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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.

Network0.0.0.0/3
Usable hosts536,870,910
Subnet mask224.0.0.0
Addresses536,870,912
Network address
0.0.0.0
Broadcast address
31.255.255.255
First usable
0.0.0.1
Last usable
31.255.255.254
Usable hosts
536,870,910 (536,870,912 less the network and broadcast addresses)
Subnet mask
224.0.0.0
Wildcard mask
31.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/3
Type
Public public
Old class
A (default /8)
As numbers
Hex 00000000 · Integer 0 to 536870911
Reverse DNS zones
0.in-addr.arpa
1.in-addr.arpa
2.in-addr.arpa
3.in-addr.arpa
4.in-addr.arpa
5.in-addr.arpa
6.in-addr.arpa
7.in-addr.arpa
8.in-addr.arpa
9.in-addr.arpa
10.in-addr.arpa
11.in-addr.arpa
12.in-addr.arpa
13.in-addr.arpa
14.in-addr.arpa
15.in-addr.arpa
and 16 more
/3 is not on a 8-bit boundary, so it takes 32 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000000.00000000.00000000.000000000.0.0.0
Subnet mask11100000.00000000.00000000.00000000224.0.0.0
Network00000000.00000000.00000000.000000000.0.0.0
Broadcast00011111.11111111.11111111.1111111131.255.255.255
Split into smaller subnets/10
/4 (2)/5 (4)/6 (8)/7 (16)/8 (32)/9 (64)/10 (128)/11 (256)/12 (512)/13 (1,024)/14 (2,048)/15 (4,096)

0.0.0.0/3 makes 128 subnets of /10.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
10.0.0.0/100.0.0.1 to 0.63.255.2540.63.255.2554,194,302
20.64.0.0/100.64.0.1 to 0.127.255.2540.127.255.2554,194,302
30.128.0.0/100.128.0.1 to 0.191.255.2540.191.255.2554,194,302
40.192.0.0/100.192.0.1 to 0.255.255.2540.255.255.2554,194,302
51.0.0.0/101.0.0.1 to 1.63.255.2541.63.255.2554,194,302
61.64.0.0/101.64.0.1 to 1.127.255.2541.127.255.2554,194,302
71.128.0.0/101.128.0.1 to 1.191.255.2541.191.255.2554,194,302
81.192.0.0/101.192.0.1 to 1.255.255.2541.255.255.2554,194,302
92.0.0.0/102.0.0.1 to 2.63.255.2542.63.255.2554,194,302
102.64.0.0/102.64.0.1 to 2.127.255.2542.127.255.2554,194,302
112.128.0.0/102.128.0.1 to 2.191.255.2542.191.255.2554,194,302
122.192.0.0/102.192.0.1 to 2.255.255.2542.255.255.2554,194,302
133.0.0.0/103.0.0.1 to 3.63.255.2543.63.255.2554,194,302
143.64.0.0/103.64.0.1 to 3.127.255.2543.127.255.2554,194,302
153.128.0.0/103.128.0.1 to 3.191.255.2543.191.255.2554,194,302
163.192.0.0/103.192.0.1 to 3.255.255.2543.255.255.2554,194,302
174.0.0.0/104.0.0.1 to 4.63.255.2544.63.255.2554,194,302
184.64.0.0/104.64.0.1 to 4.127.255.2544.127.255.2554,194,302
194.128.0.0/104.128.0.1 to 4.191.255.2544.191.255.2554,194,302
204.192.0.0/104.192.0.1 to 4.255.255.2544.255.255.2554,194,302
215.0.0.0/105.0.0.1 to 5.63.255.2545.63.255.2554,194,302
225.64.0.0/105.64.0.1 to 5.127.255.2545.127.255.2554,194,302
235.128.0.0/105.128.0.1 to 5.191.255.2545.191.255.2554,194,302
245.192.0.0/105.192.0.1 to 5.255.255.2545.255.255.2554,194,302
256.0.0.0/106.0.0.1 to 6.63.255.2546.63.255.2554,194,302
266.64.0.0/106.64.0.1 to 6.127.255.2546.127.255.2554,194,302
276.128.0.0/106.128.0.1 to 6.191.255.2546.191.255.2554,194,302
286.192.0.0/106.192.0.1 to 6.255.255.2546.255.255.2554,194,302
297.0.0.0/107.0.0.1 to 7.63.255.2547.63.255.2554,194,302
307.64.0.0/107.64.0.1 to 7.127.255.2547.127.255.2554,194,302
317.128.0.0/107.128.0.1 to 7.191.255.2547.191.255.2554,194,302
327.192.0.0/107.192.0.1 to 7.255.255.2547.255.255.2554,194,302
338.0.0.0/108.0.0.1 to 8.63.255.2548.63.255.2554,194,302
348.64.0.0/108.64.0.1 to 8.127.255.2548.127.255.2554,194,302
358.128.0.0/108.128.0.1 to 8.191.255.2548.191.255.2554,194,302
368.192.0.0/108.192.0.1 to 8.255.255.2548.255.255.2554,194,302
379.0.0.0/109.0.0.1 to 9.63.255.2549.63.255.2554,194,302
389.64.0.0/109.64.0.1 to 9.127.255.2549.127.255.2554,194,302
399.128.0.0/109.128.0.1 to 9.191.255.2549.191.255.2554,194,302
409.192.0.0/109.192.0.1 to 9.255.255.2549.255.255.2554,194,302
4110.0.0.0/1010.0.0.1 to 10.63.255.25410.63.255.2554,194,302
4210.64.0.0/1010.64.0.1 to 10.127.255.25410.127.255.2554,194,302
4310.128.0.0/1010.128.0.1 to 10.191.255.25410.191.255.2554,194,302
4410.192.0.0/1010.192.0.1 to 10.255.255.25410.255.255.2554,194,302
4511.0.0.0/1011.0.0.1 to 11.63.255.25411.63.255.2554,194,302
4611.64.0.0/1011.64.0.1 to 11.127.255.25411.127.255.2554,194,302
4711.128.0.0/1011.128.0.1 to 11.191.255.25411.191.255.2554,194,302
4811.192.0.0/1011.192.0.1 to 11.255.255.25411.255.255.2554,194,302
4912.0.0.0/1012.0.0.1 to 12.63.255.25412.63.255.2554,194,302
5012.64.0.0/1012.64.0.1 to 12.127.255.25412.127.255.2554,194,302
5112.128.0.0/1012.128.0.1 to 12.191.255.25412.191.255.2554,194,302
5212.192.0.0/1012.192.0.1 to 12.255.255.25412.255.255.2554,194,302
5313.0.0.0/1013.0.0.1 to 13.63.255.25413.63.255.2554,194,302
5413.64.0.0/1013.64.0.1 to 13.127.255.25413.127.255.2554,194,302
5513.128.0.0/1013.128.0.1 to 13.191.255.25413.191.255.2554,194,302
5613.192.0.0/1013.192.0.1 to 13.255.255.25413.255.255.2554,194,302
5714.0.0.0/1014.0.0.1 to 14.63.255.25414.63.255.2554,194,302
5814.64.0.0/1014.64.0.1 to 14.127.255.25414.127.255.2554,194,302
5914.128.0.0/1014.128.0.1 to 14.191.255.25414.191.255.2554,194,302
6014.192.0.0/1014.192.0.1 to 14.255.255.25414.255.255.2554,194,302
6115.0.0.0/1015.0.0.1 to 15.63.255.25415.63.255.2554,194,302
6215.64.0.0/1015.64.0.1 to 15.127.255.25415.127.255.2554,194,302
6315.128.0.0/1015.128.0.1 to 15.191.255.25415.191.255.2554,194,302
6415.192.0.0/1015.192.0.1 to 15.255.255.25415.255.255.2554,194,302
6516.0.0.0/1016.0.0.1 to 16.63.255.25416.63.255.2554,194,302
6616.64.0.0/1016.64.0.1 to 16.127.255.25416.127.255.2554,194,302
6716.128.0.0/1016.128.0.1 to 16.191.255.25416.191.255.2554,194,302
6816.192.0.0/1016.192.0.1 to 16.255.255.25416.255.255.2554,194,302
6917.0.0.0/1017.0.0.1 to 17.63.255.25417.63.255.2554,194,302
7017.64.0.0/1017.64.0.1 to 17.127.255.25417.127.255.2554,194,302
7117.128.0.0/1017.128.0.1 to 17.191.255.25417.191.255.2554,194,302
7217.192.0.0/1017.192.0.1 to 17.255.255.25417.255.255.2554,194,302
7318.0.0.0/1018.0.0.1 to 18.63.255.25418.63.255.2554,194,302
7418.64.0.0/1018.64.0.1 to 18.127.255.25418.127.255.2554,194,302
7518.128.0.0/1018.128.0.1 to 18.191.255.25418.191.255.2554,194,302
7618.192.0.0/1018.192.0.1 to 18.255.255.25418.255.255.2554,194,302
7719.0.0.0/1019.0.0.1 to 19.63.255.25419.63.255.2554,194,302
7819.64.0.0/1019.64.0.1 to 19.127.255.25419.127.255.2554,194,302
7919.128.0.0/1019.128.0.1 to 19.191.255.25419.191.255.2554,194,302
8019.192.0.0/1019.192.0.1 to 19.255.255.25419.255.255.2554,194,302
8120.0.0.0/1020.0.0.1 to 20.63.255.25420.63.255.2554,194,302
8220.64.0.0/1020.64.0.1 to 20.127.255.25420.127.255.2554,194,302
8320.128.0.0/1020.128.0.1 to 20.191.255.25420.191.255.2554,194,302
8420.192.0.0/1020.192.0.1 to 20.255.255.25420.255.255.2554,194,302
8521.0.0.0/1021.0.0.1 to 21.63.255.25421.63.255.2554,194,302
8621.64.0.0/1021.64.0.1 to 21.127.255.25421.127.255.2554,194,302
8721.128.0.0/1021.128.0.1 to 21.191.255.25421.191.255.2554,194,302
8821.192.0.0/1021.192.0.1 to 21.255.255.25421.255.255.2554,194,302
8922.0.0.0/1022.0.0.1 to 22.63.255.25422.63.255.2554,194,302
9022.64.0.0/1022.64.0.1 to 22.127.255.25422.127.255.2554,194,302
9122.128.0.0/1022.128.0.1 to 22.191.255.25422.191.255.2554,194,302
9222.192.0.0/1022.192.0.1 to 22.255.255.25422.255.255.2554,194,302
9323.0.0.0/1023.0.0.1 to 23.63.255.25423.63.255.2554,194,302
9423.64.0.0/1023.64.0.1 to 23.127.255.25423.127.255.2554,194,302
9523.128.0.0/1023.128.0.1 to 23.191.255.25423.191.255.2554,194,302
9623.192.0.0/1023.192.0.1 to 23.255.255.25423.255.255.2554,194,302
9724.0.0.0/1024.0.0.1 to 24.63.255.25424.63.255.2554,194,302
9824.64.0.0/1024.64.0.1 to 24.127.255.25424.127.255.2554,194,302
9924.128.0.0/1024.128.0.1 to 24.191.255.25424.191.255.2554,194,302
10024.192.0.0/1024.192.0.1 to 24.255.255.25424.255.255.2554,194,302
10125.0.0.0/1025.0.0.1 to 25.63.255.25425.63.255.2554,194,302
10225.64.0.0/1025.64.0.1 to 25.127.255.25425.127.255.2554,194,302
10325.128.0.0/1025.128.0.1 to 25.191.255.25425.191.255.2554,194,302
10425.192.0.0/1025.192.0.1 to 25.255.255.25425.255.255.2554,194,302
10526.0.0.0/1026.0.0.1 to 26.63.255.25426.63.255.2554,194,302
10626.64.0.0/1026.64.0.1 to 26.127.255.25426.127.255.2554,194,302
10726.128.0.0/1026.128.0.1 to 26.191.255.25426.191.255.2554,194,302
10826.192.0.0/1026.192.0.1 to 26.255.255.25426.255.255.2554,194,302
10927.0.0.0/1027.0.0.1 to 27.63.255.25427.63.255.2554,194,302
11027.64.0.0/1027.64.0.1 to 27.127.255.25427.127.255.2554,194,302
11127.128.0.0/1027.128.0.1 to 27.191.255.25427.191.255.2554,194,302
11227.192.0.0/1027.192.0.1 to 27.255.255.25427.255.255.2554,194,302
11328.0.0.0/1028.0.0.1 to 28.63.255.25428.63.255.2554,194,302
11428.64.0.0/1028.64.0.1 to 28.127.255.25428.127.255.2554,194,302
11528.128.0.0/1028.128.0.1 to 28.191.255.25428.191.255.2554,194,302
11628.192.0.0/1028.192.0.1 to 28.255.255.25428.255.255.2554,194,302
11729.0.0.0/1029.0.0.1 to 29.63.255.25429.63.255.2554,194,302
11829.64.0.0/1029.64.0.1 to 29.127.255.25429.127.255.2554,194,302
11929.128.0.0/1029.128.0.1 to 29.191.255.25429.191.255.2554,194,302
12029.192.0.0/1029.192.0.1 to 29.255.255.25429.255.255.2554,194,302
12130.0.0.0/1030.0.0.1 to 30.63.255.25430.63.255.2554,194,302
12230.64.0.0/1030.64.0.1 to 30.127.255.25430.127.255.2554,194,302
12330.128.0.0/1030.128.0.1 to 30.191.255.25430.191.255.2554,194,302
12430.192.0.0/1030.192.0.1 to 30.255.255.25430.255.255.2554,194,302
12531.0.0.0/1031.0.0.1 to 31.63.255.25431.63.255.2554,194,302
12631.64.0.0/1031.64.0.1 to 31.127.255.25431.127.255.2554,194,302
12731.128.0.0/1031.128.0.1 to 31.191.255.25431.191.255.2554,194,302
12831.192.0.0/1031.192.0.1 to 31.255.255.25431.255.255.2554,194,302

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.