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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.

Network198.18.192.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
198.18.192.0
Broadcast address
198.18.255.255
First usable
198.18.192.1
Last usable
198.18.255.254
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
Benchmarking 198.18.0.0/15
Network equipment testing (RFC 2544)
Old class
C (default /24)
As numbers
Hex C612C000 · Integer 3323117568 to 3323133951
Reverse DNS zones
192.18.198.in-addr.arpa
193.18.198.in-addr.arpa
194.18.198.in-addr.arpa
195.18.198.in-addr.arpa
196.18.198.in-addr.arpa
197.18.198.in-addr.arpa
198.18.198.in-addr.arpa
199.18.198.in-addr.arpa
200.18.198.in-addr.arpa
201.18.198.in-addr.arpa
202.18.198.in-addr.arpa
203.18.198.in-addr.arpa
204.18.198.in-addr.arpa
205.18.198.in-addr.arpa
206.18.198.in-addr.arpa
207.18.198.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
Address11000110.00010010.11000000.00000000198.18.192.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network11000110.00010010.11000000.00000000198.18.192.0
Broadcast11000110.00010010.11111111.11111111198.18.255.255
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)

198.18.192.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1198.18.192.0/25198.18.192.1 to 198.18.192.126198.18.192.127126
2198.18.192.128/25198.18.192.129 to 198.18.192.254198.18.192.255126
3198.18.193.0/25198.18.193.1 to 198.18.193.126198.18.193.127126
4198.18.193.128/25198.18.193.129 to 198.18.193.254198.18.193.255126
5198.18.194.0/25198.18.194.1 to 198.18.194.126198.18.194.127126
6198.18.194.128/25198.18.194.129 to 198.18.194.254198.18.194.255126
7198.18.195.0/25198.18.195.1 to 198.18.195.126198.18.195.127126
8198.18.195.128/25198.18.195.129 to 198.18.195.254198.18.195.255126
9198.18.196.0/25198.18.196.1 to 198.18.196.126198.18.196.127126
10198.18.196.128/25198.18.196.129 to 198.18.196.254198.18.196.255126
11198.18.197.0/25198.18.197.1 to 198.18.197.126198.18.197.127126
12198.18.197.128/25198.18.197.129 to 198.18.197.254198.18.197.255126
13198.18.198.0/25198.18.198.1 to 198.18.198.126198.18.198.127126
14198.18.198.128/25198.18.198.129 to 198.18.198.254198.18.198.255126
15198.18.199.0/25198.18.199.1 to 198.18.199.126198.18.199.127126
16198.18.199.128/25198.18.199.129 to 198.18.199.254198.18.199.255126
17198.18.200.0/25198.18.200.1 to 198.18.200.126198.18.200.127126
18198.18.200.128/25198.18.200.129 to 198.18.200.254198.18.200.255126
19198.18.201.0/25198.18.201.1 to 198.18.201.126198.18.201.127126
20198.18.201.128/25198.18.201.129 to 198.18.201.254198.18.201.255126
21198.18.202.0/25198.18.202.1 to 198.18.202.126198.18.202.127126
22198.18.202.128/25198.18.202.129 to 198.18.202.254198.18.202.255126
23198.18.203.0/25198.18.203.1 to 198.18.203.126198.18.203.127126
24198.18.203.128/25198.18.203.129 to 198.18.203.254198.18.203.255126
25198.18.204.0/25198.18.204.1 to 198.18.204.126198.18.204.127126
26198.18.204.128/25198.18.204.129 to 198.18.204.254198.18.204.255126
27198.18.205.0/25198.18.205.1 to 198.18.205.126198.18.205.127126
28198.18.205.128/25198.18.205.129 to 198.18.205.254198.18.205.255126
29198.18.206.0/25198.18.206.1 to 198.18.206.126198.18.206.127126
30198.18.206.128/25198.18.206.129 to 198.18.206.254198.18.206.255126
31198.18.207.0/25198.18.207.1 to 198.18.207.126198.18.207.127126
32198.18.207.128/25198.18.207.129 to 198.18.207.254198.18.207.255126
33198.18.208.0/25198.18.208.1 to 198.18.208.126198.18.208.127126
34198.18.208.128/25198.18.208.129 to 198.18.208.254198.18.208.255126
35198.18.209.0/25198.18.209.1 to 198.18.209.126198.18.209.127126
36198.18.209.128/25198.18.209.129 to 198.18.209.254198.18.209.255126
37198.18.210.0/25198.18.210.1 to 198.18.210.126198.18.210.127126
38198.18.210.128/25198.18.210.129 to 198.18.210.254198.18.210.255126
39198.18.211.0/25198.18.211.1 to 198.18.211.126198.18.211.127126
40198.18.211.128/25198.18.211.129 to 198.18.211.254198.18.211.255126
41198.18.212.0/25198.18.212.1 to 198.18.212.126198.18.212.127126
42198.18.212.128/25198.18.212.129 to 198.18.212.254198.18.212.255126
43198.18.213.0/25198.18.213.1 to 198.18.213.126198.18.213.127126
44198.18.213.128/25198.18.213.129 to 198.18.213.254198.18.213.255126
45198.18.214.0/25198.18.214.1 to 198.18.214.126198.18.214.127126
46198.18.214.128/25198.18.214.129 to 198.18.214.254198.18.214.255126
47198.18.215.0/25198.18.215.1 to 198.18.215.126198.18.215.127126
48198.18.215.128/25198.18.215.129 to 198.18.215.254198.18.215.255126
49198.18.216.0/25198.18.216.1 to 198.18.216.126198.18.216.127126
50198.18.216.128/25198.18.216.129 to 198.18.216.254198.18.216.255126
51198.18.217.0/25198.18.217.1 to 198.18.217.126198.18.217.127126
52198.18.217.128/25198.18.217.129 to 198.18.217.254198.18.217.255126
53198.18.218.0/25198.18.218.1 to 198.18.218.126198.18.218.127126
54198.18.218.128/25198.18.218.129 to 198.18.218.254198.18.218.255126
55198.18.219.0/25198.18.219.1 to 198.18.219.126198.18.219.127126
56198.18.219.128/25198.18.219.129 to 198.18.219.254198.18.219.255126
57198.18.220.0/25198.18.220.1 to 198.18.220.126198.18.220.127126
58198.18.220.128/25198.18.220.129 to 198.18.220.254198.18.220.255126
59198.18.221.0/25198.18.221.1 to 198.18.221.126198.18.221.127126
60198.18.221.128/25198.18.221.129 to 198.18.221.254198.18.221.255126
61198.18.222.0/25198.18.222.1 to 198.18.222.126198.18.222.127126
62198.18.222.128/25198.18.222.129 to 198.18.222.254198.18.222.255126
63198.18.223.0/25198.18.223.1 to 198.18.223.126198.18.223.127126
64198.18.223.128/25198.18.223.129 to 198.18.223.254198.18.223.255126
65198.18.224.0/25198.18.224.1 to 198.18.224.126198.18.224.127126
66198.18.224.128/25198.18.224.129 to 198.18.224.254198.18.224.255126
67198.18.225.0/25198.18.225.1 to 198.18.225.126198.18.225.127126
68198.18.225.128/25198.18.225.129 to 198.18.225.254198.18.225.255126
69198.18.226.0/25198.18.226.1 to 198.18.226.126198.18.226.127126
70198.18.226.128/25198.18.226.129 to 198.18.226.254198.18.226.255126
71198.18.227.0/25198.18.227.1 to 198.18.227.126198.18.227.127126
72198.18.227.128/25198.18.227.129 to 198.18.227.254198.18.227.255126
73198.18.228.0/25198.18.228.1 to 198.18.228.126198.18.228.127126
74198.18.228.128/25198.18.228.129 to 198.18.228.254198.18.228.255126
75198.18.229.0/25198.18.229.1 to 198.18.229.126198.18.229.127126
76198.18.229.128/25198.18.229.129 to 198.18.229.254198.18.229.255126
77198.18.230.0/25198.18.230.1 to 198.18.230.126198.18.230.127126
78198.18.230.128/25198.18.230.129 to 198.18.230.254198.18.230.255126
79198.18.231.0/25198.18.231.1 to 198.18.231.126198.18.231.127126
80198.18.231.128/25198.18.231.129 to 198.18.231.254198.18.231.255126
81198.18.232.0/25198.18.232.1 to 198.18.232.126198.18.232.127126
82198.18.232.128/25198.18.232.129 to 198.18.232.254198.18.232.255126
83198.18.233.0/25198.18.233.1 to 198.18.233.126198.18.233.127126
84198.18.233.128/25198.18.233.129 to 198.18.233.254198.18.233.255126
85198.18.234.0/25198.18.234.1 to 198.18.234.126198.18.234.127126
86198.18.234.128/25198.18.234.129 to 198.18.234.254198.18.234.255126
87198.18.235.0/25198.18.235.1 to 198.18.235.126198.18.235.127126
88198.18.235.128/25198.18.235.129 to 198.18.235.254198.18.235.255126
89198.18.236.0/25198.18.236.1 to 198.18.236.126198.18.236.127126
90198.18.236.128/25198.18.236.129 to 198.18.236.254198.18.236.255126
91198.18.237.0/25198.18.237.1 to 198.18.237.126198.18.237.127126
92198.18.237.128/25198.18.237.129 to 198.18.237.254198.18.237.255126
93198.18.238.0/25198.18.238.1 to 198.18.238.126198.18.238.127126
94198.18.238.128/25198.18.238.129 to 198.18.238.254198.18.238.255126
95198.18.239.0/25198.18.239.1 to 198.18.239.126198.18.239.127126
96198.18.239.128/25198.18.239.129 to 198.18.239.254198.18.239.255126
97198.18.240.0/25198.18.240.1 to 198.18.240.126198.18.240.127126
98198.18.240.128/25198.18.240.129 to 198.18.240.254198.18.240.255126
99198.18.241.0/25198.18.241.1 to 198.18.241.126198.18.241.127126
100198.18.241.128/25198.18.241.129 to 198.18.241.254198.18.241.255126
101198.18.242.0/25198.18.242.1 to 198.18.242.126198.18.242.127126
102198.18.242.128/25198.18.242.129 to 198.18.242.254198.18.242.255126
103198.18.243.0/25198.18.243.1 to 198.18.243.126198.18.243.127126
104198.18.243.128/25198.18.243.129 to 198.18.243.254198.18.243.255126
105198.18.244.0/25198.18.244.1 to 198.18.244.126198.18.244.127126
106198.18.244.128/25198.18.244.129 to 198.18.244.254198.18.244.255126
107198.18.245.0/25198.18.245.1 to 198.18.245.126198.18.245.127126
108198.18.245.128/25198.18.245.129 to 198.18.245.254198.18.245.255126
109198.18.246.0/25198.18.246.1 to 198.18.246.126198.18.246.127126
110198.18.246.128/25198.18.246.129 to 198.18.246.254198.18.246.255126
111198.18.247.0/25198.18.247.1 to 198.18.247.126198.18.247.127126
112198.18.247.128/25198.18.247.129 to 198.18.247.254198.18.247.255126
113198.18.248.0/25198.18.248.1 to 198.18.248.126198.18.248.127126
114198.18.248.128/25198.18.248.129 to 198.18.248.254198.18.248.255126
115198.18.249.0/25198.18.249.1 to 198.18.249.126198.18.249.127126
116198.18.249.128/25198.18.249.129 to 198.18.249.254198.18.249.255126
117198.18.250.0/25198.18.250.1 to 198.18.250.126198.18.250.127126
118198.18.250.128/25198.18.250.129 to 198.18.250.254198.18.250.255126
119198.18.251.0/25198.18.251.1 to 198.18.251.126198.18.251.127126
120198.18.251.128/25198.18.251.129 to 198.18.251.254198.18.251.255126
121198.18.252.0/25198.18.252.1 to 198.18.252.126198.18.252.127126
122198.18.252.128/25198.18.252.129 to 198.18.252.254198.18.252.255126
123198.18.253.0/25198.18.253.1 to 198.18.253.126198.18.253.127126
124198.18.253.128/25198.18.253.129 to 198.18.253.254198.18.253.255126
125198.18.254.0/25198.18.254.1 to 198.18.254.126198.18.254.127126
126198.18.254.128/25198.18.254.129 to 198.18.254.254198.18.254.255126
127198.18.255.0/25198.18.255.1 to 198.18.255.126198.18.255.127126
128198.18.255.128/25198.18.255.129 to 198.18.255.254198.18.255.255126

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.