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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.

Network244.64.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
244.64.0.0
Broadcast address
244.95.255.255
First usable
244.64.0.1
Last usable
244.95.255.254
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 F4400000 · Integer 4097835008 to 4099932159
Reverse DNS zones
64.244.in-addr.arpa
65.244.in-addr.arpa
66.244.in-addr.arpa
67.244.in-addr.arpa
68.244.in-addr.arpa
69.244.in-addr.arpa
70.244.in-addr.arpa
71.244.in-addr.arpa
72.244.in-addr.arpa
73.244.in-addr.arpa
74.244.in-addr.arpa
75.244.in-addr.arpa
76.244.in-addr.arpa
77.244.in-addr.arpa
78.244.in-addr.arpa
79.244.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
Address11110100.01000000.00000000.00000000244.64.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network11110100.01000000.00000000.00000000244.64.0.0
Broadcast11110100.01011111.11111111.11111111244.95.255.255
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)

244.64.0.0/11 makes 128 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1244.64.0.0/18244.64.0.1 to 244.64.63.254244.64.63.25516,382
2244.64.64.0/18244.64.64.1 to 244.64.127.254244.64.127.25516,382
3244.64.128.0/18244.64.128.1 to 244.64.191.254244.64.191.25516,382
4244.64.192.0/18244.64.192.1 to 244.64.255.254244.64.255.25516,382
5244.65.0.0/18244.65.0.1 to 244.65.63.254244.65.63.25516,382
6244.65.64.0/18244.65.64.1 to 244.65.127.254244.65.127.25516,382
7244.65.128.0/18244.65.128.1 to 244.65.191.254244.65.191.25516,382
8244.65.192.0/18244.65.192.1 to 244.65.255.254244.65.255.25516,382
9244.66.0.0/18244.66.0.1 to 244.66.63.254244.66.63.25516,382
10244.66.64.0/18244.66.64.1 to 244.66.127.254244.66.127.25516,382
11244.66.128.0/18244.66.128.1 to 244.66.191.254244.66.191.25516,382
12244.66.192.0/18244.66.192.1 to 244.66.255.254244.66.255.25516,382
13244.67.0.0/18244.67.0.1 to 244.67.63.254244.67.63.25516,382
14244.67.64.0/18244.67.64.1 to 244.67.127.254244.67.127.25516,382
15244.67.128.0/18244.67.128.1 to 244.67.191.254244.67.191.25516,382
16244.67.192.0/18244.67.192.1 to 244.67.255.254244.67.255.25516,382
17244.68.0.0/18244.68.0.1 to 244.68.63.254244.68.63.25516,382
18244.68.64.0/18244.68.64.1 to 244.68.127.254244.68.127.25516,382
19244.68.128.0/18244.68.128.1 to 244.68.191.254244.68.191.25516,382
20244.68.192.0/18244.68.192.1 to 244.68.255.254244.68.255.25516,382
21244.69.0.0/18244.69.0.1 to 244.69.63.254244.69.63.25516,382
22244.69.64.0/18244.69.64.1 to 244.69.127.254244.69.127.25516,382
23244.69.128.0/18244.69.128.1 to 244.69.191.254244.69.191.25516,382
24244.69.192.0/18244.69.192.1 to 244.69.255.254244.69.255.25516,382
25244.70.0.0/18244.70.0.1 to 244.70.63.254244.70.63.25516,382
26244.70.64.0/18244.70.64.1 to 244.70.127.254244.70.127.25516,382
27244.70.128.0/18244.70.128.1 to 244.70.191.254244.70.191.25516,382
28244.70.192.0/18244.70.192.1 to 244.70.255.254244.70.255.25516,382
29244.71.0.0/18244.71.0.1 to 244.71.63.254244.71.63.25516,382
30244.71.64.0/18244.71.64.1 to 244.71.127.254244.71.127.25516,382
31244.71.128.0/18244.71.128.1 to 244.71.191.254244.71.191.25516,382
32244.71.192.0/18244.71.192.1 to 244.71.255.254244.71.255.25516,382
33244.72.0.0/18244.72.0.1 to 244.72.63.254244.72.63.25516,382
34244.72.64.0/18244.72.64.1 to 244.72.127.254244.72.127.25516,382
35244.72.128.0/18244.72.128.1 to 244.72.191.254244.72.191.25516,382
36244.72.192.0/18244.72.192.1 to 244.72.255.254244.72.255.25516,382
37244.73.0.0/18244.73.0.1 to 244.73.63.254244.73.63.25516,382
38244.73.64.0/18244.73.64.1 to 244.73.127.254244.73.127.25516,382
39244.73.128.0/18244.73.128.1 to 244.73.191.254244.73.191.25516,382
40244.73.192.0/18244.73.192.1 to 244.73.255.254244.73.255.25516,382
41244.74.0.0/18244.74.0.1 to 244.74.63.254244.74.63.25516,382
42244.74.64.0/18244.74.64.1 to 244.74.127.254244.74.127.25516,382
43244.74.128.0/18244.74.128.1 to 244.74.191.254244.74.191.25516,382
44244.74.192.0/18244.74.192.1 to 244.74.255.254244.74.255.25516,382
45244.75.0.0/18244.75.0.1 to 244.75.63.254244.75.63.25516,382
46244.75.64.0/18244.75.64.1 to 244.75.127.254244.75.127.25516,382
47244.75.128.0/18244.75.128.1 to 244.75.191.254244.75.191.25516,382
48244.75.192.0/18244.75.192.1 to 244.75.255.254244.75.255.25516,382
49244.76.0.0/18244.76.0.1 to 244.76.63.254244.76.63.25516,382
50244.76.64.0/18244.76.64.1 to 244.76.127.254244.76.127.25516,382
51244.76.128.0/18244.76.128.1 to 244.76.191.254244.76.191.25516,382
52244.76.192.0/18244.76.192.1 to 244.76.255.254244.76.255.25516,382
53244.77.0.0/18244.77.0.1 to 244.77.63.254244.77.63.25516,382
54244.77.64.0/18244.77.64.1 to 244.77.127.254244.77.127.25516,382
55244.77.128.0/18244.77.128.1 to 244.77.191.254244.77.191.25516,382
56244.77.192.0/18244.77.192.1 to 244.77.255.254244.77.255.25516,382
57244.78.0.0/18244.78.0.1 to 244.78.63.254244.78.63.25516,382
58244.78.64.0/18244.78.64.1 to 244.78.127.254244.78.127.25516,382
59244.78.128.0/18244.78.128.1 to 244.78.191.254244.78.191.25516,382
60244.78.192.0/18244.78.192.1 to 244.78.255.254244.78.255.25516,382
61244.79.0.0/18244.79.0.1 to 244.79.63.254244.79.63.25516,382
62244.79.64.0/18244.79.64.1 to 244.79.127.254244.79.127.25516,382
63244.79.128.0/18244.79.128.1 to 244.79.191.254244.79.191.25516,382
64244.79.192.0/18244.79.192.1 to 244.79.255.254244.79.255.25516,382
65244.80.0.0/18244.80.0.1 to 244.80.63.254244.80.63.25516,382
66244.80.64.0/18244.80.64.1 to 244.80.127.254244.80.127.25516,382
67244.80.128.0/18244.80.128.1 to 244.80.191.254244.80.191.25516,382
68244.80.192.0/18244.80.192.1 to 244.80.255.254244.80.255.25516,382
69244.81.0.0/18244.81.0.1 to 244.81.63.254244.81.63.25516,382
70244.81.64.0/18244.81.64.1 to 244.81.127.254244.81.127.25516,382
71244.81.128.0/18244.81.128.1 to 244.81.191.254244.81.191.25516,382
72244.81.192.0/18244.81.192.1 to 244.81.255.254244.81.255.25516,382
73244.82.0.0/18244.82.0.1 to 244.82.63.254244.82.63.25516,382
74244.82.64.0/18244.82.64.1 to 244.82.127.254244.82.127.25516,382
75244.82.128.0/18244.82.128.1 to 244.82.191.254244.82.191.25516,382
76244.82.192.0/18244.82.192.1 to 244.82.255.254244.82.255.25516,382
77244.83.0.0/18244.83.0.1 to 244.83.63.254244.83.63.25516,382
78244.83.64.0/18244.83.64.1 to 244.83.127.254244.83.127.25516,382
79244.83.128.0/18244.83.128.1 to 244.83.191.254244.83.191.25516,382
80244.83.192.0/18244.83.192.1 to 244.83.255.254244.83.255.25516,382
81244.84.0.0/18244.84.0.1 to 244.84.63.254244.84.63.25516,382
82244.84.64.0/18244.84.64.1 to 244.84.127.254244.84.127.25516,382
83244.84.128.0/18244.84.128.1 to 244.84.191.254244.84.191.25516,382
84244.84.192.0/18244.84.192.1 to 244.84.255.254244.84.255.25516,382
85244.85.0.0/18244.85.0.1 to 244.85.63.254244.85.63.25516,382
86244.85.64.0/18244.85.64.1 to 244.85.127.254244.85.127.25516,382
87244.85.128.0/18244.85.128.1 to 244.85.191.254244.85.191.25516,382
88244.85.192.0/18244.85.192.1 to 244.85.255.254244.85.255.25516,382
89244.86.0.0/18244.86.0.1 to 244.86.63.254244.86.63.25516,382
90244.86.64.0/18244.86.64.1 to 244.86.127.254244.86.127.25516,382
91244.86.128.0/18244.86.128.1 to 244.86.191.254244.86.191.25516,382
92244.86.192.0/18244.86.192.1 to 244.86.255.254244.86.255.25516,382
93244.87.0.0/18244.87.0.1 to 244.87.63.254244.87.63.25516,382
94244.87.64.0/18244.87.64.1 to 244.87.127.254244.87.127.25516,382
95244.87.128.0/18244.87.128.1 to 244.87.191.254244.87.191.25516,382
96244.87.192.0/18244.87.192.1 to 244.87.255.254244.87.255.25516,382
97244.88.0.0/18244.88.0.1 to 244.88.63.254244.88.63.25516,382
98244.88.64.0/18244.88.64.1 to 244.88.127.254244.88.127.25516,382
99244.88.128.0/18244.88.128.1 to 244.88.191.254244.88.191.25516,382
100244.88.192.0/18244.88.192.1 to 244.88.255.254244.88.255.25516,382
101244.89.0.0/18244.89.0.1 to 244.89.63.254244.89.63.25516,382
102244.89.64.0/18244.89.64.1 to 244.89.127.254244.89.127.25516,382
103244.89.128.0/18244.89.128.1 to 244.89.191.254244.89.191.25516,382
104244.89.192.0/18244.89.192.1 to 244.89.255.254244.89.255.25516,382
105244.90.0.0/18244.90.0.1 to 244.90.63.254244.90.63.25516,382
106244.90.64.0/18244.90.64.1 to 244.90.127.254244.90.127.25516,382
107244.90.128.0/18244.90.128.1 to 244.90.191.254244.90.191.25516,382
108244.90.192.0/18244.90.192.1 to 244.90.255.254244.90.255.25516,382
109244.91.0.0/18244.91.0.1 to 244.91.63.254244.91.63.25516,382
110244.91.64.0/18244.91.64.1 to 244.91.127.254244.91.127.25516,382
111244.91.128.0/18244.91.128.1 to 244.91.191.254244.91.191.25516,382
112244.91.192.0/18244.91.192.1 to 244.91.255.254244.91.255.25516,382
113244.92.0.0/18244.92.0.1 to 244.92.63.254244.92.63.25516,382
114244.92.64.0/18244.92.64.1 to 244.92.127.254244.92.127.25516,382
115244.92.128.0/18244.92.128.1 to 244.92.191.254244.92.191.25516,382
116244.92.192.0/18244.92.192.1 to 244.92.255.254244.92.255.25516,382
117244.93.0.0/18244.93.0.1 to 244.93.63.254244.93.63.25516,382
118244.93.64.0/18244.93.64.1 to 244.93.127.254244.93.127.25516,382
119244.93.128.0/18244.93.128.1 to 244.93.191.254244.93.191.25516,382
120244.93.192.0/18244.93.192.1 to 244.93.255.254244.93.255.25516,382
121244.94.0.0/18244.94.0.1 to 244.94.63.254244.94.63.25516,382
122244.94.64.0/18244.94.64.1 to 244.94.127.254244.94.127.25516,382
123244.94.128.0/18244.94.128.1 to 244.94.191.254244.94.191.25516,382
124244.94.192.0/18244.94.192.1 to 244.94.255.254244.94.255.25516,382
125244.95.0.0/18244.95.0.1 to 244.95.63.254244.95.63.25516,382
126244.95.64.0/18244.95.64.1 to 244.95.127.254244.95.127.25516,382
127244.95.128.0/18244.95.128.1 to 244.95.191.254244.95.191.25516,382
128244.95.192.0/18244.95.192.1 to 244.95.255.254244.95.255.25516,382

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.