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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.

Network153.0.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
153.0.0.0
Broadcast address
153.15.255.255
First usable
153.0.0.1
Last usable
153.15.255.254
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
Public public
Old class
B (default /16)
As numbers
Hex 99000000 · Integer 2566914048 to 2567962623
Reverse DNS zones
0.153.in-addr.arpa
1.153.in-addr.arpa
2.153.in-addr.arpa
3.153.in-addr.arpa
4.153.in-addr.arpa
5.153.in-addr.arpa
6.153.in-addr.arpa
7.153.in-addr.arpa
8.153.in-addr.arpa
9.153.in-addr.arpa
10.153.in-addr.arpa
11.153.in-addr.arpa
12.153.in-addr.arpa
13.153.in-addr.arpa
14.153.in-addr.arpa
15.153.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
Address10011001.00000000.00000000.00000000153.0.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10011001.00000000.00000000.00000000153.0.0.0
Broadcast10011001.00001111.11111111.11111111153.15.255.255
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)

153.0.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1153.0.0.0/19153.0.0.1 to 153.0.31.254153.0.31.2558,190
2153.0.32.0/19153.0.32.1 to 153.0.63.254153.0.63.2558,190
3153.0.64.0/19153.0.64.1 to 153.0.95.254153.0.95.2558,190
4153.0.96.0/19153.0.96.1 to 153.0.127.254153.0.127.2558,190
5153.0.128.0/19153.0.128.1 to 153.0.159.254153.0.159.2558,190
6153.0.160.0/19153.0.160.1 to 153.0.191.254153.0.191.2558,190
7153.0.192.0/19153.0.192.1 to 153.0.223.254153.0.223.2558,190
8153.0.224.0/19153.0.224.1 to 153.0.255.254153.0.255.2558,190
9153.1.0.0/19153.1.0.1 to 153.1.31.254153.1.31.2558,190
10153.1.32.0/19153.1.32.1 to 153.1.63.254153.1.63.2558,190
11153.1.64.0/19153.1.64.1 to 153.1.95.254153.1.95.2558,190
12153.1.96.0/19153.1.96.1 to 153.1.127.254153.1.127.2558,190
13153.1.128.0/19153.1.128.1 to 153.1.159.254153.1.159.2558,190
14153.1.160.0/19153.1.160.1 to 153.1.191.254153.1.191.2558,190
15153.1.192.0/19153.1.192.1 to 153.1.223.254153.1.223.2558,190
16153.1.224.0/19153.1.224.1 to 153.1.255.254153.1.255.2558,190
17153.2.0.0/19153.2.0.1 to 153.2.31.254153.2.31.2558,190
18153.2.32.0/19153.2.32.1 to 153.2.63.254153.2.63.2558,190
19153.2.64.0/19153.2.64.1 to 153.2.95.254153.2.95.2558,190
20153.2.96.0/19153.2.96.1 to 153.2.127.254153.2.127.2558,190
21153.2.128.0/19153.2.128.1 to 153.2.159.254153.2.159.2558,190
22153.2.160.0/19153.2.160.1 to 153.2.191.254153.2.191.2558,190
23153.2.192.0/19153.2.192.1 to 153.2.223.254153.2.223.2558,190
24153.2.224.0/19153.2.224.1 to 153.2.255.254153.2.255.2558,190
25153.3.0.0/19153.3.0.1 to 153.3.31.254153.3.31.2558,190
26153.3.32.0/19153.3.32.1 to 153.3.63.254153.3.63.2558,190
27153.3.64.0/19153.3.64.1 to 153.3.95.254153.3.95.2558,190
28153.3.96.0/19153.3.96.1 to 153.3.127.254153.3.127.2558,190
29153.3.128.0/19153.3.128.1 to 153.3.159.254153.3.159.2558,190
30153.3.160.0/19153.3.160.1 to 153.3.191.254153.3.191.2558,190
31153.3.192.0/19153.3.192.1 to 153.3.223.254153.3.223.2558,190
32153.3.224.0/19153.3.224.1 to 153.3.255.254153.3.255.2558,190
33153.4.0.0/19153.4.0.1 to 153.4.31.254153.4.31.2558,190
34153.4.32.0/19153.4.32.1 to 153.4.63.254153.4.63.2558,190
35153.4.64.0/19153.4.64.1 to 153.4.95.254153.4.95.2558,190
36153.4.96.0/19153.4.96.1 to 153.4.127.254153.4.127.2558,190
37153.4.128.0/19153.4.128.1 to 153.4.159.254153.4.159.2558,190
38153.4.160.0/19153.4.160.1 to 153.4.191.254153.4.191.2558,190
39153.4.192.0/19153.4.192.1 to 153.4.223.254153.4.223.2558,190
40153.4.224.0/19153.4.224.1 to 153.4.255.254153.4.255.2558,190
41153.5.0.0/19153.5.0.1 to 153.5.31.254153.5.31.2558,190
42153.5.32.0/19153.5.32.1 to 153.5.63.254153.5.63.2558,190
43153.5.64.0/19153.5.64.1 to 153.5.95.254153.5.95.2558,190
44153.5.96.0/19153.5.96.1 to 153.5.127.254153.5.127.2558,190
45153.5.128.0/19153.5.128.1 to 153.5.159.254153.5.159.2558,190
46153.5.160.0/19153.5.160.1 to 153.5.191.254153.5.191.2558,190
47153.5.192.0/19153.5.192.1 to 153.5.223.254153.5.223.2558,190
48153.5.224.0/19153.5.224.1 to 153.5.255.254153.5.255.2558,190
49153.6.0.0/19153.6.0.1 to 153.6.31.254153.6.31.2558,190
50153.6.32.0/19153.6.32.1 to 153.6.63.254153.6.63.2558,190
51153.6.64.0/19153.6.64.1 to 153.6.95.254153.6.95.2558,190
52153.6.96.0/19153.6.96.1 to 153.6.127.254153.6.127.2558,190
53153.6.128.0/19153.6.128.1 to 153.6.159.254153.6.159.2558,190
54153.6.160.0/19153.6.160.1 to 153.6.191.254153.6.191.2558,190
55153.6.192.0/19153.6.192.1 to 153.6.223.254153.6.223.2558,190
56153.6.224.0/19153.6.224.1 to 153.6.255.254153.6.255.2558,190
57153.7.0.0/19153.7.0.1 to 153.7.31.254153.7.31.2558,190
58153.7.32.0/19153.7.32.1 to 153.7.63.254153.7.63.2558,190
59153.7.64.0/19153.7.64.1 to 153.7.95.254153.7.95.2558,190
60153.7.96.0/19153.7.96.1 to 153.7.127.254153.7.127.2558,190
61153.7.128.0/19153.7.128.1 to 153.7.159.254153.7.159.2558,190
62153.7.160.0/19153.7.160.1 to 153.7.191.254153.7.191.2558,190
63153.7.192.0/19153.7.192.1 to 153.7.223.254153.7.223.2558,190
64153.7.224.0/19153.7.224.1 to 153.7.255.254153.7.255.2558,190
65153.8.0.0/19153.8.0.1 to 153.8.31.254153.8.31.2558,190
66153.8.32.0/19153.8.32.1 to 153.8.63.254153.8.63.2558,190
67153.8.64.0/19153.8.64.1 to 153.8.95.254153.8.95.2558,190
68153.8.96.0/19153.8.96.1 to 153.8.127.254153.8.127.2558,190
69153.8.128.0/19153.8.128.1 to 153.8.159.254153.8.159.2558,190
70153.8.160.0/19153.8.160.1 to 153.8.191.254153.8.191.2558,190
71153.8.192.0/19153.8.192.1 to 153.8.223.254153.8.223.2558,190
72153.8.224.0/19153.8.224.1 to 153.8.255.254153.8.255.2558,190
73153.9.0.0/19153.9.0.1 to 153.9.31.254153.9.31.2558,190
74153.9.32.0/19153.9.32.1 to 153.9.63.254153.9.63.2558,190
75153.9.64.0/19153.9.64.1 to 153.9.95.254153.9.95.2558,190
76153.9.96.0/19153.9.96.1 to 153.9.127.254153.9.127.2558,190
77153.9.128.0/19153.9.128.1 to 153.9.159.254153.9.159.2558,190
78153.9.160.0/19153.9.160.1 to 153.9.191.254153.9.191.2558,190
79153.9.192.0/19153.9.192.1 to 153.9.223.254153.9.223.2558,190
80153.9.224.0/19153.9.224.1 to 153.9.255.254153.9.255.2558,190
81153.10.0.0/19153.10.0.1 to 153.10.31.254153.10.31.2558,190
82153.10.32.0/19153.10.32.1 to 153.10.63.254153.10.63.2558,190
83153.10.64.0/19153.10.64.1 to 153.10.95.254153.10.95.2558,190
84153.10.96.0/19153.10.96.1 to 153.10.127.254153.10.127.2558,190
85153.10.128.0/19153.10.128.1 to 153.10.159.254153.10.159.2558,190
86153.10.160.0/19153.10.160.1 to 153.10.191.254153.10.191.2558,190
87153.10.192.0/19153.10.192.1 to 153.10.223.254153.10.223.2558,190
88153.10.224.0/19153.10.224.1 to 153.10.255.254153.10.255.2558,190
89153.11.0.0/19153.11.0.1 to 153.11.31.254153.11.31.2558,190
90153.11.32.0/19153.11.32.1 to 153.11.63.254153.11.63.2558,190
91153.11.64.0/19153.11.64.1 to 153.11.95.254153.11.95.2558,190
92153.11.96.0/19153.11.96.1 to 153.11.127.254153.11.127.2558,190
93153.11.128.0/19153.11.128.1 to 153.11.159.254153.11.159.2558,190
94153.11.160.0/19153.11.160.1 to 153.11.191.254153.11.191.2558,190
95153.11.192.0/19153.11.192.1 to 153.11.223.254153.11.223.2558,190
96153.11.224.0/19153.11.224.1 to 153.11.255.254153.11.255.2558,190
97153.12.0.0/19153.12.0.1 to 153.12.31.254153.12.31.2558,190
98153.12.32.0/19153.12.32.1 to 153.12.63.254153.12.63.2558,190
99153.12.64.0/19153.12.64.1 to 153.12.95.254153.12.95.2558,190
100153.12.96.0/19153.12.96.1 to 153.12.127.254153.12.127.2558,190
101153.12.128.0/19153.12.128.1 to 153.12.159.254153.12.159.2558,190
102153.12.160.0/19153.12.160.1 to 153.12.191.254153.12.191.2558,190
103153.12.192.0/19153.12.192.1 to 153.12.223.254153.12.223.2558,190
104153.12.224.0/19153.12.224.1 to 153.12.255.254153.12.255.2558,190
105153.13.0.0/19153.13.0.1 to 153.13.31.254153.13.31.2558,190
106153.13.32.0/19153.13.32.1 to 153.13.63.254153.13.63.2558,190
107153.13.64.0/19153.13.64.1 to 153.13.95.254153.13.95.2558,190
108153.13.96.0/19153.13.96.1 to 153.13.127.254153.13.127.2558,190
109153.13.128.0/19153.13.128.1 to 153.13.159.254153.13.159.2558,190
110153.13.160.0/19153.13.160.1 to 153.13.191.254153.13.191.2558,190
111153.13.192.0/19153.13.192.1 to 153.13.223.254153.13.223.2558,190
112153.13.224.0/19153.13.224.1 to 153.13.255.254153.13.255.2558,190
113153.14.0.0/19153.14.0.1 to 153.14.31.254153.14.31.2558,190
114153.14.32.0/19153.14.32.1 to 153.14.63.254153.14.63.2558,190
115153.14.64.0/19153.14.64.1 to 153.14.95.254153.14.95.2558,190
116153.14.96.0/19153.14.96.1 to 153.14.127.254153.14.127.2558,190
117153.14.128.0/19153.14.128.1 to 153.14.159.254153.14.159.2558,190
118153.14.160.0/19153.14.160.1 to 153.14.191.254153.14.191.2558,190
119153.14.192.0/19153.14.192.1 to 153.14.223.254153.14.223.2558,190
120153.14.224.0/19153.14.224.1 to 153.14.255.254153.14.255.2558,190
121153.15.0.0/19153.15.0.1 to 153.15.31.254153.15.31.2558,190
122153.15.32.0/19153.15.32.1 to 153.15.63.254153.15.63.2558,190
123153.15.64.0/19153.15.64.1 to 153.15.95.254153.15.95.2558,190
124153.15.96.0/19153.15.96.1 to 153.15.127.254153.15.127.2558,190
125153.15.128.0/19153.15.128.1 to 153.15.159.254153.15.159.2558,190
126153.15.160.0/19153.15.160.1 to 153.15.191.254153.15.191.2558,190
127153.15.192.0/19153.15.192.1 to 153.15.223.254153.15.223.2558,190
128153.15.224.0/19153.15.224.1 to 153.15.255.254153.15.255.2558,190

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.