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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.

Network253.176.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
253.176.0.0
Broadcast address
253.191.255.255
First usable
253.176.0.1
Last usable
253.191.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FDB00000 · Integer 4256169984 to 4257218559
Reverse DNS zones
176.253.in-addr.arpa
177.253.in-addr.arpa
178.253.in-addr.arpa
179.253.in-addr.arpa
180.253.in-addr.arpa
181.253.in-addr.arpa
182.253.in-addr.arpa
183.253.in-addr.arpa
184.253.in-addr.arpa
185.253.in-addr.arpa
186.253.in-addr.arpa
187.253.in-addr.arpa
188.253.in-addr.arpa
189.253.in-addr.arpa
190.253.in-addr.arpa
191.253.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111101.10110000.00000000.00000000253.176.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11111101.10110000.00000000.00000000253.176.0.0
Broadcast11111101.10111111.11111111.11111111253.191.255.255
Split into smaller subnets/19
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

253.176.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1253.176.0.0/19253.176.0.1 to 253.176.31.254253.176.31.2558,190
2253.176.32.0/19253.176.32.1 to 253.176.63.254253.176.63.2558,190
3253.176.64.0/19253.176.64.1 to 253.176.95.254253.176.95.2558,190
4253.176.96.0/19253.176.96.1 to 253.176.127.254253.176.127.2558,190
5253.176.128.0/19253.176.128.1 to 253.176.159.254253.176.159.2558,190
6253.176.160.0/19253.176.160.1 to 253.176.191.254253.176.191.2558,190
7253.176.192.0/19253.176.192.1 to 253.176.223.254253.176.223.2558,190
8253.176.224.0/19253.176.224.1 to 253.176.255.254253.176.255.2558,190
9253.177.0.0/19253.177.0.1 to 253.177.31.254253.177.31.2558,190
10253.177.32.0/19253.177.32.1 to 253.177.63.254253.177.63.2558,190
11253.177.64.0/19253.177.64.1 to 253.177.95.254253.177.95.2558,190
12253.177.96.0/19253.177.96.1 to 253.177.127.254253.177.127.2558,190
13253.177.128.0/19253.177.128.1 to 253.177.159.254253.177.159.2558,190
14253.177.160.0/19253.177.160.1 to 253.177.191.254253.177.191.2558,190
15253.177.192.0/19253.177.192.1 to 253.177.223.254253.177.223.2558,190
16253.177.224.0/19253.177.224.1 to 253.177.255.254253.177.255.2558,190
17253.178.0.0/19253.178.0.1 to 253.178.31.254253.178.31.2558,190
18253.178.32.0/19253.178.32.1 to 253.178.63.254253.178.63.2558,190
19253.178.64.0/19253.178.64.1 to 253.178.95.254253.178.95.2558,190
20253.178.96.0/19253.178.96.1 to 253.178.127.254253.178.127.2558,190
21253.178.128.0/19253.178.128.1 to 253.178.159.254253.178.159.2558,190
22253.178.160.0/19253.178.160.1 to 253.178.191.254253.178.191.2558,190
23253.178.192.0/19253.178.192.1 to 253.178.223.254253.178.223.2558,190
24253.178.224.0/19253.178.224.1 to 253.178.255.254253.178.255.2558,190
25253.179.0.0/19253.179.0.1 to 253.179.31.254253.179.31.2558,190
26253.179.32.0/19253.179.32.1 to 253.179.63.254253.179.63.2558,190
27253.179.64.0/19253.179.64.1 to 253.179.95.254253.179.95.2558,190
28253.179.96.0/19253.179.96.1 to 253.179.127.254253.179.127.2558,190
29253.179.128.0/19253.179.128.1 to 253.179.159.254253.179.159.2558,190
30253.179.160.0/19253.179.160.1 to 253.179.191.254253.179.191.2558,190
31253.179.192.0/19253.179.192.1 to 253.179.223.254253.179.223.2558,190
32253.179.224.0/19253.179.224.1 to 253.179.255.254253.179.255.2558,190
33253.180.0.0/19253.180.0.1 to 253.180.31.254253.180.31.2558,190
34253.180.32.0/19253.180.32.1 to 253.180.63.254253.180.63.2558,190
35253.180.64.0/19253.180.64.1 to 253.180.95.254253.180.95.2558,190
36253.180.96.0/19253.180.96.1 to 253.180.127.254253.180.127.2558,190
37253.180.128.0/19253.180.128.1 to 253.180.159.254253.180.159.2558,190
38253.180.160.0/19253.180.160.1 to 253.180.191.254253.180.191.2558,190
39253.180.192.0/19253.180.192.1 to 253.180.223.254253.180.223.2558,190
40253.180.224.0/19253.180.224.1 to 253.180.255.254253.180.255.2558,190
41253.181.0.0/19253.181.0.1 to 253.181.31.254253.181.31.2558,190
42253.181.32.0/19253.181.32.1 to 253.181.63.254253.181.63.2558,190
43253.181.64.0/19253.181.64.1 to 253.181.95.254253.181.95.2558,190
44253.181.96.0/19253.181.96.1 to 253.181.127.254253.181.127.2558,190
45253.181.128.0/19253.181.128.1 to 253.181.159.254253.181.159.2558,190
46253.181.160.0/19253.181.160.1 to 253.181.191.254253.181.191.2558,190
47253.181.192.0/19253.181.192.1 to 253.181.223.254253.181.223.2558,190
48253.181.224.0/19253.181.224.1 to 253.181.255.254253.181.255.2558,190
49253.182.0.0/19253.182.0.1 to 253.182.31.254253.182.31.2558,190
50253.182.32.0/19253.182.32.1 to 253.182.63.254253.182.63.2558,190
51253.182.64.0/19253.182.64.1 to 253.182.95.254253.182.95.2558,190
52253.182.96.0/19253.182.96.1 to 253.182.127.254253.182.127.2558,190
53253.182.128.0/19253.182.128.1 to 253.182.159.254253.182.159.2558,190
54253.182.160.0/19253.182.160.1 to 253.182.191.254253.182.191.2558,190
55253.182.192.0/19253.182.192.1 to 253.182.223.254253.182.223.2558,190
56253.182.224.0/19253.182.224.1 to 253.182.255.254253.182.255.2558,190
57253.183.0.0/19253.183.0.1 to 253.183.31.254253.183.31.2558,190
58253.183.32.0/19253.183.32.1 to 253.183.63.254253.183.63.2558,190
59253.183.64.0/19253.183.64.1 to 253.183.95.254253.183.95.2558,190
60253.183.96.0/19253.183.96.1 to 253.183.127.254253.183.127.2558,190
61253.183.128.0/19253.183.128.1 to 253.183.159.254253.183.159.2558,190
62253.183.160.0/19253.183.160.1 to 253.183.191.254253.183.191.2558,190
63253.183.192.0/19253.183.192.1 to 253.183.223.254253.183.223.2558,190
64253.183.224.0/19253.183.224.1 to 253.183.255.254253.183.255.2558,190
65253.184.0.0/19253.184.0.1 to 253.184.31.254253.184.31.2558,190
66253.184.32.0/19253.184.32.1 to 253.184.63.254253.184.63.2558,190
67253.184.64.0/19253.184.64.1 to 253.184.95.254253.184.95.2558,190
68253.184.96.0/19253.184.96.1 to 253.184.127.254253.184.127.2558,190
69253.184.128.0/19253.184.128.1 to 253.184.159.254253.184.159.2558,190
70253.184.160.0/19253.184.160.1 to 253.184.191.254253.184.191.2558,190
71253.184.192.0/19253.184.192.1 to 253.184.223.254253.184.223.2558,190
72253.184.224.0/19253.184.224.1 to 253.184.255.254253.184.255.2558,190
73253.185.0.0/19253.185.0.1 to 253.185.31.254253.185.31.2558,190
74253.185.32.0/19253.185.32.1 to 253.185.63.254253.185.63.2558,190
75253.185.64.0/19253.185.64.1 to 253.185.95.254253.185.95.2558,190
76253.185.96.0/19253.185.96.1 to 253.185.127.254253.185.127.2558,190
77253.185.128.0/19253.185.128.1 to 253.185.159.254253.185.159.2558,190
78253.185.160.0/19253.185.160.1 to 253.185.191.254253.185.191.2558,190
79253.185.192.0/19253.185.192.1 to 253.185.223.254253.185.223.2558,190
80253.185.224.0/19253.185.224.1 to 253.185.255.254253.185.255.2558,190
81253.186.0.0/19253.186.0.1 to 253.186.31.254253.186.31.2558,190
82253.186.32.0/19253.186.32.1 to 253.186.63.254253.186.63.2558,190
83253.186.64.0/19253.186.64.1 to 253.186.95.254253.186.95.2558,190
84253.186.96.0/19253.186.96.1 to 253.186.127.254253.186.127.2558,190
85253.186.128.0/19253.186.128.1 to 253.186.159.254253.186.159.2558,190
86253.186.160.0/19253.186.160.1 to 253.186.191.254253.186.191.2558,190
87253.186.192.0/19253.186.192.1 to 253.186.223.254253.186.223.2558,190
88253.186.224.0/19253.186.224.1 to 253.186.255.254253.186.255.2558,190
89253.187.0.0/19253.187.0.1 to 253.187.31.254253.187.31.2558,190
90253.187.32.0/19253.187.32.1 to 253.187.63.254253.187.63.2558,190
91253.187.64.0/19253.187.64.1 to 253.187.95.254253.187.95.2558,190
92253.187.96.0/19253.187.96.1 to 253.187.127.254253.187.127.2558,190
93253.187.128.0/19253.187.128.1 to 253.187.159.254253.187.159.2558,190
94253.187.160.0/19253.187.160.1 to 253.187.191.254253.187.191.2558,190
95253.187.192.0/19253.187.192.1 to 253.187.223.254253.187.223.2558,190
96253.187.224.0/19253.187.224.1 to 253.187.255.254253.187.255.2558,190
97253.188.0.0/19253.188.0.1 to 253.188.31.254253.188.31.2558,190
98253.188.32.0/19253.188.32.1 to 253.188.63.254253.188.63.2558,190
99253.188.64.0/19253.188.64.1 to 253.188.95.254253.188.95.2558,190
100253.188.96.0/19253.188.96.1 to 253.188.127.254253.188.127.2558,190
101253.188.128.0/19253.188.128.1 to 253.188.159.254253.188.159.2558,190
102253.188.160.0/19253.188.160.1 to 253.188.191.254253.188.191.2558,190
103253.188.192.0/19253.188.192.1 to 253.188.223.254253.188.223.2558,190
104253.188.224.0/19253.188.224.1 to 253.188.255.254253.188.255.2558,190
105253.189.0.0/19253.189.0.1 to 253.189.31.254253.189.31.2558,190
106253.189.32.0/19253.189.32.1 to 253.189.63.254253.189.63.2558,190
107253.189.64.0/19253.189.64.1 to 253.189.95.254253.189.95.2558,190
108253.189.96.0/19253.189.96.1 to 253.189.127.254253.189.127.2558,190
109253.189.128.0/19253.189.128.1 to 253.189.159.254253.189.159.2558,190
110253.189.160.0/19253.189.160.1 to 253.189.191.254253.189.191.2558,190
111253.189.192.0/19253.189.192.1 to 253.189.223.254253.189.223.2558,190
112253.189.224.0/19253.189.224.1 to 253.189.255.254253.189.255.2558,190
113253.190.0.0/19253.190.0.1 to 253.190.31.254253.190.31.2558,190
114253.190.32.0/19253.190.32.1 to 253.190.63.254253.190.63.2558,190
115253.190.64.0/19253.190.64.1 to 253.190.95.254253.190.95.2558,190
116253.190.96.0/19253.190.96.1 to 253.190.127.254253.190.127.2558,190
117253.190.128.0/19253.190.128.1 to 253.190.159.254253.190.159.2558,190
118253.190.160.0/19253.190.160.1 to 253.190.191.254253.190.191.2558,190
119253.190.192.0/19253.190.192.1 to 253.190.223.254253.190.223.2558,190
120253.190.224.0/19253.190.224.1 to 253.190.255.254253.190.255.2558,190
121253.191.0.0/19253.191.0.1 to 253.191.31.254253.191.31.2558,190
122253.191.32.0/19253.191.32.1 to 253.191.63.254253.191.63.2558,190
123253.191.64.0/19253.191.64.1 to 253.191.95.254253.191.95.2558,190
124253.191.96.0/19253.191.96.1 to 253.191.127.254253.191.127.2558,190
125253.191.128.0/19253.191.128.1 to 253.191.159.254253.191.159.2558,190
126253.191.160.0/19253.191.160.1 to 253.191.191.254253.191.191.2558,190
127253.191.192.0/19253.191.192.1 to 253.191.223.254253.191.223.2558,190
128253.191.224.0/19253.191.224.1 to 253.191.255.254253.191.255.2558,190

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.