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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.

Network117.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
117.0.0.0
Broadcast address
117.127.255.255
First usable
117.0.0.1
Last usable
117.127.255.254
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
A (default /8)
As numbers
Hex 75000000 · Integer 1962934272 to 1971322879
Reverse DNS zones
0.117.in-addr.arpa
1.117.in-addr.arpa
2.117.in-addr.arpa
3.117.in-addr.arpa
4.117.in-addr.arpa
5.117.in-addr.arpa
6.117.in-addr.arpa
7.117.in-addr.arpa
8.117.in-addr.arpa
9.117.in-addr.arpa
10.117.in-addr.arpa
11.117.in-addr.arpa
12.117.in-addr.arpa
13.117.in-addr.arpa
14.117.in-addr.arpa
15.117.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
Address01110101.00000000.00000000.00000000117.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01110101.00000000.00000000.00000000117.0.0.0
Broadcast01110101.01111111.11111111.11111111117.127.255.255
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)

117.0.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1117.0.0.0/16117.0.0.1 to 117.0.255.254117.0.255.25565,534
2117.1.0.0/16117.1.0.1 to 117.1.255.254117.1.255.25565,534
3117.2.0.0/16117.2.0.1 to 117.2.255.254117.2.255.25565,534
4117.3.0.0/16117.3.0.1 to 117.3.255.254117.3.255.25565,534
5117.4.0.0/16117.4.0.1 to 117.4.255.254117.4.255.25565,534
6117.5.0.0/16117.5.0.1 to 117.5.255.254117.5.255.25565,534
7117.6.0.0/16117.6.0.1 to 117.6.255.254117.6.255.25565,534
8117.7.0.0/16117.7.0.1 to 117.7.255.254117.7.255.25565,534
9117.8.0.0/16117.8.0.1 to 117.8.255.254117.8.255.25565,534
10117.9.0.0/16117.9.0.1 to 117.9.255.254117.9.255.25565,534
11117.10.0.0/16117.10.0.1 to 117.10.255.254117.10.255.25565,534
12117.11.0.0/16117.11.0.1 to 117.11.255.254117.11.255.25565,534
13117.12.0.0/16117.12.0.1 to 117.12.255.254117.12.255.25565,534
14117.13.0.0/16117.13.0.1 to 117.13.255.254117.13.255.25565,534
15117.14.0.0/16117.14.0.1 to 117.14.255.254117.14.255.25565,534
16117.15.0.0/16117.15.0.1 to 117.15.255.254117.15.255.25565,534
17117.16.0.0/16117.16.0.1 to 117.16.255.254117.16.255.25565,534
18117.17.0.0/16117.17.0.1 to 117.17.255.254117.17.255.25565,534
19117.18.0.0/16117.18.0.1 to 117.18.255.254117.18.255.25565,534
20117.19.0.0/16117.19.0.1 to 117.19.255.254117.19.255.25565,534
21117.20.0.0/16117.20.0.1 to 117.20.255.254117.20.255.25565,534
22117.21.0.0/16117.21.0.1 to 117.21.255.254117.21.255.25565,534
23117.22.0.0/16117.22.0.1 to 117.22.255.254117.22.255.25565,534
24117.23.0.0/16117.23.0.1 to 117.23.255.254117.23.255.25565,534
25117.24.0.0/16117.24.0.1 to 117.24.255.254117.24.255.25565,534
26117.25.0.0/16117.25.0.1 to 117.25.255.254117.25.255.25565,534
27117.26.0.0/16117.26.0.1 to 117.26.255.254117.26.255.25565,534
28117.27.0.0/16117.27.0.1 to 117.27.255.254117.27.255.25565,534
29117.28.0.0/16117.28.0.1 to 117.28.255.254117.28.255.25565,534
30117.29.0.0/16117.29.0.1 to 117.29.255.254117.29.255.25565,534
31117.30.0.0/16117.30.0.1 to 117.30.255.254117.30.255.25565,534
32117.31.0.0/16117.31.0.1 to 117.31.255.254117.31.255.25565,534
33117.32.0.0/16117.32.0.1 to 117.32.255.254117.32.255.25565,534
34117.33.0.0/16117.33.0.1 to 117.33.255.254117.33.255.25565,534
35117.34.0.0/16117.34.0.1 to 117.34.255.254117.34.255.25565,534
36117.35.0.0/16117.35.0.1 to 117.35.255.254117.35.255.25565,534
37117.36.0.0/16117.36.0.1 to 117.36.255.254117.36.255.25565,534
38117.37.0.0/16117.37.0.1 to 117.37.255.254117.37.255.25565,534
39117.38.0.0/16117.38.0.1 to 117.38.255.254117.38.255.25565,534
40117.39.0.0/16117.39.0.1 to 117.39.255.254117.39.255.25565,534
41117.40.0.0/16117.40.0.1 to 117.40.255.254117.40.255.25565,534
42117.41.0.0/16117.41.0.1 to 117.41.255.254117.41.255.25565,534
43117.42.0.0/16117.42.0.1 to 117.42.255.254117.42.255.25565,534
44117.43.0.0/16117.43.0.1 to 117.43.255.254117.43.255.25565,534
45117.44.0.0/16117.44.0.1 to 117.44.255.254117.44.255.25565,534
46117.45.0.0/16117.45.0.1 to 117.45.255.254117.45.255.25565,534
47117.46.0.0/16117.46.0.1 to 117.46.255.254117.46.255.25565,534
48117.47.0.0/16117.47.0.1 to 117.47.255.254117.47.255.25565,534
49117.48.0.0/16117.48.0.1 to 117.48.255.254117.48.255.25565,534
50117.49.0.0/16117.49.0.1 to 117.49.255.254117.49.255.25565,534
51117.50.0.0/16117.50.0.1 to 117.50.255.254117.50.255.25565,534
52117.51.0.0/16117.51.0.1 to 117.51.255.254117.51.255.25565,534
53117.52.0.0/16117.52.0.1 to 117.52.255.254117.52.255.25565,534
54117.53.0.0/16117.53.0.1 to 117.53.255.254117.53.255.25565,534
55117.54.0.0/16117.54.0.1 to 117.54.255.254117.54.255.25565,534
56117.55.0.0/16117.55.0.1 to 117.55.255.254117.55.255.25565,534
57117.56.0.0/16117.56.0.1 to 117.56.255.254117.56.255.25565,534
58117.57.0.0/16117.57.0.1 to 117.57.255.254117.57.255.25565,534
59117.58.0.0/16117.58.0.1 to 117.58.255.254117.58.255.25565,534
60117.59.0.0/16117.59.0.1 to 117.59.255.254117.59.255.25565,534
61117.60.0.0/16117.60.0.1 to 117.60.255.254117.60.255.25565,534
62117.61.0.0/16117.61.0.1 to 117.61.255.254117.61.255.25565,534
63117.62.0.0/16117.62.0.1 to 117.62.255.254117.62.255.25565,534
64117.63.0.0/16117.63.0.1 to 117.63.255.254117.63.255.25565,534
65117.64.0.0/16117.64.0.1 to 117.64.255.254117.64.255.25565,534
66117.65.0.0/16117.65.0.1 to 117.65.255.254117.65.255.25565,534
67117.66.0.0/16117.66.0.1 to 117.66.255.254117.66.255.25565,534
68117.67.0.0/16117.67.0.1 to 117.67.255.254117.67.255.25565,534
69117.68.0.0/16117.68.0.1 to 117.68.255.254117.68.255.25565,534
70117.69.0.0/16117.69.0.1 to 117.69.255.254117.69.255.25565,534
71117.70.0.0/16117.70.0.1 to 117.70.255.254117.70.255.25565,534
72117.71.0.0/16117.71.0.1 to 117.71.255.254117.71.255.25565,534
73117.72.0.0/16117.72.0.1 to 117.72.255.254117.72.255.25565,534
74117.73.0.0/16117.73.0.1 to 117.73.255.254117.73.255.25565,534
75117.74.0.0/16117.74.0.1 to 117.74.255.254117.74.255.25565,534
76117.75.0.0/16117.75.0.1 to 117.75.255.254117.75.255.25565,534
77117.76.0.0/16117.76.0.1 to 117.76.255.254117.76.255.25565,534
78117.77.0.0/16117.77.0.1 to 117.77.255.254117.77.255.25565,534
79117.78.0.0/16117.78.0.1 to 117.78.255.254117.78.255.25565,534
80117.79.0.0/16117.79.0.1 to 117.79.255.254117.79.255.25565,534
81117.80.0.0/16117.80.0.1 to 117.80.255.254117.80.255.25565,534
82117.81.0.0/16117.81.0.1 to 117.81.255.254117.81.255.25565,534
83117.82.0.0/16117.82.0.1 to 117.82.255.254117.82.255.25565,534
84117.83.0.0/16117.83.0.1 to 117.83.255.254117.83.255.25565,534
85117.84.0.0/16117.84.0.1 to 117.84.255.254117.84.255.25565,534
86117.85.0.0/16117.85.0.1 to 117.85.255.254117.85.255.25565,534
87117.86.0.0/16117.86.0.1 to 117.86.255.254117.86.255.25565,534
88117.87.0.0/16117.87.0.1 to 117.87.255.254117.87.255.25565,534
89117.88.0.0/16117.88.0.1 to 117.88.255.254117.88.255.25565,534
90117.89.0.0/16117.89.0.1 to 117.89.255.254117.89.255.25565,534
91117.90.0.0/16117.90.0.1 to 117.90.255.254117.90.255.25565,534
92117.91.0.0/16117.91.0.1 to 117.91.255.254117.91.255.25565,534
93117.92.0.0/16117.92.0.1 to 117.92.255.254117.92.255.25565,534
94117.93.0.0/16117.93.0.1 to 117.93.255.254117.93.255.25565,534
95117.94.0.0/16117.94.0.1 to 117.94.255.254117.94.255.25565,534
96117.95.0.0/16117.95.0.1 to 117.95.255.254117.95.255.25565,534
97117.96.0.0/16117.96.0.1 to 117.96.255.254117.96.255.25565,534
98117.97.0.0/16117.97.0.1 to 117.97.255.254117.97.255.25565,534
99117.98.0.0/16117.98.0.1 to 117.98.255.254117.98.255.25565,534
100117.99.0.0/16117.99.0.1 to 117.99.255.254117.99.255.25565,534
101117.100.0.0/16117.100.0.1 to 117.100.255.254117.100.255.25565,534
102117.101.0.0/16117.101.0.1 to 117.101.255.254117.101.255.25565,534
103117.102.0.0/16117.102.0.1 to 117.102.255.254117.102.255.25565,534
104117.103.0.0/16117.103.0.1 to 117.103.255.254117.103.255.25565,534
105117.104.0.0/16117.104.0.1 to 117.104.255.254117.104.255.25565,534
106117.105.0.0/16117.105.0.1 to 117.105.255.254117.105.255.25565,534
107117.106.0.0/16117.106.0.1 to 117.106.255.254117.106.255.25565,534
108117.107.0.0/16117.107.0.1 to 117.107.255.254117.107.255.25565,534
109117.108.0.0/16117.108.0.1 to 117.108.255.254117.108.255.25565,534
110117.109.0.0/16117.109.0.1 to 117.109.255.254117.109.255.25565,534
111117.110.0.0/16117.110.0.1 to 117.110.255.254117.110.255.25565,534
112117.111.0.0/16117.111.0.1 to 117.111.255.254117.111.255.25565,534
113117.112.0.0/16117.112.0.1 to 117.112.255.254117.112.255.25565,534
114117.113.0.0/16117.113.0.1 to 117.113.255.254117.113.255.25565,534
115117.114.0.0/16117.114.0.1 to 117.114.255.254117.114.255.25565,534
116117.115.0.0/16117.115.0.1 to 117.115.255.254117.115.255.25565,534
117117.116.0.0/16117.116.0.1 to 117.116.255.254117.116.255.25565,534
118117.117.0.0/16117.117.0.1 to 117.117.255.254117.117.255.25565,534
119117.118.0.0/16117.118.0.1 to 117.118.255.254117.118.255.25565,534
120117.119.0.0/16117.119.0.1 to 117.119.255.254117.119.255.25565,534
121117.120.0.0/16117.120.0.1 to 117.120.255.254117.120.255.25565,534
122117.121.0.0/16117.121.0.1 to 117.121.255.254117.121.255.25565,534
123117.122.0.0/16117.122.0.1 to 117.122.255.254117.122.255.25565,534
124117.123.0.0/16117.123.0.1 to 117.123.255.254117.123.255.25565,534
125117.124.0.0/16117.124.0.1 to 117.124.255.254117.124.255.25565,534
126117.125.0.0/16117.125.0.1 to 117.125.255.254117.125.255.25565,534
127117.126.0.0/16117.126.0.1 to 117.126.255.254117.126.255.25565,534
128117.127.0.0/16117.127.0.1 to 117.127.255.254117.127.255.25565,534

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.