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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.

Network155.80.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
155.80.0.0
Broadcast address
155.87.255.255
First usable
155.80.0.1
Last usable
155.87.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
B (default /16)
As numbers
Hex 9B500000 · Integer 2605711360 to 2606235647
Reverse DNS zones
80.155.in-addr.arpa
81.155.in-addr.arpa
82.155.in-addr.arpa
83.155.in-addr.arpa
84.155.in-addr.arpa
85.155.in-addr.arpa
86.155.in-addr.arpa
87.155.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10011011.01010000.00000000.00000000155.80.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network10011011.01010000.00000000.00000000155.80.0.0
Broadcast10011011.01010111.11111111.11111111155.87.255.255
Split into smaller subnets/20
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

155.80.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1155.80.0.0/20155.80.0.1 to 155.80.15.254155.80.15.2554,094
2155.80.16.0/20155.80.16.1 to 155.80.31.254155.80.31.2554,094
3155.80.32.0/20155.80.32.1 to 155.80.47.254155.80.47.2554,094
4155.80.48.0/20155.80.48.1 to 155.80.63.254155.80.63.2554,094
5155.80.64.0/20155.80.64.1 to 155.80.79.254155.80.79.2554,094
6155.80.80.0/20155.80.80.1 to 155.80.95.254155.80.95.2554,094
7155.80.96.0/20155.80.96.1 to 155.80.111.254155.80.111.2554,094
8155.80.112.0/20155.80.112.1 to 155.80.127.254155.80.127.2554,094
9155.80.128.0/20155.80.128.1 to 155.80.143.254155.80.143.2554,094
10155.80.144.0/20155.80.144.1 to 155.80.159.254155.80.159.2554,094
11155.80.160.0/20155.80.160.1 to 155.80.175.254155.80.175.2554,094
12155.80.176.0/20155.80.176.1 to 155.80.191.254155.80.191.2554,094
13155.80.192.0/20155.80.192.1 to 155.80.207.254155.80.207.2554,094
14155.80.208.0/20155.80.208.1 to 155.80.223.254155.80.223.2554,094
15155.80.224.0/20155.80.224.1 to 155.80.239.254155.80.239.2554,094
16155.80.240.0/20155.80.240.1 to 155.80.255.254155.80.255.2554,094
17155.81.0.0/20155.81.0.1 to 155.81.15.254155.81.15.2554,094
18155.81.16.0/20155.81.16.1 to 155.81.31.254155.81.31.2554,094
19155.81.32.0/20155.81.32.1 to 155.81.47.254155.81.47.2554,094
20155.81.48.0/20155.81.48.1 to 155.81.63.254155.81.63.2554,094
21155.81.64.0/20155.81.64.1 to 155.81.79.254155.81.79.2554,094
22155.81.80.0/20155.81.80.1 to 155.81.95.254155.81.95.2554,094
23155.81.96.0/20155.81.96.1 to 155.81.111.254155.81.111.2554,094
24155.81.112.0/20155.81.112.1 to 155.81.127.254155.81.127.2554,094
25155.81.128.0/20155.81.128.1 to 155.81.143.254155.81.143.2554,094
26155.81.144.0/20155.81.144.1 to 155.81.159.254155.81.159.2554,094
27155.81.160.0/20155.81.160.1 to 155.81.175.254155.81.175.2554,094
28155.81.176.0/20155.81.176.1 to 155.81.191.254155.81.191.2554,094
29155.81.192.0/20155.81.192.1 to 155.81.207.254155.81.207.2554,094
30155.81.208.0/20155.81.208.1 to 155.81.223.254155.81.223.2554,094
31155.81.224.0/20155.81.224.1 to 155.81.239.254155.81.239.2554,094
32155.81.240.0/20155.81.240.1 to 155.81.255.254155.81.255.2554,094
33155.82.0.0/20155.82.0.1 to 155.82.15.254155.82.15.2554,094
34155.82.16.0/20155.82.16.1 to 155.82.31.254155.82.31.2554,094
35155.82.32.0/20155.82.32.1 to 155.82.47.254155.82.47.2554,094
36155.82.48.0/20155.82.48.1 to 155.82.63.254155.82.63.2554,094
37155.82.64.0/20155.82.64.1 to 155.82.79.254155.82.79.2554,094
38155.82.80.0/20155.82.80.1 to 155.82.95.254155.82.95.2554,094
39155.82.96.0/20155.82.96.1 to 155.82.111.254155.82.111.2554,094
40155.82.112.0/20155.82.112.1 to 155.82.127.254155.82.127.2554,094
41155.82.128.0/20155.82.128.1 to 155.82.143.254155.82.143.2554,094
42155.82.144.0/20155.82.144.1 to 155.82.159.254155.82.159.2554,094
43155.82.160.0/20155.82.160.1 to 155.82.175.254155.82.175.2554,094
44155.82.176.0/20155.82.176.1 to 155.82.191.254155.82.191.2554,094
45155.82.192.0/20155.82.192.1 to 155.82.207.254155.82.207.2554,094
46155.82.208.0/20155.82.208.1 to 155.82.223.254155.82.223.2554,094
47155.82.224.0/20155.82.224.1 to 155.82.239.254155.82.239.2554,094
48155.82.240.0/20155.82.240.1 to 155.82.255.254155.82.255.2554,094
49155.83.0.0/20155.83.0.1 to 155.83.15.254155.83.15.2554,094
50155.83.16.0/20155.83.16.1 to 155.83.31.254155.83.31.2554,094
51155.83.32.0/20155.83.32.1 to 155.83.47.254155.83.47.2554,094
52155.83.48.0/20155.83.48.1 to 155.83.63.254155.83.63.2554,094
53155.83.64.0/20155.83.64.1 to 155.83.79.254155.83.79.2554,094
54155.83.80.0/20155.83.80.1 to 155.83.95.254155.83.95.2554,094
55155.83.96.0/20155.83.96.1 to 155.83.111.254155.83.111.2554,094
56155.83.112.0/20155.83.112.1 to 155.83.127.254155.83.127.2554,094
57155.83.128.0/20155.83.128.1 to 155.83.143.254155.83.143.2554,094
58155.83.144.0/20155.83.144.1 to 155.83.159.254155.83.159.2554,094
59155.83.160.0/20155.83.160.1 to 155.83.175.254155.83.175.2554,094
60155.83.176.0/20155.83.176.1 to 155.83.191.254155.83.191.2554,094
61155.83.192.0/20155.83.192.1 to 155.83.207.254155.83.207.2554,094
62155.83.208.0/20155.83.208.1 to 155.83.223.254155.83.223.2554,094
63155.83.224.0/20155.83.224.1 to 155.83.239.254155.83.239.2554,094
64155.83.240.0/20155.83.240.1 to 155.83.255.254155.83.255.2554,094
65155.84.0.0/20155.84.0.1 to 155.84.15.254155.84.15.2554,094
66155.84.16.0/20155.84.16.1 to 155.84.31.254155.84.31.2554,094
67155.84.32.0/20155.84.32.1 to 155.84.47.254155.84.47.2554,094
68155.84.48.0/20155.84.48.1 to 155.84.63.254155.84.63.2554,094
69155.84.64.0/20155.84.64.1 to 155.84.79.254155.84.79.2554,094
70155.84.80.0/20155.84.80.1 to 155.84.95.254155.84.95.2554,094
71155.84.96.0/20155.84.96.1 to 155.84.111.254155.84.111.2554,094
72155.84.112.0/20155.84.112.1 to 155.84.127.254155.84.127.2554,094
73155.84.128.0/20155.84.128.1 to 155.84.143.254155.84.143.2554,094
74155.84.144.0/20155.84.144.1 to 155.84.159.254155.84.159.2554,094
75155.84.160.0/20155.84.160.1 to 155.84.175.254155.84.175.2554,094
76155.84.176.0/20155.84.176.1 to 155.84.191.254155.84.191.2554,094
77155.84.192.0/20155.84.192.1 to 155.84.207.254155.84.207.2554,094
78155.84.208.0/20155.84.208.1 to 155.84.223.254155.84.223.2554,094
79155.84.224.0/20155.84.224.1 to 155.84.239.254155.84.239.2554,094
80155.84.240.0/20155.84.240.1 to 155.84.255.254155.84.255.2554,094
81155.85.0.0/20155.85.0.1 to 155.85.15.254155.85.15.2554,094
82155.85.16.0/20155.85.16.1 to 155.85.31.254155.85.31.2554,094
83155.85.32.0/20155.85.32.1 to 155.85.47.254155.85.47.2554,094
84155.85.48.0/20155.85.48.1 to 155.85.63.254155.85.63.2554,094
85155.85.64.0/20155.85.64.1 to 155.85.79.254155.85.79.2554,094
86155.85.80.0/20155.85.80.1 to 155.85.95.254155.85.95.2554,094
87155.85.96.0/20155.85.96.1 to 155.85.111.254155.85.111.2554,094
88155.85.112.0/20155.85.112.1 to 155.85.127.254155.85.127.2554,094
89155.85.128.0/20155.85.128.1 to 155.85.143.254155.85.143.2554,094
90155.85.144.0/20155.85.144.1 to 155.85.159.254155.85.159.2554,094
91155.85.160.0/20155.85.160.1 to 155.85.175.254155.85.175.2554,094
92155.85.176.0/20155.85.176.1 to 155.85.191.254155.85.191.2554,094
93155.85.192.0/20155.85.192.1 to 155.85.207.254155.85.207.2554,094
94155.85.208.0/20155.85.208.1 to 155.85.223.254155.85.223.2554,094
95155.85.224.0/20155.85.224.1 to 155.85.239.254155.85.239.2554,094
96155.85.240.0/20155.85.240.1 to 155.85.255.254155.85.255.2554,094
97155.86.0.0/20155.86.0.1 to 155.86.15.254155.86.15.2554,094
98155.86.16.0/20155.86.16.1 to 155.86.31.254155.86.31.2554,094
99155.86.32.0/20155.86.32.1 to 155.86.47.254155.86.47.2554,094
100155.86.48.0/20155.86.48.1 to 155.86.63.254155.86.63.2554,094
101155.86.64.0/20155.86.64.1 to 155.86.79.254155.86.79.2554,094
102155.86.80.0/20155.86.80.1 to 155.86.95.254155.86.95.2554,094
103155.86.96.0/20155.86.96.1 to 155.86.111.254155.86.111.2554,094
104155.86.112.0/20155.86.112.1 to 155.86.127.254155.86.127.2554,094
105155.86.128.0/20155.86.128.1 to 155.86.143.254155.86.143.2554,094
106155.86.144.0/20155.86.144.1 to 155.86.159.254155.86.159.2554,094
107155.86.160.0/20155.86.160.1 to 155.86.175.254155.86.175.2554,094
108155.86.176.0/20155.86.176.1 to 155.86.191.254155.86.191.2554,094
109155.86.192.0/20155.86.192.1 to 155.86.207.254155.86.207.2554,094
110155.86.208.0/20155.86.208.1 to 155.86.223.254155.86.223.2554,094
111155.86.224.0/20155.86.224.1 to 155.86.239.254155.86.239.2554,094
112155.86.240.0/20155.86.240.1 to 155.86.255.254155.86.255.2554,094
113155.87.0.0/20155.87.0.1 to 155.87.15.254155.87.15.2554,094
114155.87.16.0/20155.87.16.1 to 155.87.31.254155.87.31.2554,094
115155.87.32.0/20155.87.32.1 to 155.87.47.254155.87.47.2554,094
116155.87.48.0/20155.87.48.1 to 155.87.63.254155.87.63.2554,094
117155.87.64.0/20155.87.64.1 to 155.87.79.254155.87.79.2554,094
118155.87.80.0/20155.87.80.1 to 155.87.95.254155.87.95.2554,094
119155.87.96.0/20155.87.96.1 to 155.87.111.254155.87.111.2554,094
120155.87.112.0/20155.87.112.1 to 155.87.127.254155.87.127.2554,094
121155.87.128.0/20155.87.128.1 to 155.87.143.254155.87.143.2554,094
122155.87.144.0/20155.87.144.1 to 155.87.159.254155.87.159.2554,094
123155.87.160.0/20155.87.160.1 to 155.87.175.254155.87.175.2554,094
124155.87.176.0/20155.87.176.1 to 155.87.191.254155.87.191.2554,094
125155.87.192.0/20155.87.192.1 to 155.87.207.254155.87.207.2554,094
126155.87.208.0/20155.87.208.1 to 155.87.223.254155.87.223.2554,094
127155.87.224.0/20155.87.224.1 to 155.87.239.254155.87.239.2554,094
128155.87.240.0/20155.87.240.1 to 155.87.255.254155.87.255.2554,094

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.