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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.

Network254.78.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
254.78.0.0
Broadcast address
254.78.63.255
First usable
254.78.0.1
Last usable
254.78.63.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FE4E0000 · Integer 4266524672 to 4266541055
Reverse DNS zones
0.78.254.in-addr.arpa
1.78.254.in-addr.arpa
2.78.254.in-addr.arpa
3.78.254.in-addr.arpa
4.78.254.in-addr.arpa
5.78.254.in-addr.arpa
6.78.254.in-addr.arpa
7.78.254.in-addr.arpa
8.78.254.in-addr.arpa
9.78.254.in-addr.arpa
10.78.254.in-addr.arpa
11.78.254.in-addr.arpa
12.78.254.in-addr.arpa
13.78.254.in-addr.arpa
14.78.254.in-addr.arpa
15.78.254.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
Address11111110.01001110.00000000.00000000254.78.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network11111110.01001110.00000000.00000000254.78.0.0
Broadcast11111110.01001110.00111111.11111111254.78.63.255
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)

254.78.0.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1254.78.0.0/25254.78.0.1 to 254.78.0.126254.78.0.127126
2254.78.0.128/25254.78.0.129 to 254.78.0.254254.78.0.255126
3254.78.1.0/25254.78.1.1 to 254.78.1.126254.78.1.127126
4254.78.1.128/25254.78.1.129 to 254.78.1.254254.78.1.255126
5254.78.2.0/25254.78.2.1 to 254.78.2.126254.78.2.127126
6254.78.2.128/25254.78.2.129 to 254.78.2.254254.78.2.255126
7254.78.3.0/25254.78.3.1 to 254.78.3.126254.78.3.127126
8254.78.3.128/25254.78.3.129 to 254.78.3.254254.78.3.255126
9254.78.4.0/25254.78.4.1 to 254.78.4.126254.78.4.127126
10254.78.4.128/25254.78.4.129 to 254.78.4.254254.78.4.255126
11254.78.5.0/25254.78.5.1 to 254.78.5.126254.78.5.127126
12254.78.5.128/25254.78.5.129 to 254.78.5.254254.78.5.255126
13254.78.6.0/25254.78.6.1 to 254.78.6.126254.78.6.127126
14254.78.6.128/25254.78.6.129 to 254.78.6.254254.78.6.255126
15254.78.7.0/25254.78.7.1 to 254.78.7.126254.78.7.127126
16254.78.7.128/25254.78.7.129 to 254.78.7.254254.78.7.255126
17254.78.8.0/25254.78.8.1 to 254.78.8.126254.78.8.127126
18254.78.8.128/25254.78.8.129 to 254.78.8.254254.78.8.255126
19254.78.9.0/25254.78.9.1 to 254.78.9.126254.78.9.127126
20254.78.9.128/25254.78.9.129 to 254.78.9.254254.78.9.255126
21254.78.10.0/25254.78.10.1 to 254.78.10.126254.78.10.127126
22254.78.10.128/25254.78.10.129 to 254.78.10.254254.78.10.255126
23254.78.11.0/25254.78.11.1 to 254.78.11.126254.78.11.127126
24254.78.11.128/25254.78.11.129 to 254.78.11.254254.78.11.255126
25254.78.12.0/25254.78.12.1 to 254.78.12.126254.78.12.127126
26254.78.12.128/25254.78.12.129 to 254.78.12.254254.78.12.255126
27254.78.13.0/25254.78.13.1 to 254.78.13.126254.78.13.127126
28254.78.13.128/25254.78.13.129 to 254.78.13.254254.78.13.255126
29254.78.14.0/25254.78.14.1 to 254.78.14.126254.78.14.127126
30254.78.14.128/25254.78.14.129 to 254.78.14.254254.78.14.255126
31254.78.15.0/25254.78.15.1 to 254.78.15.126254.78.15.127126
32254.78.15.128/25254.78.15.129 to 254.78.15.254254.78.15.255126
33254.78.16.0/25254.78.16.1 to 254.78.16.126254.78.16.127126
34254.78.16.128/25254.78.16.129 to 254.78.16.254254.78.16.255126
35254.78.17.0/25254.78.17.1 to 254.78.17.126254.78.17.127126
36254.78.17.128/25254.78.17.129 to 254.78.17.254254.78.17.255126
37254.78.18.0/25254.78.18.1 to 254.78.18.126254.78.18.127126
38254.78.18.128/25254.78.18.129 to 254.78.18.254254.78.18.255126
39254.78.19.0/25254.78.19.1 to 254.78.19.126254.78.19.127126
40254.78.19.128/25254.78.19.129 to 254.78.19.254254.78.19.255126
41254.78.20.0/25254.78.20.1 to 254.78.20.126254.78.20.127126
42254.78.20.128/25254.78.20.129 to 254.78.20.254254.78.20.255126
43254.78.21.0/25254.78.21.1 to 254.78.21.126254.78.21.127126
44254.78.21.128/25254.78.21.129 to 254.78.21.254254.78.21.255126
45254.78.22.0/25254.78.22.1 to 254.78.22.126254.78.22.127126
46254.78.22.128/25254.78.22.129 to 254.78.22.254254.78.22.255126
47254.78.23.0/25254.78.23.1 to 254.78.23.126254.78.23.127126
48254.78.23.128/25254.78.23.129 to 254.78.23.254254.78.23.255126
49254.78.24.0/25254.78.24.1 to 254.78.24.126254.78.24.127126
50254.78.24.128/25254.78.24.129 to 254.78.24.254254.78.24.255126
51254.78.25.0/25254.78.25.1 to 254.78.25.126254.78.25.127126
52254.78.25.128/25254.78.25.129 to 254.78.25.254254.78.25.255126
53254.78.26.0/25254.78.26.1 to 254.78.26.126254.78.26.127126
54254.78.26.128/25254.78.26.129 to 254.78.26.254254.78.26.255126
55254.78.27.0/25254.78.27.1 to 254.78.27.126254.78.27.127126
56254.78.27.128/25254.78.27.129 to 254.78.27.254254.78.27.255126
57254.78.28.0/25254.78.28.1 to 254.78.28.126254.78.28.127126
58254.78.28.128/25254.78.28.129 to 254.78.28.254254.78.28.255126
59254.78.29.0/25254.78.29.1 to 254.78.29.126254.78.29.127126
60254.78.29.128/25254.78.29.129 to 254.78.29.254254.78.29.255126
61254.78.30.0/25254.78.30.1 to 254.78.30.126254.78.30.127126
62254.78.30.128/25254.78.30.129 to 254.78.30.254254.78.30.255126
63254.78.31.0/25254.78.31.1 to 254.78.31.126254.78.31.127126
64254.78.31.128/25254.78.31.129 to 254.78.31.254254.78.31.255126
65254.78.32.0/25254.78.32.1 to 254.78.32.126254.78.32.127126
66254.78.32.128/25254.78.32.129 to 254.78.32.254254.78.32.255126
67254.78.33.0/25254.78.33.1 to 254.78.33.126254.78.33.127126
68254.78.33.128/25254.78.33.129 to 254.78.33.254254.78.33.255126
69254.78.34.0/25254.78.34.1 to 254.78.34.126254.78.34.127126
70254.78.34.128/25254.78.34.129 to 254.78.34.254254.78.34.255126
71254.78.35.0/25254.78.35.1 to 254.78.35.126254.78.35.127126
72254.78.35.128/25254.78.35.129 to 254.78.35.254254.78.35.255126
73254.78.36.0/25254.78.36.1 to 254.78.36.126254.78.36.127126
74254.78.36.128/25254.78.36.129 to 254.78.36.254254.78.36.255126
75254.78.37.0/25254.78.37.1 to 254.78.37.126254.78.37.127126
76254.78.37.128/25254.78.37.129 to 254.78.37.254254.78.37.255126
77254.78.38.0/25254.78.38.1 to 254.78.38.126254.78.38.127126
78254.78.38.128/25254.78.38.129 to 254.78.38.254254.78.38.255126
79254.78.39.0/25254.78.39.1 to 254.78.39.126254.78.39.127126
80254.78.39.128/25254.78.39.129 to 254.78.39.254254.78.39.255126
81254.78.40.0/25254.78.40.1 to 254.78.40.126254.78.40.127126
82254.78.40.128/25254.78.40.129 to 254.78.40.254254.78.40.255126
83254.78.41.0/25254.78.41.1 to 254.78.41.126254.78.41.127126
84254.78.41.128/25254.78.41.129 to 254.78.41.254254.78.41.255126
85254.78.42.0/25254.78.42.1 to 254.78.42.126254.78.42.127126
86254.78.42.128/25254.78.42.129 to 254.78.42.254254.78.42.255126
87254.78.43.0/25254.78.43.1 to 254.78.43.126254.78.43.127126
88254.78.43.128/25254.78.43.129 to 254.78.43.254254.78.43.255126
89254.78.44.0/25254.78.44.1 to 254.78.44.126254.78.44.127126
90254.78.44.128/25254.78.44.129 to 254.78.44.254254.78.44.255126
91254.78.45.0/25254.78.45.1 to 254.78.45.126254.78.45.127126
92254.78.45.128/25254.78.45.129 to 254.78.45.254254.78.45.255126
93254.78.46.0/25254.78.46.1 to 254.78.46.126254.78.46.127126
94254.78.46.128/25254.78.46.129 to 254.78.46.254254.78.46.255126
95254.78.47.0/25254.78.47.1 to 254.78.47.126254.78.47.127126
96254.78.47.128/25254.78.47.129 to 254.78.47.254254.78.47.255126
97254.78.48.0/25254.78.48.1 to 254.78.48.126254.78.48.127126
98254.78.48.128/25254.78.48.129 to 254.78.48.254254.78.48.255126
99254.78.49.0/25254.78.49.1 to 254.78.49.126254.78.49.127126
100254.78.49.128/25254.78.49.129 to 254.78.49.254254.78.49.255126
101254.78.50.0/25254.78.50.1 to 254.78.50.126254.78.50.127126
102254.78.50.128/25254.78.50.129 to 254.78.50.254254.78.50.255126
103254.78.51.0/25254.78.51.1 to 254.78.51.126254.78.51.127126
104254.78.51.128/25254.78.51.129 to 254.78.51.254254.78.51.255126
105254.78.52.0/25254.78.52.1 to 254.78.52.126254.78.52.127126
106254.78.52.128/25254.78.52.129 to 254.78.52.254254.78.52.255126
107254.78.53.0/25254.78.53.1 to 254.78.53.126254.78.53.127126
108254.78.53.128/25254.78.53.129 to 254.78.53.254254.78.53.255126
109254.78.54.0/25254.78.54.1 to 254.78.54.126254.78.54.127126
110254.78.54.128/25254.78.54.129 to 254.78.54.254254.78.54.255126
111254.78.55.0/25254.78.55.1 to 254.78.55.126254.78.55.127126
112254.78.55.128/25254.78.55.129 to 254.78.55.254254.78.55.255126
113254.78.56.0/25254.78.56.1 to 254.78.56.126254.78.56.127126
114254.78.56.128/25254.78.56.129 to 254.78.56.254254.78.56.255126
115254.78.57.0/25254.78.57.1 to 254.78.57.126254.78.57.127126
116254.78.57.128/25254.78.57.129 to 254.78.57.254254.78.57.255126
117254.78.58.0/25254.78.58.1 to 254.78.58.126254.78.58.127126
118254.78.58.128/25254.78.58.129 to 254.78.58.254254.78.58.255126
119254.78.59.0/25254.78.59.1 to 254.78.59.126254.78.59.127126
120254.78.59.128/25254.78.59.129 to 254.78.59.254254.78.59.255126
121254.78.60.0/25254.78.60.1 to 254.78.60.126254.78.60.127126
122254.78.60.128/25254.78.60.129 to 254.78.60.254254.78.60.255126
123254.78.61.0/25254.78.61.1 to 254.78.61.126254.78.61.127126
124254.78.61.128/25254.78.61.129 to 254.78.61.254254.78.61.255126
125254.78.62.0/25254.78.62.1 to 254.78.62.126254.78.62.127126
126254.78.62.128/25254.78.62.129 to 254.78.62.254254.78.62.255126
127254.78.63.0/25254.78.63.1 to 254.78.63.126254.78.63.127126
128254.78.63.128/25254.78.63.129 to 254.78.63.254254.78.63.255126

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.