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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.

Network180.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
180.0.0.0
Broadcast address
180.127.255.255
First usable
180.0.0.1
Last usable
180.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
B (default /16)
As numbers
Hex B4000000 · Integer 3019898880 to 3028287487
Reverse DNS zones
0.180.in-addr.arpa
1.180.in-addr.arpa
2.180.in-addr.arpa
3.180.in-addr.arpa
4.180.in-addr.arpa
5.180.in-addr.arpa
6.180.in-addr.arpa
7.180.in-addr.arpa
8.180.in-addr.arpa
9.180.in-addr.arpa
10.180.in-addr.arpa
11.180.in-addr.arpa
12.180.in-addr.arpa
13.180.in-addr.arpa
14.180.in-addr.arpa
15.180.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110100.00000000.00000000.00000000180.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network10110100.00000000.00000000.00000000180.0.0.0
Broadcast10110100.01111111.11111111.11111111180.127.255.255
Split into smaller subnets/16
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

180.0.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1180.0.0.0/16180.0.0.1 to 180.0.255.254180.0.255.25565,534
2180.1.0.0/16180.1.0.1 to 180.1.255.254180.1.255.25565,534
3180.2.0.0/16180.2.0.1 to 180.2.255.254180.2.255.25565,534
4180.3.0.0/16180.3.0.1 to 180.3.255.254180.3.255.25565,534
5180.4.0.0/16180.4.0.1 to 180.4.255.254180.4.255.25565,534
6180.5.0.0/16180.5.0.1 to 180.5.255.254180.5.255.25565,534
7180.6.0.0/16180.6.0.1 to 180.6.255.254180.6.255.25565,534
8180.7.0.0/16180.7.0.1 to 180.7.255.254180.7.255.25565,534
9180.8.0.0/16180.8.0.1 to 180.8.255.254180.8.255.25565,534
10180.9.0.0/16180.9.0.1 to 180.9.255.254180.9.255.25565,534
11180.10.0.0/16180.10.0.1 to 180.10.255.254180.10.255.25565,534
12180.11.0.0/16180.11.0.1 to 180.11.255.254180.11.255.25565,534
13180.12.0.0/16180.12.0.1 to 180.12.255.254180.12.255.25565,534
14180.13.0.0/16180.13.0.1 to 180.13.255.254180.13.255.25565,534
15180.14.0.0/16180.14.0.1 to 180.14.255.254180.14.255.25565,534
16180.15.0.0/16180.15.0.1 to 180.15.255.254180.15.255.25565,534
17180.16.0.0/16180.16.0.1 to 180.16.255.254180.16.255.25565,534
18180.17.0.0/16180.17.0.1 to 180.17.255.254180.17.255.25565,534
19180.18.0.0/16180.18.0.1 to 180.18.255.254180.18.255.25565,534
20180.19.0.0/16180.19.0.1 to 180.19.255.254180.19.255.25565,534
21180.20.0.0/16180.20.0.1 to 180.20.255.254180.20.255.25565,534
22180.21.0.0/16180.21.0.1 to 180.21.255.254180.21.255.25565,534
23180.22.0.0/16180.22.0.1 to 180.22.255.254180.22.255.25565,534
24180.23.0.0/16180.23.0.1 to 180.23.255.254180.23.255.25565,534
25180.24.0.0/16180.24.0.1 to 180.24.255.254180.24.255.25565,534
26180.25.0.0/16180.25.0.1 to 180.25.255.254180.25.255.25565,534
27180.26.0.0/16180.26.0.1 to 180.26.255.254180.26.255.25565,534
28180.27.0.0/16180.27.0.1 to 180.27.255.254180.27.255.25565,534
29180.28.0.0/16180.28.0.1 to 180.28.255.254180.28.255.25565,534
30180.29.0.0/16180.29.0.1 to 180.29.255.254180.29.255.25565,534
31180.30.0.0/16180.30.0.1 to 180.30.255.254180.30.255.25565,534
32180.31.0.0/16180.31.0.1 to 180.31.255.254180.31.255.25565,534
33180.32.0.0/16180.32.0.1 to 180.32.255.254180.32.255.25565,534
34180.33.0.0/16180.33.0.1 to 180.33.255.254180.33.255.25565,534
35180.34.0.0/16180.34.0.1 to 180.34.255.254180.34.255.25565,534
36180.35.0.0/16180.35.0.1 to 180.35.255.254180.35.255.25565,534
37180.36.0.0/16180.36.0.1 to 180.36.255.254180.36.255.25565,534
38180.37.0.0/16180.37.0.1 to 180.37.255.254180.37.255.25565,534
39180.38.0.0/16180.38.0.1 to 180.38.255.254180.38.255.25565,534
40180.39.0.0/16180.39.0.1 to 180.39.255.254180.39.255.25565,534
41180.40.0.0/16180.40.0.1 to 180.40.255.254180.40.255.25565,534
42180.41.0.0/16180.41.0.1 to 180.41.255.254180.41.255.25565,534
43180.42.0.0/16180.42.0.1 to 180.42.255.254180.42.255.25565,534
44180.43.0.0/16180.43.0.1 to 180.43.255.254180.43.255.25565,534
45180.44.0.0/16180.44.0.1 to 180.44.255.254180.44.255.25565,534
46180.45.0.0/16180.45.0.1 to 180.45.255.254180.45.255.25565,534
47180.46.0.0/16180.46.0.1 to 180.46.255.254180.46.255.25565,534
48180.47.0.0/16180.47.0.1 to 180.47.255.254180.47.255.25565,534
49180.48.0.0/16180.48.0.1 to 180.48.255.254180.48.255.25565,534
50180.49.0.0/16180.49.0.1 to 180.49.255.254180.49.255.25565,534
51180.50.0.0/16180.50.0.1 to 180.50.255.254180.50.255.25565,534
52180.51.0.0/16180.51.0.1 to 180.51.255.254180.51.255.25565,534
53180.52.0.0/16180.52.0.1 to 180.52.255.254180.52.255.25565,534
54180.53.0.0/16180.53.0.1 to 180.53.255.254180.53.255.25565,534
55180.54.0.0/16180.54.0.1 to 180.54.255.254180.54.255.25565,534
56180.55.0.0/16180.55.0.1 to 180.55.255.254180.55.255.25565,534
57180.56.0.0/16180.56.0.1 to 180.56.255.254180.56.255.25565,534
58180.57.0.0/16180.57.0.1 to 180.57.255.254180.57.255.25565,534
59180.58.0.0/16180.58.0.1 to 180.58.255.254180.58.255.25565,534
60180.59.0.0/16180.59.0.1 to 180.59.255.254180.59.255.25565,534
61180.60.0.0/16180.60.0.1 to 180.60.255.254180.60.255.25565,534
62180.61.0.0/16180.61.0.1 to 180.61.255.254180.61.255.25565,534
63180.62.0.0/16180.62.0.1 to 180.62.255.254180.62.255.25565,534
64180.63.0.0/16180.63.0.1 to 180.63.255.254180.63.255.25565,534
65180.64.0.0/16180.64.0.1 to 180.64.255.254180.64.255.25565,534
66180.65.0.0/16180.65.0.1 to 180.65.255.254180.65.255.25565,534
67180.66.0.0/16180.66.0.1 to 180.66.255.254180.66.255.25565,534
68180.67.0.0/16180.67.0.1 to 180.67.255.254180.67.255.25565,534
69180.68.0.0/16180.68.0.1 to 180.68.255.254180.68.255.25565,534
70180.69.0.0/16180.69.0.1 to 180.69.255.254180.69.255.25565,534
71180.70.0.0/16180.70.0.1 to 180.70.255.254180.70.255.25565,534
72180.71.0.0/16180.71.0.1 to 180.71.255.254180.71.255.25565,534
73180.72.0.0/16180.72.0.1 to 180.72.255.254180.72.255.25565,534
74180.73.0.0/16180.73.0.1 to 180.73.255.254180.73.255.25565,534
75180.74.0.0/16180.74.0.1 to 180.74.255.254180.74.255.25565,534
76180.75.0.0/16180.75.0.1 to 180.75.255.254180.75.255.25565,534
77180.76.0.0/16180.76.0.1 to 180.76.255.254180.76.255.25565,534
78180.77.0.0/16180.77.0.1 to 180.77.255.254180.77.255.25565,534
79180.78.0.0/16180.78.0.1 to 180.78.255.254180.78.255.25565,534
80180.79.0.0/16180.79.0.1 to 180.79.255.254180.79.255.25565,534
81180.80.0.0/16180.80.0.1 to 180.80.255.254180.80.255.25565,534
82180.81.0.0/16180.81.0.1 to 180.81.255.254180.81.255.25565,534
83180.82.0.0/16180.82.0.1 to 180.82.255.254180.82.255.25565,534
84180.83.0.0/16180.83.0.1 to 180.83.255.254180.83.255.25565,534
85180.84.0.0/16180.84.0.1 to 180.84.255.254180.84.255.25565,534
86180.85.0.0/16180.85.0.1 to 180.85.255.254180.85.255.25565,534
87180.86.0.0/16180.86.0.1 to 180.86.255.254180.86.255.25565,534
88180.87.0.0/16180.87.0.1 to 180.87.255.254180.87.255.25565,534
89180.88.0.0/16180.88.0.1 to 180.88.255.254180.88.255.25565,534
90180.89.0.0/16180.89.0.1 to 180.89.255.254180.89.255.25565,534
91180.90.0.0/16180.90.0.1 to 180.90.255.254180.90.255.25565,534
92180.91.0.0/16180.91.0.1 to 180.91.255.254180.91.255.25565,534
93180.92.0.0/16180.92.0.1 to 180.92.255.254180.92.255.25565,534
94180.93.0.0/16180.93.0.1 to 180.93.255.254180.93.255.25565,534
95180.94.0.0/16180.94.0.1 to 180.94.255.254180.94.255.25565,534
96180.95.0.0/16180.95.0.1 to 180.95.255.254180.95.255.25565,534
97180.96.0.0/16180.96.0.1 to 180.96.255.254180.96.255.25565,534
98180.97.0.0/16180.97.0.1 to 180.97.255.254180.97.255.25565,534
99180.98.0.0/16180.98.0.1 to 180.98.255.254180.98.255.25565,534
100180.99.0.0/16180.99.0.1 to 180.99.255.254180.99.255.25565,534
101180.100.0.0/16180.100.0.1 to 180.100.255.254180.100.255.25565,534
102180.101.0.0/16180.101.0.1 to 180.101.255.254180.101.255.25565,534
103180.102.0.0/16180.102.0.1 to 180.102.255.254180.102.255.25565,534
104180.103.0.0/16180.103.0.1 to 180.103.255.254180.103.255.25565,534
105180.104.0.0/16180.104.0.1 to 180.104.255.254180.104.255.25565,534
106180.105.0.0/16180.105.0.1 to 180.105.255.254180.105.255.25565,534
107180.106.0.0/16180.106.0.1 to 180.106.255.254180.106.255.25565,534
108180.107.0.0/16180.107.0.1 to 180.107.255.254180.107.255.25565,534
109180.108.0.0/16180.108.0.1 to 180.108.255.254180.108.255.25565,534
110180.109.0.0/16180.109.0.1 to 180.109.255.254180.109.255.25565,534
111180.110.0.0/16180.110.0.1 to 180.110.255.254180.110.255.25565,534
112180.111.0.0/16180.111.0.1 to 180.111.255.254180.111.255.25565,534
113180.112.0.0/16180.112.0.1 to 180.112.255.254180.112.255.25565,534
114180.113.0.0/16180.113.0.1 to 180.113.255.254180.113.255.25565,534
115180.114.0.0/16180.114.0.1 to 180.114.255.254180.114.255.25565,534
116180.115.0.0/16180.115.0.1 to 180.115.255.254180.115.255.25565,534
117180.116.0.0/16180.116.0.1 to 180.116.255.254180.116.255.25565,534
118180.117.0.0/16180.117.0.1 to 180.117.255.254180.117.255.25565,534
119180.118.0.0/16180.118.0.1 to 180.118.255.254180.118.255.25565,534
120180.119.0.0/16180.119.0.1 to 180.119.255.254180.119.255.25565,534
121180.120.0.0/16180.120.0.1 to 180.120.255.254180.120.255.25565,534
122180.121.0.0/16180.121.0.1 to 180.121.255.254180.121.255.25565,534
123180.122.0.0/16180.122.0.1 to 180.122.255.254180.122.255.25565,534
124180.123.0.0/16180.123.0.1 to 180.123.255.254180.123.255.25565,534
125180.124.0.0/16180.124.0.1 to 180.124.255.254180.124.255.25565,534
126180.125.0.0/16180.125.0.1 to 180.125.255.254180.125.255.25565,534
127180.126.0.0/16180.126.0.1 to 180.126.255.254180.126.255.25565,534
128180.127.0.0/16180.127.0.1 to 180.127.255.254180.127.255.25565,534

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.