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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.

Network255.64.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
255.64.0.0
Broadcast address
255.95.255.255
First usable
255.64.0.1
Last usable
255.95.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FF400000 · Integer 4282384384 to 4284481535
Reverse DNS zones
64.255.in-addr.arpa
65.255.in-addr.arpa
66.255.in-addr.arpa
67.255.in-addr.arpa
68.255.in-addr.arpa
69.255.in-addr.arpa
70.255.in-addr.arpa
71.255.in-addr.arpa
72.255.in-addr.arpa
73.255.in-addr.arpa
74.255.in-addr.arpa
75.255.in-addr.arpa
76.255.in-addr.arpa
77.255.in-addr.arpa
78.255.in-addr.arpa
79.255.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111111.01000000.00000000.00000000255.64.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network11111111.01000000.00000000.00000000255.64.0.0
Broadcast11111111.01011111.11111111.11111111255.95.255.255
Split into smaller subnets/18
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

255.64.0.0/11 makes 128 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1255.64.0.0/18255.64.0.1 to 255.64.63.254255.64.63.25516,382
2255.64.64.0/18255.64.64.1 to 255.64.127.254255.64.127.25516,382
3255.64.128.0/18255.64.128.1 to 255.64.191.254255.64.191.25516,382
4255.64.192.0/18255.64.192.1 to 255.64.255.254255.64.255.25516,382
5255.65.0.0/18255.65.0.1 to 255.65.63.254255.65.63.25516,382
6255.65.64.0/18255.65.64.1 to 255.65.127.254255.65.127.25516,382
7255.65.128.0/18255.65.128.1 to 255.65.191.254255.65.191.25516,382
8255.65.192.0/18255.65.192.1 to 255.65.255.254255.65.255.25516,382
9255.66.0.0/18255.66.0.1 to 255.66.63.254255.66.63.25516,382
10255.66.64.0/18255.66.64.1 to 255.66.127.254255.66.127.25516,382
11255.66.128.0/18255.66.128.1 to 255.66.191.254255.66.191.25516,382
12255.66.192.0/18255.66.192.1 to 255.66.255.254255.66.255.25516,382
13255.67.0.0/18255.67.0.1 to 255.67.63.254255.67.63.25516,382
14255.67.64.0/18255.67.64.1 to 255.67.127.254255.67.127.25516,382
15255.67.128.0/18255.67.128.1 to 255.67.191.254255.67.191.25516,382
16255.67.192.0/18255.67.192.1 to 255.67.255.254255.67.255.25516,382
17255.68.0.0/18255.68.0.1 to 255.68.63.254255.68.63.25516,382
18255.68.64.0/18255.68.64.1 to 255.68.127.254255.68.127.25516,382
19255.68.128.0/18255.68.128.1 to 255.68.191.254255.68.191.25516,382
20255.68.192.0/18255.68.192.1 to 255.68.255.254255.68.255.25516,382
21255.69.0.0/18255.69.0.1 to 255.69.63.254255.69.63.25516,382
22255.69.64.0/18255.69.64.1 to 255.69.127.254255.69.127.25516,382
23255.69.128.0/18255.69.128.1 to 255.69.191.254255.69.191.25516,382
24255.69.192.0/18255.69.192.1 to 255.69.255.254255.69.255.25516,382
25255.70.0.0/18255.70.0.1 to 255.70.63.254255.70.63.25516,382
26255.70.64.0/18255.70.64.1 to 255.70.127.254255.70.127.25516,382
27255.70.128.0/18255.70.128.1 to 255.70.191.254255.70.191.25516,382
28255.70.192.0/18255.70.192.1 to 255.70.255.254255.70.255.25516,382
29255.71.0.0/18255.71.0.1 to 255.71.63.254255.71.63.25516,382
30255.71.64.0/18255.71.64.1 to 255.71.127.254255.71.127.25516,382
31255.71.128.0/18255.71.128.1 to 255.71.191.254255.71.191.25516,382
32255.71.192.0/18255.71.192.1 to 255.71.255.254255.71.255.25516,382
33255.72.0.0/18255.72.0.1 to 255.72.63.254255.72.63.25516,382
34255.72.64.0/18255.72.64.1 to 255.72.127.254255.72.127.25516,382
35255.72.128.0/18255.72.128.1 to 255.72.191.254255.72.191.25516,382
36255.72.192.0/18255.72.192.1 to 255.72.255.254255.72.255.25516,382
37255.73.0.0/18255.73.0.1 to 255.73.63.254255.73.63.25516,382
38255.73.64.0/18255.73.64.1 to 255.73.127.254255.73.127.25516,382
39255.73.128.0/18255.73.128.1 to 255.73.191.254255.73.191.25516,382
40255.73.192.0/18255.73.192.1 to 255.73.255.254255.73.255.25516,382
41255.74.0.0/18255.74.0.1 to 255.74.63.254255.74.63.25516,382
42255.74.64.0/18255.74.64.1 to 255.74.127.254255.74.127.25516,382
43255.74.128.0/18255.74.128.1 to 255.74.191.254255.74.191.25516,382
44255.74.192.0/18255.74.192.1 to 255.74.255.254255.74.255.25516,382
45255.75.0.0/18255.75.0.1 to 255.75.63.254255.75.63.25516,382
46255.75.64.0/18255.75.64.1 to 255.75.127.254255.75.127.25516,382
47255.75.128.0/18255.75.128.1 to 255.75.191.254255.75.191.25516,382
48255.75.192.0/18255.75.192.1 to 255.75.255.254255.75.255.25516,382
49255.76.0.0/18255.76.0.1 to 255.76.63.254255.76.63.25516,382
50255.76.64.0/18255.76.64.1 to 255.76.127.254255.76.127.25516,382
51255.76.128.0/18255.76.128.1 to 255.76.191.254255.76.191.25516,382
52255.76.192.0/18255.76.192.1 to 255.76.255.254255.76.255.25516,382
53255.77.0.0/18255.77.0.1 to 255.77.63.254255.77.63.25516,382
54255.77.64.0/18255.77.64.1 to 255.77.127.254255.77.127.25516,382
55255.77.128.0/18255.77.128.1 to 255.77.191.254255.77.191.25516,382
56255.77.192.0/18255.77.192.1 to 255.77.255.254255.77.255.25516,382
57255.78.0.0/18255.78.0.1 to 255.78.63.254255.78.63.25516,382
58255.78.64.0/18255.78.64.1 to 255.78.127.254255.78.127.25516,382
59255.78.128.0/18255.78.128.1 to 255.78.191.254255.78.191.25516,382
60255.78.192.0/18255.78.192.1 to 255.78.255.254255.78.255.25516,382
61255.79.0.0/18255.79.0.1 to 255.79.63.254255.79.63.25516,382
62255.79.64.0/18255.79.64.1 to 255.79.127.254255.79.127.25516,382
63255.79.128.0/18255.79.128.1 to 255.79.191.254255.79.191.25516,382
64255.79.192.0/18255.79.192.1 to 255.79.255.254255.79.255.25516,382
65255.80.0.0/18255.80.0.1 to 255.80.63.254255.80.63.25516,382
66255.80.64.0/18255.80.64.1 to 255.80.127.254255.80.127.25516,382
67255.80.128.0/18255.80.128.1 to 255.80.191.254255.80.191.25516,382
68255.80.192.0/18255.80.192.1 to 255.80.255.254255.80.255.25516,382
69255.81.0.0/18255.81.0.1 to 255.81.63.254255.81.63.25516,382
70255.81.64.0/18255.81.64.1 to 255.81.127.254255.81.127.25516,382
71255.81.128.0/18255.81.128.1 to 255.81.191.254255.81.191.25516,382
72255.81.192.0/18255.81.192.1 to 255.81.255.254255.81.255.25516,382
73255.82.0.0/18255.82.0.1 to 255.82.63.254255.82.63.25516,382
74255.82.64.0/18255.82.64.1 to 255.82.127.254255.82.127.25516,382
75255.82.128.0/18255.82.128.1 to 255.82.191.254255.82.191.25516,382
76255.82.192.0/18255.82.192.1 to 255.82.255.254255.82.255.25516,382
77255.83.0.0/18255.83.0.1 to 255.83.63.254255.83.63.25516,382
78255.83.64.0/18255.83.64.1 to 255.83.127.254255.83.127.25516,382
79255.83.128.0/18255.83.128.1 to 255.83.191.254255.83.191.25516,382
80255.83.192.0/18255.83.192.1 to 255.83.255.254255.83.255.25516,382
81255.84.0.0/18255.84.0.1 to 255.84.63.254255.84.63.25516,382
82255.84.64.0/18255.84.64.1 to 255.84.127.254255.84.127.25516,382
83255.84.128.0/18255.84.128.1 to 255.84.191.254255.84.191.25516,382
84255.84.192.0/18255.84.192.1 to 255.84.255.254255.84.255.25516,382
85255.85.0.0/18255.85.0.1 to 255.85.63.254255.85.63.25516,382
86255.85.64.0/18255.85.64.1 to 255.85.127.254255.85.127.25516,382
87255.85.128.0/18255.85.128.1 to 255.85.191.254255.85.191.25516,382
88255.85.192.0/18255.85.192.1 to 255.85.255.254255.85.255.25516,382
89255.86.0.0/18255.86.0.1 to 255.86.63.254255.86.63.25516,382
90255.86.64.0/18255.86.64.1 to 255.86.127.254255.86.127.25516,382
91255.86.128.0/18255.86.128.1 to 255.86.191.254255.86.191.25516,382
92255.86.192.0/18255.86.192.1 to 255.86.255.254255.86.255.25516,382
93255.87.0.0/18255.87.0.1 to 255.87.63.254255.87.63.25516,382
94255.87.64.0/18255.87.64.1 to 255.87.127.254255.87.127.25516,382
95255.87.128.0/18255.87.128.1 to 255.87.191.254255.87.191.25516,382
96255.87.192.0/18255.87.192.1 to 255.87.255.254255.87.255.25516,382
97255.88.0.0/18255.88.0.1 to 255.88.63.254255.88.63.25516,382
98255.88.64.0/18255.88.64.1 to 255.88.127.254255.88.127.25516,382
99255.88.128.0/18255.88.128.1 to 255.88.191.254255.88.191.25516,382
100255.88.192.0/18255.88.192.1 to 255.88.255.254255.88.255.25516,382
101255.89.0.0/18255.89.0.1 to 255.89.63.254255.89.63.25516,382
102255.89.64.0/18255.89.64.1 to 255.89.127.254255.89.127.25516,382
103255.89.128.0/18255.89.128.1 to 255.89.191.254255.89.191.25516,382
104255.89.192.0/18255.89.192.1 to 255.89.255.254255.89.255.25516,382
105255.90.0.0/18255.90.0.1 to 255.90.63.254255.90.63.25516,382
106255.90.64.0/18255.90.64.1 to 255.90.127.254255.90.127.25516,382
107255.90.128.0/18255.90.128.1 to 255.90.191.254255.90.191.25516,382
108255.90.192.0/18255.90.192.1 to 255.90.255.254255.90.255.25516,382
109255.91.0.0/18255.91.0.1 to 255.91.63.254255.91.63.25516,382
110255.91.64.0/18255.91.64.1 to 255.91.127.254255.91.127.25516,382
111255.91.128.0/18255.91.128.1 to 255.91.191.254255.91.191.25516,382
112255.91.192.0/18255.91.192.1 to 255.91.255.254255.91.255.25516,382
113255.92.0.0/18255.92.0.1 to 255.92.63.254255.92.63.25516,382
114255.92.64.0/18255.92.64.1 to 255.92.127.254255.92.127.25516,382
115255.92.128.0/18255.92.128.1 to 255.92.191.254255.92.191.25516,382
116255.92.192.0/18255.92.192.1 to 255.92.255.254255.92.255.25516,382
117255.93.0.0/18255.93.0.1 to 255.93.63.254255.93.63.25516,382
118255.93.64.0/18255.93.64.1 to 255.93.127.254255.93.127.25516,382
119255.93.128.0/18255.93.128.1 to 255.93.191.254255.93.191.25516,382
120255.93.192.0/18255.93.192.1 to 255.93.255.254255.93.255.25516,382
121255.94.0.0/18255.94.0.1 to 255.94.63.254255.94.63.25516,382
122255.94.64.0/18255.94.64.1 to 255.94.127.254255.94.127.25516,382
123255.94.128.0/18255.94.128.1 to 255.94.191.254255.94.191.25516,382
124255.94.192.0/18255.94.192.1 to 255.94.255.254255.94.255.25516,382
125255.95.0.0/18255.95.0.1 to 255.95.63.254255.95.63.25516,382
126255.95.64.0/18255.95.64.1 to 255.95.127.254255.95.127.25516,382
127255.95.128.0/18255.95.128.1 to 255.95.191.254255.95.191.25516,382
128255.95.192.0/18255.95.192.1 to 255.95.255.254255.95.255.25516,382

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.