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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.

Network152.4.192.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
152.4.192.0
Broadcast address
152.4.207.255
First usable
152.4.192.1
Last usable
152.4.207.254
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
B (default /16)
As numbers
Hex 9804C000 · Integer 2550448128 to 2550452223
Reverse DNS zones
192.4.152.in-addr.arpa
193.4.152.in-addr.arpa
194.4.152.in-addr.arpa
195.4.152.in-addr.arpa
196.4.152.in-addr.arpa
197.4.152.in-addr.arpa
198.4.152.in-addr.arpa
199.4.152.in-addr.arpa
200.4.152.in-addr.arpa
201.4.152.in-addr.arpa
202.4.152.in-addr.arpa
203.4.152.in-addr.arpa
204.4.152.in-addr.arpa
205.4.152.in-addr.arpa
206.4.152.in-addr.arpa
207.4.152.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
Address10011000.00000100.11000000.00000000152.4.192.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network10011000.00000100.11000000.00000000152.4.192.0
Broadcast10011000.00000100.11001111.11111111152.4.207.255
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)

152.4.192.0/20 makes 128 subnets of /27.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1152.4.192.0/27152.4.192.1 to 152.4.192.30152.4.192.3130
2152.4.192.32/27152.4.192.33 to 152.4.192.62152.4.192.6330
3152.4.192.64/27152.4.192.65 to 152.4.192.94152.4.192.9530
4152.4.192.96/27152.4.192.97 to 152.4.192.126152.4.192.12730
5152.4.192.128/27152.4.192.129 to 152.4.192.158152.4.192.15930
6152.4.192.160/27152.4.192.161 to 152.4.192.190152.4.192.19130
7152.4.192.192/27152.4.192.193 to 152.4.192.222152.4.192.22330
8152.4.192.224/27152.4.192.225 to 152.4.192.254152.4.192.25530
9152.4.193.0/27152.4.193.1 to 152.4.193.30152.4.193.3130
10152.4.193.32/27152.4.193.33 to 152.4.193.62152.4.193.6330
11152.4.193.64/27152.4.193.65 to 152.4.193.94152.4.193.9530
12152.4.193.96/27152.4.193.97 to 152.4.193.126152.4.193.12730
13152.4.193.128/27152.4.193.129 to 152.4.193.158152.4.193.15930
14152.4.193.160/27152.4.193.161 to 152.4.193.190152.4.193.19130
15152.4.193.192/27152.4.193.193 to 152.4.193.222152.4.193.22330
16152.4.193.224/27152.4.193.225 to 152.4.193.254152.4.193.25530
17152.4.194.0/27152.4.194.1 to 152.4.194.30152.4.194.3130
18152.4.194.32/27152.4.194.33 to 152.4.194.62152.4.194.6330
19152.4.194.64/27152.4.194.65 to 152.4.194.94152.4.194.9530
20152.4.194.96/27152.4.194.97 to 152.4.194.126152.4.194.12730
21152.4.194.128/27152.4.194.129 to 152.4.194.158152.4.194.15930
22152.4.194.160/27152.4.194.161 to 152.4.194.190152.4.194.19130
23152.4.194.192/27152.4.194.193 to 152.4.194.222152.4.194.22330
24152.4.194.224/27152.4.194.225 to 152.4.194.254152.4.194.25530
25152.4.195.0/27152.4.195.1 to 152.4.195.30152.4.195.3130
26152.4.195.32/27152.4.195.33 to 152.4.195.62152.4.195.6330
27152.4.195.64/27152.4.195.65 to 152.4.195.94152.4.195.9530
28152.4.195.96/27152.4.195.97 to 152.4.195.126152.4.195.12730
29152.4.195.128/27152.4.195.129 to 152.4.195.158152.4.195.15930
30152.4.195.160/27152.4.195.161 to 152.4.195.190152.4.195.19130
31152.4.195.192/27152.4.195.193 to 152.4.195.222152.4.195.22330
32152.4.195.224/27152.4.195.225 to 152.4.195.254152.4.195.25530
33152.4.196.0/27152.4.196.1 to 152.4.196.30152.4.196.3130
34152.4.196.32/27152.4.196.33 to 152.4.196.62152.4.196.6330
35152.4.196.64/27152.4.196.65 to 152.4.196.94152.4.196.9530
36152.4.196.96/27152.4.196.97 to 152.4.196.126152.4.196.12730
37152.4.196.128/27152.4.196.129 to 152.4.196.158152.4.196.15930
38152.4.196.160/27152.4.196.161 to 152.4.196.190152.4.196.19130
39152.4.196.192/27152.4.196.193 to 152.4.196.222152.4.196.22330
40152.4.196.224/27152.4.196.225 to 152.4.196.254152.4.196.25530
41152.4.197.0/27152.4.197.1 to 152.4.197.30152.4.197.3130
42152.4.197.32/27152.4.197.33 to 152.4.197.62152.4.197.6330
43152.4.197.64/27152.4.197.65 to 152.4.197.94152.4.197.9530
44152.4.197.96/27152.4.197.97 to 152.4.197.126152.4.197.12730
45152.4.197.128/27152.4.197.129 to 152.4.197.158152.4.197.15930
46152.4.197.160/27152.4.197.161 to 152.4.197.190152.4.197.19130
47152.4.197.192/27152.4.197.193 to 152.4.197.222152.4.197.22330
48152.4.197.224/27152.4.197.225 to 152.4.197.254152.4.197.25530
49152.4.198.0/27152.4.198.1 to 152.4.198.30152.4.198.3130
50152.4.198.32/27152.4.198.33 to 152.4.198.62152.4.198.6330
51152.4.198.64/27152.4.198.65 to 152.4.198.94152.4.198.9530
52152.4.198.96/27152.4.198.97 to 152.4.198.126152.4.198.12730
53152.4.198.128/27152.4.198.129 to 152.4.198.158152.4.198.15930
54152.4.198.160/27152.4.198.161 to 152.4.198.190152.4.198.19130
55152.4.198.192/27152.4.198.193 to 152.4.198.222152.4.198.22330
56152.4.198.224/27152.4.198.225 to 152.4.198.254152.4.198.25530
57152.4.199.0/27152.4.199.1 to 152.4.199.30152.4.199.3130
58152.4.199.32/27152.4.199.33 to 152.4.199.62152.4.199.6330
59152.4.199.64/27152.4.199.65 to 152.4.199.94152.4.199.9530
60152.4.199.96/27152.4.199.97 to 152.4.199.126152.4.199.12730
61152.4.199.128/27152.4.199.129 to 152.4.199.158152.4.199.15930
62152.4.199.160/27152.4.199.161 to 152.4.199.190152.4.199.19130
63152.4.199.192/27152.4.199.193 to 152.4.199.222152.4.199.22330
64152.4.199.224/27152.4.199.225 to 152.4.199.254152.4.199.25530
65152.4.200.0/27152.4.200.1 to 152.4.200.30152.4.200.3130
66152.4.200.32/27152.4.200.33 to 152.4.200.62152.4.200.6330
67152.4.200.64/27152.4.200.65 to 152.4.200.94152.4.200.9530
68152.4.200.96/27152.4.200.97 to 152.4.200.126152.4.200.12730
69152.4.200.128/27152.4.200.129 to 152.4.200.158152.4.200.15930
70152.4.200.160/27152.4.200.161 to 152.4.200.190152.4.200.19130
71152.4.200.192/27152.4.200.193 to 152.4.200.222152.4.200.22330
72152.4.200.224/27152.4.200.225 to 152.4.200.254152.4.200.25530
73152.4.201.0/27152.4.201.1 to 152.4.201.30152.4.201.3130
74152.4.201.32/27152.4.201.33 to 152.4.201.62152.4.201.6330
75152.4.201.64/27152.4.201.65 to 152.4.201.94152.4.201.9530
76152.4.201.96/27152.4.201.97 to 152.4.201.126152.4.201.12730
77152.4.201.128/27152.4.201.129 to 152.4.201.158152.4.201.15930
78152.4.201.160/27152.4.201.161 to 152.4.201.190152.4.201.19130
79152.4.201.192/27152.4.201.193 to 152.4.201.222152.4.201.22330
80152.4.201.224/27152.4.201.225 to 152.4.201.254152.4.201.25530
81152.4.202.0/27152.4.202.1 to 152.4.202.30152.4.202.3130
82152.4.202.32/27152.4.202.33 to 152.4.202.62152.4.202.6330
83152.4.202.64/27152.4.202.65 to 152.4.202.94152.4.202.9530
84152.4.202.96/27152.4.202.97 to 152.4.202.126152.4.202.12730
85152.4.202.128/27152.4.202.129 to 152.4.202.158152.4.202.15930
86152.4.202.160/27152.4.202.161 to 152.4.202.190152.4.202.19130
87152.4.202.192/27152.4.202.193 to 152.4.202.222152.4.202.22330
88152.4.202.224/27152.4.202.225 to 152.4.202.254152.4.202.25530
89152.4.203.0/27152.4.203.1 to 152.4.203.30152.4.203.3130
90152.4.203.32/27152.4.203.33 to 152.4.203.62152.4.203.6330
91152.4.203.64/27152.4.203.65 to 152.4.203.94152.4.203.9530
92152.4.203.96/27152.4.203.97 to 152.4.203.126152.4.203.12730
93152.4.203.128/27152.4.203.129 to 152.4.203.158152.4.203.15930
94152.4.203.160/27152.4.203.161 to 152.4.203.190152.4.203.19130
95152.4.203.192/27152.4.203.193 to 152.4.203.222152.4.203.22330
96152.4.203.224/27152.4.203.225 to 152.4.203.254152.4.203.25530
97152.4.204.0/27152.4.204.1 to 152.4.204.30152.4.204.3130
98152.4.204.32/27152.4.204.33 to 152.4.204.62152.4.204.6330
99152.4.204.64/27152.4.204.65 to 152.4.204.94152.4.204.9530
100152.4.204.96/27152.4.204.97 to 152.4.204.126152.4.204.12730
101152.4.204.128/27152.4.204.129 to 152.4.204.158152.4.204.15930
102152.4.204.160/27152.4.204.161 to 152.4.204.190152.4.204.19130
103152.4.204.192/27152.4.204.193 to 152.4.204.222152.4.204.22330
104152.4.204.224/27152.4.204.225 to 152.4.204.254152.4.204.25530
105152.4.205.0/27152.4.205.1 to 152.4.205.30152.4.205.3130
106152.4.205.32/27152.4.205.33 to 152.4.205.62152.4.205.6330
107152.4.205.64/27152.4.205.65 to 152.4.205.94152.4.205.9530
108152.4.205.96/27152.4.205.97 to 152.4.205.126152.4.205.12730
109152.4.205.128/27152.4.205.129 to 152.4.205.158152.4.205.15930
110152.4.205.160/27152.4.205.161 to 152.4.205.190152.4.205.19130
111152.4.205.192/27152.4.205.193 to 152.4.205.222152.4.205.22330
112152.4.205.224/27152.4.205.225 to 152.4.205.254152.4.205.25530
113152.4.206.0/27152.4.206.1 to 152.4.206.30152.4.206.3130
114152.4.206.32/27152.4.206.33 to 152.4.206.62152.4.206.6330
115152.4.206.64/27152.4.206.65 to 152.4.206.94152.4.206.9530
116152.4.206.96/27152.4.206.97 to 152.4.206.126152.4.206.12730
117152.4.206.128/27152.4.206.129 to 152.4.206.158152.4.206.15930
118152.4.206.160/27152.4.206.161 to 152.4.206.190152.4.206.19130
119152.4.206.192/27152.4.206.193 to 152.4.206.222152.4.206.22330
120152.4.206.224/27152.4.206.225 to 152.4.206.254152.4.206.25530
121152.4.207.0/27152.4.207.1 to 152.4.207.30152.4.207.3130
122152.4.207.32/27152.4.207.33 to 152.4.207.62152.4.207.6330
123152.4.207.64/27152.4.207.65 to 152.4.207.94152.4.207.9530
124152.4.207.96/27152.4.207.97 to 152.4.207.126152.4.207.12730
125152.4.207.128/27152.4.207.129 to 152.4.207.158152.4.207.15930
126152.4.207.160/27152.4.207.161 to 152.4.207.190152.4.207.19130
127152.4.207.192/27152.4.207.193 to 152.4.207.222152.4.207.22330
128152.4.207.224/27152.4.207.225 to 152.4.207.254152.4.207.25530

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.