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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.

Network160.0.0.0/3
Usable hosts536,870,910
Subnet mask224.0.0.0
Addresses536,870,912
Network address
160.0.0.0
Broadcast address
191.255.255.255
First usable
160.0.0.1
Last usable
191.255.255.254
Usable hosts
536,870,910 (536,870,912 less the network and broadcast addresses)
Subnet mask
224.0.0.0
Wildcard mask
31.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/3
Type
Public public
Old class
B (default /16)
As numbers
Hex A0000000 · Integer 2684354560 to 3221225471
Reverse DNS zones
160.in-addr.arpa
161.in-addr.arpa
162.in-addr.arpa
163.in-addr.arpa
164.in-addr.arpa
165.in-addr.arpa
166.in-addr.arpa
167.in-addr.arpa
168.in-addr.arpa
169.in-addr.arpa
170.in-addr.arpa
171.in-addr.arpa
172.in-addr.arpa
173.in-addr.arpa
174.in-addr.arpa
175.in-addr.arpa
and 16 more
/3 is not on a 8-bit boundary, so it takes 32 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100000.00000000.00000000.00000000160.0.0.0
Subnet mask11100000.00000000.00000000.00000000224.0.0.0
Network10100000.00000000.00000000.00000000160.0.0.0
Broadcast10111111.11111111.11111111.11111111191.255.255.255
Split into smaller subnets/10
/4 (2)/5 (4)/6 (8)/7 (16)/8 (32)/9 (64)/10 (128)/11 (256)/12 (512)/13 (1,024)/14 (2,048)/15 (4,096)

160.0.0.0/3 makes 128 subnets of /10.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1160.0.0.0/10160.0.0.1 to 160.63.255.254160.63.255.2554,194,302
2160.64.0.0/10160.64.0.1 to 160.127.255.254160.127.255.2554,194,302
3160.128.0.0/10160.128.0.1 to 160.191.255.254160.191.255.2554,194,302
4160.192.0.0/10160.192.0.1 to 160.255.255.254160.255.255.2554,194,302
5161.0.0.0/10161.0.0.1 to 161.63.255.254161.63.255.2554,194,302
6161.64.0.0/10161.64.0.1 to 161.127.255.254161.127.255.2554,194,302
7161.128.0.0/10161.128.0.1 to 161.191.255.254161.191.255.2554,194,302
8161.192.0.0/10161.192.0.1 to 161.255.255.254161.255.255.2554,194,302
9162.0.0.0/10162.0.0.1 to 162.63.255.254162.63.255.2554,194,302
10162.64.0.0/10162.64.0.1 to 162.127.255.254162.127.255.2554,194,302
11162.128.0.0/10162.128.0.1 to 162.191.255.254162.191.255.2554,194,302
12162.192.0.0/10162.192.0.1 to 162.255.255.254162.255.255.2554,194,302
13163.0.0.0/10163.0.0.1 to 163.63.255.254163.63.255.2554,194,302
14163.64.0.0/10163.64.0.1 to 163.127.255.254163.127.255.2554,194,302
15163.128.0.0/10163.128.0.1 to 163.191.255.254163.191.255.2554,194,302
16163.192.0.0/10163.192.0.1 to 163.255.255.254163.255.255.2554,194,302
17164.0.0.0/10164.0.0.1 to 164.63.255.254164.63.255.2554,194,302
18164.64.0.0/10164.64.0.1 to 164.127.255.254164.127.255.2554,194,302
19164.128.0.0/10164.128.0.1 to 164.191.255.254164.191.255.2554,194,302
20164.192.0.0/10164.192.0.1 to 164.255.255.254164.255.255.2554,194,302
21165.0.0.0/10165.0.0.1 to 165.63.255.254165.63.255.2554,194,302
22165.64.0.0/10165.64.0.1 to 165.127.255.254165.127.255.2554,194,302
23165.128.0.0/10165.128.0.1 to 165.191.255.254165.191.255.2554,194,302
24165.192.0.0/10165.192.0.1 to 165.255.255.254165.255.255.2554,194,302
25166.0.0.0/10166.0.0.1 to 166.63.255.254166.63.255.2554,194,302
26166.64.0.0/10166.64.0.1 to 166.127.255.254166.127.255.2554,194,302
27166.128.0.0/10166.128.0.1 to 166.191.255.254166.191.255.2554,194,302
28166.192.0.0/10166.192.0.1 to 166.255.255.254166.255.255.2554,194,302
29167.0.0.0/10167.0.0.1 to 167.63.255.254167.63.255.2554,194,302
30167.64.0.0/10167.64.0.1 to 167.127.255.254167.127.255.2554,194,302
31167.128.0.0/10167.128.0.1 to 167.191.255.254167.191.255.2554,194,302
32167.192.0.0/10167.192.0.1 to 167.255.255.254167.255.255.2554,194,302
33168.0.0.0/10168.0.0.1 to 168.63.255.254168.63.255.2554,194,302
34168.64.0.0/10168.64.0.1 to 168.127.255.254168.127.255.2554,194,302
35168.128.0.0/10168.128.0.1 to 168.191.255.254168.191.255.2554,194,302
36168.192.0.0/10168.192.0.1 to 168.255.255.254168.255.255.2554,194,302
37169.0.0.0/10169.0.0.1 to 169.63.255.254169.63.255.2554,194,302
38169.64.0.0/10169.64.0.1 to 169.127.255.254169.127.255.2554,194,302
39169.128.0.0/10169.128.0.1 to 169.191.255.254169.191.255.2554,194,302
40169.192.0.0/10169.192.0.1 to 169.255.255.254169.255.255.2554,194,302
41170.0.0.0/10170.0.0.1 to 170.63.255.254170.63.255.2554,194,302
42170.64.0.0/10170.64.0.1 to 170.127.255.254170.127.255.2554,194,302
43170.128.0.0/10170.128.0.1 to 170.191.255.254170.191.255.2554,194,302
44170.192.0.0/10170.192.0.1 to 170.255.255.254170.255.255.2554,194,302
45171.0.0.0/10171.0.0.1 to 171.63.255.254171.63.255.2554,194,302
46171.64.0.0/10171.64.0.1 to 171.127.255.254171.127.255.2554,194,302
47171.128.0.0/10171.128.0.1 to 171.191.255.254171.191.255.2554,194,302
48171.192.0.0/10171.192.0.1 to 171.255.255.254171.255.255.2554,194,302
49172.0.0.0/10172.0.0.1 to 172.63.255.254172.63.255.2554,194,302
50172.64.0.0/10172.64.0.1 to 172.127.255.254172.127.255.2554,194,302
51172.128.0.0/10172.128.0.1 to 172.191.255.254172.191.255.2554,194,302
52172.192.0.0/10172.192.0.1 to 172.255.255.254172.255.255.2554,194,302
53173.0.0.0/10173.0.0.1 to 173.63.255.254173.63.255.2554,194,302
54173.64.0.0/10173.64.0.1 to 173.127.255.254173.127.255.2554,194,302
55173.128.0.0/10173.128.0.1 to 173.191.255.254173.191.255.2554,194,302
56173.192.0.0/10173.192.0.1 to 173.255.255.254173.255.255.2554,194,302
57174.0.0.0/10174.0.0.1 to 174.63.255.254174.63.255.2554,194,302
58174.64.0.0/10174.64.0.1 to 174.127.255.254174.127.255.2554,194,302
59174.128.0.0/10174.128.0.1 to 174.191.255.254174.191.255.2554,194,302
60174.192.0.0/10174.192.0.1 to 174.255.255.254174.255.255.2554,194,302
61175.0.0.0/10175.0.0.1 to 175.63.255.254175.63.255.2554,194,302
62175.64.0.0/10175.64.0.1 to 175.127.255.254175.127.255.2554,194,302
63175.128.0.0/10175.128.0.1 to 175.191.255.254175.191.255.2554,194,302
64175.192.0.0/10175.192.0.1 to 175.255.255.254175.255.255.2554,194,302
65176.0.0.0/10176.0.0.1 to 176.63.255.254176.63.255.2554,194,302
66176.64.0.0/10176.64.0.1 to 176.127.255.254176.127.255.2554,194,302
67176.128.0.0/10176.128.0.1 to 176.191.255.254176.191.255.2554,194,302
68176.192.0.0/10176.192.0.1 to 176.255.255.254176.255.255.2554,194,302
69177.0.0.0/10177.0.0.1 to 177.63.255.254177.63.255.2554,194,302
70177.64.0.0/10177.64.0.1 to 177.127.255.254177.127.255.2554,194,302
71177.128.0.0/10177.128.0.1 to 177.191.255.254177.191.255.2554,194,302
72177.192.0.0/10177.192.0.1 to 177.255.255.254177.255.255.2554,194,302
73178.0.0.0/10178.0.0.1 to 178.63.255.254178.63.255.2554,194,302
74178.64.0.0/10178.64.0.1 to 178.127.255.254178.127.255.2554,194,302
75178.128.0.0/10178.128.0.1 to 178.191.255.254178.191.255.2554,194,302
76178.192.0.0/10178.192.0.1 to 178.255.255.254178.255.255.2554,194,302
77179.0.0.0/10179.0.0.1 to 179.63.255.254179.63.255.2554,194,302
78179.64.0.0/10179.64.0.1 to 179.127.255.254179.127.255.2554,194,302
79179.128.0.0/10179.128.0.1 to 179.191.255.254179.191.255.2554,194,302
80179.192.0.0/10179.192.0.1 to 179.255.255.254179.255.255.2554,194,302
81180.0.0.0/10180.0.0.1 to 180.63.255.254180.63.255.2554,194,302
82180.64.0.0/10180.64.0.1 to 180.127.255.254180.127.255.2554,194,302
83180.128.0.0/10180.128.0.1 to 180.191.255.254180.191.255.2554,194,302
84180.192.0.0/10180.192.0.1 to 180.255.255.254180.255.255.2554,194,302
85181.0.0.0/10181.0.0.1 to 181.63.255.254181.63.255.2554,194,302
86181.64.0.0/10181.64.0.1 to 181.127.255.254181.127.255.2554,194,302
87181.128.0.0/10181.128.0.1 to 181.191.255.254181.191.255.2554,194,302
88181.192.0.0/10181.192.0.1 to 181.255.255.254181.255.255.2554,194,302
89182.0.0.0/10182.0.0.1 to 182.63.255.254182.63.255.2554,194,302
90182.64.0.0/10182.64.0.1 to 182.127.255.254182.127.255.2554,194,302
91182.128.0.0/10182.128.0.1 to 182.191.255.254182.191.255.2554,194,302
92182.192.0.0/10182.192.0.1 to 182.255.255.254182.255.255.2554,194,302
93183.0.0.0/10183.0.0.1 to 183.63.255.254183.63.255.2554,194,302
94183.64.0.0/10183.64.0.1 to 183.127.255.254183.127.255.2554,194,302
95183.128.0.0/10183.128.0.1 to 183.191.255.254183.191.255.2554,194,302
96183.192.0.0/10183.192.0.1 to 183.255.255.254183.255.255.2554,194,302
97184.0.0.0/10184.0.0.1 to 184.63.255.254184.63.255.2554,194,302
98184.64.0.0/10184.64.0.1 to 184.127.255.254184.127.255.2554,194,302
99184.128.0.0/10184.128.0.1 to 184.191.255.254184.191.255.2554,194,302
100184.192.0.0/10184.192.0.1 to 184.255.255.254184.255.255.2554,194,302
101185.0.0.0/10185.0.0.1 to 185.63.255.254185.63.255.2554,194,302
102185.64.0.0/10185.64.0.1 to 185.127.255.254185.127.255.2554,194,302
103185.128.0.0/10185.128.0.1 to 185.191.255.254185.191.255.2554,194,302
104185.192.0.0/10185.192.0.1 to 185.255.255.254185.255.255.2554,194,302
105186.0.0.0/10186.0.0.1 to 186.63.255.254186.63.255.2554,194,302
106186.64.0.0/10186.64.0.1 to 186.127.255.254186.127.255.2554,194,302
107186.128.0.0/10186.128.0.1 to 186.191.255.254186.191.255.2554,194,302
108186.192.0.0/10186.192.0.1 to 186.255.255.254186.255.255.2554,194,302
109187.0.0.0/10187.0.0.1 to 187.63.255.254187.63.255.2554,194,302
110187.64.0.0/10187.64.0.1 to 187.127.255.254187.127.255.2554,194,302
111187.128.0.0/10187.128.0.1 to 187.191.255.254187.191.255.2554,194,302
112187.192.0.0/10187.192.0.1 to 187.255.255.254187.255.255.2554,194,302
113188.0.0.0/10188.0.0.1 to 188.63.255.254188.63.255.2554,194,302
114188.64.0.0/10188.64.0.1 to 188.127.255.254188.127.255.2554,194,302
115188.128.0.0/10188.128.0.1 to 188.191.255.254188.191.255.2554,194,302
116188.192.0.0/10188.192.0.1 to 188.255.255.254188.255.255.2554,194,302
117189.0.0.0/10189.0.0.1 to 189.63.255.254189.63.255.2554,194,302
118189.64.0.0/10189.64.0.1 to 189.127.255.254189.127.255.2554,194,302
119189.128.0.0/10189.128.0.1 to 189.191.255.254189.191.255.2554,194,302
120189.192.0.0/10189.192.0.1 to 189.255.255.254189.255.255.2554,194,302
121190.0.0.0/10190.0.0.1 to 190.63.255.254190.63.255.2554,194,302
122190.64.0.0/10190.64.0.1 to 190.127.255.254190.127.255.2554,194,302
123190.128.0.0/10190.128.0.1 to 190.191.255.254190.191.255.2554,194,302
124190.192.0.0/10190.192.0.1 to 190.255.255.254190.255.255.2554,194,302
125191.0.0.0/10191.0.0.1 to 191.63.255.254191.63.255.2554,194,302
126191.64.0.0/10191.64.0.1 to 191.127.255.254191.127.255.2554,194,302
127191.128.0.0/10191.128.0.1 to 191.191.255.254191.191.255.2554,194,302
128191.192.0.0/10191.192.0.1 to 191.255.255.254191.255.255.2554,194,302

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.