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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.

Network154.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
154.0.0.0
Broadcast address
155.255.255.255
First usable
154.0.0.1
Last usable
155.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
B (default /16)
As numbers
Hex 9A000000 · Integer 2583691264 to 2617245695
Reverse DNS zones
154.in-addr.arpa
155.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10011010.00000000.00000000.00000000154.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10011010.00000000.00000000.00000000154.0.0.0
Broadcast10011011.11111111.11111111.11111111155.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

154.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1154.0.0.0/14154.0.0.1 to 154.3.255.254154.3.255.255262,142
2154.4.0.0/14154.4.0.1 to 154.7.255.254154.7.255.255262,142
3154.8.0.0/14154.8.0.1 to 154.11.255.254154.11.255.255262,142
4154.12.0.0/14154.12.0.1 to 154.15.255.254154.15.255.255262,142
5154.16.0.0/14154.16.0.1 to 154.19.255.254154.19.255.255262,142
6154.20.0.0/14154.20.0.1 to 154.23.255.254154.23.255.255262,142
7154.24.0.0/14154.24.0.1 to 154.27.255.254154.27.255.255262,142
8154.28.0.0/14154.28.0.1 to 154.31.255.254154.31.255.255262,142
9154.32.0.0/14154.32.0.1 to 154.35.255.254154.35.255.255262,142
10154.36.0.0/14154.36.0.1 to 154.39.255.254154.39.255.255262,142
11154.40.0.0/14154.40.0.1 to 154.43.255.254154.43.255.255262,142
12154.44.0.0/14154.44.0.1 to 154.47.255.254154.47.255.255262,142
13154.48.0.0/14154.48.0.1 to 154.51.255.254154.51.255.255262,142
14154.52.0.0/14154.52.0.1 to 154.55.255.254154.55.255.255262,142
15154.56.0.0/14154.56.0.1 to 154.59.255.254154.59.255.255262,142
16154.60.0.0/14154.60.0.1 to 154.63.255.254154.63.255.255262,142
17154.64.0.0/14154.64.0.1 to 154.67.255.254154.67.255.255262,142
18154.68.0.0/14154.68.0.1 to 154.71.255.254154.71.255.255262,142
19154.72.0.0/14154.72.0.1 to 154.75.255.254154.75.255.255262,142
20154.76.0.0/14154.76.0.1 to 154.79.255.254154.79.255.255262,142
21154.80.0.0/14154.80.0.1 to 154.83.255.254154.83.255.255262,142
22154.84.0.0/14154.84.0.1 to 154.87.255.254154.87.255.255262,142
23154.88.0.0/14154.88.0.1 to 154.91.255.254154.91.255.255262,142
24154.92.0.0/14154.92.0.1 to 154.95.255.254154.95.255.255262,142
25154.96.0.0/14154.96.0.1 to 154.99.255.254154.99.255.255262,142
26154.100.0.0/14154.100.0.1 to 154.103.255.254154.103.255.255262,142
27154.104.0.0/14154.104.0.1 to 154.107.255.254154.107.255.255262,142
28154.108.0.0/14154.108.0.1 to 154.111.255.254154.111.255.255262,142
29154.112.0.0/14154.112.0.1 to 154.115.255.254154.115.255.255262,142
30154.116.0.0/14154.116.0.1 to 154.119.255.254154.119.255.255262,142
31154.120.0.0/14154.120.0.1 to 154.123.255.254154.123.255.255262,142
32154.124.0.0/14154.124.0.1 to 154.127.255.254154.127.255.255262,142
33154.128.0.0/14154.128.0.1 to 154.131.255.254154.131.255.255262,142
34154.132.0.0/14154.132.0.1 to 154.135.255.254154.135.255.255262,142
35154.136.0.0/14154.136.0.1 to 154.139.255.254154.139.255.255262,142
36154.140.0.0/14154.140.0.1 to 154.143.255.254154.143.255.255262,142
37154.144.0.0/14154.144.0.1 to 154.147.255.254154.147.255.255262,142
38154.148.0.0/14154.148.0.1 to 154.151.255.254154.151.255.255262,142
39154.152.0.0/14154.152.0.1 to 154.155.255.254154.155.255.255262,142
40154.156.0.0/14154.156.0.1 to 154.159.255.254154.159.255.255262,142
41154.160.0.0/14154.160.0.1 to 154.163.255.254154.163.255.255262,142
42154.164.0.0/14154.164.0.1 to 154.167.255.254154.167.255.255262,142
43154.168.0.0/14154.168.0.1 to 154.171.255.254154.171.255.255262,142
44154.172.0.0/14154.172.0.1 to 154.175.255.254154.175.255.255262,142
45154.176.0.0/14154.176.0.1 to 154.179.255.254154.179.255.255262,142
46154.180.0.0/14154.180.0.1 to 154.183.255.254154.183.255.255262,142
47154.184.0.0/14154.184.0.1 to 154.187.255.254154.187.255.255262,142
48154.188.0.0/14154.188.0.1 to 154.191.255.254154.191.255.255262,142
49154.192.0.0/14154.192.0.1 to 154.195.255.254154.195.255.255262,142
50154.196.0.0/14154.196.0.1 to 154.199.255.254154.199.255.255262,142
51154.200.0.0/14154.200.0.1 to 154.203.255.254154.203.255.255262,142
52154.204.0.0/14154.204.0.1 to 154.207.255.254154.207.255.255262,142
53154.208.0.0/14154.208.0.1 to 154.211.255.254154.211.255.255262,142
54154.212.0.0/14154.212.0.1 to 154.215.255.254154.215.255.255262,142
55154.216.0.0/14154.216.0.1 to 154.219.255.254154.219.255.255262,142
56154.220.0.0/14154.220.0.1 to 154.223.255.254154.223.255.255262,142
57154.224.0.0/14154.224.0.1 to 154.227.255.254154.227.255.255262,142
58154.228.0.0/14154.228.0.1 to 154.231.255.254154.231.255.255262,142
59154.232.0.0/14154.232.0.1 to 154.235.255.254154.235.255.255262,142
60154.236.0.0/14154.236.0.1 to 154.239.255.254154.239.255.255262,142
61154.240.0.0/14154.240.0.1 to 154.243.255.254154.243.255.255262,142
62154.244.0.0/14154.244.0.1 to 154.247.255.254154.247.255.255262,142
63154.248.0.0/14154.248.0.1 to 154.251.255.254154.251.255.255262,142
64154.252.0.0/14154.252.0.1 to 154.255.255.254154.255.255.255262,142
65155.0.0.0/14155.0.0.1 to 155.3.255.254155.3.255.255262,142
66155.4.0.0/14155.4.0.1 to 155.7.255.254155.7.255.255262,142
67155.8.0.0/14155.8.0.1 to 155.11.255.254155.11.255.255262,142
68155.12.0.0/14155.12.0.1 to 155.15.255.254155.15.255.255262,142
69155.16.0.0/14155.16.0.1 to 155.19.255.254155.19.255.255262,142
70155.20.0.0/14155.20.0.1 to 155.23.255.254155.23.255.255262,142
71155.24.0.0/14155.24.0.1 to 155.27.255.254155.27.255.255262,142
72155.28.0.0/14155.28.0.1 to 155.31.255.254155.31.255.255262,142
73155.32.0.0/14155.32.0.1 to 155.35.255.254155.35.255.255262,142
74155.36.0.0/14155.36.0.1 to 155.39.255.254155.39.255.255262,142
75155.40.0.0/14155.40.0.1 to 155.43.255.254155.43.255.255262,142
76155.44.0.0/14155.44.0.1 to 155.47.255.254155.47.255.255262,142
77155.48.0.0/14155.48.0.1 to 155.51.255.254155.51.255.255262,142
78155.52.0.0/14155.52.0.1 to 155.55.255.254155.55.255.255262,142
79155.56.0.0/14155.56.0.1 to 155.59.255.254155.59.255.255262,142
80155.60.0.0/14155.60.0.1 to 155.63.255.254155.63.255.255262,142
81155.64.0.0/14155.64.0.1 to 155.67.255.254155.67.255.255262,142
82155.68.0.0/14155.68.0.1 to 155.71.255.254155.71.255.255262,142
83155.72.0.0/14155.72.0.1 to 155.75.255.254155.75.255.255262,142
84155.76.0.0/14155.76.0.1 to 155.79.255.254155.79.255.255262,142
85155.80.0.0/14155.80.0.1 to 155.83.255.254155.83.255.255262,142
86155.84.0.0/14155.84.0.1 to 155.87.255.254155.87.255.255262,142
87155.88.0.0/14155.88.0.1 to 155.91.255.254155.91.255.255262,142
88155.92.0.0/14155.92.0.1 to 155.95.255.254155.95.255.255262,142
89155.96.0.0/14155.96.0.1 to 155.99.255.254155.99.255.255262,142
90155.100.0.0/14155.100.0.1 to 155.103.255.254155.103.255.255262,142
91155.104.0.0/14155.104.0.1 to 155.107.255.254155.107.255.255262,142
92155.108.0.0/14155.108.0.1 to 155.111.255.254155.111.255.255262,142
93155.112.0.0/14155.112.0.1 to 155.115.255.254155.115.255.255262,142
94155.116.0.0/14155.116.0.1 to 155.119.255.254155.119.255.255262,142
95155.120.0.0/14155.120.0.1 to 155.123.255.254155.123.255.255262,142
96155.124.0.0/14155.124.0.1 to 155.127.255.254155.127.255.255262,142
97155.128.0.0/14155.128.0.1 to 155.131.255.254155.131.255.255262,142
98155.132.0.0/14155.132.0.1 to 155.135.255.254155.135.255.255262,142
99155.136.0.0/14155.136.0.1 to 155.139.255.254155.139.255.255262,142
100155.140.0.0/14155.140.0.1 to 155.143.255.254155.143.255.255262,142
101155.144.0.0/14155.144.0.1 to 155.147.255.254155.147.255.255262,142
102155.148.0.0/14155.148.0.1 to 155.151.255.254155.151.255.255262,142
103155.152.0.0/14155.152.0.1 to 155.155.255.254155.155.255.255262,142
104155.156.0.0/14155.156.0.1 to 155.159.255.254155.159.255.255262,142
105155.160.0.0/14155.160.0.1 to 155.163.255.254155.163.255.255262,142
106155.164.0.0/14155.164.0.1 to 155.167.255.254155.167.255.255262,142
107155.168.0.0/14155.168.0.1 to 155.171.255.254155.171.255.255262,142
108155.172.0.0/14155.172.0.1 to 155.175.255.254155.175.255.255262,142
109155.176.0.0/14155.176.0.1 to 155.179.255.254155.179.255.255262,142
110155.180.0.0/14155.180.0.1 to 155.183.255.254155.183.255.255262,142
111155.184.0.0/14155.184.0.1 to 155.187.255.254155.187.255.255262,142
112155.188.0.0/14155.188.0.1 to 155.191.255.254155.191.255.255262,142
113155.192.0.0/14155.192.0.1 to 155.195.255.254155.195.255.255262,142
114155.196.0.0/14155.196.0.1 to 155.199.255.254155.199.255.255262,142
115155.200.0.0/14155.200.0.1 to 155.203.255.254155.203.255.255262,142
116155.204.0.0/14155.204.0.1 to 155.207.255.254155.207.255.255262,142
117155.208.0.0/14155.208.0.1 to 155.211.255.254155.211.255.255262,142
118155.212.0.0/14155.212.0.1 to 155.215.255.254155.215.255.255262,142
119155.216.0.0/14155.216.0.1 to 155.219.255.254155.219.255.255262,142
120155.220.0.0/14155.220.0.1 to 155.223.255.254155.223.255.255262,142
121155.224.0.0/14155.224.0.1 to 155.227.255.254155.227.255.255262,142
122155.228.0.0/14155.228.0.1 to 155.231.255.254155.231.255.255262,142
123155.232.0.0/14155.232.0.1 to 155.235.255.254155.235.255.255262,142
124155.236.0.0/14155.236.0.1 to 155.239.255.254155.239.255.255262,142
125155.240.0.0/14155.240.0.1 to 155.243.255.254155.243.255.255262,142
126155.244.0.0/14155.244.0.1 to 155.247.255.254155.247.255.255262,142
127155.248.0.0/14155.248.0.1 to 155.251.255.254155.251.255.255262,142
128155.252.0.0/14155.252.0.1 to 155.255.255.254155.255.255.255262,142

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.