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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.

Network239.100.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
239.100.64.0
Broadcast address
239.100.95.255
First usable
239.100.64.1
Last usable
239.100.95.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EF644000 · Integer 4016324608 to 4016332799
Reverse DNS zones
64.100.239.in-addr.arpa
65.100.239.in-addr.arpa
66.100.239.in-addr.arpa
67.100.239.in-addr.arpa
68.100.239.in-addr.arpa
69.100.239.in-addr.arpa
70.100.239.in-addr.arpa
71.100.239.in-addr.arpa
72.100.239.in-addr.arpa
73.100.239.in-addr.arpa
74.100.239.in-addr.arpa
75.100.239.in-addr.arpa
76.100.239.in-addr.arpa
77.100.239.in-addr.arpa
78.100.239.in-addr.arpa
79.100.239.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11101111.01100100.01000000.00000000239.100.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network11101111.01100100.01000000.00000000239.100.64.0
Broadcast11101111.01100100.01011111.11111111239.100.95.255
Split into smaller subnets/26
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

239.100.64.0/19 makes 128 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1239.100.64.0/26239.100.64.1 to 239.100.64.62239.100.64.6362
2239.100.64.64/26239.100.64.65 to 239.100.64.126239.100.64.12762
3239.100.64.128/26239.100.64.129 to 239.100.64.190239.100.64.19162
4239.100.64.192/26239.100.64.193 to 239.100.64.254239.100.64.25562
5239.100.65.0/26239.100.65.1 to 239.100.65.62239.100.65.6362
6239.100.65.64/26239.100.65.65 to 239.100.65.126239.100.65.12762
7239.100.65.128/26239.100.65.129 to 239.100.65.190239.100.65.19162
8239.100.65.192/26239.100.65.193 to 239.100.65.254239.100.65.25562
9239.100.66.0/26239.100.66.1 to 239.100.66.62239.100.66.6362
10239.100.66.64/26239.100.66.65 to 239.100.66.126239.100.66.12762
11239.100.66.128/26239.100.66.129 to 239.100.66.190239.100.66.19162
12239.100.66.192/26239.100.66.193 to 239.100.66.254239.100.66.25562
13239.100.67.0/26239.100.67.1 to 239.100.67.62239.100.67.6362
14239.100.67.64/26239.100.67.65 to 239.100.67.126239.100.67.12762
15239.100.67.128/26239.100.67.129 to 239.100.67.190239.100.67.19162
16239.100.67.192/26239.100.67.193 to 239.100.67.254239.100.67.25562
17239.100.68.0/26239.100.68.1 to 239.100.68.62239.100.68.6362
18239.100.68.64/26239.100.68.65 to 239.100.68.126239.100.68.12762
19239.100.68.128/26239.100.68.129 to 239.100.68.190239.100.68.19162
20239.100.68.192/26239.100.68.193 to 239.100.68.254239.100.68.25562
21239.100.69.0/26239.100.69.1 to 239.100.69.62239.100.69.6362
22239.100.69.64/26239.100.69.65 to 239.100.69.126239.100.69.12762
23239.100.69.128/26239.100.69.129 to 239.100.69.190239.100.69.19162
24239.100.69.192/26239.100.69.193 to 239.100.69.254239.100.69.25562
25239.100.70.0/26239.100.70.1 to 239.100.70.62239.100.70.6362
26239.100.70.64/26239.100.70.65 to 239.100.70.126239.100.70.12762
27239.100.70.128/26239.100.70.129 to 239.100.70.190239.100.70.19162
28239.100.70.192/26239.100.70.193 to 239.100.70.254239.100.70.25562
29239.100.71.0/26239.100.71.1 to 239.100.71.62239.100.71.6362
30239.100.71.64/26239.100.71.65 to 239.100.71.126239.100.71.12762
31239.100.71.128/26239.100.71.129 to 239.100.71.190239.100.71.19162
32239.100.71.192/26239.100.71.193 to 239.100.71.254239.100.71.25562
33239.100.72.0/26239.100.72.1 to 239.100.72.62239.100.72.6362
34239.100.72.64/26239.100.72.65 to 239.100.72.126239.100.72.12762
35239.100.72.128/26239.100.72.129 to 239.100.72.190239.100.72.19162
36239.100.72.192/26239.100.72.193 to 239.100.72.254239.100.72.25562
37239.100.73.0/26239.100.73.1 to 239.100.73.62239.100.73.6362
38239.100.73.64/26239.100.73.65 to 239.100.73.126239.100.73.12762
39239.100.73.128/26239.100.73.129 to 239.100.73.190239.100.73.19162
40239.100.73.192/26239.100.73.193 to 239.100.73.254239.100.73.25562
41239.100.74.0/26239.100.74.1 to 239.100.74.62239.100.74.6362
42239.100.74.64/26239.100.74.65 to 239.100.74.126239.100.74.12762
43239.100.74.128/26239.100.74.129 to 239.100.74.190239.100.74.19162
44239.100.74.192/26239.100.74.193 to 239.100.74.254239.100.74.25562
45239.100.75.0/26239.100.75.1 to 239.100.75.62239.100.75.6362
46239.100.75.64/26239.100.75.65 to 239.100.75.126239.100.75.12762
47239.100.75.128/26239.100.75.129 to 239.100.75.190239.100.75.19162
48239.100.75.192/26239.100.75.193 to 239.100.75.254239.100.75.25562
49239.100.76.0/26239.100.76.1 to 239.100.76.62239.100.76.6362
50239.100.76.64/26239.100.76.65 to 239.100.76.126239.100.76.12762
51239.100.76.128/26239.100.76.129 to 239.100.76.190239.100.76.19162
52239.100.76.192/26239.100.76.193 to 239.100.76.254239.100.76.25562
53239.100.77.0/26239.100.77.1 to 239.100.77.62239.100.77.6362
54239.100.77.64/26239.100.77.65 to 239.100.77.126239.100.77.12762
55239.100.77.128/26239.100.77.129 to 239.100.77.190239.100.77.19162
56239.100.77.192/26239.100.77.193 to 239.100.77.254239.100.77.25562
57239.100.78.0/26239.100.78.1 to 239.100.78.62239.100.78.6362
58239.100.78.64/26239.100.78.65 to 239.100.78.126239.100.78.12762
59239.100.78.128/26239.100.78.129 to 239.100.78.190239.100.78.19162
60239.100.78.192/26239.100.78.193 to 239.100.78.254239.100.78.25562
61239.100.79.0/26239.100.79.1 to 239.100.79.62239.100.79.6362
62239.100.79.64/26239.100.79.65 to 239.100.79.126239.100.79.12762
63239.100.79.128/26239.100.79.129 to 239.100.79.190239.100.79.19162
64239.100.79.192/26239.100.79.193 to 239.100.79.254239.100.79.25562
65239.100.80.0/26239.100.80.1 to 239.100.80.62239.100.80.6362
66239.100.80.64/26239.100.80.65 to 239.100.80.126239.100.80.12762
67239.100.80.128/26239.100.80.129 to 239.100.80.190239.100.80.19162
68239.100.80.192/26239.100.80.193 to 239.100.80.254239.100.80.25562
69239.100.81.0/26239.100.81.1 to 239.100.81.62239.100.81.6362
70239.100.81.64/26239.100.81.65 to 239.100.81.126239.100.81.12762
71239.100.81.128/26239.100.81.129 to 239.100.81.190239.100.81.19162
72239.100.81.192/26239.100.81.193 to 239.100.81.254239.100.81.25562
73239.100.82.0/26239.100.82.1 to 239.100.82.62239.100.82.6362
74239.100.82.64/26239.100.82.65 to 239.100.82.126239.100.82.12762
75239.100.82.128/26239.100.82.129 to 239.100.82.190239.100.82.19162
76239.100.82.192/26239.100.82.193 to 239.100.82.254239.100.82.25562
77239.100.83.0/26239.100.83.1 to 239.100.83.62239.100.83.6362
78239.100.83.64/26239.100.83.65 to 239.100.83.126239.100.83.12762
79239.100.83.128/26239.100.83.129 to 239.100.83.190239.100.83.19162
80239.100.83.192/26239.100.83.193 to 239.100.83.254239.100.83.25562
81239.100.84.0/26239.100.84.1 to 239.100.84.62239.100.84.6362
82239.100.84.64/26239.100.84.65 to 239.100.84.126239.100.84.12762
83239.100.84.128/26239.100.84.129 to 239.100.84.190239.100.84.19162
84239.100.84.192/26239.100.84.193 to 239.100.84.254239.100.84.25562
85239.100.85.0/26239.100.85.1 to 239.100.85.62239.100.85.6362
86239.100.85.64/26239.100.85.65 to 239.100.85.126239.100.85.12762
87239.100.85.128/26239.100.85.129 to 239.100.85.190239.100.85.19162
88239.100.85.192/26239.100.85.193 to 239.100.85.254239.100.85.25562
89239.100.86.0/26239.100.86.1 to 239.100.86.62239.100.86.6362
90239.100.86.64/26239.100.86.65 to 239.100.86.126239.100.86.12762
91239.100.86.128/26239.100.86.129 to 239.100.86.190239.100.86.19162
92239.100.86.192/26239.100.86.193 to 239.100.86.254239.100.86.25562
93239.100.87.0/26239.100.87.1 to 239.100.87.62239.100.87.6362
94239.100.87.64/26239.100.87.65 to 239.100.87.126239.100.87.12762
95239.100.87.128/26239.100.87.129 to 239.100.87.190239.100.87.19162
96239.100.87.192/26239.100.87.193 to 239.100.87.254239.100.87.25562
97239.100.88.0/26239.100.88.1 to 239.100.88.62239.100.88.6362
98239.100.88.64/26239.100.88.65 to 239.100.88.126239.100.88.12762
99239.100.88.128/26239.100.88.129 to 239.100.88.190239.100.88.19162
100239.100.88.192/26239.100.88.193 to 239.100.88.254239.100.88.25562
101239.100.89.0/26239.100.89.1 to 239.100.89.62239.100.89.6362
102239.100.89.64/26239.100.89.65 to 239.100.89.126239.100.89.12762
103239.100.89.128/26239.100.89.129 to 239.100.89.190239.100.89.19162
104239.100.89.192/26239.100.89.193 to 239.100.89.254239.100.89.25562
105239.100.90.0/26239.100.90.1 to 239.100.90.62239.100.90.6362
106239.100.90.64/26239.100.90.65 to 239.100.90.126239.100.90.12762
107239.100.90.128/26239.100.90.129 to 239.100.90.190239.100.90.19162
108239.100.90.192/26239.100.90.193 to 239.100.90.254239.100.90.25562
109239.100.91.0/26239.100.91.1 to 239.100.91.62239.100.91.6362
110239.100.91.64/26239.100.91.65 to 239.100.91.126239.100.91.12762
111239.100.91.128/26239.100.91.129 to 239.100.91.190239.100.91.19162
112239.100.91.192/26239.100.91.193 to 239.100.91.254239.100.91.25562
113239.100.92.0/26239.100.92.1 to 239.100.92.62239.100.92.6362
114239.100.92.64/26239.100.92.65 to 239.100.92.126239.100.92.12762
115239.100.92.128/26239.100.92.129 to 239.100.92.190239.100.92.19162
116239.100.92.192/26239.100.92.193 to 239.100.92.254239.100.92.25562
117239.100.93.0/26239.100.93.1 to 239.100.93.62239.100.93.6362
118239.100.93.64/26239.100.93.65 to 239.100.93.126239.100.93.12762
119239.100.93.128/26239.100.93.129 to 239.100.93.190239.100.93.19162
120239.100.93.192/26239.100.93.193 to 239.100.93.254239.100.93.25562
121239.100.94.0/26239.100.94.1 to 239.100.94.62239.100.94.6362
122239.100.94.64/26239.100.94.65 to 239.100.94.126239.100.94.12762
123239.100.94.128/26239.100.94.129 to 239.100.94.190239.100.94.19162
124239.100.94.192/26239.100.94.193 to 239.100.94.254239.100.94.25562
125239.100.95.0/26239.100.95.1 to 239.100.95.62239.100.95.6362
126239.100.95.64/26239.100.95.65 to 239.100.95.126239.100.95.12762
127239.100.95.128/26239.100.95.129 to 239.100.95.190239.100.95.19162
128239.100.95.192/26239.100.95.193 to 239.100.95.254239.100.95.25562

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.