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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.

Network198.18.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
198.18.0.0
Broadcast address
198.19.255.255
First usable
198.18.0.1
Last usable
198.19.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Benchmarking 198.18.0.0/15
Network equipment testing (RFC 2544)
Old class
C (default /24)
As numbers
Hex C6120000 · Integer 3323068416 to 3323199487
Reverse DNS zones
18.198.in-addr.arpa
19.198.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000110.00010010.00000000.00000000198.18.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network11000110.00010010.00000000.00000000198.18.0.0
Broadcast11000110.00010011.11111111.11111111198.19.255.255
Split into smaller subnets/22
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

198.18.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1198.18.0.0/22198.18.0.1 to 198.18.3.254198.18.3.2551,022
2198.18.4.0/22198.18.4.1 to 198.18.7.254198.18.7.2551,022
3198.18.8.0/22198.18.8.1 to 198.18.11.254198.18.11.2551,022
4198.18.12.0/22198.18.12.1 to 198.18.15.254198.18.15.2551,022
5198.18.16.0/22198.18.16.1 to 198.18.19.254198.18.19.2551,022
6198.18.20.0/22198.18.20.1 to 198.18.23.254198.18.23.2551,022
7198.18.24.0/22198.18.24.1 to 198.18.27.254198.18.27.2551,022
8198.18.28.0/22198.18.28.1 to 198.18.31.254198.18.31.2551,022
9198.18.32.0/22198.18.32.1 to 198.18.35.254198.18.35.2551,022
10198.18.36.0/22198.18.36.1 to 198.18.39.254198.18.39.2551,022
11198.18.40.0/22198.18.40.1 to 198.18.43.254198.18.43.2551,022
12198.18.44.0/22198.18.44.1 to 198.18.47.254198.18.47.2551,022
13198.18.48.0/22198.18.48.1 to 198.18.51.254198.18.51.2551,022
14198.18.52.0/22198.18.52.1 to 198.18.55.254198.18.55.2551,022
15198.18.56.0/22198.18.56.1 to 198.18.59.254198.18.59.2551,022
16198.18.60.0/22198.18.60.1 to 198.18.63.254198.18.63.2551,022
17198.18.64.0/22198.18.64.1 to 198.18.67.254198.18.67.2551,022
18198.18.68.0/22198.18.68.1 to 198.18.71.254198.18.71.2551,022
19198.18.72.0/22198.18.72.1 to 198.18.75.254198.18.75.2551,022
20198.18.76.0/22198.18.76.1 to 198.18.79.254198.18.79.2551,022
21198.18.80.0/22198.18.80.1 to 198.18.83.254198.18.83.2551,022
22198.18.84.0/22198.18.84.1 to 198.18.87.254198.18.87.2551,022
23198.18.88.0/22198.18.88.1 to 198.18.91.254198.18.91.2551,022
24198.18.92.0/22198.18.92.1 to 198.18.95.254198.18.95.2551,022
25198.18.96.0/22198.18.96.1 to 198.18.99.254198.18.99.2551,022
26198.18.100.0/22198.18.100.1 to 198.18.103.254198.18.103.2551,022
27198.18.104.0/22198.18.104.1 to 198.18.107.254198.18.107.2551,022
28198.18.108.0/22198.18.108.1 to 198.18.111.254198.18.111.2551,022
29198.18.112.0/22198.18.112.1 to 198.18.115.254198.18.115.2551,022
30198.18.116.0/22198.18.116.1 to 198.18.119.254198.18.119.2551,022
31198.18.120.0/22198.18.120.1 to 198.18.123.254198.18.123.2551,022
32198.18.124.0/22198.18.124.1 to 198.18.127.254198.18.127.2551,022
33198.18.128.0/22198.18.128.1 to 198.18.131.254198.18.131.2551,022
34198.18.132.0/22198.18.132.1 to 198.18.135.254198.18.135.2551,022
35198.18.136.0/22198.18.136.1 to 198.18.139.254198.18.139.2551,022
36198.18.140.0/22198.18.140.1 to 198.18.143.254198.18.143.2551,022
37198.18.144.0/22198.18.144.1 to 198.18.147.254198.18.147.2551,022
38198.18.148.0/22198.18.148.1 to 198.18.151.254198.18.151.2551,022
39198.18.152.0/22198.18.152.1 to 198.18.155.254198.18.155.2551,022
40198.18.156.0/22198.18.156.1 to 198.18.159.254198.18.159.2551,022
41198.18.160.0/22198.18.160.1 to 198.18.163.254198.18.163.2551,022
42198.18.164.0/22198.18.164.1 to 198.18.167.254198.18.167.2551,022
43198.18.168.0/22198.18.168.1 to 198.18.171.254198.18.171.2551,022
44198.18.172.0/22198.18.172.1 to 198.18.175.254198.18.175.2551,022
45198.18.176.0/22198.18.176.1 to 198.18.179.254198.18.179.2551,022
46198.18.180.0/22198.18.180.1 to 198.18.183.254198.18.183.2551,022
47198.18.184.0/22198.18.184.1 to 198.18.187.254198.18.187.2551,022
48198.18.188.0/22198.18.188.1 to 198.18.191.254198.18.191.2551,022
49198.18.192.0/22198.18.192.1 to 198.18.195.254198.18.195.2551,022
50198.18.196.0/22198.18.196.1 to 198.18.199.254198.18.199.2551,022
51198.18.200.0/22198.18.200.1 to 198.18.203.254198.18.203.2551,022
52198.18.204.0/22198.18.204.1 to 198.18.207.254198.18.207.2551,022
53198.18.208.0/22198.18.208.1 to 198.18.211.254198.18.211.2551,022
54198.18.212.0/22198.18.212.1 to 198.18.215.254198.18.215.2551,022
55198.18.216.0/22198.18.216.1 to 198.18.219.254198.18.219.2551,022
56198.18.220.0/22198.18.220.1 to 198.18.223.254198.18.223.2551,022
57198.18.224.0/22198.18.224.1 to 198.18.227.254198.18.227.2551,022
58198.18.228.0/22198.18.228.1 to 198.18.231.254198.18.231.2551,022
59198.18.232.0/22198.18.232.1 to 198.18.235.254198.18.235.2551,022
60198.18.236.0/22198.18.236.1 to 198.18.239.254198.18.239.2551,022
61198.18.240.0/22198.18.240.1 to 198.18.243.254198.18.243.2551,022
62198.18.244.0/22198.18.244.1 to 198.18.247.254198.18.247.2551,022
63198.18.248.0/22198.18.248.1 to 198.18.251.254198.18.251.2551,022
64198.18.252.0/22198.18.252.1 to 198.18.255.254198.18.255.2551,022
65198.19.0.0/22198.19.0.1 to 198.19.3.254198.19.3.2551,022
66198.19.4.0/22198.19.4.1 to 198.19.7.254198.19.7.2551,022
67198.19.8.0/22198.19.8.1 to 198.19.11.254198.19.11.2551,022
68198.19.12.0/22198.19.12.1 to 198.19.15.254198.19.15.2551,022
69198.19.16.0/22198.19.16.1 to 198.19.19.254198.19.19.2551,022
70198.19.20.0/22198.19.20.1 to 198.19.23.254198.19.23.2551,022
71198.19.24.0/22198.19.24.1 to 198.19.27.254198.19.27.2551,022
72198.19.28.0/22198.19.28.1 to 198.19.31.254198.19.31.2551,022
73198.19.32.0/22198.19.32.1 to 198.19.35.254198.19.35.2551,022
74198.19.36.0/22198.19.36.1 to 198.19.39.254198.19.39.2551,022
75198.19.40.0/22198.19.40.1 to 198.19.43.254198.19.43.2551,022
76198.19.44.0/22198.19.44.1 to 198.19.47.254198.19.47.2551,022
77198.19.48.0/22198.19.48.1 to 198.19.51.254198.19.51.2551,022
78198.19.52.0/22198.19.52.1 to 198.19.55.254198.19.55.2551,022
79198.19.56.0/22198.19.56.1 to 198.19.59.254198.19.59.2551,022
80198.19.60.0/22198.19.60.1 to 198.19.63.254198.19.63.2551,022
81198.19.64.0/22198.19.64.1 to 198.19.67.254198.19.67.2551,022
82198.19.68.0/22198.19.68.1 to 198.19.71.254198.19.71.2551,022
83198.19.72.0/22198.19.72.1 to 198.19.75.254198.19.75.2551,022
84198.19.76.0/22198.19.76.1 to 198.19.79.254198.19.79.2551,022
85198.19.80.0/22198.19.80.1 to 198.19.83.254198.19.83.2551,022
86198.19.84.0/22198.19.84.1 to 198.19.87.254198.19.87.2551,022
87198.19.88.0/22198.19.88.1 to 198.19.91.254198.19.91.2551,022
88198.19.92.0/22198.19.92.1 to 198.19.95.254198.19.95.2551,022
89198.19.96.0/22198.19.96.1 to 198.19.99.254198.19.99.2551,022
90198.19.100.0/22198.19.100.1 to 198.19.103.254198.19.103.2551,022
91198.19.104.0/22198.19.104.1 to 198.19.107.254198.19.107.2551,022
92198.19.108.0/22198.19.108.1 to 198.19.111.254198.19.111.2551,022
93198.19.112.0/22198.19.112.1 to 198.19.115.254198.19.115.2551,022
94198.19.116.0/22198.19.116.1 to 198.19.119.254198.19.119.2551,022
95198.19.120.0/22198.19.120.1 to 198.19.123.254198.19.123.2551,022
96198.19.124.0/22198.19.124.1 to 198.19.127.254198.19.127.2551,022
97198.19.128.0/22198.19.128.1 to 198.19.131.254198.19.131.2551,022
98198.19.132.0/22198.19.132.1 to 198.19.135.254198.19.135.2551,022
99198.19.136.0/22198.19.136.1 to 198.19.139.254198.19.139.2551,022
100198.19.140.0/22198.19.140.1 to 198.19.143.254198.19.143.2551,022
101198.19.144.0/22198.19.144.1 to 198.19.147.254198.19.147.2551,022
102198.19.148.0/22198.19.148.1 to 198.19.151.254198.19.151.2551,022
103198.19.152.0/22198.19.152.1 to 198.19.155.254198.19.155.2551,022
104198.19.156.0/22198.19.156.1 to 198.19.159.254198.19.159.2551,022
105198.19.160.0/22198.19.160.1 to 198.19.163.254198.19.163.2551,022
106198.19.164.0/22198.19.164.1 to 198.19.167.254198.19.167.2551,022
107198.19.168.0/22198.19.168.1 to 198.19.171.254198.19.171.2551,022
108198.19.172.0/22198.19.172.1 to 198.19.175.254198.19.175.2551,022
109198.19.176.0/22198.19.176.1 to 198.19.179.254198.19.179.2551,022
110198.19.180.0/22198.19.180.1 to 198.19.183.254198.19.183.2551,022
111198.19.184.0/22198.19.184.1 to 198.19.187.254198.19.187.2551,022
112198.19.188.0/22198.19.188.1 to 198.19.191.254198.19.191.2551,022
113198.19.192.0/22198.19.192.1 to 198.19.195.254198.19.195.2551,022
114198.19.196.0/22198.19.196.1 to 198.19.199.254198.19.199.2551,022
115198.19.200.0/22198.19.200.1 to 198.19.203.254198.19.203.2551,022
116198.19.204.0/22198.19.204.1 to 198.19.207.254198.19.207.2551,022
117198.19.208.0/22198.19.208.1 to 198.19.211.254198.19.211.2551,022
118198.19.212.0/22198.19.212.1 to 198.19.215.254198.19.215.2551,022
119198.19.216.0/22198.19.216.1 to 198.19.219.254198.19.219.2551,022
120198.19.220.0/22198.19.220.1 to 198.19.223.254198.19.223.2551,022
121198.19.224.0/22198.19.224.1 to 198.19.227.254198.19.227.2551,022
122198.19.228.0/22198.19.228.1 to 198.19.231.254198.19.231.2551,022
123198.19.232.0/22198.19.232.1 to 198.19.235.254198.19.235.2551,022
124198.19.236.0/22198.19.236.1 to 198.19.239.254198.19.239.2551,022
125198.19.240.0/22198.19.240.1 to 198.19.243.254198.19.243.2551,022
126198.19.244.0/22198.19.244.1 to 198.19.247.254198.19.247.2551,022
127198.19.248.0/22198.19.248.1 to 198.19.251.254198.19.251.2551,022
128198.19.252.0/22198.19.252.1 to 198.19.255.254198.19.255.2551,022

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.