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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.

Network188.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
188.0.0.0
Broadcast address
188.127.255.255
First usable
188.0.0.1
Last usable
188.127.255.254
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 BC000000 · Integer 3154116608 to 3162505215
Reverse DNS zones
0.188.in-addr.arpa
1.188.in-addr.arpa
2.188.in-addr.arpa
3.188.in-addr.arpa
4.188.in-addr.arpa
5.188.in-addr.arpa
6.188.in-addr.arpa
7.188.in-addr.arpa
8.188.in-addr.arpa
9.188.in-addr.arpa
10.188.in-addr.arpa
11.188.in-addr.arpa
12.188.in-addr.arpa
13.188.in-addr.arpa
14.188.in-addr.arpa
15.188.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
Address10111100.00000000.00000000.00000000188.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network10111100.00000000.00000000.00000000188.0.0.0
Broadcast10111100.01111111.11111111.11111111188.127.255.255
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)

188.0.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1188.0.0.0/16188.0.0.1 to 188.0.255.254188.0.255.25565,534
2188.1.0.0/16188.1.0.1 to 188.1.255.254188.1.255.25565,534
3188.2.0.0/16188.2.0.1 to 188.2.255.254188.2.255.25565,534
4188.3.0.0/16188.3.0.1 to 188.3.255.254188.3.255.25565,534
5188.4.0.0/16188.4.0.1 to 188.4.255.254188.4.255.25565,534
6188.5.0.0/16188.5.0.1 to 188.5.255.254188.5.255.25565,534
7188.6.0.0/16188.6.0.1 to 188.6.255.254188.6.255.25565,534
8188.7.0.0/16188.7.0.1 to 188.7.255.254188.7.255.25565,534
9188.8.0.0/16188.8.0.1 to 188.8.255.254188.8.255.25565,534
10188.9.0.0/16188.9.0.1 to 188.9.255.254188.9.255.25565,534
11188.10.0.0/16188.10.0.1 to 188.10.255.254188.10.255.25565,534
12188.11.0.0/16188.11.0.1 to 188.11.255.254188.11.255.25565,534
13188.12.0.0/16188.12.0.1 to 188.12.255.254188.12.255.25565,534
14188.13.0.0/16188.13.0.1 to 188.13.255.254188.13.255.25565,534
15188.14.0.0/16188.14.0.1 to 188.14.255.254188.14.255.25565,534
16188.15.0.0/16188.15.0.1 to 188.15.255.254188.15.255.25565,534
17188.16.0.0/16188.16.0.1 to 188.16.255.254188.16.255.25565,534
18188.17.0.0/16188.17.0.1 to 188.17.255.254188.17.255.25565,534
19188.18.0.0/16188.18.0.1 to 188.18.255.254188.18.255.25565,534
20188.19.0.0/16188.19.0.1 to 188.19.255.254188.19.255.25565,534
21188.20.0.0/16188.20.0.1 to 188.20.255.254188.20.255.25565,534
22188.21.0.0/16188.21.0.1 to 188.21.255.254188.21.255.25565,534
23188.22.0.0/16188.22.0.1 to 188.22.255.254188.22.255.25565,534
24188.23.0.0/16188.23.0.1 to 188.23.255.254188.23.255.25565,534
25188.24.0.0/16188.24.0.1 to 188.24.255.254188.24.255.25565,534
26188.25.0.0/16188.25.0.1 to 188.25.255.254188.25.255.25565,534
27188.26.0.0/16188.26.0.1 to 188.26.255.254188.26.255.25565,534
28188.27.0.0/16188.27.0.1 to 188.27.255.254188.27.255.25565,534
29188.28.0.0/16188.28.0.1 to 188.28.255.254188.28.255.25565,534
30188.29.0.0/16188.29.0.1 to 188.29.255.254188.29.255.25565,534
31188.30.0.0/16188.30.0.1 to 188.30.255.254188.30.255.25565,534
32188.31.0.0/16188.31.0.1 to 188.31.255.254188.31.255.25565,534
33188.32.0.0/16188.32.0.1 to 188.32.255.254188.32.255.25565,534
34188.33.0.0/16188.33.0.1 to 188.33.255.254188.33.255.25565,534
35188.34.0.0/16188.34.0.1 to 188.34.255.254188.34.255.25565,534
36188.35.0.0/16188.35.0.1 to 188.35.255.254188.35.255.25565,534
37188.36.0.0/16188.36.0.1 to 188.36.255.254188.36.255.25565,534
38188.37.0.0/16188.37.0.1 to 188.37.255.254188.37.255.25565,534
39188.38.0.0/16188.38.0.1 to 188.38.255.254188.38.255.25565,534
40188.39.0.0/16188.39.0.1 to 188.39.255.254188.39.255.25565,534
41188.40.0.0/16188.40.0.1 to 188.40.255.254188.40.255.25565,534
42188.41.0.0/16188.41.0.1 to 188.41.255.254188.41.255.25565,534
43188.42.0.0/16188.42.0.1 to 188.42.255.254188.42.255.25565,534
44188.43.0.0/16188.43.0.1 to 188.43.255.254188.43.255.25565,534
45188.44.0.0/16188.44.0.1 to 188.44.255.254188.44.255.25565,534
46188.45.0.0/16188.45.0.1 to 188.45.255.254188.45.255.25565,534
47188.46.0.0/16188.46.0.1 to 188.46.255.254188.46.255.25565,534
48188.47.0.0/16188.47.0.1 to 188.47.255.254188.47.255.25565,534
49188.48.0.0/16188.48.0.1 to 188.48.255.254188.48.255.25565,534
50188.49.0.0/16188.49.0.1 to 188.49.255.254188.49.255.25565,534
51188.50.0.0/16188.50.0.1 to 188.50.255.254188.50.255.25565,534
52188.51.0.0/16188.51.0.1 to 188.51.255.254188.51.255.25565,534
53188.52.0.0/16188.52.0.1 to 188.52.255.254188.52.255.25565,534
54188.53.0.0/16188.53.0.1 to 188.53.255.254188.53.255.25565,534
55188.54.0.0/16188.54.0.1 to 188.54.255.254188.54.255.25565,534
56188.55.0.0/16188.55.0.1 to 188.55.255.254188.55.255.25565,534
57188.56.0.0/16188.56.0.1 to 188.56.255.254188.56.255.25565,534
58188.57.0.0/16188.57.0.1 to 188.57.255.254188.57.255.25565,534
59188.58.0.0/16188.58.0.1 to 188.58.255.254188.58.255.25565,534
60188.59.0.0/16188.59.0.1 to 188.59.255.254188.59.255.25565,534
61188.60.0.0/16188.60.0.1 to 188.60.255.254188.60.255.25565,534
62188.61.0.0/16188.61.0.1 to 188.61.255.254188.61.255.25565,534
63188.62.0.0/16188.62.0.1 to 188.62.255.254188.62.255.25565,534
64188.63.0.0/16188.63.0.1 to 188.63.255.254188.63.255.25565,534
65188.64.0.0/16188.64.0.1 to 188.64.255.254188.64.255.25565,534
66188.65.0.0/16188.65.0.1 to 188.65.255.254188.65.255.25565,534
67188.66.0.0/16188.66.0.1 to 188.66.255.254188.66.255.25565,534
68188.67.0.0/16188.67.0.1 to 188.67.255.254188.67.255.25565,534
69188.68.0.0/16188.68.0.1 to 188.68.255.254188.68.255.25565,534
70188.69.0.0/16188.69.0.1 to 188.69.255.254188.69.255.25565,534
71188.70.0.0/16188.70.0.1 to 188.70.255.254188.70.255.25565,534
72188.71.0.0/16188.71.0.1 to 188.71.255.254188.71.255.25565,534
73188.72.0.0/16188.72.0.1 to 188.72.255.254188.72.255.25565,534
74188.73.0.0/16188.73.0.1 to 188.73.255.254188.73.255.25565,534
75188.74.0.0/16188.74.0.1 to 188.74.255.254188.74.255.25565,534
76188.75.0.0/16188.75.0.1 to 188.75.255.254188.75.255.25565,534
77188.76.0.0/16188.76.0.1 to 188.76.255.254188.76.255.25565,534
78188.77.0.0/16188.77.0.1 to 188.77.255.254188.77.255.25565,534
79188.78.0.0/16188.78.0.1 to 188.78.255.254188.78.255.25565,534
80188.79.0.0/16188.79.0.1 to 188.79.255.254188.79.255.25565,534
81188.80.0.0/16188.80.0.1 to 188.80.255.254188.80.255.25565,534
82188.81.0.0/16188.81.0.1 to 188.81.255.254188.81.255.25565,534
83188.82.0.0/16188.82.0.1 to 188.82.255.254188.82.255.25565,534
84188.83.0.0/16188.83.0.1 to 188.83.255.254188.83.255.25565,534
85188.84.0.0/16188.84.0.1 to 188.84.255.254188.84.255.25565,534
86188.85.0.0/16188.85.0.1 to 188.85.255.254188.85.255.25565,534
87188.86.0.0/16188.86.0.1 to 188.86.255.254188.86.255.25565,534
88188.87.0.0/16188.87.0.1 to 188.87.255.254188.87.255.25565,534
89188.88.0.0/16188.88.0.1 to 188.88.255.254188.88.255.25565,534
90188.89.0.0/16188.89.0.1 to 188.89.255.254188.89.255.25565,534
91188.90.0.0/16188.90.0.1 to 188.90.255.254188.90.255.25565,534
92188.91.0.0/16188.91.0.1 to 188.91.255.254188.91.255.25565,534
93188.92.0.0/16188.92.0.1 to 188.92.255.254188.92.255.25565,534
94188.93.0.0/16188.93.0.1 to 188.93.255.254188.93.255.25565,534
95188.94.0.0/16188.94.0.1 to 188.94.255.254188.94.255.25565,534
96188.95.0.0/16188.95.0.1 to 188.95.255.254188.95.255.25565,534
97188.96.0.0/16188.96.0.1 to 188.96.255.254188.96.255.25565,534
98188.97.0.0/16188.97.0.1 to 188.97.255.254188.97.255.25565,534
99188.98.0.0/16188.98.0.1 to 188.98.255.254188.98.255.25565,534
100188.99.0.0/16188.99.0.1 to 188.99.255.254188.99.255.25565,534
101188.100.0.0/16188.100.0.1 to 188.100.255.254188.100.255.25565,534
102188.101.0.0/16188.101.0.1 to 188.101.255.254188.101.255.25565,534
103188.102.0.0/16188.102.0.1 to 188.102.255.254188.102.255.25565,534
104188.103.0.0/16188.103.0.1 to 188.103.255.254188.103.255.25565,534
105188.104.0.0/16188.104.0.1 to 188.104.255.254188.104.255.25565,534
106188.105.0.0/16188.105.0.1 to 188.105.255.254188.105.255.25565,534
107188.106.0.0/16188.106.0.1 to 188.106.255.254188.106.255.25565,534
108188.107.0.0/16188.107.0.1 to 188.107.255.254188.107.255.25565,534
109188.108.0.0/16188.108.0.1 to 188.108.255.254188.108.255.25565,534
110188.109.0.0/16188.109.0.1 to 188.109.255.254188.109.255.25565,534
111188.110.0.0/16188.110.0.1 to 188.110.255.254188.110.255.25565,534
112188.111.0.0/16188.111.0.1 to 188.111.255.254188.111.255.25565,534
113188.112.0.0/16188.112.0.1 to 188.112.255.254188.112.255.25565,534
114188.113.0.0/16188.113.0.1 to 188.113.255.254188.113.255.25565,534
115188.114.0.0/16188.114.0.1 to 188.114.255.254188.114.255.25565,534
116188.115.0.0/16188.115.0.1 to 188.115.255.254188.115.255.25565,534
117188.116.0.0/16188.116.0.1 to 188.116.255.254188.116.255.25565,534
118188.117.0.0/16188.117.0.1 to 188.117.255.254188.117.255.25565,534
119188.118.0.0/16188.118.0.1 to 188.118.255.254188.118.255.25565,534
120188.119.0.0/16188.119.0.1 to 188.119.255.254188.119.255.25565,534
121188.120.0.0/16188.120.0.1 to 188.120.255.254188.120.255.25565,534
122188.121.0.0/16188.121.0.1 to 188.121.255.254188.121.255.25565,534
123188.122.0.0/16188.122.0.1 to 188.122.255.254188.122.255.25565,534
124188.123.0.0/16188.123.0.1 to 188.123.255.254188.123.255.25565,534
125188.124.0.0/16188.124.0.1 to 188.124.255.254188.124.255.25565,534
126188.125.0.0/16188.125.0.1 to 188.125.255.254188.125.255.25565,534
127188.126.0.0/16188.126.0.1 to 188.126.255.254188.126.255.25565,534
128188.127.0.0/16188.127.0.1 to 188.127.255.254188.127.255.25565,534

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.