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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.

Network3.64.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
3.64.0.0
Broadcast address
3.127.255.255
First usable
3.64.0.1
Last usable
3.127.255.254
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 03400000 · Integer 54525952 to 58720255
Reverse DNS zones
64.3.in-addr.arpa
65.3.in-addr.arpa
66.3.in-addr.arpa
67.3.in-addr.arpa
68.3.in-addr.arpa
69.3.in-addr.arpa
70.3.in-addr.arpa
71.3.in-addr.arpa
72.3.in-addr.arpa
73.3.in-addr.arpa
74.3.in-addr.arpa
75.3.in-addr.arpa
76.3.in-addr.arpa
77.3.in-addr.arpa
78.3.in-addr.arpa
79.3.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
Address00000011.01000000.00000000.000000003.64.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00000011.01000000.00000000.000000003.64.0.0
Broadcast00000011.01111111.11111111.111111113.127.255.255
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)

3.64.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
13.64.0.0/173.64.0.1 to 3.64.127.2543.64.127.25532,766
23.64.128.0/173.64.128.1 to 3.64.255.2543.64.255.25532,766
33.65.0.0/173.65.0.1 to 3.65.127.2543.65.127.25532,766
43.65.128.0/173.65.128.1 to 3.65.255.2543.65.255.25532,766
53.66.0.0/173.66.0.1 to 3.66.127.2543.66.127.25532,766
63.66.128.0/173.66.128.1 to 3.66.255.2543.66.255.25532,766
73.67.0.0/173.67.0.1 to 3.67.127.2543.67.127.25532,766
83.67.128.0/173.67.128.1 to 3.67.255.2543.67.255.25532,766
93.68.0.0/173.68.0.1 to 3.68.127.2543.68.127.25532,766
103.68.128.0/173.68.128.1 to 3.68.255.2543.68.255.25532,766
113.69.0.0/173.69.0.1 to 3.69.127.2543.69.127.25532,766
123.69.128.0/173.69.128.1 to 3.69.255.2543.69.255.25532,766
133.70.0.0/173.70.0.1 to 3.70.127.2543.70.127.25532,766
143.70.128.0/173.70.128.1 to 3.70.255.2543.70.255.25532,766
153.71.0.0/173.71.0.1 to 3.71.127.2543.71.127.25532,766
163.71.128.0/173.71.128.1 to 3.71.255.2543.71.255.25532,766
173.72.0.0/173.72.0.1 to 3.72.127.2543.72.127.25532,766
183.72.128.0/173.72.128.1 to 3.72.255.2543.72.255.25532,766
193.73.0.0/173.73.0.1 to 3.73.127.2543.73.127.25532,766
203.73.128.0/173.73.128.1 to 3.73.255.2543.73.255.25532,766
213.74.0.0/173.74.0.1 to 3.74.127.2543.74.127.25532,766
223.74.128.0/173.74.128.1 to 3.74.255.2543.74.255.25532,766
233.75.0.0/173.75.0.1 to 3.75.127.2543.75.127.25532,766
243.75.128.0/173.75.128.1 to 3.75.255.2543.75.255.25532,766
253.76.0.0/173.76.0.1 to 3.76.127.2543.76.127.25532,766
263.76.128.0/173.76.128.1 to 3.76.255.2543.76.255.25532,766
273.77.0.0/173.77.0.1 to 3.77.127.2543.77.127.25532,766
283.77.128.0/173.77.128.1 to 3.77.255.2543.77.255.25532,766
293.78.0.0/173.78.0.1 to 3.78.127.2543.78.127.25532,766
303.78.128.0/173.78.128.1 to 3.78.255.2543.78.255.25532,766
313.79.0.0/173.79.0.1 to 3.79.127.2543.79.127.25532,766
323.79.128.0/173.79.128.1 to 3.79.255.2543.79.255.25532,766
333.80.0.0/173.80.0.1 to 3.80.127.2543.80.127.25532,766
343.80.128.0/173.80.128.1 to 3.80.255.2543.80.255.25532,766
353.81.0.0/173.81.0.1 to 3.81.127.2543.81.127.25532,766
363.81.128.0/173.81.128.1 to 3.81.255.2543.81.255.25532,766
373.82.0.0/173.82.0.1 to 3.82.127.2543.82.127.25532,766
383.82.128.0/173.82.128.1 to 3.82.255.2543.82.255.25532,766
393.83.0.0/173.83.0.1 to 3.83.127.2543.83.127.25532,766
403.83.128.0/173.83.128.1 to 3.83.255.2543.83.255.25532,766
413.84.0.0/173.84.0.1 to 3.84.127.2543.84.127.25532,766
423.84.128.0/173.84.128.1 to 3.84.255.2543.84.255.25532,766
433.85.0.0/173.85.0.1 to 3.85.127.2543.85.127.25532,766
443.85.128.0/173.85.128.1 to 3.85.255.2543.85.255.25532,766
453.86.0.0/173.86.0.1 to 3.86.127.2543.86.127.25532,766
463.86.128.0/173.86.128.1 to 3.86.255.2543.86.255.25532,766
473.87.0.0/173.87.0.1 to 3.87.127.2543.87.127.25532,766
483.87.128.0/173.87.128.1 to 3.87.255.2543.87.255.25532,766
493.88.0.0/173.88.0.1 to 3.88.127.2543.88.127.25532,766
503.88.128.0/173.88.128.1 to 3.88.255.2543.88.255.25532,766
513.89.0.0/173.89.0.1 to 3.89.127.2543.89.127.25532,766
523.89.128.0/173.89.128.1 to 3.89.255.2543.89.255.25532,766
533.90.0.0/173.90.0.1 to 3.90.127.2543.90.127.25532,766
543.90.128.0/173.90.128.1 to 3.90.255.2543.90.255.25532,766
553.91.0.0/173.91.0.1 to 3.91.127.2543.91.127.25532,766
563.91.128.0/173.91.128.1 to 3.91.255.2543.91.255.25532,766
573.92.0.0/173.92.0.1 to 3.92.127.2543.92.127.25532,766
583.92.128.0/173.92.128.1 to 3.92.255.2543.92.255.25532,766
593.93.0.0/173.93.0.1 to 3.93.127.2543.93.127.25532,766
603.93.128.0/173.93.128.1 to 3.93.255.2543.93.255.25532,766
613.94.0.0/173.94.0.1 to 3.94.127.2543.94.127.25532,766
623.94.128.0/173.94.128.1 to 3.94.255.2543.94.255.25532,766
633.95.0.0/173.95.0.1 to 3.95.127.2543.95.127.25532,766
643.95.128.0/173.95.128.1 to 3.95.255.2543.95.255.25532,766
653.96.0.0/173.96.0.1 to 3.96.127.2543.96.127.25532,766
663.96.128.0/173.96.128.1 to 3.96.255.2543.96.255.25532,766
673.97.0.0/173.97.0.1 to 3.97.127.2543.97.127.25532,766
683.97.128.0/173.97.128.1 to 3.97.255.2543.97.255.25532,766
693.98.0.0/173.98.0.1 to 3.98.127.2543.98.127.25532,766
703.98.128.0/173.98.128.1 to 3.98.255.2543.98.255.25532,766
713.99.0.0/173.99.0.1 to 3.99.127.2543.99.127.25532,766
723.99.128.0/173.99.128.1 to 3.99.255.2543.99.255.25532,766
733.100.0.0/173.100.0.1 to 3.100.127.2543.100.127.25532,766
743.100.128.0/173.100.128.1 to 3.100.255.2543.100.255.25532,766
753.101.0.0/173.101.0.1 to 3.101.127.2543.101.127.25532,766
763.101.128.0/173.101.128.1 to 3.101.255.2543.101.255.25532,766
773.102.0.0/173.102.0.1 to 3.102.127.2543.102.127.25532,766
783.102.128.0/173.102.128.1 to 3.102.255.2543.102.255.25532,766
793.103.0.0/173.103.0.1 to 3.103.127.2543.103.127.25532,766
803.103.128.0/173.103.128.1 to 3.103.255.2543.103.255.25532,766
813.104.0.0/173.104.0.1 to 3.104.127.2543.104.127.25532,766
823.104.128.0/173.104.128.1 to 3.104.255.2543.104.255.25532,766
833.105.0.0/173.105.0.1 to 3.105.127.2543.105.127.25532,766
843.105.128.0/173.105.128.1 to 3.105.255.2543.105.255.25532,766
853.106.0.0/173.106.0.1 to 3.106.127.2543.106.127.25532,766
863.106.128.0/173.106.128.1 to 3.106.255.2543.106.255.25532,766
873.107.0.0/173.107.0.1 to 3.107.127.2543.107.127.25532,766
883.107.128.0/173.107.128.1 to 3.107.255.2543.107.255.25532,766
893.108.0.0/173.108.0.1 to 3.108.127.2543.108.127.25532,766
903.108.128.0/173.108.128.1 to 3.108.255.2543.108.255.25532,766
913.109.0.0/173.109.0.1 to 3.109.127.2543.109.127.25532,766
923.109.128.0/173.109.128.1 to 3.109.255.2543.109.255.25532,766
933.110.0.0/173.110.0.1 to 3.110.127.2543.110.127.25532,766
943.110.128.0/173.110.128.1 to 3.110.255.2543.110.255.25532,766
953.111.0.0/173.111.0.1 to 3.111.127.2543.111.127.25532,766
963.111.128.0/173.111.128.1 to 3.111.255.2543.111.255.25532,766
973.112.0.0/173.112.0.1 to 3.112.127.2543.112.127.25532,766
983.112.128.0/173.112.128.1 to 3.112.255.2543.112.255.25532,766
993.113.0.0/173.113.0.1 to 3.113.127.2543.113.127.25532,766
1003.113.128.0/173.113.128.1 to 3.113.255.2543.113.255.25532,766
1013.114.0.0/173.114.0.1 to 3.114.127.2543.114.127.25532,766
1023.114.128.0/173.114.128.1 to 3.114.255.2543.114.255.25532,766
1033.115.0.0/173.115.0.1 to 3.115.127.2543.115.127.25532,766
1043.115.128.0/173.115.128.1 to 3.115.255.2543.115.255.25532,766
1053.116.0.0/173.116.0.1 to 3.116.127.2543.116.127.25532,766
1063.116.128.0/173.116.128.1 to 3.116.255.2543.116.255.25532,766
1073.117.0.0/173.117.0.1 to 3.117.127.2543.117.127.25532,766
1083.117.128.0/173.117.128.1 to 3.117.255.2543.117.255.25532,766
1093.118.0.0/173.118.0.1 to 3.118.127.2543.118.127.25532,766
1103.118.128.0/173.118.128.1 to 3.118.255.2543.118.255.25532,766
1113.119.0.0/173.119.0.1 to 3.119.127.2543.119.127.25532,766
1123.119.128.0/173.119.128.1 to 3.119.255.2543.119.255.25532,766
1133.120.0.0/173.120.0.1 to 3.120.127.2543.120.127.25532,766
1143.120.128.0/173.120.128.1 to 3.120.255.2543.120.255.25532,766
1153.121.0.0/173.121.0.1 to 3.121.127.2543.121.127.25532,766
1163.121.128.0/173.121.128.1 to 3.121.255.2543.121.255.25532,766
1173.122.0.0/173.122.0.1 to 3.122.127.2543.122.127.25532,766
1183.122.128.0/173.122.128.1 to 3.122.255.2543.122.255.25532,766
1193.123.0.0/173.123.0.1 to 3.123.127.2543.123.127.25532,766
1203.123.128.0/173.123.128.1 to 3.123.255.2543.123.255.25532,766
1213.124.0.0/173.124.0.1 to 3.124.127.2543.124.127.25532,766
1223.124.128.0/173.124.128.1 to 3.124.255.2543.124.255.25532,766
1233.125.0.0/173.125.0.1 to 3.125.127.2543.125.127.25532,766
1243.125.128.0/173.125.128.1 to 3.125.255.2543.125.255.25532,766
1253.126.0.0/173.126.0.1 to 3.126.127.2543.126.127.25532,766
1263.126.128.0/173.126.128.1 to 3.126.255.2543.126.255.25532,766
1273.127.0.0/173.127.0.1 to 3.127.127.2543.127.127.25532,766
1283.127.128.0/173.127.128.1 to 3.127.255.2543.127.255.25532,766

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.