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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.

Network115.2.96.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
115.2.96.0
Broadcast address
115.2.111.255
First usable
115.2.96.1
Last usable
115.2.111.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
A (default /8)
As numbers
Hex 73026000 · Integer 1929535488 to 1929539583
Reverse DNS zones
96.2.115.in-addr.arpa
97.2.115.in-addr.arpa
98.2.115.in-addr.arpa
99.2.115.in-addr.arpa
100.2.115.in-addr.arpa
101.2.115.in-addr.arpa
102.2.115.in-addr.arpa
103.2.115.in-addr.arpa
104.2.115.in-addr.arpa
105.2.115.in-addr.arpa
106.2.115.in-addr.arpa
107.2.115.in-addr.arpa
108.2.115.in-addr.arpa
109.2.115.in-addr.arpa
110.2.115.in-addr.arpa
111.2.115.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01110011.00000010.01100000.00000000115.2.96.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network01110011.00000010.01100000.00000000115.2.96.0
Broadcast01110011.00000010.01101111.11111111115.2.111.255
Split into smaller subnets/27
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

115.2.96.0/20 makes 128 subnets of /27.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1115.2.96.0/27115.2.96.1 to 115.2.96.30115.2.96.3130
2115.2.96.32/27115.2.96.33 to 115.2.96.62115.2.96.6330
3115.2.96.64/27115.2.96.65 to 115.2.96.94115.2.96.9530
4115.2.96.96/27115.2.96.97 to 115.2.96.126115.2.96.12730
5115.2.96.128/27115.2.96.129 to 115.2.96.158115.2.96.15930
6115.2.96.160/27115.2.96.161 to 115.2.96.190115.2.96.19130
7115.2.96.192/27115.2.96.193 to 115.2.96.222115.2.96.22330
8115.2.96.224/27115.2.96.225 to 115.2.96.254115.2.96.25530
9115.2.97.0/27115.2.97.1 to 115.2.97.30115.2.97.3130
10115.2.97.32/27115.2.97.33 to 115.2.97.62115.2.97.6330
11115.2.97.64/27115.2.97.65 to 115.2.97.94115.2.97.9530
12115.2.97.96/27115.2.97.97 to 115.2.97.126115.2.97.12730
13115.2.97.128/27115.2.97.129 to 115.2.97.158115.2.97.15930
14115.2.97.160/27115.2.97.161 to 115.2.97.190115.2.97.19130
15115.2.97.192/27115.2.97.193 to 115.2.97.222115.2.97.22330
16115.2.97.224/27115.2.97.225 to 115.2.97.254115.2.97.25530
17115.2.98.0/27115.2.98.1 to 115.2.98.30115.2.98.3130
18115.2.98.32/27115.2.98.33 to 115.2.98.62115.2.98.6330
19115.2.98.64/27115.2.98.65 to 115.2.98.94115.2.98.9530
20115.2.98.96/27115.2.98.97 to 115.2.98.126115.2.98.12730
21115.2.98.128/27115.2.98.129 to 115.2.98.158115.2.98.15930
22115.2.98.160/27115.2.98.161 to 115.2.98.190115.2.98.19130
23115.2.98.192/27115.2.98.193 to 115.2.98.222115.2.98.22330
24115.2.98.224/27115.2.98.225 to 115.2.98.254115.2.98.25530
25115.2.99.0/27115.2.99.1 to 115.2.99.30115.2.99.3130
26115.2.99.32/27115.2.99.33 to 115.2.99.62115.2.99.6330
27115.2.99.64/27115.2.99.65 to 115.2.99.94115.2.99.9530
28115.2.99.96/27115.2.99.97 to 115.2.99.126115.2.99.12730
29115.2.99.128/27115.2.99.129 to 115.2.99.158115.2.99.15930
30115.2.99.160/27115.2.99.161 to 115.2.99.190115.2.99.19130
31115.2.99.192/27115.2.99.193 to 115.2.99.222115.2.99.22330
32115.2.99.224/27115.2.99.225 to 115.2.99.254115.2.99.25530
33115.2.100.0/27115.2.100.1 to 115.2.100.30115.2.100.3130
34115.2.100.32/27115.2.100.33 to 115.2.100.62115.2.100.6330
35115.2.100.64/27115.2.100.65 to 115.2.100.94115.2.100.9530
36115.2.100.96/27115.2.100.97 to 115.2.100.126115.2.100.12730
37115.2.100.128/27115.2.100.129 to 115.2.100.158115.2.100.15930
38115.2.100.160/27115.2.100.161 to 115.2.100.190115.2.100.19130
39115.2.100.192/27115.2.100.193 to 115.2.100.222115.2.100.22330
40115.2.100.224/27115.2.100.225 to 115.2.100.254115.2.100.25530
41115.2.101.0/27115.2.101.1 to 115.2.101.30115.2.101.3130
42115.2.101.32/27115.2.101.33 to 115.2.101.62115.2.101.6330
43115.2.101.64/27115.2.101.65 to 115.2.101.94115.2.101.9530
44115.2.101.96/27115.2.101.97 to 115.2.101.126115.2.101.12730
45115.2.101.128/27115.2.101.129 to 115.2.101.158115.2.101.15930
46115.2.101.160/27115.2.101.161 to 115.2.101.190115.2.101.19130
47115.2.101.192/27115.2.101.193 to 115.2.101.222115.2.101.22330
48115.2.101.224/27115.2.101.225 to 115.2.101.254115.2.101.25530
49115.2.102.0/27115.2.102.1 to 115.2.102.30115.2.102.3130
50115.2.102.32/27115.2.102.33 to 115.2.102.62115.2.102.6330
51115.2.102.64/27115.2.102.65 to 115.2.102.94115.2.102.9530
52115.2.102.96/27115.2.102.97 to 115.2.102.126115.2.102.12730
53115.2.102.128/27115.2.102.129 to 115.2.102.158115.2.102.15930
54115.2.102.160/27115.2.102.161 to 115.2.102.190115.2.102.19130
55115.2.102.192/27115.2.102.193 to 115.2.102.222115.2.102.22330
56115.2.102.224/27115.2.102.225 to 115.2.102.254115.2.102.25530
57115.2.103.0/27115.2.103.1 to 115.2.103.30115.2.103.3130
58115.2.103.32/27115.2.103.33 to 115.2.103.62115.2.103.6330
59115.2.103.64/27115.2.103.65 to 115.2.103.94115.2.103.9530
60115.2.103.96/27115.2.103.97 to 115.2.103.126115.2.103.12730
61115.2.103.128/27115.2.103.129 to 115.2.103.158115.2.103.15930
62115.2.103.160/27115.2.103.161 to 115.2.103.190115.2.103.19130
63115.2.103.192/27115.2.103.193 to 115.2.103.222115.2.103.22330
64115.2.103.224/27115.2.103.225 to 115.2.103.254115.2.103.25530
65115.2.104.0/27115.2.104.1 to 115.2.104.30115.2.104.3130
66115.2.104.32/27115.2.104.33 to 115.2.104.62115.2.104.6330
67115.2.104.64/27115.2.104.65 to 115.2.104.94115.2.104.9530
68115.2.104.96/27115.2.104.97 to 115.2.104.126115.2.104.12730
69115.2.104.128/27115.2.104.129 to 115.2.104.158115.2.104.15930
70115.2.104.160/27115.2.104.161 to 115.2.104.190115.2.104.19130
71115.2.104.192/27115.2.104.193 to 115.2.104.222115.2.104.22330
72115.2.104.224/27115.2.104.225 to 115.2.104.254115.2.104.25530
73115.2.105.0/27115.2.105.1 to 115.2.105.30115.2.105.3130
74115.2.105.32/27115.2.105.33 to 115.2.105.62115.2.105.6330
75115.2.105.64/27115.2.105.65 to 115.2.105.94115.2.105.9530
76115.2.105.96/27115.2.105.97 to 115.2.105.126115.2.105.12730
77115.2.105.128/27115.2.105.129 to 115.2.105.158115.2.105.15930
78115.2.105.160/27115.2.105.161 to 115.2.105.190115.2.105.19130
79115.2.105.192/27115.2.105.193 to 115.2.105.222115.2.105.22330
80115.2.105.224/27115.2.105.225 to 115.2.105.254115.2.105.25530
81115.2.106.0/27115.2.106.1 to 115.2.106.30115.2.106.3130
82115.2.106.32/27115.2.106.33 to 115.2.106.62115.2.106.6330
83115.2.106.64/27115.2.106.65 to 115.2.106.94115.2.106.9530
84115.2.106.96/27115.2.106.97 to 115.2.106.126115.2.106.12730
85115.2.106.128/27115.2.106.129 to 115.2.106.158115.2.106.15930
86115.2.106.160/27115.2.106.161 to 115.2.106.190115.2.106.19130
87115.2.106.192/27115.2.106.193 to 115.2.106.222115.2.106.22330
88115.2.106.224/27115.2.106.225 to 115.2.106.254115.2.106.25530
89115.2.107.0/27115.2.107.1 to 115.2.107.30115.2.107.3130
90115.2.107.32/27115.2.107.33 to 115.2.107.62115.2.107.6330
91115.2.107.64/27115.2.107.65 to 115.2.107.94115.2.107.9530
92115.2.107.96/27115.2.107.97 to 115.2.107.126115.2.107.12730
93115.2.107.128/27115.2.107.129 to 115.2.107.158115.2.107.15930
94115.2.107.160/27115.2.107.161 to 115.2.107.190115.2.107.19130
95115.2.107.192/27115.2.107.193 to 115.2.107.222115.2.107.22330
96115.2.107.224/27115.2.107.225 to 115.2.107.254115.2.107.25530
97115.2.108.0/27115.2.108.1 to 115.2.108.30115.2.108.3130
98115.2.108.32/27115.2.108.33 to 115.2.108.62115.2.108.6330
99115.2.108.64/27115.2.108.65 to 115.2.108.94115.2.108.9530
100115.2.108.96/27115.2.108.97 to 115.2.108.126115.2.108.12730
101115.2.108.128/27115.2.108.129 to 115.2.108.158115.2.108.15930
102115.2.108.160/27115.2.108.161 to 115.2.108.190115.2.108.19130
103115.2.108.192/27115.2.108.193 to 115.2.108.222115.2.108.22330
104115.2.108.224/27115.2.108.225 to 115.2.108.254115.2.108.25530
105115.2.109.0/27115.2.109.1 to 115.2.109.30115.2.109.3130
106115.2.109.32/27115.2.109.33 to 115.2.109.62115.2.109.6330
107115.2.109.64/27115.2.109.65 to 115.2.109.94115.2.109.9530
108115.2.109.96/27115.2.109.97 to 115.2.109.126115.2.109.12730
109115.2.109.128/27115.2.109.129 to 115.2.109.158115.2.109.15930
110115.2.109.160/27115.2.109.161 to 115.2.109.190115.2.109.19130
111115.2.109.192/27115.2.109.193 to 115.2.109.222115.2.109.22330
112115.2.109.224/27115.2.109.225 to 115.2.109.254115.2.109.25530
113115.2.110.0/27115.2.110.1 to 115.2.110.30115.2.110.3130
114115.2.110.32/27115.2.110.33 to 115.2.110.62115.2.110.6330
115115.2.110.64/27115.2.110.65 to 115.2.110.94115.2.110.9530
116115.2.110.96/27115.2.110.97 to 115.2.110.126115.2.110.12730
117115.2.110.128/27115.2.110.129 to 115.2.110.158115.2.110.15930
118115.2.110.160/27115.2.110.161 to 115.2.110.190115.2.110.19130
119115.2.110.192/27115.2.110.193 to 115.2.110.222115.2.110.22330
120115.2.110.224/27115.2.110.225 to 115.2.110.254115.2.110.25530
121115.2.111.0/27115.2.111.1 to 115.2.111.30115.2.111.3130
122115.2.111.32/27115.2.111.33 to 115.2.111.62115.2.111.6330
123115.2.111.64/27115.2.111.65 to 115.2.111.94115.2.111.9530
124115.2.111.96/27115.2.111.97 to 115.2.111.126115.2.111.12730
125115.2.111.128/27115.2.111.129 to 115.2.111.158115.2.111.15930
126115.2.111.160/27115.2.111.161 to 115.2.111.190115.2.111.19130
127115.2.111.192/27115.2.111.193 to 115.2.111.222115.2.111.22330
128115.2.111.224/27115.2.111.225 to 115.2.111.254115.2.111.25530

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.