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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.

Network32.0.0.0/4
Usable hosts268,435,454
Subnet mask240.0.0.0
Addresses268,435,456
Network address
32.0.0.0
Broadcast address
47.255.255.255
First usable
32.0.0.1
Last usable
47.255.255.254
Usable hosts
268,435,454 (268,435,456 less the network and broadcast addresses)
Subnet mask
240.0.0.0
Wildcard mask
15.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/4
Type
Public public
Old class
A (default /8)
As numbers
Hex 20000000 · Integer 536870912 to 805306367
Reverse DNS zones
32.in-addr.arpa
33.in-addr.arpa
34.in-addr.arpa
35.in-addr.arpa
36.in-addr.arpa
37.in-addr.arpa
38.in-addr.arpa
39.in-addr.arpa
40.in-addr.arpa
41.in-addr.arpa
42.in-addr.arpa
43.in-addr.arpa
44.in-addr.arpa
45.in-addr.arpa
46.in-addr.arpa
47.in-addr.arpa
/4 is not on a 8-bit boundary, so it takes 16 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00100000.00000000.00000000.0000000032.0.0.0
Subnet mask11110000.00000000.00000000.00000000240.0.0.0
Network00100000.00000000.00000000.0000000032.0.0.0
Broadcast00101111.11111111.11111111.1111111147.255.255.255
Split into smaller subnets/11
/5 (2)/6 (4)/7 (8)/8 (16)/9 (32)/10 (64)/11 (128)/12 (256)/13 (512)/14 (1,024)/15 (2,048)/16 (4,096)

32.0.0.0/4 makes 128 subnets of /11.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
132.0.0.0/1132.0.0.1 to 32.31.255.25432.31.255.2552,097,150
232.32.0.0/1132.32.0.1 to 32.63.255.25432.63.255.2552,097,150
332.64.0.0/1132.64.0.1 to 32.95.255.25432.95.255.2552,097,150
432.96.0.0/1132.96.0.1 to 32.127.255.25432.127.255.2552,097,150
532.128.0.0/1132.128.0.1 to 32.159.255.25432.159.255.2552,097,150
632.160.0.0/1132.160.0.1 to 32.191.255.25432.191.255.2552,097,150
732.192.0.0/1132.192.0.1 to 32.223.255.25432.223.255.2552,097,150
832.224.0.0/1132.224.0.1 to 32.255.255.25432.255.255.2552,097,150
933.0.0.0/1133.0.0.1 to 33.31.255.25433.31.255.2552,097,150
1033.32.0.0/1133.32.0.1 to 33.63.255.25433.63.255.2552,097,150
1133.64.0.0/1133.64.0.1 to 33.95.255.25433.95.255.2552,097,150
1233.96.0.0/1133.96.0.1 to 33.127.255.25433.127.255.2552,097,150
1333.128.0.0/1133.128.0.1 to 33.159.255.25433.159.255.2552,097,150
1433.160.0.0/1133.160.0.1 to 33.191.255.25433.191.255.2552,097,150
1533.192.0.0/1133.192.0.1 to 33.223.255.25433.223.255.2552,097,150
1633.224.0.0/1133.224.0.1 to 33.255.255.25433.255.255.2552,097,150
1734.0.0.0/1134.0.0.1 to 34.31.255.25434.31.255.2552,097,150
1834.32.0.0/1134.32.0.1 to 34.63.255.25434.63.255.2552,097,150
1934.64.0.0/1134.64.0.1 to 34.95.255.25434.95.255.2552,097,150
2034.96.0.0/1134.96.0.1 to 34.127.255.25434.127.255.2552,097,150
2134.128.0.0/1134.128.0.1 to 34.159.255.25434.159.255.2552,097,150
2234.160.0.0/1134.160.0.1 to 34.191.255.25434.191.255.2552,097,150
2334.192.0.0/1134.192.0.1 to 34.223.255.25434.223.255.2552,097,150
2434.224.0.0/1134.224.0.1 to 34.255.255.25434.255.255.2552,097,150
2535.0.0.0/1135.0.0.1 to 35.31.255.25435.31.255.2552,097,150
2635.32.0.0/1135.32.0.1 to 35.63.255.25435.63.255.2552,097,150
2735.64.0.0/1135.64.0.1 to 35.95.255.25435.95.255.2552,097,150
2835.96.0.0/1135.96.0.1 to 35.127.255.25435.127.255.2552,097,150
2935.128.0.0/1135.128.0.1 to 35.159.255.25435.159.255.2552,097,150
3035.160.0.0/1135.160.0.1 to 35.191.255.25435.191.255.2552,097,150
3135.192.0.0/1135.192.0.1 to 35.223.255.25435.223.255.2552,097,150
3235.224.0.0/1135.224.0.1 to 35.255.255.25435.255.255.2552,097,150
3336.0.0.0/1136.0.0.1 to 36.31.255.25436.31.255.2552,097,150
3436.32.0.0/1136.32.0.1 to 36.63.255.25436.63.255.2552,097,150
3536.64.0.0/1136.64.0.1 to 36.95.255.25436.95.255.2552,097,150
3636.96.0.0/1136.96.0.1 to 36.127.255.25436.127.255.2552,097,150
3736.128.0.0/1136.128.0.1 to 36.159.255.25436.159.255.2552,097,150
3836.160.0.0/1136.160.0.1 to 36.191.255.25436.191.255.2552,097,150
3936.192.0.0/1136.192.0.1 to 36.223.255.25436.223.255.2552,097,150
4036.224.0.0/1136.224.0.1 to 36.255.255.25436.255.255.2552,097,150
4137.0.0.0/1137.0.0.1 to 37.31.255.25437.31.255.2552,097,150
4237.32.0.0/1137.32.0.1 to 37.63.255.25437.63.255.2552,097,150
4337.64.0.0/1137.64.0.1 to 37.95.255.25437.95.255.2552,097,150
4437.96.0.0/1137.96.0.1 to 37.127.255.25437.127.255.2552,097,150
4537.128.0.0/1137.128.0.1 to 37.159.255.25437.159.255.2552,097,150
4637.160.0.0/1137.160.0.1 to 37.191.255.25437.191.255.2552,097,150
4737.192.0.0/1137.192.0.1 to 37.223.255.25437.223.255.2552,097,150
4837.224.0.0/1137.224.0.1 to 37.255.255.25437.255.255.2552,097,150
4938.0.0.0/1138.0.0.1 to 38.31.255.25438.31.255.2552,097,150
5038.32.0.0/1138.32.0.1 to 38.63.255.25438.63.255.2552,097,150
5138.64.0.0/1138.64.0.1 to 38.95.255.25438.95.255.2552,097,150
5238.96.0.0/1138.96.0.1 to 38.127.255.25438.127.255.2552,097,150
5338.128.0.0/1138.128.0.1 to 38.159.255.25438.159.255.2552,097,150
5438.160.0.0/1138.160.0.1 to 38.191.255.25438.191.255.2552,097,150
5538.192.0.0/1138.192.0.1 to 38.223.255.25438.223.255.2552,097,150
5638.224.0.0/1138.224.0.1 to 38.255.255.25438.255.255.2552,097,150
5739.0.0.0/1139.0.0.1 to 39.31.255.25439.31.255.2552,097,150
5839.32.0.0/1139.32.0.1 to 39.63.255.25439.63.255.2552,097,150
5939.64.0.0/1139.64.0.1 to 39.95.255.25439.95.255.2552,097,150
6039.96.0.0/1139.96.0.1 to 39.127.255.25439.127.255.2552,097,150
6139.128.0.0/1139.128.0.1 to 39.159.255.25439.159.255.2552,097,150
6239.160.0.0/1139.160.0.1 to 39.191.255.25439.191.255.2552,097,150
6339.192.0.0/1139.192.0.1 to 39.223.255.25439.223.255.2552,097,150
6439.224.0.0/1139.224.0.1 to 39.255.255.25439.255.255.2552,097,150
6540.0.0.0/1140.0.0.1 to 40.31.255.25440.31.255.2552,097,150
6640.32.0.0/1140.32.0.1 to 40.63.255.25440.63.255.2552,097,150
6740.64.0.0/1140.64.0.1 to 40.95.255.25440.95.255.2552,097,150
6840.96.0.0/1140.96.0.1 to 40.127.255.25440.127.255.2552,097,150
6940.128.0.0/1140.128.0.1 to 40.159.255.25440.159.255.2552,097,150
7040.160.0.0/1140.160.0.1 to 40.191.255.25440.191.255.2552,097,150
7140.192.0.0/1140.192.0.1 to 40.223.255.25440.223.255.2552,097,150
7240.224.0.0/1140.224.0.1 to 40.255.255.25440.255.255.2552,097,150
7341.0.0.0/1141.0.0.1 to 41.31.255.25441.31.255.2552,097,150
7441.32.0.0/1141.32.0.1 to 41.63.255.25441.63.255.2552,097,150
7541.64.0.0/1141.64.0.1 to 41.95.255.25441.95.255.2552,097,150
7641.96.0.0/1141.96.0.1 to 41.127.255.25441.127.255.2552,097,150
7741.128.0.0/1141.128.0.1 to 41.159.255.25441.159.255.2552,097,150
7841.160.0.0/1141.160.0.1 to 41.191.255.25441.191.255.2552,097,150
7941.192.0.0/1141.192.0.1 to 41.223.255.25441.223.255.2552,097,150
8041.224.0.0/1141.224.0.1 to 41.255.255.25441.255.255.2552,097,150
8142.0.0.0/1142.0.0.1 to 42.31.255.25442.31.255.2552,097,150
8242.32.0.0/1142.32.0.1 to 42.63.255.25442.63.255.2552,097,150
8342.64.0.0/1142.64.0.1 to 42.95.255.25442.95.255.2552,097,150
8442.96.0.0/1142.96.0.1 to 42.127.255.25442.127.255.2552,097,150
8542.128.0.0/1142.128.0.1 to 42.159.255.25442.159.255.2552,097,150
8642.160.0.0/1142.160.0.1 to 42.191.255.25442.191.255.2552,097,150
8742.192.0.0/1142.192.0.1 to 42.223.255.25442.223.255.2552,097,150
8842.224.0.0/1142.224.0.1 to 42.255.255.25442.255.255.2552,097,150
8943.0.0.0/1143.0.0.1 to 43.31.255.25443.31.255.2552,097,150
9043.32.0.0/1143.32.0.1 to 43.63.255.25443.63.255.2552,097,150
9143.64.0.0/1143.64.0.1 to 43.95.255.25443.95.255.2552,097,150
9243.96.0.0/1143.96.0.1 to 43.127.255.25443.127.255.2552,097,150
9343.128.0.0/1143.128.0.1 to 43.159.255.25443.159.255.2552,097,150
9443.160.0.0/1143.160.0.1 to 43.191.255.25443.191.255.2552,097,150
9543.192.0.0/1143.192.0.1 to 43.223.255.25443.223.255.2552,097,150
9643.224.0.0/1143.224.0.1 to 43.255.255.25443.255.255.2552,097,150
9744.0.0.0/1144.0.0.1 to 44.31.255.25444.31.255.2552,097,150
9844.32.0.0/1144.32.0.1 to 44.63.255.25444.63.255.2552,097,150
9944.64.0.0/1144.64.0.1 to 44.95.255.25444.95.255.2552,097,150
10044.96.0.0/1144.96.0.1 to 44.127.255.25444.127.255.2552,097,150
10144.128.0.0/1144.128.0.1 to 44.159.255.25444.159.255.2552,097,150
10244.160.0.0/1144.160.0.1 to 44.191.255.25444.191.255.2552,097,150
10344.192.0.0/1144.192.0.1 to 44.223.255.25444.223.255.2552,097,150
10444.224.0.0/1144.224.0.1 to 44.255.255.25444.255.255.2552,097,150
10545.0.0.0/1145.0.0.1 to 45.31.255.25445.31.255.2552,097,150
10645.32.0.0/1145.32.0.1 to 45.63.255.25445.63.255.2552,097,150
10745.64.0.0/1145.64.0.1 to 45.95.255.25445.95.255.2552,097,150
10845.96.0.0/1145.96.0.1 to 45.127.255.25445.127.255.2552,097,150
10945.128.0.0/1145.128.0.1 to 45.159.255.25445.159.255.2552,097,150
11045.160.0.0/1145.160.0.1 to 45.191.255.25445.191.255.2552,097,150
11145.192.0.0/1145.192.0.1 to 45.223.255.25445.223.255.2552,097,150
11245.224.0.0/1145.224.0.1 to 45.255.255.25445.255.255.2552,097,150
11346.0.0.0/1146.0.0.1 to 46.31.255.25446.31.255.2552,097,150
11446.32.0.0/1146.32.0.1 to 46.63.255.25446.63.255.2552,097,150
11546.64.0.0/1146.64.0.1 to 46.95.255.25446.95.255.2552,097,150
11646.96.0.0/1146.96.0.1 to 46.127.255.25446.127.255.2552,097,150
11746.128.0.0/1146.128.0.1 to 46.159.255.25446.159.255.2552,097,150
11846.160.0.0/1146.160.0.1 to 46.191.255.25446.191.255.2552,097,150
11946.192.0.0/1146.192.0.1 to 46.223.255.25446.223.255.2552,097,150
12046.224.0.0/1146.224.0.1 to 46.255.255.25446.255.255.2552,097,150
12147.0.0.0/1147.0.0.1 to 47.31.255.25447.31.255.2552,097,150
12247.32.0.0/1147.32.0.1 to 47.63.255.25447.63.255.2552,097,150
12347.64.0.0/1147.64.0.1 to 47.95.255.25447.95.255.2552,097,150
12447.96.0.0/1147.96.0.1 to 47.127.255.25447.127.255.2552,097,150
12547.128.0.0/1147.128.0.1 to 47.159.255.25447.159.255.2552,097,150
12647.160.0.0/1147.160.0.1 to 47.191.255.25447.191.255.2552,097,150
12747.192.0.0/1147.192.0.1 to 47.223.255.25447.223.255.2552,097,150
12847.224.0.0/1147.224.0.1 to 47.255.255.25447.255.255.2552,097,150

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.