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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.

Network237.26.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
237.26.0.0
Broadcast address
237.27.255.255
First usable
237.26.0.1
Last usable
237.27.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex ED1A0000 · Integer 3977904128 to 3978035199
Reverse DNS zones
26.237.in-addr.arpa
27.237.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
Address11101101.00011010.00000000.00000000237.26.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network11101101.00011010.00000000.00000000237.26.0.0
Broadcast11101101.00011011.11111111.11111111237.27.255.255
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)

237.26.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1237.26.0.0/22237.26.0.1 to 237.26.3.254237.26.3.2551,022
2237.26.4.0/22237.26.4.1 to 237.26.7.254237.26.7.2551,022
3237.26.8.0/22237.26.8.1 to 237.26.11.254237.26.11.2551,022
4237.26.12.0/22237.26.12.1 to 237.26.15.254237.26.15.2551,022
5237.26.16.0/22237.26.16.1 to 237.26.19.254237.26.19.2551,022
6237.26.20.0/22237.26.20.1 to 237.26.23.254237.26.23.2551,022
7237.26.24.0/22237.26.24.1 to 237.26.27.254237.26.27.2551,022
8237.26.28.0/22237.26.28.1 to 237.26.31.254237.26.31.2551,022
9237.26.32.0/22237.26.32.1 to 237.26.35.254237.26.35.2551,022
10237.26.36.0/22237.26.36.1 to 237.26.39.254237.26.39.2551,022
11237.26.40.0/22237.26.40.1 to 237.26.43.254237.26.43.2551,022
12237.26.44.0/22237.26.44.1 to 237.26.47.254237.26.47.2551,022
13237.26.48.0/22237.26.48.1 to 237.26.51.254237.26.51.2551,022
14237.26.52.0/22237.26.52.1 to 237.26.55.254237.26.55.2551,022
15237.26.56.0/22237.26.56.1 to 237.26.59.254237.26.59.2551,022
16237.26.60.0/22237.26.60.1 to 237.26.63.254237.26.63.2551,022
17237.26.64.0/22237.26.64.1 to 237.26.67.254237.26.67.2551,022
18237.26.68.0/22237.26.68.1 to 237.26.71.254237.26.71.2551,022
19237.26.72.0/22237.26.72.1 to 237.26.75.254237.26.75.2551,022
20237.26.76.0/22237.26.76.1 to 237.26.79.254237.26.79.2551,022
21237.26.80.0/22237.26.80.1 to 237.26.83.254237.26.83.2551,022
22237.26.84.0/22237.26.84.1 to 237.26.87.254237.26.87.2551,022
23237.26.88.0/22237.26.88.1 to 237.26.91.254237.26.91.2551,022
24237.26.92.0/22237.26.92.1 to 237.26.95.254237.26.95.2551,022
25237.26.96.0/22237.26.96.1 to 237.26.99.254237.26.99.2551,022
26237.26.100.0/22237.26.100.1 to 237.26.103.254237.26.103.2551,022
27237.26.104.0/22237.26.104.1 to 237.26.107.254237.26.107.2551,022
28237.26.108.0/22237.26.108.1 to 237.26.111.254237.26.111.2551,022
29237.26.112.0/22237.26.112.1 to 237.26.115.254237.26.115.2551,022
30237.26.116.0/22237.26.116.1 to 237.26.119.254237.26.119.2551,022
31237.26.120.0/22237.26.120.1 to 237.26.123.254237.26.123.2551,022
32237.26.124.0/22237.26.124.1 to 237.26.127.254237.26.127.2551,022
33237.26.128.0/22237.26.128.1 to 237.26.131.254237.26.131.2551,022
34237.26.132.0/22237.26.132.1 to 237.26.135.254237.26.135.2551,022
35237.26.136.0/22237.26.136.1 to 237.26.139.254237.26.139.2551,022
36237.26.140.0/22237.26.140.1 to 237.26.143.254237.26.143.2551,022
37237.26.144.0/22237.26.144.1 to 237.26.147.254237.26.147.2551,022
38237.26.148.0/22237.26.148.1 to 237.26.151.254237.26.151.2551,022
39237.26.152.0/22237.26.152.1 to 237.26.155.254237.26.155.2551,022
40237.26.156.0/22237.26.156.1 to 237.26.159.254237.26.159.2551,022
41237.26.160.0/22237.26.160.1 to 237.26.163.254237.26.163.2551,022
42237.26.164.0/22237.26.164.1 to 237.26.167.254237.26.167.2551,022
43237.26.168.0/22237.26.168.1 to 237.26.171.254237.26.171.2551,022
44237.26.172.0/22237.26.172.1 to 237.26.175.254237.26.175.2551,022
45237.26.176.0/22237.26.176.1 to 237.26.179.254237.26.179.2551,022
46237.26.180.0/22237.26.180.1 to 237.26.183.254237.26.183.2551,022
47237.26.184.0/22237.26.184.1 to 237.26.187.254237.26.187.2551,022
48237.26.188.0/22237.26.188.1 to 237.26.191.254237.26.191.2551,022
49237.26.192.0/22237.26.192.1 to 237.26.195.254237.26.195.2551,022
50237.26.196.0/22237.26.196.1 to 237.26.199.254237.26.199.2551,022
51237.26.200.0/22237.26.200.1 to 237.26.203.254237.26.203.2551,022
52237.26.204.0/22237.26.204.1 to 237.26.207.254237.26.207.2551,022
53237.26.208.0/22237.26.208.1 to 237.26.211.254237.26.211.2551,022
54237.26.212.0/22237.26.212.1 to 237.26.215.254237.26.215.2551,022
55237.26.216.0/22237.26.216.1 to 237.26.219.254237.26.219.2551,022
56237.26.220.0/22237.26.220.1 to 237.26.223.254237.26.223.2551,022
57237.26.224.0/22237.26.224.1 to 237.26.227.254237.26.227.2551,022
58237.26.228.0/22237.26.228.1 to 237.26.231.254237.26.231.2551,022
59237.26.232.0/22237.26.232.1 to 237.26.235.254237.26.235.2551,022
60237.26.236.0/22237.26.236.1 to 237.26.239.254237.26.239.2551,022
61237.26.240.0/22237.26.240.1 to 237.26.243.254237.26.243.2551,022
62237.26.244.0/22237.26.244.1 to 237.26.247.254237.26.247.2551,022
63237.26.248.0/22237.26.248.1 to 237.26.251.254237.26.251.2551,022
64237.26.252.0/22237.26.252.1 to 237.26.255.254237.26.255.2551,022
65237.27.0.0/22237.27.0.1 to 237.27.3.254237.27.3.2551,022
66237.27.4.0/22237.27.4.1 to 237.27.7.254237.27.7.2551,022
67237.27.8.0/22237.27.8.1 to 237.27.11.254237.27.11.2551,022
68237.27.12.0/22237.27.12.1 to 237.27.15.254237.27.15.2551,022
69237.27.16.0/22237.27.16.1 to 237.27.19.254237.27.19.2551,022
70237.27.20.0/22237.27.20.1 to 237.27.23.254237.27.23.2551,022
71237.27.24.0/22237.27.24.1 to 237.27.27.254237.27.27.2551,022
72237.27.28.0/22237.27.28.1 to 237.27.31.254237.27.31.2551,022
73237.27.32.0/22237.27.32.1 to 237.27.35.254237.27.35.2551,022
74237.27.36.0/22237.27.36.1 to 237.27.39.254237.27.39.2551,022
75237.27.40.0/22237.27.40.1 to 237.27.43.254237.27.43.2551,022
76237.27.44.0/22237.27.44.1 to 237.27.47.254237.27.47.2551,022
77237.27.48.0/22237.27.48.1 to 237.27.51.254237.27.51.2551,022
78237.27.52.0/22237.27.52.1 to 237.27.55.254237.27.55.2551,022
79237.27.56.0/22237.27.56.1 to 237.27.59.254237.27.59.2551,022
80237.27.60.0/22237.27.60.1 to 237.27.63.254237.27.63.2551,022
81237.27.64.0/22237.27.64.1 to 237.27.67.254237.27.67.2551,022
82237.27.68.0/22237.27.68.1 to 237.27.71.254237.27.71.2551,022
83237.27.72.0/22237.27.72.1 to 237.27.75.254237.27.75.2551,022
84237.27.76.0/22237.27.76.1 to 237.27.79.254237.27.79.2551,022
85237.27.80.0/22237.27.80.1 to 237.27.83.254237.27.83.2551,022
86237.27.84.0/22237.27.84.1 to 237.27.87.254237.27.87.2551,022
87237.27.88.0/22237.27.88.1 to 237.27.91.254237.27.91.2551,022
88237.27.92.0/22237.27.92.1 to 237.27.95.254237.27.95.2551,022
89237.27.96.0/22237.27.96.1 to 237.27.99.254237.27.99.2551,022
90237.27.100.0/22237.27.100.1 to 237.27.103.254237.27.103.2551,022
91237.27.104.0/22237.27.104.1 to 237.27.107.254237.27.107.2551,022
92237.27.108.0/22237.27.108.1 to 237.27.111.254237.27.111.2551,022
93237.27.112.0/22237.27.112.1 to 237.27.115.254237.27.115.2551,022
94237.27.116.0/22237.27.116.1 to 237.27.119.254237.27.119.2551,022
95237.27.120.0/22237.27.120.1 to 237.27.123.254237.27.123.2551,022
96237.27.124.0/22237.27.124.1 to 237.27.127.254237.27.127.2551,022
97237.27.128.0/22237.27.128.1 to 237.27.131.254237.27.131.2551,022
98237.27.132.0/22237.27.132.1 to 237.27.135.254237.27.135.2551,022
99237.27.136.0/22237.27.136.1 to 237.27.139.254237.27.139.2551,022
100237.27.140.0/22237.27.140.1 to 237.27.143.254237.27.143.2551,022
101237.27.144.0/22237.27.144.1 to 237.27.147.254237.27.147.2551,022
102237.27.148.0/22237.27.148.1 to 237.27.151.254237.27.151.2551,022
103237.27.152.0/22237.27.152.1 to 237.27.155.254237.27.155.2551,022
104237.27.156.0/22237.27.156.1 to 237.27.159.254237.27.159.2551,022
105237.27.160.0/22237.27.160.1 to 237.27.163.254237.27.163.2551,022
106237.27.164.0/22237.27.164.1 to 237.27.167.254237.27.167.2551,022
107237.27.168.0/22237.27.168.1 to 237.27.171.254237.27.171.2551,022
108237.27.172.0/22237.27.172.1 to 237.27.175.254237.27.175.2551,022
109237.27.176.0/22237.27.176.1 to 237.27.179.254237.27.179.2551,022
110237.27.180.0/22237.27.180.1 to 237.27.183.254237.27.183.2551,022
111237.27.184.0/22237.27.184.1 to 237.27.187.254237.27.187.2551,022
112237.27.188.0/22237.27.188.1 to 237.27.191.254237.27.191.2551,022
113237.27.192.0/22237.27.192.1 to 237.27.195.254237.27.195.2551,022
114237.27.196.0/22237.27.196.1 to 237.27.199.254237.27.199.2551,022
115237.27.200.0/22237.27.200.1 to 237.27.203.254237.27.203.2551,022
116237.27.204.0/22237.27.204.1 to 237.27.207.254237.27.207.2551,022
117237.27.208.0/22237.27.208.1 to 237.27.211.254237.27.211.2551,022
118237.27.212.0/22237.27.212.1 to 237.27.215.254237.27.215.2551,022
119237.27.216.0/22237.27.216.1 to 237.27.219.254237.27.219.2551,022
120237.27.220.0/22237.27.220.1 to 237.27.223.254237.27.223.2551,022
121237.27.224.0/22237.27.224.1 to 237.27.227.254237.27.227.2551,022
122237.27.228.0/22237.27.228.1 to 237.27.231.254237.27.231.2551,022
123237.27.232.0/22237.27.232.1 to 237.27.235.254237.27.235.2551,022
124237.27.236.0/22237.27.236.1 to 237.27.239.254237.27.239.2551,022
125237.27.240.0/22237.27.240.1 to 237.27.243.254237.27.243.2551,022
126237.27.244.0/22237.27.244.1 to 237.27.247.254237.27.247.2551,022
127237.27.248.0/22237.27.248.1 to 237.27.251.254237.27.251.2551,022
128237.27.252.0/22237.27.252.1 to 237.27.255.254237.27.255.2551,022

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.