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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.

Network239.30.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
239.30.64.0
Broadcast address
239.30.95.255
First usable
239.30.64.1
Last usable
239.30.95.254
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 EF1E4000 · Integer 4011737088 to 4011745279
Reverse DNS zones
64.30.239.in-addr.arpa
65.30.239.in-addr.arpa
66.30.239.in-addr.arpa
67.30.239.in-addr.arpa
68.30.239.in-addr.arpa
69.30.239.in-addr.arpa
70.30.239.in-addr.arpa
71.30.239.in-addr.arpa
72.30.239.in-addr.arpa
73.30.239.in-addr.arpa
74.30.239.in-addr.arpa
75.30.239.in-addr.arpa
76.30.239.in-addr.arpa
77.30.239.in-addr.arpa
78.30.239.in-addr.arpa
79.30.239.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
Address11101111.00011110.01000000.00000000239.30.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network11101111.00011110.01000000.00000000239.30.64.0
Broadcast11101111.00011110.01011111.11111111239.30.95.255
Split into smaller subnets/25
/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)

239.30.64.0/19 makes 64 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1239.30.64.0/25239.30.64.1 to 239.30.64.126239.30.64.127126
2239.30.64.128/25239.30.64.129 to 239.30.64.254239.30.64.255126
3239.30.65.0/25239.30.65.1 to 239.30.65.126239.30.65.127126
4239.30.65.128/25239.30.65.129 to 239.30.65.254239.30.65.255126
5239.30.66.0/25239.30.66.1 to 239.30.66.126239.30.66.127126
6239.30.66.128/25239.30.66.129 to 239.30.66.254239.30.66.255126
7239.30.67.0/25239.30.67.1 to 239.30.67.126239.30.67.127126
8239.30.67.128/25239.30.67.129 to 239.30.67.254239.30.67.255126
9239.30.68.0/25239.30.68.1 to 239.30.68.126239.30.68.127126
10239.30.68.128/25239.30.68.129 to 239.30.68.254239.30.68.255126
11239.30.69.0/25239.30.69.1 to 239.30.69.126239.30.69.127126
12239.30.69.128/25239.30.69.129 to 239.30.69.254239.30.69.255126
13239.30.70.0/25239.30.70.1 to 239.30.70.126239.30.70.127126
14239.30.70.128/25239.30.70.129 to 239.30.70.254239.30.70.255126
15239.30.71.0/25239.30.71.1 to 239.30.71.126239.30.71.127126
16239.30.71.128/25239.30.71.129 to 239.30.71.254239.30.71.255126
17239.30.72.0/25239.30.72.1 to 239.30.72.126239.30.72.127126
18239.30.72.128/25239.30.72.129 to 239.30.72.254239.30.72.255126
19239.30.73.0/25239.30.73.1 to 239.30.73.126239.30.73.127126
20239.30.73.128/25239.30.73.129 to 239.30.73.254239.30.73.255126
21239.30.74.0/25239.30.74.1 to 239.30.74.126239.30.74.127126
22239.30.74.128/25239.30.74.129 to 239.30.74.254239.30.74.255126
23239.30.75.0/25239.30.75.1 to 239.30.75.126239.30.75.127126
24239.30.75.128/25239.30.75.129 to 239.30.75.254239.30.75.255126
25239.30.76.0/25239.30.76.1 to 239.30.76.126239.30.76.127126
26239.30.76.128/25239.30.76.129 to 239.30.76.254239.30.76.255126
27239.30.77.0/25239.30.77.1 to 239.30.77.126239.30.77.127126
28239.30.77.128/25239.30.77.129 to 239.30.77.254239.30.77.255126
29239.30.78.0/25239.30.78.1 to 239.30.78.126239.30.78.127126
30239.30.78.128/25239.30.78.129 to 239.30.78.254239.30.78.255126
31239.30.79.0/25239.30.79.1 to 239.30.79.126239.30.79.127126
32239.30.79.128/25239.30.79.129 to 239.30.79.254239.30.79.255126
33239.30.80.0/25239.30.80.1 to 239.30.80.126239.30.80.127126
34239.30.80.128/25239.30.80.129 to 239.30.80.254239.30.80.255126
35239.30.81.0/25239.30.81.1 to 239.30.81.126239.30.81.127126
36239.30.81.128/25239.30.81.129 to 239.30.81.254239.30.81.255126
37239.30.82.0/25239.30.82.1 to 239.30.82.126239.30.82.127126
38239.30.82.128/25239.30.82.129 to 239.30.82.254239.30.82.255126
39239.30.83.0/25239.30.83.1 to 239.30.83.126239.30.83.127126
40239.30.83.128/25239.30.83.129 to 239.30.83.254239.30.83.255126
41239.30.84.0/25239.30.84.1 to 239.30.84.126239.30.84.127126
42239.30.84.128/25239.30.84.129 to 239.30.84.254239.30.84.255126
43239.30.85.0/25239.30.85.1 to 239.30.85.126239.30.85.127126
44239.30.85.128/25239.30.85.129 to 239.30.85.254239.30.85.255126
45239.30.86.0/25239.30.86.1 to 239.30.86.126239.30.86.127126
46239.30.86.128/25239.30.86.129 to 239.30.86.254239.30.86.255126
47239.30.87.0/25239.30.87.1 to 239.30.87.126239.30.87.127126
48239.30.87.128/25239.30.87.129 to 239.30.87.254239.30.87.255126
49239.30.88.0/25239.30.88.1 to 239.30.88.126239.30.88.127126
50239.30.88.128/25239.30.88.129 to 239.30.88.254239.30.88.255126
51239.30.89.0/25239.30.89.1 to 239.30.89.126239.30.89.127126
52239.30.89.128/25239.30.89.129 to 239.30.89.254239.30.89.255126
53239.30.90.0/25239.30.90.1 to 239.30.90.126239.30.90.127126
54239.30.90.128/25239.30.90.129 to 239.30.90.254239.30.90.255126
55239.30.91.0/25239.30.91.1 to 239.30.91.126239.30.91.127126
56239.30.91.128/25239.30.91.129 to 239.30.91.254239.30.91.255126
57239.30.92.0/25239.30.92.1 to 239.30.92.126239.30.92.127126
58239.30.92.128/25239.30.92.129 to 239.30.92.254239.30.92.255126
59239.30.93.0/25239.30.93.1 to 239.30.93.126239.30.93.127126
60239.30.93.128/25239.30.93.129 to 239.30.93.254239.30.93.255126
61239.30.94.0/25239.30.94.1 to 239.30.94.126239.30.94.127126
62239.30.94.128/25239.30.94.129 to 239.30.94.254239.30.94.255126
63239.30.95.0/25239.30.95.1 to 239.30.95.126239.30.95.127126
64239.30.95.128/25239.30.95.129 to 239.30.95.254239.30.95.255126

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.