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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.

Network4.128.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
4.128.0.0
Broadcast address
4.191.255.255
First usable
4.128.0.1
Last usable
4.191.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
A (default /8)
As numbers
Hex 04800000 · Integer 75497472 to 79691775
Reverse DNS zones
128.4.in-addr.arpa
129.4.in-addr.arpa
130.4.in-addr.arpa
131.4.in-addr.arpa
132.4.in-addr.arpa
133.4.in-addr.arpa
134.4.in-addr.arpa
135.4.in-addr.arpa
136.4.in-addr.arpa
137.4.in-addr.arpa
138.4.in-addr.arpa
139.4.in-addr.arpa
140.4.in-addr.arpa
141.4.in-addr.arpa
142.4.in-addr.arpa
143.4.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000100.10000000.00000000.000000004.128.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00000100.10000000.00000000.000000004.128.0.0
Broadcast00000100.10111111.11111111.111111114.191.255.255
Split into smaller subnets/17
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

4.128.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
14.128.0.0/174.128.0.1 to 4.128.127.2544.128.127.25532,766
24.128.128.0/174.128.128.1 to 4.128.255.2544.128.255.25532,766
34.129.0.0/174.129.0.1 to 4.129.127.2544.129.127.25532,766
44.129.128.0/174.129.128.1 to 4.129.255.2544.129.255.25532,766
54.130.0.0/174.130.0.1 to 4.130.127.2544.130.127.25532,766
64.130.128.0/174.130.128.1 to 4.130.255.2544.130.255.25532,766
74.131.0.0/174.131.0.1 to 4.131.127.2544.131.127.25532,766
84.131.128.0/174.131.128.1 to 4.131.255.2544.131.255.25532,766
94.132.0.0/174.132.0.1 to 4.132.127.2544.132.127.25532,766
104.132.128.0/174.132.128.1 to 4.132.255.2544.132.255.25532,766
114.133.0.0/174.133.0.1 to 4.133.127.2544.133.127.25532,766
124.133.128.0/174.133.128.1 to 4.133.255.2544.133.255.25532,766
134.134.0.0/174.134.0.1 to 4.134.127.2544.134.127.25532,766
144.134.128.0/174.134.128.1 to 4.134.255.2544.134.255.25532,766
154.135.0.0/174.135.0.1 to 4.135.127.2544.135.127.25532,766
164.135.128.0/174.135.128.1 to 4.135.255.2544.135.255.25532,766
174.136.0.0/174.136.0.1 to 4.136.127.2544.136.127.25532,766
184.136.128.0/174.136.128.1 to 4.136.255.2544.136.255.25532,766
194.137.0.0/174.137.0.1 to 4.137.127.2544.137.127.25532,766
204.137.128.0/174.137.128.1 to 4.137.255.2544.137.255.25532,766
214.138.0.0/174.138.0.1 to 4.138.127.2544.138.127.25532,766
224.138.128.0/174.138.128.1 to 4.138.255.2544.138.255.25532,766
234.139.0.0/174.139.0.1 to 4.139.127.2544.139.127.25532,766
244.139.128.0/174.139.128.1 to 4.139.255.2544.139.255.25532,766
254.140.0.0/174.140.0.1 to 4.140.127.2544.140.127.25532,766
264.140.128.0/174.140.128.1 to 4.140.255.2544.140.255.25532,766
274.141.0.0/174.141.0.1 to 4.141.127.2544.141.127.25532,766
284.141.128.0/174.141.128.1 to 4.141.255.2544.141.255.25532,766
294.142.0.0/174.142.0.1 to 4.142.127.2544.142.127.25532,766
304.142.128.0/174.142.128.1 to 4.142.255.2544.142.255.25532,766
314.143.0.0/174.143.0.1 to 4.143.127.2544.143.127.25532,766
324.143.128.0/174.143.128.1 to 4.143.255.2544.143.255.25532,766
334.144.0.0/174.144.0.1 to 4.144.127.2544.144.127.25532,766
344.144.128.0/174.144.128.1 to 4.144.255.2544.144.255.25532,766
354.145.0.0/174.145.0.1 to 4.145.127.2544.145.127.25532,766
364.145.128.0/174.145.128.1 to 4.145.255.2544.145.255.25532,766
374.146.0.0/174.146.0.1 to 4.146.127.2544.146.127.25532,766
384.146.128.0/174.146.128.1 to 4.146.255.2544.146.255.25532,766
394.147.0.0/174.147.0.1 to 4.147.127.2544.147.127.25532,766
404.147.128.0/174.147.128.1 to 4.147.255.2544.147.255.25532,766
414.148.0.0/174.148.0.1 to 4.148.127.2544.148.127.25532,766
424.148.128.0/174.148.128.1 to 4.148.255.2544.148.255.25532,766
434.149.0.0/174.149.0.1 to 4.149.127.2544.149.127.25532,766
444.149.128.0/174.149.128.1 to 4.149.255.2544.149.255.25532,766
454.150.0.0/174.150.0.1 to 4.150.127.2544.150.127.25532,766
464.150.128.0/174.150.128.1 to 4.150.255.2544.150.255.25532,766
474.151.0.0/174.151.0.1 to 4.151.127.2544.151.127.25532,766
484.151.128.0/174.151.128.1 to 4.151.255.2544.151.255.25532,766
494.152.0.0/174.152.0.1 to 4.152.127.2544.152.127.25532,766
504.152.128.0/174.152.128.1 to 4.152.255.2544.152.255.25532,766
514.153.0.0/174.153.0.1 to 4.153.127.2544.153.127.25532,766
524.153.128.0/174.153.128.1 to 4.153.255.2544.153.255.25532,766
534.154.0.0/174.154.0.1 to 4.154.127.2544.154.127.25532,766
544.154.128.0/174.154.128.1 to 4.154.255.2544.154.255.25532,766
554.155.0.0/174.155.0.1 to 4.155.127.2544.155.127.25532,766
564.155.128.0/174.155.128.1 to 4.155.255.2544.155.255.25532,766
574.156.0.0/174.156.0.1 to 4.156.127.2544.156.127.25532,766
584.156.128.0/174.156.128.1 to 4.156.255.2544.156.255.25532,766
594.157.0.0/174.157.0.1 to 4.157.127.2544.157.127.25532,766
604.157.128.0/174.157.128.1 to 4.157.255.2544.157.255.25532,766
614.158.0.0/174.158.0.1 to 4.158.127.2544.158.127.25532,766
624.158.128.0/174.158.128.1 to 4.158.255.2544.158.255.25532,766
634.159.0.0/174.159.0.1 to 4.159.127.2544.159.127.25532,766
644.159.128.0/174.159.128.1 to 4.159.255.2544.159.255.25532,766
654.160.0.0/174.160.0.1 to 4.160.127.2544.160.127.25532,766
664.160.128.0/174.160.128.1 to 4.160.255.2544.160.255.25532,766
674.161.0.0/174.161.0.1 to 4.161.127.2544.161.127.25532,766
684.161.128.0/174.161.128.1 to 4.161.255.2544.161.255.25532,766
694.162.0.0/174.162.0.1 to 4.162.127.2544.162.127.25532,766
704.162.128.0/174.162.128.1 to 4.162.255.2544.162.255.25532,766
714.163.0.0/174.163.0.1 to 4.163.127.2544.163.127.25532,766
724.163.128.0/174.163.128.1 to 4.163.255.2544.163.255.25532,766
734.164.0.0/174.164.0.1 to 4.164.127.2544.164.127.25532,766
744.164.128.0/174.164.128.1 to 4.164.255.2544.164.255.25532,766
754.165.0.0/174.165.0.1 to 4.165.127.2544.165.127.25532,766
764.165.128.0/174.165.128.1 to 4.165.255.2544.165.255.25532,766
774.166.0.0/174.166.0.1 to 4.166.127.2544.166.127.25532,766
784.166.128.0/174.166.128.1 to 4.166.255.2544.166.255.25532,766
794.167.0.0/174.167.0.1 to 4.167.127.2544.167.127.25532,766
804.167.128.0/174.167.128.1 to 4.167.255.2544.167.255.25532,766
814.168.0.0/174.168.0.1 to 4.168.127.2544.168.127.25532,766
824.168.128.0/174.168.128.1 to 4.168.255.2544.168.255.25532,766
834.169.0.0/174.169.0.1 to 4.169.127.2544.169.127.25532,766
844.169.128.0/174.169.128.1 to 4.169.255.2544.169.255.25532,766
854.170.0.0/174.170.0.1 to 4.170.127.2544.170.127.25532,766
864.170.128.0/174.170.128.1 to 4.170.255.2544.170.255.25532,766
874.171.0.0/174.171.0.1 to 4.171.127.2544.171.127.25532,766
884.171.128.0/174.171.128.1 to 4.171.255.2544.171.255.25532,766
894.172.0.0/174.172.0.1 to 4.172.127.2544.172.127.25532,766
904.172.128.0/174.172.128.1 to 4.172.255.2544.172.255.25532,766
914.173.0.0/174.173.0.1 to 4.173.127.2544.173.127.25532,766
924.173.128.0/174.173.128.1 to 4.173.255.2544.173.255.25532,766
934.174.0.0/174.174.0.1 to 4.174.127.2544.174.127.25532,766
944.174.128.0/174.174.128.1 to 4.174.255.2544.174.255.25532,766
954.175.0.0/174.175.0.1 to 4.175.127.2544.175.127.25532,766
964.175.128.0/174.175.128.1 to 4.175.255.2544.175.255.25532,766
974.176.0.0/174.176.0.1 to 4.176.127.2544.176.127.25532,766
984.176.128.0/174.176.128.1 to 4.176.255.2544.176.255.25532,766
994.177.0.0/174.177.0.1 to 4.177.127.2544.177.127.25532,766
1004.177.128.0/174.177.128.1 to 4.177.255.2544.177.255.25532,766
1014.178.0.0/174.178.0.1 to 4.178.127.2544.178.127.25532,766
1024.178.128.0/174.178.128.1 to 4.178.255.2544.178.255.25532,766
1034.179.0.0/174.179.0.1 to 4.179.127.2544.179.127.25532,766
1044.179.128.0/174.179.128.1 to 4.179.255.2544.179.255.25532,766
1054.180.0.0/174.180.0.1 to 4.180.127.2544.180.127.25532,766
1064.180.128.0/174.180.128.1 to 4.180.255.2544.180.255.25532,766
1074.181.0.0/174.181.0.1 to 4.181.127.2544.181.127.25532,766
1084.181.128.0/174.181.128.1 to 4.181.255.2544.181.255.25532,766
1094.182.0.0/174.182.0.1 to 4.182.127.2544.182.127.25532,766
1104.182.128.0/174.182.128.1 to 4.182.255.2544.182.255.25532,766
1114.183.0.0/174.183.0.1 to 4.183.127.2544.183.127.25532,766
1124.183.128.0/174.183.128.1 to 4.183.255.2544.183.255.25532,766
1134.184.0.0/174.184.0.1 to 4.184.127.2544.184.127.25532,766
1144.184.128.0/174.184.128.1 to 4.184.255.2544.184.255.25532,766
1154.185.0.0/174.185.0.1 to 4.185.127.2544.185.127.25532,766
1164.185.128.0/174.185.128.1 to 4.185.255.2544.185.255.25532,766
1174.186.0.0/174.186.0.1 to 4.186.127.2544.186.127.25532,766
1184.186.128.0/174.186.128.1 to 4.186.255.2544.186.255.25532,766
1194.187.0.0/174.187.0.1 to 4.187.127.2544.187.127.25532,766
1204.187.128.0/174.187.128.1 to 4.187.255.2544.187.255.25532,766
1214.188.0.0/174.188.0.1 to 4.188.127.2544.188.127.25532,766
1224.188.128.0/174.188.128.1 to 4.188.255.2544.188.255.25532,766
1234.189.0.0/174.189.0.1 to 4.189.127.2544.189.127.25532,766
1244.189.128.0/174.189.128.1 to 4.189.255.2544.189.255.25532,766
1254.190.0.0/174.190.0.1 to 4.190.127.2544.190.127.25532,766
1264.190.128.0/174.190.128.1 to 4.190.255.2544.190.255.25532,766
1274.191.0.0/174.191.0.1 to 4.191.127.2544.191.127.25532,766
1284.191.128.0/174.191.128.1 to 4.191.255.2544.191.255.25532,766

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.