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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.

Network153.2.192.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
153.2.192.0
Broadcast address
153.2.255.255
First usable
153.2.192.1
Last usable
153.2.255.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
B (default /16)
As numbers
Hex 9902C000 · Integer 2567094272 to 2567110655
Reverse DNS zones
192.2.153.in-addr.arpa
193.2.153.in-addr.arpa
194.2.153.in-addr.arpa
195.2.153.in-addr.arpa
196.2.153.in-addr.arpa
197.2.153.in-addr.arpa
198.2.153.in-addr.arpa
199.2.153.in-addr.arpa
200.2.153.in-addr.arpa
201.2.153.in-addr.arpa
202.2.153.in-addr.arpa
203.2.153.in-addr.arpa
204.2.153.in-addr.arpa
205.2.153.in-addr.arpa
206.2.153.in-addr.arpa
207.2.153.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10011001.00000010.11000000.00000000153.2.192.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network10011001.00000010.11000000.00000000153.2.192.0
Broadcast10011001.00000010.11111111.11111111153.2.255.255
Split into smaller subnets/25
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

153.2.192.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1153.2.192.0/25153.2.192.1 to 153.2.192.126153.2.192.127126
2153.2.192.128/25153.2.192.129 to 153.2.192.254153.2.192.255126
3153.2.193.0/25153.2.193.1 to 153.2.193.126153.2.193.127126
4153.2.193.128/25153.2.193.129 to 153.2.193.254153.2.193.255126
5153.2.194.0/25153.2.194.1 to 153.2.194.126153.2.194.127126
6153.2.194.128/25153.2.194.129 to 153.2.194.254153.2.194.255126
7153.2.195.0/25153.2.195.1 to 153.2.195.126153.2.195.127126
8153.2.195.128/25153.2.195.129 to 153.2.195.254153.2.195.255126
9153.2.196.0/25153.2.196.1 to 153.2.196.126153.2.196.127126
10153.2.196.128/25153.2.196.129 to 153.2.196.254153.2.196.255126
11153.2.197.0/25153.2.197.1 to 153.2.197.126153.2.197.127126
12153.2.197.128/25153.2.197.129 to 153.2.197.254153.2.197.255126
13153.2.198.0/25153.2.198.1 to 153.2.198.126153.2.198.127126
14153.2.198.128/25153.2.198.129 to 153.2.198.254153.2.198.255126
15153.2.199.0/25153.2.199.1 to 153.2.199.126153.2.199.127126
16153.2.199.128/25153.2.199.129 to 153.2.199.254153.2.199.255126
17153.2.200.0/25153.2.200.1 to 153.2.200.126153.2.200.127126
18153.2.200.128/25153.2.200.129 to 153.2.200.254153.2.200.255126
19153.2.201.0/25153.2.201.1 to 153.2.201.126153.2.201.127126
20153.2.201.128/25153.2.201.129 to 153.2.201.254153.2.201.255126
21153.2.202.0/25153.2.202.1 to 153.2.202.126153.2.202.127126
22153.2.202.128/25153.2.202.129 to 153.2.202.254153.2.202.255126
23153.2.203.0/25153.2.203.1 to 153.2.203.126153.2.203.127126
24153.2.203.128/25153.2.203.129 to 153.2.203.254153.2.203.255126
25153.2.204.0/25153.2.204.1 to 153.2.204.126153.2.204.127126
26153.2.204.128/25153.2.204.129 to 153.2.204.254153.2.204.255126
27153.2.205.0/25153.2.205.1 to 153.2.205.126153.2.205.127126
28153.2.205.128/25153.2.205.129 to 153.2.205.254153.2.205.255126
29153.2.206.0/25153.2.206.1 to 153.2.206.126153.2.206.127126
30153.2.206.128/25153.2.206.129 to 153.2.206.254153.2.206.255126
31153.2.207.0/25153.2.207.1 to 153.2.207.126153.2.207.127126
32153.2.207.128/25153.2.207.129 to 153.2.207.254153.2.207.255126
33153.2.208.0/25153.2.208.1 to 153.2.208.126153.2.208.127126
34153.2.208.128/25153.2.208.129 to 153.2.208.254153.2.208.255126
35153.2.209.0/25153.2.209.1 to 153.2.209.126153.2.209.127126
36153.2.209.128/25153.2.209.129 to 153.2.209.254153.2.209.255126
37153.2.210.0/25153.2.210.1 to 153.2.210.126153.2.210.127126
38153.2.210.128/25153.2.210.129 to 153.2.210.254153.2.210.255126
39153.2.211.0/25153.2.211.1 to 153.2.211.126153.2.211.127126
40153.2.211.128/25153.2.211.129 to 153.2.211.254153.2.211.255126
41153.2.212.0/25153.2.212.1 to 153.2.212.126153.2.212.127126
42153.2.212.128/25153.2.212.129 to 153.2.212.254153.2.212.255126
43153.2.213.0/25153.2.213.1 to 153.2.213.126153.2.213.127126
44153.2.213.128/25153.2.213.129 to 153.2.213.254153.2.213.255126
45153.2.214.0/25153.2.214.1 to 153.2.214.126153.2.214.127126
46153.2.214.128/25153.2.214.129 to 153.2.214.254153.2.214.255126
47153.2.215.0/25153.2.215.1 to 153.2.215.126153.2.215.127126
48153.2.215.128/25153.2.215.129 to 153.2.215.254153.2.215.255126
49153.2.216.0/25153.2.216.1 to 153.2.216.126153.2.216.127126
50153.2.216.128/25153.2.216.129 to 153.2.216.254153.2.216.255126
51153.2.217.0/25153.2.217.1 to 153.2.217.126153.2.217.127126
52153.2.217.128/25153.2.217.129 to 153.2.217.254153.2.217.255126
53153.2.218.0/25153.2.218.1 to 153.2.218.126153.2.218.127126
54153.2.218.128/25153.2.218.129 to 153.2.218.254153.2.218.255126
55153.2.219.0/25153.2.219.1 to 153.2.219.126153.2.219.127126
56153.2.219.128/25153.2.219.129 to 153.2.219.254153.2.219.255126
57153.2.220.0/25153.2.220.1 to 153.2.220.126153.2.220.127126
58153.2.220.128/25153.2.220.129 to 153.2.220.254153.2.220.255126
59153.2.221.0/25153.2.221.1 to 153.2.221.126153.2.221.127126
60153.2.221.128/25153.2.221.129 to 153.2.221.254153.2.221.255126
61153.2.222.0/25153.2.222.1 to 153.2.222.126153.2.222.127126
62153.2.222.128/25153.2.222.129 to 153.2.222.254153.2.222.255126
63153.2.223.0/25153.2.223.1 to 153.2.223.126153.2.223.127126
64153.2.223.128/25153.2.223.129 to 153.2.223.254153.2.223.255126
65153.2.224.0/25153.2.224.1 to 153.2.224.126153.2.224.127126
66153.2.224.128/25153.2.224.129 to 153.2.224.254153.2.224.255126
67153.2.225.0/25153.2.225.1 to 153.2.225.126153.2.225.127126
68153.2.225.128/25153.2.225.129 to 153.2.225.254153.2.225.255126
69153.2.226.0/25153.2.226.1 to 153.2.226.126153.2.226.127126
70153.2.226.128/25153.2.226.129 to 153.2.226.254153.2.226.255126
71153.2.227.0/25153.2.227.1 to 153.2.227.126153.2.227.127126
72153.2.227.128/25153.2.227.129 to 153.2.227.254153.2.227.255126
73153.2.228.0/25153.2.228.1 to 153.2.228.126153.2.228.127126
74153.2.228.128/25153.2.228.129 to 153.2.228.254153.2.228.255126
75153.2.229.0/25153.2.229.1 to 153.2.229.126153.2.229.127126
76153.2.229.128/25153.2.229.129 to 153.2.229.254153.2.229.255126
77153.2.230.0/25153.2.230.1 to 153.2.230.126153.2.230.127126
78153.2.230.128/25153.2.230.129 to 153.2.230.254153.2.230.255126
79153.2.231.0/25153.2.231.1 to 153.2.231.126153.2.231.127126
80153.2.231.128/25153.2.231.129 to 153.2.231.254153.2.231.255126
81153.2.232.0/25153.2.232.1 to 153.2.232.126153.2.232.127126
82153.2.232.128/25153.2.232.129 to 153.2.232.254153.2.232.255126
83153.2.233.0/25153.2.233.1 to 153.2.233.126153.2.233.127126
84153.2.233.128/25153.2.233.129 to 153.2.233.254153.2.233.255126
85153.2.234.0/25153.2.234.1 to 153.2.234.126153.2.234.127126
86153.2.234.128/25153.2.234.129 to 153.2.234.254153.2.234.255126
87153.2.235.0/25153.2.235.1 to 153.2.235.126153.2.235.127126
88153.2.235.128/25153.2.235.129 to 153.2.235.254153.2.235.255126
89153.2.236.0/25153.2.236.1 to 153.2.236.126153.2.236.127126
90153.2.236.128/25153.2.236.129 to 153.2.236.254153.2.236.255126
91153.2.237.0/25153.2.237.1 to 153.2.237.126153.2.237.127126
92153.2.237.128/25153.2.237.129 to 153.2.237.254153.2.237.255126
93153.2.238.0/25153.2.238.1 to 153.2.238.126153.2.238.127126
94153.2.238.128/25153.2.238.129 to 153.2.238.254153.2.238.255126
95153.2.239.0/25153.2.239.1 to 153.2.239.126153.2.239.127126
96153.2.239.128/25153.2.239.129 to 153.2.239.254153.2.239.255126
97153.2.240.0/25153.2.240.1 to 153.2.240.126153.2.240.127126
98153.2.240.128/25153.2.240.129 to 153.2.240.254153.2.240.255126
99153.2.241.0/25153.2.241.1 to 153.2.241.126153.2.241.127126
100153.2.241.128/25153.2.241.129 to 153.2.241.254153.2.241.255126
101153.2.242.0/25153.2.242.1 to 153.2.242.126153.2.242.127126
102153.2.242.128/25153.2.242.129 to 153.2.242.254153.2.242.255126
103153.2.243.0/25153.2.243.1 to 153.2.243.126153.2.243.127126
104153.2.243.128/25153.2.243.129 to 153.2.243.254153.2.243.255126
105153.2.244.0/25153.2.244.1 to 153.2.244.126153.2.244.127126
106153.2.244.128/25153.2.244.129 to 153.2.244.254153.2.244.255126
107153.2.245.0/25153.2.245.1 to 153.2.245.126153.2.245.127126
108153.2.245.128/25153.2.245.129 to 153.2.245.254153.2.245.255126
109153.2.246.0/25153.2.246.1 to 153.2.246.126153.2.246.127126
110153.2.246.128/25153.2.246.129 to 153.2.246.254153.2.246.255126
111153.2.247.0/25153.2.247.1 to 153.2.247.126153.2.247.127126
112153.2.247.128/25153.2.247.129 to 153.2.247.254153.2.247.255126
113153.2.248.0/25153.2.248.1 to 153.2.248.126153.2.248.127126
114153.2.248.128/25153.2.248.129 to 153.2.248.254153.2.248.255126
115153.2.249.0/25153.2.249.1 to 153.2.249.126153.2.249.127126
116153.2.249.128/25153.2.249.129 to 153.2.249.254153.2.249.255126
117153.2.250.0/25153.2.250.1 to 153.2.250.126153.2.250.127126
118153.2.250.128/25153.2.250.129 to 153.2.250.254153.2.250.255126
119153.2.251.0/25153.2.251.1 to 153.2.251.126153.2.251.127126
120153.2.251.128/25153.2.251.129 to 153.2.251.254153.2.251.255126
121153.2.252.0/25153.2.252.1 to 153.2.252.126153.2.252.127126
122153.2.252.128/25153.2.252.129 to 153.2.252.254153.2.252.255126
123153.2.253.0/25153.2.253.1 to 153.2.253.126153.2.253.127126
124153.2.253.128/25153.2.253.129 to 153.2.253.254153.2.253.255126
125153.2.254.0/25153.2.254.1 to 153.2.254.126153.2.254.127126
126153.2.254.128/25153.2.254.129 to 153.2.254.254153.2.254.255126
127153.2.255.0/25153.2.255.1 to 153.2.255.126153.2.255.127126
128153.2.255.128/25153.2.255.129 to 153.2.255.254153.2.255.255126

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.