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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.

Network129.0.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
129.0.0.0
Broadcast address
129.31.255.255
First usable
129.0.0.1
Last usable
129.31.255.254
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
Public public
Old class
B (default /16)
As numbers
Hex 81000000 · Integer 2164260864 to 2166358015
Reverse DNS zones
0.129.in-addr.arpa
1.129.in-addr.arpa
2.129.in-addr.arpa
3.129.in-addr.arpa
4.129.in-addr.arpa
5.129.in-addr.arpa
6.129.in-addr.arpa
7.129.in-addr.arpa
8.129.in-addr.arpa
9.129.in-addr.arpa
10.129.in-addr.arpa
11.129.in-addr.arpa
12.129.in-addr.arpa
13.129.in-addr.arpa
14.129.in-addr.arpa
15.129.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
Address10000001.00000000.00000000.00000000129.0.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network10000001.00000000.00000000.00000000129.0.0.0
Broadcast10000001.00011111.11111111.11111111129.31.255.255
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)

129.0.0.0/11 makes 128 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1129.0.0.0/18129.0.0.1 to 129.0.63.254129.0.63.25516,382
2129.0.64.0/18129.0.64.1 to 129.0.127.254129.0.127.25516,382
3129.0.128.0/18129.0.128.1 to 129.0.191.254129.0.191.25516,382
4129.0.192.0/18129.0.192.1 to 129.0.255.254129.0.255.25516,382
5129.1.0.0/18129.1.0.1 to 129.1.63.254129.1.63.25516,382
6129.1.64.0/18129.1.64.1 to 129.1.127.254129.1.127.25516,382
7129.1.128.0/18129.1.128.1 to 129.1.191.254129.1.191.25516,382
8129.1.192.0/18129.1.192.1 to 129.1.255.254129.1.255.25516,382
9129.2.0.0/18129.2.0.1 to 129.2.63.254129.2.63.25516,382
10129.2.64.0/18129.2.64.1 to 129.2.127.254129.2.127.25516,382
11129.2.128.0/18129.2.128.1 to 129.2.191.254129.2.191.25516,382
12129.2.192.0/18129.2.192.1 to 129.2.255.254129.2.255.25516,382
13129.3.0.0/18129.3.0.1 to 129.3.63.254129.3.63.25516,382
14129.3.64.0/18129.3.64.1 to 129.3.127.254129.3.127.25516,382
15129.3.128.0/18129.3.128.1 to 129.3.191.254129.3.191.25516,382
16129.3.192.0/18129.3.192.1 to 129.3.255.254129.3.255.25516,382
17129.4.0.0/18129.4.0.1 to 129.4.63.254129.4.63.25516,382
18129.4.64.0/18129.4.64.1 to 129.4.127.254129.4.127.25516,382
19129.4.128.0/18129.4.128.1 to 129.4.191.254129.4.191.25516,382
20129.4.192.0/18129.4.192.1 to 129.4.255.254129.4.255.25516,382
21129.5.0.0/18129.5.0.1 to 129.5.63.254129.5.63.25516,382
22129.5.64.0/18129.5.64.1 to 129.5.127.254129.5.127.25516,382
23129.5.128.0/18129.5.128.1 to 129.5.191.254129.5.191.25516,382
24129.5.192.0/18129.5.192.1 to 129.5.255.254129.5.255.25516,382
25129.6.0.0/18129.6.0.1 to 129.6.63.254129.6.63.25516,382
26129.6.64.0/18129.6.64.1 to 129.6.127.254129.6.127.25516,382
27129.6.128.0/18129.6.128.1 to 129.6.191.254129.6.191.25516,382
28129.6.192.0/18129.6.192.1 to 129.6.255.254129.6.255.25516,382
29129.7.0.0/18129.7.0.1 to 129.7.63.254129.7.63.25516,382
30129.7.64.0/18129.7.64.1 to 129.7.127.254129.7.127.25516,382
31129.7.128.0/18129.7.128.1 to 129.7.191.254129.7.191.25516,382
32129.7.192.0/18129.7.192.1 to 129.7.255.254129.7.255.25516,382
33129.8.0.0/18129.8.0.1 to 129.8.63.254129.8.63.25516,382
34129.8.64.0/18129.8.64.1 to 129.8.127.254129.8.127.25516,382
35129.8.128.0/18129.8.128.1 to 129.8.191.254129.8.191.25516,382
36129.8.192.0/18129.8.192.1 to 129.8.255.254129.8.255.25516,382
37129.9.0.0/18129.9.0.1 to 129.9.63.254129.9.63.25516,382
38129.9.64.0/18129.9.64.1 to 129.9.127.254129.9.127.25516,382
39129.9.128.0/18129.9.128.1 to 129.9.191.254129.9.191.25516,382
40129.9.192.0/18129.9.192.1 to 129.9.255.254129.9.255.25516,382
41129.10.0.0/18129.10.0.1 to 129.10.63.254129.10.63.25516,382
42129.10.64.0/18129.10.64.1 to 129.10.127.254129.10.127.25516,382
43129.10.128.0/18129.10.128.1 to 129.10.191.254129.10.191.25516,382
44129.10.192.0/18129.10.192.1 to 129.10.255.254129.10.255.25516,382
45129.11.0.0/18129.11.0.1 to 129.11.63.254129.11.63.25516,382
46129.11.64.0/18129.11.64.1 to 129.11.127.254129.11.127.25516,382
47129.11.128.0/18129.11.128.1 to 129.11.191.254129.11.191.25516,382
48129.11.192.0/18129.11.192.1 to 129.11.255.254129.11.255.25516,382
49129.12.0.0/18129.12.0.1 to 129.12.63.254129.12.63.25516,382
50129.12.64.0/18129.12.64.1 to 129.12.127.254129.12.127.25516,382
51129.12.128.0/18129.12.128.1 to 129.12.191.254129.12.191.25516,382
52129.12.192.0/18129.12.192.1 to 129.12.255.254129.12.255.25516,382
53129.13.0.0/18129.13.0.1 to 129.13.63.254129.13.63.25516,382
54129.13.64.0/18129.13.64.1 to 129.13.127.254129.13.127.25516,382
55129.13.128.0/18129.13.128.1 to 129.13.191.254129.13.191.25516,382
56129.13.192.0/18129.13.192.1 to 129.13.255.254129.13.255.25516,382
57129.14.0.0/18129.14.0.1 to 129.14.63.254129.14.63.25516,382
58129.14.64.0/18129.14.64.1 to 129.14.127.254129.14.127.25516,382
59129.14.128.0/18129.14.128.1 to 129.14.191.254129.14.191.25516,382
60129.14.192.0/18129.14.192.1 to 129.14.255.254129.14.255.25516,382
61129.15.0.0/18129.15.0.1 to 129.15.63.254129.15.63.25516,382
62129.15.64.0/18129.15.64.1 to 129.15.127.254129.15.127.25516,382
63129.15.128.0/18129.15.128.1 to 129.15.191.254129.15.191.25516,382
64129.15.192.0/18129.15.192.1 to 129.15.255.254129.15.255.25516,382
65129.16.0.0/18129.16.0.1 to 129.16.63.254129.16.63.25516,382
66129.16.64.0/18129.16.64.1 to 129.16.127.254129.16.127.25516,382
67129.16.128.0/18129.16.128.1 to 129.16.191.254129.16.191.25516,382
68129.16.192.0/18129.16.192.1 to 129.16.255.254129.16.255.25516,382
69129.17.0.0/18129.17.0.1 to 129.17.63.254129.17.63.25516,382
70129.17.64.0/18129.17.64.1 to 129.17.127.254129.17.127.25516,382
71129.17.128.0/18129.17.128.1 to 129.17.191.254129.17.191.25516,382
72129.17.192.0/18129.17.192.1 to 129.17.255.254129.17.255.25516,382
73129.18.0.0/18129.18.0.1 to 129.18.63.254129.18.63.25516,382
74129.18.64.0/18129.18.64.1 to 129.18.127.254129.18.127.25516,382
75129.18.128.0/18129.18.128.1 to 129.18.191.254129.18.191.25516,382
76129.18.192.0/18129.18.192.1 to 129.18.255.254129.18.255.25516,382
77129.19.0.0/18129.19.0.1 to 129.19.63.254129.19.63.25516,382
78129.19.64.0/18129.19.64.1 to 129.19.127.254129.19.127.25516,382
79129.19.128.0/18129.19.128.1 to 129.19.191.254129.19.191.25516,382
80129.19.192.0/18129.19.192.1 to 129.19.255.254129.19.255.25516,382
81129.20.0.0/18129.20.0.1 to 129.20.63.254129.20.63.25516,382
82129.20.64.0/18129.20.64.1 to 129.20.127.254129.20.127.25516,382
83129.20.128.0/18129.20.128.1 to 129.20.191.254129.20.191.25516,382
84129.20.192.0/18129.20.192.1 to 129.20.255.254129.20.255.25516,382
85129.21.0.0/18129.21.0.1 to 129.21.63.254129.21.63.25516,382
86129.21.64.0/18129.21.64.1 to 129.21.127.254129.21.127.25516,382
87129.21.128.0/18129.21.128.1 to 129.21.191.254129.21.191.25516,382
88129.21.192.0/18129.21.192.1 to 129.21.255.254129.21.255.25516,382
89129.22.0.0/18129.22.0.1 to 129.22.63.254129.22.63.25516,382
90129.22.64.0/18129.22.64.1 to 129.22.127.254129.22.127.25516,382
91129.22.128.0/18129.22.128.1 to 129.22.191.254129.22.191.25516,382
92129.22.192.0/18129.22.192.1 to 129.22.255.254129.22.255.25516,382
93129.23.0.0/18129.23.0.1 to 129.23.63.254129.23.63.25516,382
94129.23.64.0/18129.23.64.1 to 129.23.127.254129.23.127.25516,382
95129.23.128.0/18129.23.128.1 to 129.23.191.254129.23.191.25516,382
96129.23.192.0/18129.23.192.1 to 129.23.255.254129.23.255.25516,382
97129.24.0.0/18129.24.0.1 to 129.24.63.254129.24.63.25516,382
98129.24.64.0/18129.24.64.1 to 129.24.127.254129.24.127.25516,382
99129.24.128.0/18129.24.128.1 to 129.24.191.254129.24.191.25516,382
100129.24.192.0/18129.24.192.1 to 129.24.255.254129.24.255.25516,382
101129.25.0.0/18129.25.0.1 to 129.25.63.254129.25.63.25516,382
102129.25.64.0/18129.25.64.1 to 129.25.127.254129.25.127.25516,382
103129.25.128.0/18129.25.128.1 to 129.25.191.254129.25.191.25516,382
104129.25.192.0/18129.25.192.1 to 129.25.255.254129.25.255.25516,382
105129.26.0.0/18129.26.0.1 to 129.26.63.254129.26.63.25516,382
106129.26.64.0/18129.26.64.1 to 129.26.127.254129.26.127.25516,382
107129.26.128.0/18129.26.128.1 to 129.26.191.254129.26.191.25516,382
108129.26.192.0/18129.26.192.1 to 129.26.255.254129.26.255.25516,382
109129.27.0.0/18129.27.0.1 to 129.27.63.254129.27.63.25516,382
110129.27.64.0/18129.27.64.1 to 129.27.127.254129.27.127.25516,382
111129.27.128.0/18129.27.128.1 to 129.27.191.254129.27.191.25516,382
112129.27.192.0/18129.27.192.1 to 129.27.255.254129.27.255.25516,382
113129.28.0.0/18129.28.0.1 to 129.28.63.254129.28.63.25516,382
114129.28.64.0/18129.28.64.1 to 129.28.127.254129.28.127.25516,382
115129.28.128.0/18129.28.128.1 to 129.28.191.254129.28.191.25516,382
116129.28.192.0/18129.28.192.1 to 129.28.255.254129.28.255.25516,382
117129.29.0.0/18129.29.0.1 to 129.29.63.254129.29.63.25516,382
118129.29.64.0/18129.29.64.1 to 129.29.127.254129.29.127.25516,382
119129.29.128.0/18129.29.128.1 to 129.29.191.254129.29.191.25516,382
120129.29.192.0/18129.29.192.1 to 129.29.255.254129.29.255.25516,382
121129.30.0.0/18129.30.0.1 to 129.30.63.254129.30.63.25516,382
122129.30.64.0/18129.30.64.1 to 129.30.127.254129.30.127.25516,382
123129.30.128.0/18129.30.128.1 to 129.30.191.254129.30.191.25516,382
124129.30.192.0/18129.30.192.1 to 129.30.255.254129.30.255.25516,382
125129.31.0.0/18129.31.0.1 to 129.31.63.254129.31.63.25516,382
126129.31.64.0/18129.31.64.1 to 129.31.127.254129.31.127.25516,382
127129.31.128.0/18129.31.128.1 to 129.31.191.254129.31.191.25516,382
128129.31.192.0/18129.31.192.1 to 129.31.255.254129.31.255.25516,382

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.