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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.

Network64.0.0.0/3
Usable hosts536,870,910
Subnet mask224.0.0.0
Addresses536,870,912
Network address
64.0.0.0
Broadcast address
95.255.255.255
First usable
64.0.0.1
Last usable
95.255.255.254
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 40000000 · Integer 1073741824 to 1610612735
Reverse DNS zones
64.in-addr.arpa
65.in-addr.arpa
66.in-addr.arpa
67.in-addr.arpa
68.in-addr.arpa
69.in-addr.arpa
70.in-addr.arpa
71.in-addr.arpa
72.in-addr.arpa
73.in-addr.arpa
74.in-addr.arpa
75.in-addr.arpa
76.in-addr.arpa
77.in-addr.arpa
78.in-addr.arpa
79.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
Address01000000.00000000.00000000.0000000064.0.0.0
Subnet mask11100000.00000000.00000000.00000000224.0.0.0
Network01000000.00000000.00000000.0000000064.0.0.0
Broadcast01011111.11111111.11111111.1111111195.255.255.255
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)

64.0.0.0/3 makes 128 subnets of /10.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
164.0.0.0/1064.0.0.1 to 64.63.255.25464.63.255.2554,194,302
264.64.0.0/1064.64.0.1 to 64.127.255.25464.127.255.2554,194,302
364.128.0.0/1064.128.0.1 to 64.191.255.25464.191.255.2554,194,302
464.192.0.0/1064.192.0.1 to 64.255.255.25464.255.255.2554,194,302
565.0.0.0/1065.0.0.1 to 65.63.255.25465.63.255.2554,194,302
665.64.0.0/1065.64.0.1 to 65.127.255.25465.127.255.2554,194,302
765.128.0.0/1065.128.0.1 to 65.191.255.25465.191.255.2554,194,302
865.192.0.0/1065.192.0.1 to 65.255.255.25465.255.255.2554,194,302
966.0.0.0/1066.0.0.1 to 66.63.255.25466.63.255.2554,194,302
1066.64.0.0/1066.64.0.1 to 66.127.255.25466.127.255.2554,194,302
1166.128.0.0/1066.128.0.1 to 66.191.255.25466.191.255.2554,194,302
1266.192.0.0/1066.192.0.1 to 66.255.255.25466.255.255.2554,194,302
1367.0.0.0/1067.0.0.1 to 67.63.255.25467.63.255.2554,194,302
1467.64.0.0/1067.64.0.1 to 67.127.255.25467.127.255.2554,194,302
1567.128.0.0/1067.128.0.1 to 67.191.255.25467.191.255.2554,194,302
1667.192.0.0/1067.192.0.1 to 67.255.255.25467.255.255.2554,194,302
1768.0.0.0/1068.0.0.1 to 68.63.255.25468.63.255.2554,194,302
1868.64.0.0/1068.64.0.1 to 68.127.255.25468.127.255.2554,194,302
1968.128.0.0/1068.128.0.1 to 68.191.255.25468.191.255.2554,194,302
2068.192.0.0/1068.192.0.1 to 68.255.255.25468.255.255.2554,194,302
2169.0.0.0/1069.0.0.1 to 69.63.255.25469.63.255.2554,194,302
2269.64.0.0/1069.64.0.1 to 69.127.255.25469.127.255.2554,194,302
2369.128.0.0/1069.128.0.1 to 69.191.255.25469.191.255.2554,194,302
2469.192.0.0/1069.192.0.1 to 69.255.255.25469.255.255.2554,194,302
2570.0.0.0/1070.0.0.1 to 70.63.255.25470.63.255.2554,194,302
2670.64.0.0/1070.64.0.1 to 70.127.255.25470.127.255.2554,194,302
2770.128.0.0/1070.128.0.1 to 70.191.255.25470.191.255.2554,194,302
2870.192.0.0/1070.192.0.1 to 70.255.255.25470.255.255.2554,194,302
2971.0.0.0/1071.0.0.1 to 71.63.255.25471.63.255.2554,194,302
3071.64.0.0/1071.64.0.1 to 71.127.255.25471.127.255.2554,194,302
3171.128.0.0/1071.128.0.1 to 71.191.255.25471.191.255.2554,194,302
3271.192.0.0/1071.192.0.1 to 71.255.255.25471.255.255.2554,194,302
3372.0.0.0/1072.0.0.1 to 72.63.255.25472.63.255.2554,194,302
3472.64.0.0/1072.64.0.1 to 72.127.255.25472.127.255.2554,194,302
3572.128.0.0/1072.128.0.1 to 72.191.255.25472.191.255.2554,194,302
3672.192.0.0/1072.192.0.1 to 72.255.255.25472.255.255.2554,194,302
3773.0.0.0/1073.0.0.1 to 73.63.255.25473.63.255.2554,194,302
3873.64.0.0/1073.64.0.1 to 73.127.255.25473.127.255.2554,194,302
3973.128.0.0/1073.128.0.1 to 73.191.255.25473.191.255.2554,194,302
4073.192.0.0/1073.192.0.1 to 73.255.255.25473.255.255.2554,194,302
4174.0.0.0/1074.0.0.1 to 74.63.255.25474.63.255.2554,194,302
4274.64.0.0/1074.64.0.1 to 74.127.255.25474.127.255.2554,194,302
4374.128.0.0/1074.128.0.1 to 74.191.255.25474.191.255.2554,194,302
4474.192.0.0/1074.192.0.1 to 74.255.255.25474.255.255.2554,194,302
4575.0.0.0/1075.0.0.1 to 75.63.255.25475.63.255.2554,194,302
4675.64.0.0/1075.64.0.1 to 75.127.255.25475.127.255.2554,194,302
4775.128.0.0/1075.128.0.1 to 75.191.255.25475.191.255.2554,194,302
4875.192.0.0/1075.192.0.1 to 75.255.255.25475.255.255.2554,194,302
4976.0.0.0/1076.0.0.1 to 76.63.255.25476.63.255.2554,194,302
5076.64.0.0/1076.64.0.1 to 76.127.255.25476.127.255.2554,194,302
5176.128.0.0/1076.128.0.1 to 76.191.255.25476.191.255.2554,194,302
5276.192.0.0/1076.192.0.1 to 76.255.255.25476.255.255.2554,194,302
5377.0.0.0/1077.0.0.1 to 77.63.255.25477.63.255.2554,194,302
5477.64.0.0/1077.64.0.1 to 77.127.255.25477.127.255.2554,194,302
5577.128.0.0/1077.128.0.1 to 77.191.255.25477.191.255.2554,194,302
5677.192.0.0/1077.192.0.1 to 77.255.255.25477.255.255.2554,194,302
5778.0.0.0/1078.0.0.1 to 78.63.255.25478.63.255.2554,194,302
5878.64.0.0/1078.64.0.1 to 78.127.255.25478.127.255.2554,194,302
5978.128.0.0/1078.128.0.1 to 78.191.255.25478.191.255.2554,194,302
6078.192.0.0/1078.192.0.1 to 78.255.255.25478.255.255.2554,194,302
6179.0.0.0/1079.0.0.1 to 79.63.255.25479.63.255.2554,194,302
6279.64.0.0/1079.64.0.1 to 79.127.255.25479.127.255.2554,194,302
6379.128.0.0/1079.128.0.1 to 79.191.255.25479.191.255.2554,194,302
6479.192.0.0/1079.192.0.1 to 79.255.255.25479.255.255.2554,194,302
6580.0.0.0/1080.0.0.1 to 80.63.255.25480.63.255.2554,194,302
6680.64.0.0/1080.64.0.1 to 80.127.255.25480.127.255.2554,194,302
6780.128.0.0/1080.128.0.1 to 80.191.255.25480.191.255.2554,194,302
6880.192.0.0/1080.192.0.1 to 80.255.255.25480.255.255.2554,194,302
6981.0.0.0/1081.0.0.1 to 81.63.255.25481.63.255.2554,194,302
7081.64.0.0/1081.64.0.1 to 81.127.255.25481.127.255.2554,194,302
7181.128.0.0/1081.128.0.1 to 81.191.255.25481.191.255.2554,194,302
7281.192.0.0/1081.192.0.1 to 81.255.255.25481.255.255.2554,194,302
7382.0.0.0/1082.0.0.1 to 82.63.255.25482.63.255.2554,194,302
7482.64.0.0/1082.64.0.1 to 82.127.255.25482.127.255.2554,194,302
7582.128.0.0/1082.128.0.1 to 82.191.255.25482.191.255.2554,194,302
7682.192.0.0/1082.192.0.1 to 82.255.255.25482.255.255.2554,194,302
7783.0.0.0/1083.0.0.1 to 83.63.255.25483.63.255.2554,194,302
7883.64.0.0/1083.64.0.1 to 83.127.255.25483.127.255.2554,194,302
7983.128.0.0/1083.128.0.1 to 83.191.255.25483.191.255.2554,194,302
8083.192.0.0/1083.192.0.1 to 83.255.255.25483.255.255.2554,194,302
8184.0.0.0/1084.0.0.1 to 84.63.255.25484.63.255.2554,194,302
8284.64.0.0/1084.64.0.1 to 84.127.255.25484.127.255.2554,194,302
8384.128.0.0/1084.128.0.1 to 84.191.255.25484.191.255.2554,194,302
8484.192.0.0/1084.192.0.1 to 84.255.255.25484.255.255.2554,194,302
8585.0.0.0/1085.0.0.1 to 85.63.255.25485.63.255.2554,194,302
8685.64.0.0/1085.64.0.1 to 85.127.255.25485.127.255.2554,194,302
8785.128.0.0/1085.128.0.1 to 85.191.255.25485.191.255.2554,194,302
8885.192.0.0/1085.192.0.1 to 85.255.255.25485.255.255.2554,194,302
8986.0.0.0/1086.0.0.1 to 86.63.255.25486.63.255.2554,194,302
9086.64.0.0/1086.64.0.1 to 86.127.255.25486.127.255.2554,194,302
9186.128.0.0/1086.128.0.1 to 86.191.255.25486.191.255.2554,194,302
9286.192.0.0/1086.192.0.1 to 86.255.255.25486.255.255.2554,194,302
9387.0.0.0/1087.0.0.1 to 87.63.255.25487.63.255.2554,194,302
9487.64.0.0/1087.64.0.1 to 87.127.255.25487.127.255.2554,194,302
9587.128.0.0/1087.128.0.1 to 87.191.255.25487.191.255.2554,194,302
9687.192.0.0/1087.192.0.1 to 87.255.255.25487.255.255.2554,194,302
9788.0.0.0/1088.0.0.1 to 88.63.255.25488.63.255.2554,194,302
9888.64.0.0/1088.64.0.1 to 88.127.255.25488.127.255.2554,194,302
9988.128.0.0/1088.128.0.1 to 88.191.255.25488.191.255.2554,194,302
10088.192.0.0/1088.192.0.1 to 88.255.255.25488.255.255.2554,194,302
10189.0.0.0/1089.0.0.1 to 89.63.255.25489.63.255.2554,194,302
10289.64.0.0/1089.64.0.1 to 89.127.255.25489.127.255.2554,194,302
10389.128.0.0/1089.128.0.1 to 89.191.255.25489.191.255.2554,194,302
10489.192.0.0/1089.192.0.1 to 89.255.255.25489.255.255.2554,194,302
10590.0.0.0/1090.0.0.1 to 90.63.255.25490.63.255.2554,194,302
10690.64.0.0/1090.64.0.1 to 90.127.255.25490.127.255.2554,194,302
10790.128.0.0/1090.128.0.1 to 90.191.255.25490.191.255.2554,194,302
10890.192.0.0/1090.192.0.1 to 90.255.255.25490.255.255.2554,194,302
10991.0.0.0/1091.0.0.1 to 91.63.255.25491.63.255.2554,194,302
11091.64.0.0/1091.64.0.1 to 91.127.255.25491.127.255.2554,194,302
11191.128.0.0/1091.128.0.1 to 91.191.255.25491.191.255.2554,194,302
11291.192.0.0/1091.192.0.1 to 91.255.255.25491.255.255.2554,194,302
11392.0.0.0/1092.0.0.1 to 92.63.255.25492.63.255.2554,194,302
11492.64.0.0/1092.64.0.1 to 92.127.255.25492.127.255.2554,194,302
11592.128.0.0/1092.128.0.1 to 92.191.255.25492.191.255.2554,194,302
11692.192.0.0/1092.192.0.1 to 92.255.255.25492.255.255.2554,194,302
11793.0.0.0/1093.0.0.1 to 93.63.255.25493.63.255.2554,194,302
11893.64.0.0/1093.64.0.1 to 93.127.255.25493.127.255.2554,194,302
11993.128.0.0/1093.128.0.1 to 93.191.255.25493.191.255.2554,194,302
12093.192.0.0/1093.192.0.1 to 93.255.255.25493.255.255.2554,194,302
12194.0.0.0/1094.0.0.1 to 94.63.255.25494.63.255.2554,194,302
12294.64.0.0/1094.64.0.1 to 94.127.255.25494.127.255.2554,194,302
12394.128.0.0/1094.128.0.1 to 94.191.255.25494.191.255.2554,194,302
12494.192.0.0/1094.192.0.1 to 94.255.255.25494.255.255.2554,194,302
12595.0.0.0/1095.0.0.1 to 95.63.255.25495.63.255.2554,194,302
12695.64.0.0/1095.64.0.1 to 95.127.255.25495.127.255.2554,194,302
12795.128.0.0/1095.128.0.1 to 95.191.255.25495.191.255.2554,194,302
12895.192.0.0/1095.192.0.1 to 95.255.255.25495.255.255.2554,194,302

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.