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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.

Network155.76.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
155.76.0.0
Broadcast address
155.77.255.255
First usable
155.76.0.1
Last usable
155.77.255.254
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
Public public
Old class
B (default /16)
As numbers
Hex 9B4C0000 · Integer 2605449216 to 2605580287
Reverse DNS zones
76.155.in-addr.arpa
77.155.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
Address10011011.01001100.00000000.00000000155.76.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network10011011.01001100.00000000.00000000155.76.0.0
Broadcast10011011.01001101.11111111.11111111155.77.255.255
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)

155.76.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1155.76.0.0/22155.76.0.1 to 155.76.3.254155.76.3.2551,022
2155.76.4.0/22155.76.4.1 to 155.76.7.254155.76.7.2551,022
3155.76.8.0/22155.76.8.1 to 155.76.11.254155.76.11.2551,022
4155.76.12.0/22155.76.12.1 to 155.76.15.254155.76.15.2551,022
5155.76.16.0/22155.76.16.1 to 155.76.19.254155.76.19.2551,022
6155.76.20.0/22155.76.20.1 to 155.76.23.254155.76.23.2551,022
7155.76.24.0/22155.76.24.1 to 155.76.27.254155.76.27.2551,022
8155.76.28.0/22155.76.28.1 to 155.76.31.254155.76.31.2551,022
9155.76.32.0/22155.76.32.1 to 155.76.35.254155.76.35.2551,022
10155.76.36.0/22155.76.36.1 to 155.76.39.254155.76.39.2551,022
11155.76.40.0/22155.76.40.1 to 155.76.43.254155.76.43.2551,022
12155.76.44.0/22155.76.44.1 to 155.76.47.254155.76.47.2551,022
13155.76.48.0/22155.76.48.1 to 155.76.51.254155.76.51.2551,022
14155.76.52.0/22155.76.52.1 to 155.76.55.254155.76.55.2551,022
15155.76.56.0/22155.76.56.1 to 155.76.59.254155.76.59.2551,022
16155.76.60.0/22155.76.60.1 to 155.76.63.254155.76.63.2551,022
17155.76.64.0/22155.76.64.1 to 155.76.67.254155.76.67.2551,022
18155.76.68.0/22155.76.68.1 to 155.76.71.254155.76.71.2551,022
19155.76.72.0/22155.76.72.1 to 155.76.75.254155.76.75.2551,022
20155.76.76.0/22155.76.76.1 to 155.76.79.254155.76.79.2551,022
21155.76.80.0/22155.76.80.1 to 155.76.83.254155.76.83.2551,022
22155.76.84.0/22155.76.84.1 to 155.76.87.254155.76.87.2551,022
23155.76.88.0/22155.76.88.1 to 155.76.91.254155.76.91.2551,022
24155.76.92.0/22155.76.92.1 to 155.76.95.254155.76.95.2551,022
25155.76.96.0/22155.76.96.1 to 155.76.99.254155.76.99.2551,022
26155.76.100.0/22155.76.100.1 to 155.76.103.254155.76.103.2551,022
27155.76.104.0/22155.76.104.1 to 155.76.107.254155.76.107.2551,022
28155.76.108.0/22155.76.108.1 to 155.76.111.254155.76.111.2551,022
29155.76.112.0/22155.76.112.1 to 155.76.115.254155.76.115.2551,022
30155.76.116.0/22155.76.116.1 to 155.76.119.254155.76.119.2551,022
31155.76.120.0/22155.76.120.1 to 155.76.123.254155.76.123.2551,022
32155.76.124.0/22155.76.124.1 to 155.76.127.254155.76.127.2551,022
33155.76.128.0/22155.76.128.1 to 155.76.131.254155.76.131.2551,022
34155.76.132.0/22155.76.132.1 to 155.76.135.254155.76.135.2551,022
35155.76.136.0/22155.76.136.1 to 155.76.139.254155.76.139.2551,022
36155.76.140.0/22155.76.140.1 to 155.76.143.254155.76.143.2551,022
37155.76.144.0/22155.76.144.1 to 155.76.147.254155.76.147.2551,022
38155.76.148.0/22155.76.148.1 to 155.76.151.254155.76.151.2551,022
39155.76.152.0/22155.76.152.1 to 155.76.155.254155.76.155.2551,022
40155.76.156.0/22155.76.156.1 to 155.76.159.254155.76.159.2551,022
41155.76.160.0/22155.76.160.1 to 155.76.163.254155.76.163.2551,022
42155.76.164.0/22155.76.164.1 to 155.76.167.254155.76.167.2551,022
43155.76.168.0/22155.76.168.1 to 155.76.171.254155.76.171.2551,022
44155.76.172.0/22155.76.172.1 to 155.76.175.254155.76.175.2551,022
45155.76.176.0/22155.76.176.1 to 155.76.179.254155.76.179.2551,022
46155.76.180.0/22155.76.180.1 to 155.76.183.254155.76.183.2551,022
47155.76.184.0/22155.76.184.1 to 155.76.187.254155.76.187.2551,022
48155.76.188.0/22155.76.188.1 to 155.76.191.254155.76.191.2551,022
49155.76.192.0/22155.76.192.1 to 155.76.195.254155.76.195.2551,022
50155.76.196.0/22155.76.196.1 to 155.76.199.254155.76.199.2551,022
51155.76.200.0/22155.76.200.1 to 155.76.203.254155.76.203.2551,022
52155.76.204.0/22155.76.204.1 to 155.76.207.254155.76.207.2551,022
53155.76.208.0/22155.76.208.1 to 155.76.211.254155.76.211.2551,022
54155.76.212.0/22155.76.212.1 to 155.76.215.254155.76.215.2551,022
55155.76.216.0/22155.76.216.1 to 155.76.219.254155.76.219.2551,022
56155.76.220.0/22155.76.220.1 to 155.76.223.254155.76.223.2551,022
57155.76.224.0/22155.76.224.1 to 155.76.227.254155.76.227.2551,022
58155.76.228.0/22155.76.228.1 to 155.76.231.254155.76.231.2551,022
59155.76.232.0/22155.76.232.1 to 155.76.235.254155.76.235.2551,022
60155.76.236.0/22155.76.236.1 to 155.76.239.254155.76.239.2551,022
61155.76.240.0/22155.76.240.1 to 155.76.243.254155.76.243.2551,022
62155.76.244.0/22155.76.244.1 to 155.76.247.254155.76.247.2551,022
63155.76.248.0/22155.76.248.1 to 155.76.251.254155.76.251.2551,022
64155.76.252.0/22155.76.252.1 to 155.76.255.254155.76.255.2551,022
65155.77.0.0/22155.77.0.1 to 155.77.3.254155.77.3.2551,022
66155.77.4.0/22155.77.4.1 to 155.77.7.254155.77.7.2551,022
67155.77.8.0/22155.77.8.1 to 155.77.11.254155.77.11.2551,022
68155.77.12.0/22155.77.12.1 to 155.77.15.254155.77.15.2551,022
69155.77.16.0/22155.77.16.1 to 155.77.19.254155.77.19.2551,022
70155.77.20.0/22155.77.20.1 to 155.77.23.254155.77.23.2551,022
71155.77.24.0/22155.77.24.1 to 155.77.27.254155.77.27.2551,022
72155.77.28.0/22155.77.28.1 to 155.77.31.254155.77.31.2551,022
73155.77.32.0/22155.77.32.1 to 155.77.35.254155.77.35.2551,022
74155.77.36.0/22155.77.36.1 to 155.77.39.254155.77.39.2551,022
75155.77.40.0/22155.77.40.1 to 155.77.43.254155.77.43.2551,022
76155.77.44.0/22155.77.44.1 to 155.77.47.254155.77.47.2551,022
77155.77.48.0/22155.77.48.1 to 155.77.51.254155.77.51.2551,022
78155.77.52.0/22155.77.52.1 to 155.77.55.254155.77.55.2551,022
79155.77.56.0/22155.77.56.1 to 155.77.59.254155.77.59.2551,022
80155.77.60.0/22155.77.60.1 to 155.77.63.254155.77.63.2551,022
81155.77.64.0/22155.77.64.1 to 155.77.67.254155.77.67.2551,022
82155.77.68.0/22155.77.68.1 to 155.77.71.254155.77.71.2551,022
83155.77.72.0/22155.77.72.1 to 155.77.75.254155.77.75.2551,022
84155.77.76.0/22155.77.76.1 to 155.77.79.254155.77.79.2551,022
85155.77.80.0/22155.77.80.1 to 155.77.83.254155.77.83.2551,022
86155.77.84.0/22155.77.84.1 to 155.77.87.254155.77.87.2551,022
87155.77.88.0/22155.77.88.1 to 155.77.91.254155.77.91.2551,022
88155.77.92.0/22155.77.92.1 to 155.77.95.254155.77.95.2551,022
89155.77.96.0/22155.77.96.1 to 155.77.99.254155.77.99.2551,022
90155.77.100.0/22155.77.100.1 to 155.77.103.254155.77.103.2551,022
91155.77.104.0/22155.77.104.1 to 155.77.107.254155.77.107.2551,022
92155.77.108.0/22155.77.108.1 to 155.77.111.254155.77.111.2551,022
93155.77.112.0/22155.77.112.1 to 155.77.115.254155.77.115.2551,022
94155.77.116.0/22155.77.116.1 to 155.77.119.254155.77.119.2551,022
95155.77.120.0/22155.77.120.1 to 155.77.123.254155.77.123.2551,022
96155.77.124.0/22155.77.124.1 to 155.77.127.254155.77.127.2551,022
97155.77.128.0/22155.77.128.1 to 155.77.131.254155.77.131.2551,022
98155.77.132.0/22155.77.132.1 to 155.77.135.254155.77.135.2551,022
99155.77.136.0/22155.77.136.1 to 155.77.139.254155.77.139.2551,022
100155.77.140.0/22155.77.140.1 to 155.77.143.254155.77.143.2551,022
101155.77.144.0/22155.77.144.1 to 155.77.147.254155.77.147.2551,022
102155.77.148.0/22155.77.148.1 to 155.77.151.254155.77.151.2551,022
103155.77.152.0/22155.77.152.1 to 155.77.155.254155.77.155.2551,022
104155.77.156.0/22155.77.156.1 to 155.77.159.254155.77.159.2551,022
105155.77.160.0/22155.77.160.1 to 155.77.163.254155.77.163.2551,022
106155.77.164.0/22155.77.164.1 to 155.77.167.254155.77.167.2551,022
107155.77.168.0/22155.77.168.1 to 155.77.171.254155.77.171.2551,022
108155.77.172.0/22155.77.172.1 to 155.77.175.254155.77.175.2551,022
109155.77.176.0/22155.77.176.1 to 155.77.179.254155.77.179.2551,022
110155.77.180.0/22155.77.180.1 to 155.77.183.254155.77.183.2551,022
111155.77.184.0/22155.77.184.1 to 155.77.187.254155.77.187.2551,022
112155.77.188.0/22155.77.188.1 to 155.77.191.254155.77.191.2551,022
113155.77.192.0/22155.77.192.1 to 155.77.195.254155.77.195.2551,022
114155.77.196.0/22155.77.196.1 to 155.77.199.254155.77.199.2551,022
115155.77.200.0/22155.77.200.1 to 155.77.203.254155.77.203.2551,022
116155.77.204.0/22155.77.204.1 to 155.77.207.254155.77.207.2551,022
117155.77.208.0/22155.77.208.1 to 155.77.211.254155.77.211.2551,022
118155.77.212.0/22155.77.212.1 to 155.77.215.254155.77.215.2551,022
119155.77.216.0/22155.77.216.1 to 155.77.219.254155.77.219.2551,022
120155.77.220.0/22155.77.220.1 to 155.77.223.254155.77.223.2551,022
121155.77.224.0/22155.77.224.1 to 155.77.227.254155.77.227.2551,022
122155.77.228.0/22155.77.228.1 to 155.77.231.254155.77.231.2551,022
123155.77.232.0/22155.77.232.1 to 155.77.235.254155.77.235.2551,022
124155.77.236.0/22155.77.236.1 to 155.77.239.254155.77.239.2551,022
125155.77.240.0/22155.77.240.1 to 155.77.243.254155.77.243.2551,022
126155.77.244.0/22155.77.244.1 to 155.77.247.254155.77.247.2551,022
127155.77.248.0/22155.77.248.1 to 155.77.251.254155.77.251.2551,022
128155.77.252.0/22155.77.252.1 to 155.77.255.254155.77.255.2551,022

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.