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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.

Network167.7.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
167.7.0.0
Broadcast address
167.7.127.255
First usable
167.7.0.1
Last usable
167.7.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
B (default /16)
As numbers
Hex A7070000 · Integer 2802253824 to 2802286591
Reverse DNS zones
0.7.167.in-addr.arpa
1.7.167.in-addr.arpa
2.7.167.in-addr.arpa
3.7.167.in-addr.arpa
4.7.167.in-addr.arpa
5.7.167.in-addr.arpa
6.7.167.in-addr.arpa
7.7.167.in-addr.arpa
8.7.167.in-addr.arpa
9.7.167.in-addr.arpa
10.7.167.in-addr.arpa
11.7.167.in-addr.arpa
12.7.167.in-addr.arpa
13.7.167.in-addr.arpa
14.7.167.in-addr.arpa
15.7.167.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100111.00000111.00000000.00000000167.7.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10100111.00000111.00000000.00000000167.7.0.0
Broadcast10100111.00000111.01111111.11111111167.7.127.255
Split into smaller subnets/24
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

167.7.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1167.7.0.0/24167.7.0.1 to 167.7.0.254167.7.0.255254
2167.7.1.0/24167.7.1.1 to 167.7.1.254167.7.1.255254
3167.7.2.0/24167.7.2.1 to 167.7.2.254167.7.2.255254
4167.7.3.0/24167.7.3.1 to 167.7.3.254167.7.3.255254
5167.7.4.0/24167.7.4.1 to 167.7.4.254167.7.4.255254
6167.7.5.0/24167.7.5.1 to 167.7.5.254167.7.5.255254
7167.7.6.0/24167.7.6.1 to 167.7.6.254167.7.6.255254
8167.7.7.0/24167.7.7.1 to 167.7.7.254167.7.7.255254
9167.7.8.0/24167.7.8.1 to 167.7.8.254167.7.8.255254
10167.7.9.0/24167.7.9.1 to 167.7.9.254167.7.9.255254
11167.7.10.0/24167.7.10.1 to 167.7.10.254167.7.10.255254
12167.7.11.0/24167.7.11.1 to 167.7.11.254167.7.11.255254
13167.7.12.0/24167.7.12.1 to 167.7.12.254167.7.12.255254
14167.7.13.0/24167.7.13.1 to 167.7.13.254167.7.13.255254
15167.7.14.0/24167.7.14.1 to 167.7.14.254167.7.14.255254
16167.7.15.0/24167.7.15.1 to 167.7.15.254167.7.15.255254
17167.7.16.0/24167.7.16.1 to 167.7.16.254167.7.16.255254
18167.7.17.0/24167.7.17.1 to 167.7.17.254167.7.17.255254
19167.7.18.0/24167.7.18.1 to 167.7.18.254167.7.18.255254
20167.7.19.0/24167.7.19.1 to 167.7.19.254167.7.19.255254
21167.7.20.0/24167.7.20.1 to 167.7.20.254167.7.20.255254
22167.7.21.0/24167.7.21.1 to 167.7.21.254167.7.21.255254
23167.7.22.0/24167.7.22.1 to 167.7.22.254167.7.22.255254
24167.7.23.0/24167.7.23.1 to 167.7.23.254167.7.23.255254
25167.7.24.0/24167.7.24.1 to 167.7.24.254167.7.24.255254
26167.7.25.0/24167.7.25.1 to 167.7.25.254167.7.25.255254
27167.7.26.0/24167.7.26.1 to 167.7.26.254167.7.26.255254
28167.7.27.0/24167.7.27.1 to 167.7.27.254167.7.27.255254
29167.7.28.0/24167.7.28.1 to 167.7.28.254167.7.28.255254
30167.7.29.0/24167.7.29.1 to 167.7.29.254167.7.29.255254
31167.7.30.0/24167.7.30.1 to 167.7.30.254167.7.30.255254
32167.7.31.0/24167.7.31.1 to 167.7.31.254167.7.31.255254
33167.7.32.0/24167.7.32.1 to 167.7.32.254167.7.32.255254
34167.7.33.0/24167.7.33.1 to 167.7.33.254167.7.33.255254
35167.7.34.0/24167.7.34.1 to 167.7.34.254167.7.34.255254
36167.7.35.0/24167.7.35.1 to 167.7.35.254167.7.35.255254
37167.7.36.0/24167.7.36.1 to 167.7.36.254167.7.36.255254
38167.7.37.0/24167.7.37.1 to 167.7.37.254167.7.37.255254
39167.7.38.0/24167.7.38.1 to 167.7.38.254167.7.38.255254
40167.7.39.0/24167.7.39.1 to 167.7.39.254167.7.39.255254
41167.7.40.0/24167.7.40.1 to 167.7.40.254167.7.40.255254
42167.7.41.0/24167.7.41.1 to 167.7.41.254167.7.41.255254
43167.7.42.0/24167.7.42.1 to 167.7.42.254167.7.42.255254
44167.7.43.0/24167.7.43.1 to 167.7.43.254167.7.43.255254
45167.7.44.0/24167.7.44.1 to 167.7.44.254167.7.44.255254
46167.7.45.0/24167.7.45.1 to 167.7.45.254167.7.45.255254
47167.7.46.0/24167.7.46.1 to 167.7.46.254167.7.46.255254
48167.7.47.0/24167.7.47.1 to 167.7.47.254167.7.47.255254
49167.7.48.0/24167.7.48.1 to 167.7.48.254167.7.48.255254
50167.7.49.0/24167.7.49.1 to 167.7.49.254167.7.49.255254
51167.7.50.0/24167.7.50.1 to 167.7.50.254167.7.50.255254
52167.7.51.0/24167.7.51.1 to 167.7.51.254167.7.51.255254
53167.7.52.0/24167.7.52.1 to 167.7.52.254167.7.52.255254
54167.7.53.0/24167.7.53.1 to 167.7.53.254167.7.53.255254
55167.7.54.0/24167.7.54.1 to 167.7.54.254167.7.54.255254
56167.7.55.0/24167.7.55.1 to 167.7.55.254167.7.55.255254
57167.7.56.0/24167.7.56.1 to 167.7.56.254167.7.56.255254
58167.7.57.0/24167.7.57.1 to 167.7.57.254167.7.57.255254
59167.7.58.0/24167.7.58.1 to 167.7.58.254167.7.58.255254
60167.7.59.0/24167.7.59.1 to 167.7.59.254167.7.59.255254
61167.7.60.0/24167.7.60.1 to 167.7.60.254167.7.60.255254
62167.7.61.0/24167.7.61.1 to 167.7.61.254167.7.61.255254
63167.7.62.0/24167.7.62.1 to 167.7.62.254167.7.62.255254
64167.7.63.0/24167.7.63.1 to 167.7.63.254167.7.63.255254
65167.7.64.0/24167.7.64.1 to 167.7.64.254167.7.64.255254
66167.7.65.0/24167.7.65.1 to 167.7.65.254167.7.65.255254
67167.7.66.0/24167.7.66.1 to 167.7.66.254167.7.66.255254
68167.7.67.0/24167.7.67.1 to 167.7.67.254167.7.67.255254
69167.7.68.0/24167.7.68.1 to 167.7.68.254167.7.68.255254
70167.7.69.0/24167.7.69.1 to 167.7.69.254167.7.69.255254
71167.7.70.0/24167.7.70.1 to 167.7.70.254167.7.70.255254
72167.7.71.0/24167.7.71.1 to 167.7.71.254167.7.71.255254
73167.7.72.0/24167.7.72.1 to 167.7.72.254167.7.72.255254
74167.7.73.0/24167.7.73.1 to 167.7.73.254167.7.73.255254
75167.7.74.0/24167.7.74.1 to 167.7.74.254167.7.74.255254
76167.7.75.0/24167.7.75.1 to 167.7.75.254167.7.75.255254
77167.7.76.0/24167.7.76.1 to 167.7.76.254167.7.76.255254
78167.7.77.0/24167.7.77.1 to 167.7.77.254167.7.77.255254
79167.7.78.0/24167.7.78.1 to 167.7.78.254167.7.78.255254
80167.7.79.0/24167.7.79.1 to 167.7.79.254167.7.79.255254
81167.7.80.0/24167.7.80.1 to 167.7.80.254167.7.80.255254
82167.7.81.0/24167.7.81.1 to 167.7.81.254167.7.81.255254
83167.7.82.0/24167.7.82.1 to 167.7.82.254167.7.82.255254
84167.7.83.0/24167.7.83.1 to 167.7.83.254167.7.83.255254
85167.7.84.0/24167.7.84.1 to 167.7.84.254167.7.84.255254
86167.7.85.0/24167.7.85.1 to 167.7.85.254167.7.85.255254
87167.7.86.0/24167.7.86.1 to 167.7.86.254167.7.86.255254
88167.7.87.0/24167.7.87.1 to 167.7.87.254167.7.87.255254
89167.7.88.0/24167.7.88.1 to 167.7.88.254167.7.88.255254
90167.7.89.0/24167.7.89.1 to 167.7.89.254167.7.89.255254
91167.7.90.0/24167.7.90.1 to 167.7.90.254167.7.90.255254
92167.7.91.0/24167.7.91.1 to 167.7.91.254167.7.91.255254
93167.7.92.0/24167.7.92.1 to 167.7.92.254167.7.92.255254
94167.7.93.0/24167.7.93.1 to 167.7.93.254167.7.93.255254
95167.7.94.0/24167.7.94.1 to 167.7.94.254167.7.94.255254
96167.7.95.0/24167.7.95.1 to 167.7.95.254167.7.95.255254
97167.7.96.0/24167.7.96.1 to 167.7.96.254167.7.96.255254
98167.7.97.0/24167.7.97.1 to 167.7.97.254167.7.97.255254
99167.7.98.0/24167.7.98.1 to 167.7.98.254167.7.98.255254
100167.7.99.0/24167.7.99.1 to 167.7.99.254167.7.99.255254
101167.7.100.0/24167.7.100.1 to 167.7.100.254167.7.100.255254
102167.7.101.0/24167.7.101.1 to 167.7.101.254167.7.101.255254
103167.7.102.0/24167.7.102.1 to 167.7.102.254167.7.102.255254
104167.7.103.0/24167.7.103.1 to 167.7.103.254167.7.103.255254
105167.7.104.0/24167.7.104.1 to 167.7.104.254167.7.104.255254
106167.7.105.0/24167.7.105.1 to 167.7.105.254167.7.105.255254
107167.7.106.0/24167.7.106.1 to 167.7.106.254167.7.106.255254
108167.7.107.0/24167.7.107.1 to 167.7.107.254167.7.107.255254
109167.7.108.0/24167.7.108.1 to 167.7.108.254167.7.108.255254
110167.7.109.0/24167.7.109.1 to 167.7.109.254167.7.109.255254
111167.7.110.0/24167.7.110.1 to 167.7.110.254167.7.110.255254
112167.7.111.0/24167.7.111.1 to 167.7.111.254167.7.111.255254
113167.7.112.0/24167.7.112.1 to 167.7.112.254167.7.112.255254
114167.7.113.0/24167.7.113.1 to 167.7.113.254167.7.113.255254
115167.7.114.0/24167.7.114.1 to 167.7.114.254167.7.114.255254
116167.7.115.0/24167.7.115.1 to 167.7.115.254167.7.115.255254
117167.7.116.0/24167.7.116.1 to 167.7.116.254167.7.116.255254
118167.7.117.0/24167.7.117.1 to 167.7.117.254167.7.117.255254
119167.7.118.0/24167.7.118.1 to 167.7.118.254167.7.118.255254
120167.7.119.0/24167.7.119.1 to 167.7.119.254167.7.119.255254
121167.7.120.0/24167.7.120.1 to 167.7.120.254167.7.120.255254
122167.7.121.0/24167.7.121.1 to 167.7.121.254167.7.121.255254
123167.7.122.0/24167.7.122.1 to 167.7.122.254167.7.122.255254
124167.7.123.0/24167.7.123.1 to 167.7.123.254167.7.123.255254
125167.7.124.0/24167.7.124.1 to 167.7.124.254167.7.124.255254
126167.7.125.0/24167.7.125.1 to 167.7.125.254167.7.125.255254
127167.7.126.0/24167.7.126.1 to 167.7.126.254167.7.126.255254
128167.7.127.0/24167.7.127.1 to 167.7.127.254167.7.127.255254

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.