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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.

Network211.26.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
211.26.0.0
Broadcast address
211.27.255.255
First usable
211.26.0.1
Last usable
211.27.255.254
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
C (default /24)
As numbers
Hex D31A0000 · Integer 3541696512 to 3541827583
Reverse DNS zones
26.211.in-addr.arpa
27.211.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
Address11010011.00011010.00000000.00000000211.26.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network11010011.00011010.00000000.00000000211.26.0.0
Broadcast11010011.00011011.11111111.11111111211.27.255.255
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)

211.26.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1211.26.0.0/22211.26.0.1 to 211.26.3.254211.26.3.2551,022
2211.26.4.0/22211.26.4.1 to 211.26.7.254211.26.7.2551,022
3211.26.8.0/22211.26.8.1 to 211.26.11.254211.26.11.2551,022
4211.26.12.0/22211.26.12.1 to 211.26.15.254211.26.15.2551,022
5211.26.16.0/22211.26.16.1 to 211.26.19.254211.26.19.2551,022
6211.26.20.0/22211.26.20.1 to 211.26.23.254211.26.23.2551,022
7211.26.24.0/22211.26.24.1 to 211.26.27.254211.26.27.2551,022
8211.26.28.0/22211.26.28.1 to 211.26.31.254211.26.31.2551,022
9211.26.32.0/22211.26.32.1 to 211.26.35.254211.26.35.2551,022
10211.26.36.0/22211.26.36.1 to 211.26.39.254211.26.39.2551,022
11211.26.40.0/22211.26.40.1 to 211.26.43.254211.26.43.2551,022
12211.26.44.0/22211.26.44.1 to 211.26.47.254211.26.47.2551,022
13211.26.48.0/22211.26.48.1 to 211.26.51.254211.26.51.2551,022
14211.26.52.0/22211.26.52.1 to 211.26.55.254211.26.55.2551,022
15211.26.56.0/22211.26.56.1 to 211.26.59.254211.26.59.2551,022
16211.26.60.0/22211.26.60.1 to 211.26.63.254211.26.63.2551,022
17211.26.64.0/22211.26.64.1 to 211.26.67.254211.26.67.2551,022
18211.26.68.0/22211.26.68.1 to 211.26.71.254211.26.71.2551,022
19211.26.72.0/22211.26.72.1 to 211.26.75.254211.26.75.2551,022
20211.26.76.0/22211.26.76.1 to 211.26.79.254211.26.79.2551,022
21211.26.80.0/22211.26.80.1 to 211.26.83.254211.26.83.2551,022
22211.26.84.0/22211.26.84.1 to 211.26.87.254211.26.87.2551,022
23211.26.88.0/22211.26.88.1 to 211.26.91.254211.26.91.2551,022
24211.26.92.0/22211.26.92.1 to 211.26.95.254211.26.95.2551,022
25211.26.96.0/22211.26.96.1 to 211.26.99.254211.26.99.2551,022
26211.26.100.0/22211.26.100.1 to 211.26.103.254211.26.103.2551,022
27211.26.104.0/22211.26.104.1 to 211.26.107.254211.26.107.2551,022
28211.26.108.0/22211.26.108.1 to 211.26.111.254211.26.111.2551,022
29211.26.112.0/22211.26.112.1 to 211.26.115.254211.26.115.2551,022
30211.26.116.0/22211.26.116.1 to 211.26.119.254211.26.119.2551,022
31211.26.120.0/22211.26.120.1 to 211.26.123.254211.26.123.2551,022
32211.26.124.0/22211.26.124.1 to 211.26.127.254211.26.127.2551,022
33211.26.128.0/22211.26.128.1 to 211.26.131.254211.26.131.2551,022
34211.26.132.0/22211.26.132.1 to 211.26.135.254211.26.135.2551,022
35211.26.136.0/22211.26.136.1 to 211.26.139.254211.26.139.2551,022
36211.26.140.0/22211.26.140.1 to 211.26.143.254211.26.143.2551,022
37211.26.144.0/22211.26.144.1 to 211.26.147.254211.26.147.2551,022
38211.26.148.0/22211.26.148.1 to 211.26.151.254211.26.151.2551,022
39211.26.152.0/22211.26.152.1 to 211.26.155.254211.26.155.2551,022
40211.26.156.0/22211.26.156.1 to 211.26.159.254211.26.159.2551,022
41211.26.160.0/22211.26.160.1 to 211.26.163.254211.26.163.2551,022
42211.26.164.0/22211.26.164.1 to 211.26.167.254211.26.167.2551,022
43211.26.168.0/22211.26.168.1 to 211.26.171.254211.26.171.2551,022
44211.26.172.0/22211.26.172.1 to 211.26.175.254211.26.175.2551,022
45211.26.176.0/22211.26.176.1 to 211.26.179.254211.26.179.2551,022
46211.26.180.0/22211.26.180.1 to 211.26.183.254211.26.183.2551,022
47211.26.184.0/22211.26.184.1 to 211.26.187.254211.26.187.2551,022
48211.26.188.0/22211.26.188.1 to 211.26.191.254211.26.191.2551,022
49211.26.192.0/22211.26.192.1 to 211.26.195.254211.26.195.2551,022
50211.26.196.0/22211.26.196.1 to 211.26.199.254211.26.199.2551,022
51211.26.200.0/22211.26.200.1 to 211.26.203.254211.26.203.2551,022
52211.26.204.0/22211.26.204.1 to 211.26.207.254211.26.207.2551,022
53211.26.208.0/22211.26.208.1 to 211.26.211.254211.26.211.2551,022
54211.26.212.0/22211.26.212.1 to 211.26.215.254211.26.215.2551,022
55211.26.216.0/22211.26.216.1 to 211.26.219.254211.26.219.2551,022
56211.26.220.0/22211.26.220.1 to 211.26.223.254211.26.223.2551,022
57211.26.224.0/22211.26.224.1 to 211.26.227.254211.26.227.2551,022
58211.26.228.0/22211.26.228.1 to 211.26.231.254211.26.231.2551,022
59211.26.232.0/22211.26.232.1 to 211.26.235.254211.26.235.2551,022
60211.26.236.0/22211.26.236.1 to 211.26.239.254211.26.239.2551,022
61211.26.240.0/22211.26.240.1 to 211.26.243.254211.26.243.2551,022
62211.26.244.0/22211.26.244.1 to 211.26.247.254211.26.247.2551,022
63211.26.248.0/22211.26.248.1 to 211.26.251.254211.26.251.2551,022
64211.26.252.0/22211.26.252.1 to 211.26.255.254211.26.255.2551,022
65211.27.0.0/22211.27.0.1 to 211.27.3.254211.27.3.2551,022
66211.27.4.0/22211.27.4.1 to 211.27.7.254211.27.7.2551,022
67211.27.8.0/22211.27.8.1 to 211.27.11.254211.27.11.2551,022
68211.27.12.0/22211.27.12.1 to 211.27.15.254211.27.15.2551,022
69211.27.16.0/22211.27.16.1 to 211.27.19.254211.27.19.2551,022
70211.27.20.0/22211.27.20.1 to 211.27.23.254211.27.23.2551,022
71211.27.24.0/22211.27.24.1 to 211.27.27.254211.27.27.2551,022
72211.27.28.0/22211.27.28.1 to 211.27.31.254211.27.31.2551,022
73211.27.32.0/22211.27.32.1 to 211.27.35.254211.27.35.2551,022
74211.27.36.0/22211.27.36.1 to 211.27.39.254211.27.39.2551,022
75211.27.40.0/22211.27.40.1 to 211.27.43.254211.27.43.2551,022
76211.27.44.0/22211.27.44.1 to 211.27.47.254211.27.47.2551,022
77211.27.48.0/22211.27.48.1 to 211.27.51.254211.27.51.2551,022
78211.27.52.0/22211.27.52.1 to 211.27.55.254211.27.55.2551,022
79211.27.56.0/22211.27.56.1 to 211.27.59.254211.27.59.2551,022
80211.27.60.0/22211.27.60.1 to 211.27.63.254211.27.63.2551,022
81211.27.64.0/22211.27.64.1 to 211.27.67.254211.27.67.2551,022
82211.27.68.0/22211.27.68.1 to 211.27.71.254211.27.71.2551,022
83211.27.72.0/22211.27.72.1 to 211.27.75.254211.27.75.2551,022
84211.27.76.0/22211.27.76.1 to 211.27.79.254211.27.79.2551,022
85211.27.80.0/22211.27.80.1 to 211.27.83.254211.27.83.2551,022
86211.27.84.0/22211.27.84.1 to 211.27.87.254211.27.87.2551,022
87211.27.88.0/22211.27.88.1 to 211.27.91.254211.27.91.2551,022
88211.27.92.0/22211.27.92.1 to 211.27.95.254211.27.95.2551,022
89211.27.96.0/22211.27.96.1 to 211.27.99.254211.27.99.2551,022
90211.27.100.0/22211.27.100.1 to 211.27.103.254211.27.103.2551,022
91211.27.104.0/22211.27.104.1 to 211.27.107.254211.27.107.2551,022
92211.27.108.0/22211.27.108.1 to 211.27.111.254211.27.111.2551,022
93211.27.112.0/22211.27.112.1 to 211.27.115.254211.27.115.2551,022
94211.27.116.0/22211.27.116.1 to 211.27.119.254211.27.119.2551,022
95211.27.120.0/22211.27.120.1 to 211.27.123.254211.27.123.2551,022
96211.27.124.0/22211.27.124.1 to 211.27.127.254211.27.127.2551,022
97211.27.128.0/22211.27.128.1 to 211.27.131.254211.27.131.2551,022
98211.27.132.0/22211.27.132.1 to 211.27.135.254211.27.135.2551,022
99211.27.136.0/22211.27.136.1 to 211.27.139.254211.27.139.2551,022
100211.27.140.0/22211.27.140.1 to 211.27.143.254211.27.143.2551,022
101211.27.144.0/22211.27.144.1 to 211.27.147.254211.27.147.2551,022
102211.27.148.0/22211.27.148.1 to 211.27.151.254211.27.151.2551,022
103211.27.152.0/22211.27.152.1 to 211.27.155.254211.27.155.2551,022
104211.27.156.0/22211.27.156.1 to 211.27.159.254211.27.159.2551,022
105211.27.160.0/22211.27.160.1 to 211.27.163.254211.27.163.2551,022
106211.27.164.0/22211.27.164.1 to 211.27.167.254211.27.167.2551,022
107211.27.168.0/22211.27.168.1 to 211.27.171.254211.27.171.2551,022
108211.27.172.0/22211.27.172.1 to 211.27.175.254211.27.175.2551,022
109211.27.176.0/22211.27.176.1 to 211.27.179.254211.27.179.2551,022
110211.27.180.0/22211.27.180.1 to 211.27.183.254211.27.183.2551,022
111211.27.184.0/22211.27.184.1 to 211.27.187.254211.27.187.2551,022
112211.27.188.0/22211.27.188.1 to 211.27.191.254211.27.191.2551,022
113211.27.192.0/22211.27.192.1 to 211.27.195.254211.27.195.2551,022
114211.27.196.0/22211.27.196.1 to 211.27.199.254211.27.199.2551,022
115211.27.200.0/22211.27.200.1 to 211.27.203.254211.27.203.2551,022
116211.27.204.0/22211.27.204.1 to 211.27.207.254211.27.207.2551,022
117211.27.208.0/22211.27.208.1 to 211.27.211.254211.27.211.2551,022
118211.27.212.0/22211.27.212.1 to 211.27.215.254211.27.215.2551,022
119211.27.216.0/22211.27.216.1 to 211.27.219.254211.27.219.2551,022
120211.27.220.0/22211.27.220.1 to 211.27.223.254211.27.223.2551,022
121211.27.224.0/22211.27.224.1 to 211.27.227.254211.27.227.2551,022
122211.27.228.0/22211.27.228.1 to 211.27.231.254211.27.231.2551,022
123211.27.232.0/22211.27.232.1 to 211.27.235.254211.27.235.2551,022
124211.27.236.0/22211.27.236.1 to 211.27.239.254211.27.239.2551,022
125211.27.240.0/22211.27.240.1 to 211.27.243.254211.27.243.2551,022
126211.27.244.0/22211.27.244.1 to 211.27.247.254211.27.247.2551,022
127211.27.248.0/22211.27.248.1 to 211.27.251.254211.27.251.2551,022
128211.27.252.0/22211.27.252.1 to 211.27.255.254211.27.255.2551,022

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.