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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.

Network234.128.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
234.128.0.0
Broadcast address
234.191.255.255
First usable
234.128.0.1
Last usable
234.191.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EA800000 · Integer 3934257152 to 3938451455
Reverse DNS zones
128.234.in-addr.arpa
129.234.in-addr.arpa
130.234.in-addr.arpa
131.234.in-addr.arpa
132.234.in-addr.arpa
133.234.in-addr.arpa
134.234.in-addr.arpa
135.234.in-addr.arpa
136.234.in-addr.arpa
137.234.in-addr.arpa
138.234.in-addr.arpa
139.234.in-addr.arpa
140.234.in-addr.arpa
141.234.in-addr.arpa
142.234.in-addr.arpa
143.234.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11101010.10000000.00000000.00000000234.128.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11101010.10000000.00000000.00000000234.128.0.0
Broadcast11101010.10111111.11111111.11111111234.191.255.255
Split into smaller subnets/17
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

234.128.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1234.128.0.0/17234.128.0.1 to 234.128.127.254234.128.127.25532,766
2234.128.128.0/17234.128.128.1 to 234.128.255.254234.128.255.25532,766
3234.129.0.0/17234.129.0.1 to 234.129.127.254234.129.127.25532,766
4234.129.128.0/17234.129.128.1 to 234.129.255.254234.129.255.25532,766
5234.130.0.0/17234.130.0.1 to 234.130.127.254234.130.127.25532,766
6234.130.128.0/17234.130.128.1 to 234.130.255.254234.130.255.25532,766
7234.131.0.0/17234.131.0.1 to 234.131.127.254234.131.127.25532,766
8234.131.128.0/17234.131.128.1 to 234.131.255.254234.131.255.25532,766
9234.132.0.0/17234.132.0.1 to 234.132.127.254234.132.127.25532,766
10234.132.128.0/17234.132.128.1 to 234.132.255.254234.132.255.25532,766
11234.133.0.0/17234.133.0.1 to 234.133.127.254234.133.127.25532,766
12234.133.128.0/17234.133.128.1 to 234.133.255.254234.133.255.25532,766
13234.134.0.0/17234.134.0.1 to 234.134.127.254234.134.127.25532,766
14234.134.128.0/17234.134.128.1 to 234.134.255.254234.134.255.25532,766
15234.135.0.0/17234.135.0.1 to 234.135.127.254234.135.127.25532,766
16234.135.128.0/17234.135.128.1 to 234.135.255.254234.135.255.25532,766
17234.136.0.0/17234.136.0.1 to 234.136.127.254234.136.127.25532,766
18234.136.128.0/17234.136.128.1 to 234.136.255.254234.136.255.25532,766
19234.137.0.0/17234.137.0.1 to 234.137.127.254234.137.127.25532,766
20234.137.128.0/17234.137.128.1 to 234.137.255.254234.137.255.25532,766
21234.138.0.0/17234.138.0.1 to 234.138.127.254234.138.127.25532,766
22234.138.128.0/17234.138.128.1 to 234.138.255.254234.138.255.25532,766
23234.139.0.0/17234.139.0.1 to 234.139.127.254234.139.127.25532,766
24234.139.128.0/17234.139.128.1 to 234.139.255.254234.139.255.25532,766
25234.140.0.0/17234.140.0.1 to 234.140.127.254234.140.127.25532,766
26234.140.128.0/17234.140.128.1 to 234.140.255.254234.140.255.25532,766
27234.141.0.0/17234.141.0.1 to 234.141.127.254234.141.127.25532,766
28234.141.128.0/17234.141.128.1 to 234.141.255.254234.141.255.25532,766
29234.142.0.0/17234.142.0.1 to 234.142.127.254234.142.127.25532,766
30234.142.128.0/17234.142.128.1 to 234.142.255.254234.142.255.25532,766
31234.143.0.0/17234.143.0.1 to 234.143.127.254234.143.127.25532,766
32234.143.128.0/17234.143.128.1 to 234.143.255.254234.143.255.25532,766
33234.144.0.0/17234.144.0.1 to 234.144.127.254234.144.127.25532,766
34234.144.128.0/17234.144.128.1 to 234.144.255.254234.144.255.25532,766
35234.145.0.0/17234.145.0.1 to 234.145.127.254234.145.127.25532,766
36234.145.128.0/17234.145.128.1 to 234.145.255.254234.145.255.25532,766
37234.146.0.0/17234.146.0.1 to 234.146.127.254234.146.127.25532,766
38234.146.128.0/17234.146.128.1 to 234.146.255.254234.146.255.25532,766
39234.147.0.0/17234.147.0.1 to 234.147.127.254234.147.127.25532,766
40234.147.128.0/17234.147.128.1 to 234.147.255.254234.147.255.25532,766
41234.148.0.0/17234.148.0.1 to 234.148.127.254234.148.127.25532,766
42234.148.128.0/17234.148.128.1 to 234.148.255.254234.148.255.25532,766
43234.149.0.0/17234.149.0.1 to 234.149.127.254234.149.127.25532,766
44234.149.128.0/17234.149.128.1 to 234.149.255.254234.149.255.25532,766
45234.150.0.0/17234.150.0.1 to 234.150.127.254234.150.127.25532,766
46234.150.128.0/17234.150.128.1 to 234.150.255.254234.150.255.25532,766
47234.151.0.0/17234.151.0.1 to 234.151.127.254234.151.127.25532,766
48234.151.128.0/17234.151.128.1 to 234.151.255.254234.151.255.25532,766
49234.152.0.0/17234.152.0.1 to 234.152.127.254234.152.127.25532,766
50234.152.128.0/17234.152.128.1 to 234.152.255.254234.152.255.25532,766
51234.153.0.0/17234.153.0.1 to 234.153.127.254234.153.127.25532,766
52234.153.128.0/17234.153.128.1 to 234.153.255.254234.153.255.25532,766
53234.154.0.0/17234.154.0.1 to 234.154.127.254234.154.127.25532,766
54234.154.128.0/17234.154.128.1 to 234.154.255.254234.154.255.25532,766
55234.155.0.0/17234.155.0.1 to 234.155.127.254234.155.127.25532,766
56234.155.128.0/17234.155.128.1 to 234.155.255.254234.155.255.25532,766
57234.156.0.0/17234.156.0.1 to 234.156.127.254234.156.127.25532,766
58234.156.128.0/17234.156.128.1 to 234.156.255.254234.156.255.25532,766
59234.157.0.0/17234.157.0.1 to 234.157.127.254234.157.127.25532,766
60234.157.128.0/17234.157.128.1 to 234.157.255.254234.157.255.25532,766
61234.158.0.0/17234.158.0.1 to 234.158.127.254234.158.127.25532,766
62234.158.128.0/17234.158.128.1 to 234.158.255.254234.158.255.25532,766
63234.159.0.0/17234.159.0.1 to 234.159.127.254234.159.127.25532,766
64234.159.128.0/17234.159.128.1 to 234.159.255.254234.159.255.25532,766
65234.160.0.0/17234.160.0.1 to 234.160.127.254234.160.127.25532,766
66234.160.128.0/17234.160.128.1 to 234.160.255.254234.160.255.25532,766
67234.161.0.0/17234.161.0.1 to 234.161.127.254234.161.127.25532,766
68234.161.128.0/17234.161.128.1 to 234.161.255.254234.161.255.25532,766
69234.162.0.0/17234.162.0.1 to 234.162.127.254234.162.127.25532,766
70234.162.128.0/17234.162.128.1 to 234.162.255.254234.162.255.25532,766
71234.163.0.0/17234.163.0.1 to 234.163.127.254234.163.127.25532,766
72234.163.128.0/17234.163.128.1 to 234.163.255.254234.163.255.25532,766
73234.164.0.0/17234.164.0.1 to 234.164.127.254234.164.127.25532,766
74234.164.128.0/17234.164.128.1 to 234.164.255.254234.164.255.25532,766
75234.165.0.0/17234.165.0.1 to 234.165.127.254234.165.127.25532,766
76234.165.128.0/17234.165.128.1 to 234.165.255.254234.165.255.25532,766
77234.166.0.0/17234.166.0.1 to 234.166.127.254234.166.127.25532,766
78234.166.128.0/17234.166.128.1 to 234.166.255.254234.166.255.25532,766
79234.167.0.0/17234.167.0.1 to 234.167.127.254234.167.127.25532,766
80234.167.128.0/17234.167.128.1 to 234.167.255.254234.167.255.25532,766
81234.168.0.0/17234.168.0.1 to 234.168.127.254234.168.127.25532,766
82234.168.128.0/17234.168.128.1 to 234.168.255.254234.168.255.25532,766
83234.169.0.0/17234.169.0.1 to 234.169.127.254234.169.127.25532,766
84234.169.128.0/17234.169.128.1 to 234.169.255.254234.169.255.25532,766
85234.170.0.0/17234.170.0.1 to 234.170.127.254234.170.127.25532,766
86234.170.128.0/17234.170.128.1 to 234.170.255.254234.170.255.25532,766
87234.171.0.0/17234.171.0.1 to 234.171.127.254234.171.127.25532,766
88234.171.128.0/17234.171.128.1 to 234.171.255.254234.171.255.25532,766
89234.172.0.0/17234.172.0.1 to 234.172.127.254234.172.127.25532,766
90234.172.128.0/17234.172.128.1 to 234.172.255.254234.172.255.25532,766
91234.173.0.0/17234.173.0.1 to 234.173.127.254234.173.127.25532,766
92234.173.128.0/17234.173.128.1 to 234.173.255.254234.173.255.25532,766
93234.174.0.0/17234.174.0.1 to 234.174.127.254234.174.127.25532,766
94234.174.128.0/17234.174.128.1 to 234.174.255.254234.174.255.25532,766
95234.175.0.0/17234.175.0.1 to 234.175.127.254234.175.127.25532,766
96234.175.128.0/17234.175.128.1 to 234.175.255.254234.175.255.25532,766
97234.176.0.0/17234.176.0.1 to 234.176.127.254234.176.127.25532,766
98234.176.128.0/17234.176.128.1 to 234.176.255.254234.176.255.25532,766
99234.177.0.0/17234.177.0.1 to 234.177.127.254234.177.127.25532,766
100234.177.128.0/17234.177.128.1 to 234.177.255.254234.177.255.25532,766
101234.178.0.0/17234.178.0.1 to 234.178.127.254234.178.127.25532,766
102234.178.128.0/17234.178.128.1 to 234.178.255.254234.178.255.25532,766
103234.179.0.0/17234.179.0.1 to 234.179.127.254234.179.127.25532,766
104234.179.128.0/17234.179.128.1 to 234.179.255.254234.179.255.25532,766
105234.180.0.0/17234.180.0.1 to 234.180.127.254234.180.127.25532,766
106234.180.128.0/17234.180.128.1 to 234.180.255.254234.180.255.25532,766
107234.181.0.0/17234.181.0.1 to 234.181.127.254234.181.127.25532,766
108234.181.128.0/17234.181.128.1 to 234.181.255.254234.181.255.25532,766
109234.182.0.0/17234.182.0.1 to 234.182.127.254234.182.127.25532,766
110234.182.128.0/17234.182.128.1 to 234.182.255.254234.182.255.25532,766
111234.183.0.0/17234.183.0.1 to 234.183.127.254234.183.127.25532,766
112234.183.128.0/17234.183.128.1 to 234.183.255.254234.183.255.25532,766
113234.184.0.0/17234.184.0.1 to 234.184.127.254234.184.127.25532,766
114234.184.128.0/17234.184.128.1 to 234.184.255.254234.184.255.25532,766
115234.185.0.0/17234.185.0.1 to 234.185.127.254234.185.127.25532,766
116234.185.128.0/17234.185.128.1 to 234.185.255.254234.185.255.25532,766
117234.186.0.0/17234.186.0.1 to 234.186.127.254234.186.127.25532,766
118234.186.128.0/17234.186.128.1 to 234.186.255.254234.186.255.25532,766
119234.187.0.0/17234.187.0.1 to 234.187.127.254234.187.127.25532,766
120234.187.128.0/17234.187.128.1 to 234.187.255.254234.187.255.25532,766
121234.188.0.0/17234.188.0.1 to 234.188.127.254234.188.127.25532,766
122234.188.128.0/17234.188.128.1 to 234.188.255.254234.188.255.25532,766
123234.189.0.0/17234.189.0.1 to 234.189.127.254234.189.127.25532,766
124234.189.128.0/17234.189.128.1 to 234.189.255.254234.189.255.25532,766
125234.190.0.0/17234.190.0.1 to 234.190.127.254234.190.127.25532,766
126234.190.128.0/17234.190.128.1 to 234.190.255.254234.190.255.25532,766
127234.191.0.0/17234.191.0.1 to 234.191.127.254234.191.127.25532,766
128234.191.128.0/17234.191.128.1 to 234.191.255.254234.191.255.25532,766

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.