7.255.255262,142
34.8.0.0/144.8.0.1 to 4.11.255.2544.11.255.255262,142
44.12.0.0/144.12.0.1 to 4.15.255.2544.15.255.255262,142
54.16.0.0/144.16.0.1 to 4.19.255.2544.19.255.255262,142
64.20.0.0/144.20.0.1 to 4.23.255.2544.23.255.255262,142
74.24.0.0/144.24.0.1 to 4.27.255.2544.27.255.255262,142
84.28.0.0/144.28.0.1 to 4.31.255.2544.31.255.255262,142
94.32.0.0/144.32.0.1 to 4.35.255.2544.35.255.255262,142
104.36.0.0/144.36.0.1 to 4.39.255.2544.39.255.255262,142
114.40.0.0/144.40.0.1 to 4.43.255.2544.43.255.255262,142
124.44.0.0/144.44.0.1 to 4.47.255.2544.47.255.255262,142
134.48.0.0/144.48.0.1 to 4.51.255.2544.51.255.255262,142
144.52.0.0/144.52.0.1 to 4.55.255.2544.55.255.255262,142
154.56.0.0/144.56.0.1 to 4.59.255.2544.59.255.255262,142
164.60.0.0/144.60.0.1 to 4.63.255.2544.63.255.255262,142
174.64.0.0/144.64.0.1 to 4.67.255.2544.67.255.255262,142
184.68.0.0/144.68.0.1 to 4.71.255.2544.71.255.255262,142
194.72.0.0/144.72.0.1 to 4.75.255.2544.75.255.255262,142
204.76.0.0/144.76.0.1 to 4.79.255.2544.79.255.255262,142
214.80.0.0/144.80.0.1 to 4.83.255.2544.83.255.255262,142
224.84.0.0/144.84.0.1 to 4.87.255.2544.87.255.255262,142
234.88.0.0/144.88.0.1 to 4.91.255.2544.91.255.255262,142
244.92.0.0/144.92.0.1 to 4.95.255.2544.95.255.255262,142
254.96.0.0/144.96.0.1 to 4.99.255.2544.99.255.255262,142
264.100.0.0/144.100.0.1 to 4.103.255.2544.103.255.255262,142
274.104.0.0/144.104.0.1 to 4.107.255.2544.107.255.255262,142
284.108.0.0/144.108.0.1 to 4.111.255.2544.111.255.255262,142
294.112.0.0/144.112.0.1 to 4.115.255.2544.115.255.255262,142
304.116.0.0/144.116.0.1 to 4.119.255.2544.119.255.255262,142
314.120.0.0/144.120.0.1 to 4.123.255.2544.123.255.255262,142
324.124.0.0/144.124.0.1 to 4.127.255.2544.127.255.255262,142
334.128.0.0/144.128.0.1 to 4.131.255.2544.131.255.255262,142
344.132.0.0/144.132.0.1 to 4.135.255.2544.135.255.255262,142
354.136.0.0/144.136.0.1 to 4.139.255.2544.139.255.255262,142
364.140.0.0/144.140.0.1 to 4.143.255.2544.143.255.255262,142
374.144.0.0/144.144.0.1 to 4.147.255.2544.147.255.255262,142
384.148.0.0/144.148.0.1 to 4.151.255.2544.151.255.255262,142
394.152.0.0/144.152.0.1 to 4.155.255.2544.155.255.255262,142
404.156.0.0/144.156.0.1 to 4.159.255.2544.159.255.255262,142
414.160.0.0/144.160.0.1 to 4.163.255.2544.163.255.255262,142
424.164.0.0/144.164.0.1 to 4.167.255.2544.167.255.255262,142
434.168.0.0/144.168.0.1 to 4.171.255.2544.171.255.255262,142
444.172.0.0/144.172.0.1 to 4.175.255.2544.175.255.255262,142
454.176.0.0/144.176.0.1 to 4.179.255.2544.179.255.255262,142
464.180.0.0/144.180.0.1 to 4.183.255.2544.183.255.255262,142
474.184.0.0/144.184.0.1 to 4.187.255.2544.187.255.255262,142
484.188.0.0/144.188.0.1 to 4.191.255.2544.191.255.255262,142
494.192.0.0/144.192.0.1 to 4.195.255.2544.195.255.255262,142
504.196.0.0/144.196.0.1 to 4.199.255.2544.199.255.255262,142
514.200.0.0/144.200.0.1 to 4.203.255.2544.203.255.255262,142
524.204.0.0/144.204.0.1 to 4.207.255.2544.207.255.255262,142
534.208.0.0/144.208.0.1 to 4.211.255.2544.211.255.255262,142
544.212.0.0/144.212.0.1 to 4.215.255.2544.215.255.255262,142
554.216.0.0/144.216.0.1 to 4.219.255.2544.219.255.255262,142
564.220.0.0/144.220.0.1 to 4.223.255.2544.223.255.255262,142
574.224.0.0/144.224.0.1 to 4.227.255.2544.227.255.255262,142
584.228.0.0/144.228.0.1 to 4.231.255.2544.231.255.255262,142
594.232.0.0/144.232.0.1 to 4.235.255.2544.235.255.255262,142
604.236.0.0/144.236.0.1 to 4.239.255.2544.239.255.255262,142
614.240.0.0/144.240.0.1 to 4.243.255.2544.243.255.255262,142
624.244.0.0/144.244.0.1 to 4.247.255.2544.247.255.255262,142
634.248.0.0/144.248.0.1 to 4.251.255.2544.251.255.255262,142
644.252.0.0/144.252.0.1 to 4.255.255.2544.255.255.255262,142
655.0.0.0/145.0.0.1 to 5.3.255.2545.3.255.255262,142
665.4.0.0/145.4.0.1 to 5.7.255.2545.7.255.255262,142
675.8.0.0/145.8.0.1 to 5.11.255.2545.11.255.255262,142
685.12.0.0/145.12.0.1 to 5.15.255.2545.15.255.255262,142
695.16.0.0/145.16.0.1 to 5.19.255.2545.19.255.255262,142
705.20.0.0/145.20.0.1 to 5.23.255.2545.23.255.255262,142
715.24.0.0/145.24.0.1 to 5.27.255.2545.27.255.255262,142
725.28.0.0/145.28.0.1 to 5.31.255.2545.31.255.255262,142
735.32.0.0/145.32.0.1 to 5.35.255.2545.35.255.255262,142
745.36.0.0/145.36.0.1 to 5.39.255.2545.39.255.255262,142
755.40.0.0/145.40.0.1 to 5.43.255.2545.43.255.255262,142
765.44.0.0/145.44.0.1 to 5.47.255.2545.47.255.255262,142
775.48.0.0/145.48.0.1 to 5.51.255.2545.51.255.255262,142
785.52.0.0/145.52.0.1 to 5.55.255.2545.55.255.255262,142
795.56.0.0/145.56.0.1 to 5.59.255.2545.59.255.255262,142
805.60.0.0/145.60.0.1 to 5.63.255.2545.63.255.255262,142
815.64.0.0/145.64.0.1 to 5.67.255.2545.67.255.255262,142
825.68.0.0/145.68.0.1 to 5.71.255.2545.71.255.255262,142
835.72.0.0/145.72.0.1 to 5.75.255.2545.75.255.255262,142
845.76.0.0/145.76.0.1 to 5.79.255.2545.79.255.255262,142
855.80.0.0/145.80.0.1 to 5.83.255.2545.83.255.255262,142
865.84.0.0/145.84.0.1 to 5.87.255.2545.87.255.255262,142
875.88.0.0/145.88.0.1 to 5.91.255.2545.91.255.255262,142
885.92.0.0/145.92.0.1 to 5.95.255.2545.95.255.255262,142
895.96.0.0/145.96.0.1 to 5.99.255.2545.99.255.255262,142
905.100.0.0/145.100.0.1 to 5.103.255.2545.103.255.255262,142
915.104.0.0/145.104.0.1 to 5.107.255.2545.107.255.255262,142
925.108.0.0/145.108.0.1 to 5.111.255.2545.111.255.255262,142
935.112.0.0/145.112.0.1 to 5.115.255.2545.115.255.255262,142
945.116.0.0/145.116.0.1 to 5.119.255.2545.119.255.255262,142
955.120.0.0/145.120.0.1 to 5.123.255.2545.123.255.255262,142
965.124.0.0/145.124.0.1 to 5.127.255.2545.127.255.255262,142
975.128.0.0/145.128.0.1 to 5.131.255.2545.131.255.255262,142
985.132.0.0/145.132.0.1 to 5.135.255.2545.135.255.255262,142
995.136.0.0/145.136.0.1 to 5.139.255.2545.139.255.255262,142
1005.140.0.0/145.140.0.1 to 5.143.255.2545.143.255.255262,142
1015.144.0.0/145.144.0.1 to 5.147.255.2545.147.255.255262,142
1025.148.0.0/145.148.0.1 to 5.151.255.2545.151.255.255262,142
1035.152.0.0/145.152.0.1 to 5.155.255.2545.155.255.255262,142
1045.156.0.0/145.156.0.1 to 5.159.255.2545.159.255.255262,142
1055.160.0.0/145.160.0.1 to 5.163.255.2545.163.255.255262,142
1065.164.0.0/145.164.0.1 to 5.167.255.2545.167.255.255262,142
1075.168.0.0/145.168.0.1 to 5.171.255.2545.171.255.255262,142
1085.172.0.0/145.172.0.1 to 5.175.255.2545.175.255.255262,142
1095.176.0.0/145.176.0.1 to 5.179.255.2545.179.255.255262,142
1105.180.0.0/145.180.0.1 to 5.183.255.2545.183.255.255262,142
1115.184.0.0/145.184.0.1 to 5.187.255.2545.187.255.255262,142
1125.188.0.0/145.188.0.1 to 5.191.255.2545.191.255.255262,142
1135.192.0.0/145.192.0.1 to 5.195.255.2545.195.255.255262,142
1145.196.0.0/145.196.0.1 to 5.199.255.2545.199.255.255262,142
1155.200.0.0/145.200.0.1 to 5.203.255.2545.203.255.255262,142
1165.204.0.0/145.204.0.1 to 5.207.255.2545.207.255.255262,142
1175.208.0.0/145.208.0.1 to 5.211.255.2545.211.255.255262,142
1185.212.0.0/145.212.0.1 to 5.215.255.2545.215.255.255262,142
1195.216.0.0/145.216.0.1 to 5.219.255.2545.219.255.255262,142
1205.220.0.0/145.220.0.1 to 5.223.255.2545.223.255.255262,142
1215.224.0.0/145.224.0.1 to 5.227.255.2545.227.255.255262,142
1225.228.0.0/145.228.0.1 to 5.231.255.2545.231.255.255262,142
1235.232.0.0/145.232.0.1 to 5.235.255.2545.235.255.255262,142
1245.236.0.0/145.236.0.1 to 5.239.255.2545.239.255.255262,142
1255.240.0.0/145.240.0.1 to 5.243.255.2545.243.255.255262,142
1265.244.0.0/145.244.0.1 to 5.247.255.2545.247.255.255262,142
1275.248.0.0/145.248.0.1 to 5.251.255.2545.251.255.255262,142
1285.252.0.0/145.252.0.1 to 5.255.255.2545.255.255.255262,142

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.