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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.

Network246.76.112.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
246.76.112.0
Broadcast address
246.76.127.255
First usable
246.76.112.1
Last usable
246.76.127.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F64C7000 · Integer 4132204544 to 4132208639
Reverse DNS zones
112.76.246.in-addr.arpa
113.76.246.in-addr.arpa
114.76.246.in-addr.arpa
115.76.246.in-addr.arpa
116.76.246.in-addr.arpa
117.76.246.in-addr.arpa
118.76.246.in-addr.arpa
119.76.246.in-addr.arpa
120.76.246.in-addr.arpa
121.76.246.in-addr.arpa
122.76.246.in-addr.arpa
123.76.246.in-addr.arpa
124.76.246.in-addr.arpa
125.76.246.in-addr.arpa
126.76.246.in-addr.arpa
127.76.246.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
Address11110110.01001100.01110000.00000000246.76.112.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network11110110.01001100.01110000.00000000246.76.112.0
Broadcast11110110.01001100.01111111.11111111246.76.127.255
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)

246.76.112.0/20 makes 128 subnets of /27.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1246.76.112.0/27246.76.112.1 to 246.76.112.30246.76.112.3130
2246.76.112.32/27246.76.112.33 to 246.76.112.62246.76.112.6330
3246.76.112.64/27246.76.112.65 to 246.76.112.94246.76.112.9530
4246.76.112.96/27246.76.112.97 to 246.76.112.126246.76.112.12730
5246.76.112.128/27246.76.112.129 to 246.76.112.158246.76.112.15930
6246.76.112.160/27246.76.112.161 to 246.76.112.190246.76.112.19130
7246.76.112.192/27246.76.112.193 to 246.76.112.222246.76.112.22330
8246.76.112.224/27246.76.112.225 to 246.76.112.254246.76.112.25530
9246.76.113.0/27246.76.113.1 to 246.76.113.30246.76.113.3130
10246.76.113.32/27246.76.113.33 to 246.76.113.62246.76.113.6330
11246.76.113.64/27246.76.113.65 to 246.76.113.94246.76.113.9530
12246.76.113.96/27246.76.113.97 to 246.76.113.126246.76.113.12730
13246.76.113.128/27246.76.113.129 to 246.76.113.158246.76.113.15930
14246.76.113.160/27246.76.113.161 to 246.76.113.190246.76.113.19130
15246.76.113.192/27246.76.113.193 to 246.76.113.222246.76.113.22330
16246.76.113.224/27246.76.113.225 to 246.76.113.254246.76.113.25530
17246.76.114.0/27246.76.114.1 to 246.76.114.30246.76.114.3130
18246.76.114.32/27246.76.114.33 to 246.76.114.62246.76.114.6330
19246.76.114.64/27246.76.114.65 to 246.76.114.94246.76.114.9530
20246.76.114.96/27246.76.114.97 to 246.76.114.126246.76.114.12730
21246.76.114.128/27246.76.114.129 to 246.76.114.158246.76.114.15930
22246.76.114.160/27246.76.114.161 to 246.76.114.190246.76.114.19130
23246.76.114.192/27246.76.114.193 to 246.76.114.222246.76.114.22330
24246.76.114.224/27246.76.114.225 to 246.76.114.254246.76.114.25530
25246.76.115.0/27246.76.115.1 to 246.76.115.30246.76.115.3130
26246.76.115.32/27246.76.115.33 to 246.76.115.62246.76.115.6330
27246.76.115.64/27246.76.115.65 to 246.76.115.94246.76.115.9530
28246.76.115.96/27246.76.115.97 to 246.76.115.126246.76.115.12730
29246.76.115.128/27246.76.115.129 to 246.76.115.158246.76.115.15930
30246.76.115.160/27246.76.115.161 to 246.76.115.190246.76.115.19130
31246.76.115.192/27246.76.115.193 to 246.76.115.222246.76.115.22330
32246.76.115.224/27246.76.115.225 to 246.76.115.254246.76.115.25530
33246.76.116.0/27246.76.116.1 to 246.76.116.30246.76.116.3130
34246.76.116.32/27246.76.116.33 to 246.76.116.62246.76.116.6330
35246.76.116.64/27246.76.116.65 to 246.76.116.94246.76.116.9530
36246.76.116.96/27246.76.116.97 to 246.76.116.126246.76.116.12730
37246.76.116.128/27246.76.116.129 to 246.76.116.158246.76.116.15930
38246.76.116.160/27246.76.116.161 to 246.76.116.190246.76.116.19130
39246.76.116.192/27246.76.116.193 to 246.76.116.222246.76.116.22330
40246.76.116.224/27246.76.116.225 to 246.76.116.254246.76.116.25530
41246.76.117.0/27246.76.117.1 to 246.76.117.30246.76.117.3130
42246.76.117.32/27246.76.117.33 to 246.76.117.62246.76.117.6330
43246.76.117.64/27246.76.117.65 to 246.76.117.94246.76.117.9530
44246.76.117.96/27246.76.117.97 to 246.76.117.126246.76.117.12730
45246.76.117.128/27246.76.117.129 to 246.76.117.158246.76.117.15930
46246.76.117.160/27246.76.117.161 to 246.76.117.190246.76.117.19130
47246.76.117.192/27246.76.117.193 to 246.76.117.222246.76.117.22330
48246.76.117.224/27246.76.117.225 to 246.76.117.254246.76.117.25530
49246.76.118.0/27246.76.118.1 to 246.76.118.30246.76.118.3130
50246.76.118.32/27246.76.118.33 to 246.76.118.62246.76.118.6330
51246.76.118.64/27246.76.118.65 to 246.76.118.94246.76.118.9530
52246.76.118.96/27246.76.118.97 to 246.76.118.126246.76.118.12730
53246.76.118.128/27246.76.118.129 to 246.76.118.158246.76.118.15930
54246.76.118.160/27246.76.118.161 to 246.76.118.190246.76.118.19130
55246.76.118.192/27246.76.118.193 to 246.76.118.222246.76.118.22330
56246.76.118.224/27246.76.118.225 to 246.76.118.254246.76.118.25530
57246.76.119.0/27246.76.119.1 to 246.76.119.30246.76.119.3130
58246.76.119.32/27246.76.119.33 to 246.76.119.62246.76.119.6330
59246.76.119.64/27246.76.119.65 to 246.76.119.94246.76.119.9530
60246.76.119.96/27246.76.119.97 to 246.76.119.126246.76.119.12730
61246.76.119.128/27246.76.119.129 to 246.76.119.158246.76.119.15930
62246.76.119.160/27246.76.119.161 to 246.76.119.190246.76.119.19130
63246.76.119.192/27246.76.119.193 to 246.76.119.222246.76.119.22330
64246.76.119.224/27246.76.119.225 to 246.76.119.254246.76.119.25530
65246.76.120.0/27246.76.120.1 to 246.76.120.30246.76.120.3130
66246.76.120.32/27246.76.120.33 to 246.76.120.62246.76.120.6330
67246.76.120.64/27246.76.120.65 to 246.76.120.94246.76.120.9530
68246.76.120.96/27246.76.120.97 to 246.76.120.126246.76.120.12730
69246.76.120.128/27246.76.120.129 to 246.76.120.158246.76.120.15930
70246.76.120.160/27246.76.120.161 to 246.76.120.190246.76.120.19130
71246.76.120.192/27246.76.120.193 to 246.76.120.222246.76.120.22330
72246.76.120.224/27246.76.120.225 to 246.76.120.254246.76.120.25530
73246.76.121.0/27246.76.121.1 to 246.76.121.30246.76.121.3130
74246.76.121.32/27246.76.121.33 to 246.76.121.62246.76.121.6330
75246.76.121.64/27246.76.121.65 to 246.76.121.94246.76.121.9530
76246.76.121.96/27246.76.121.97 to 246.76.121.126246.76.121.12730
77246.76.121.128/27246.76.121.129 to 246.76.121.158246.76.121.15930
78246.76.121.160/27246.76.121.161 to 246.76.121.190246.76.121.19130
79246.76.121.192/27246.76.121.193 to 246.76.121.222246.76.121.22330
80246.76.121.224/27246.76.121.225 to 246.76.121.254246.76.121.25530
81246.76.122.0/27246.76.122.1 to 246.76.122.30246.76.122.3130
82246.76.122.32/27246.76.122.33 to 246.76.122.62246.76.122.6330
83246.76.122.64/27246.76.122.65 to 246.76.122.94246.76.122.9530
84246.76.122.96/27246.76.122.97 to 246.76.122.126246.76.122.12730
85246.76.122.128/27246.76.122.129 to 246.76.122.158246.76.122.15930
86246.76.122.160/27246.76.122.161 to 246.76.122.190246.76.122.19130
87246.76.122.192/27246.76.122.193 to 246.76.122.222246.76.122.22330
88246.76.122.224/27246.76.122.225 to 246.76.122.254246.76.122.25530
89246.76.123.0/27246.76.123.1 to 246.76.123.30246.76.123.3130
90246.76.123.32/27246.76.123.33 to 246.76.123.62246.76.123.6330
91246.76.123.64/27246.76.123.65 to 246.76.123.94246.76.123.9530
92246.76.123.96/27246.76.123.97 to 246.76.123.126246.76.123.12730
93246.76.123.128/27246.76.123.129 to 246.76.123.158246.76.123.15930
94246.76.123.160/27246.76.123.161 to 246.76.123.190246.76.123.19130
95246.76.123.192/27246.76.123.193 to 246.76.123.222246.76.123.22330
96246.76.123.224/27246.76.123.225 to 246.76.123.254246.76.123.25530
97246.76.124.0/27246.76.124.1 to 246.76.124.30246.76.124.3130
98246.76.124.32/27246.76.124.33 to 246.76.124.62246.76.124.6330
99246.76.124.64/27246.76.124.65 to 246.76.124.94246.76.124.9530
100246.76.124.96/27246.76.124.97 to 246.76.124.126246.76.124.12730
101246.76.124.128/27246.76.124.129 to 246.76.124.158246.76.124.15930
102246.76.124.160/27246.76.124.161 to 246.76.124.190246.76.124.19130
103246.76.124.192/27246.76.124.193 to 246.76.124.222246.76.124.22330
104246.76.124.224/27246.76.124.225 to 246.76.124.254246.76.124.25530
105246.76.125.0/27246.76.125.1 to 246.76.125.30246.76.125.3130
106246.76.125.32/27246.76.125.33 to 246.76.125.62246.76.125.6330
107246.76.125.64/27246.76.125.65 to 246.76.125.94246.76.125.9530
108246.76.125.96/27246.76.125.97 to 246.76.125.126246.76.125.12730
109246.76.125.128/27246.76.125.129 to 246.76.125.158246.76.125.15930
110246.76.125.160/27246.76.125.161 to 246.76.125.190246.76.125.19130
111246.76.125.192/27246.76.125.193 to 246.76.125.222246.76.125.22330
112246.76.125.224/27246.76.125.225 to 246.76.125.254246.76.125.25530
113246.76.126.0/27246.76.126.1 to 246.76.126.30246.76.126.3130
114246.76.126.32/27246.76.126.33 to 246.76.126.62246.76.126.6330
115246.76.126.64/27246.76.126.65 to 246.76.126.94246.76.126.9530
116246.76.126.96/27246.76.126.97 to 246.76.126.126246.76.126.12730
117246.76.126.128/27246.76.126.129 to 246.76.126.158246.76.126.15930
118246.76.126.160/27246.76.126.161 to 246.76.126.190246.76.126.19130
119246.76.126.192/27246.76.126.193 to 246.76.126.222246.76.126.22330
120246.76.126.224/27246.76.126.225 to 246.76.126.254246.76.126.25530
121246.76.127.0/27246.76.127.1 to 246.76.127.30246.76.127.3130
122246.76.127.32/27246.76.127.33 to 246.76.127.62246.76.127.6330
123246.76.127.64/27246.76.127.65 to 246.76.127.94246.76.127.9530
124246.76.127.96/27246.76.127.97 to 246.76.127.126246.76.127.12730
125246.76.127.128/27246.76.127.129 to 246.76.127.158246.76.127.15930
126246.76.127.160/27246.76.127.161 to 246.76.127.190246.76.127.19130
127246.76.127.192/27246.76.127.193 to 246.76.127.222246.76.127.22330
128246.76.127.224/27246.76.127.225 to 246.76.127.254246.76.127.25530

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.