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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.

Network74.4.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
74.4.64.0
Broadcast address
74.4.95.255
First usable
74.4.64.1
Last usable
74.4.95.254
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
Public public
Old class
A (default /8)
As numbers
Hex 4A044000 · Integer 1241792512 to 1241800703
Reverse DNS zones
64.4.74.in-addr.arpa
65.4.74.in-addr.arpa
66.4.74.in-addr.arpa
67.4.74.in-addr.arpa
68.4.74.in-addr.arpa
69.4.74.in-addr.arpa
70.4.74.in-addr.arpa
71.4.74.in-addr.arpa
72.4.74.in-addr.arpa
73.4.74.in-addr.arpa
74.4.74.in-addr.arpa
75.4.74.in-addr.arpa
76.4.74.in-addr.arpa
77.4.74.in-addr.arpa
78.4.74.in-addr.arpa
79.4.74.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
Address01001010.00000100.01000000.0000000074.4.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network01001010.00000100.01000000.0000000074.4.64.0
Broadcast01001010.00000100.01011111.1111111174.4.95.255
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)

74.4.64.0/19 makes 128 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
174.4.64.0/2674.4.64.1 to 74.4.64.6274.4.64.6362
274.4.64.64/2674.4.64.65 to 74.4.64.12674.4.64.12762
374.4.64.128/2674.4.64.129 to 74.4.64.19074.4.64.19162
474.4.64.192/2674.4.64.193 to 74.4.64.25474.4.64.25562
574.4.65.0/2674.4.65.1 to 74.4.65.6274.4.65.6362
674.4.65.64/2674.4.65.65 to 74.4.65.12674.4.65.12762
774.4.65.128/2674.4.65.129 to 74.4.65.19074.4.65.19162
874.4.65.192/2674.4.65.193 to 74.4.65.25474.4.65.25562
974.4.66.0/2674.4.66.1 to 74.4.66.6274.4.66.6362
1074.4.66.64/2674.4.66.65 to 74.4.66.12674.4.66.12762
1174.4.66.128/2674.4.66.129 to 74.4.66.19074.4.66.19162
1274.4.66.192/2674.4.66.193 to 74.4.66.25474.4.66.25562
1374.4.67.0/2674.4.67.1 to 74.4.67.6274.4.67.6362
1474.4.67.64/2674.4.67.65 to 74.4.67.12674.4.67.12762
1574.4.67.128/2674.4.67.129 to 74.4.67.19074.4.67.19162
1674.4.67.192/2674.4.67.193 to 74.4.67.25474.4.67.25562
1774.4.68.0/2674.4.68.1 to 74.4.68.6274.4.68.6362
1874.4.68.64/2674.4.68.65 to 74.4.68.12674.4.68.12762
1974.4.68.128/2674.4.68.129 to 74.4.68.19074.4.68.19162
2074.4.68.192/2674.4.68.193 to 74.4.68.25474.4.68.25562
2174.4.69.0/2674.4.69.1 to 74.4.69.6274.4.69.6362
2274.4.69.64/2674.4.69.65 to 74.4.69.12674.4.69.12762
2374.4.69.128/2674.4.69.129 to 74.4.69.19074.4.69.19162
2474.4.69.192/2674.4.69.193 to 74.4.69.25474.4.69.25562
2574.4.70.0/2674.4.70.1 to 74.4.70.6274.4.70.6362
2674.4.70.64/2674.4.70.65 to 74.4.70.12674.4.70.12762
2774.4.70.128/2674.4.70.129 to 74.4.70.19074.4.70.19162
2874.4.70.192/2674.4.70.193 to 74.4.70.25474.4.70.25562
2974.4.71.0/2674.4.71.1 to 74.4.71.6274.4.71.6362
3074.4.71.64/2674.4.71.65 to 74.4.71.12674.4.71.12762
3174.4.71.128/2674.4.71.129 to 74.4.71.19074.4.71.19162
3274.4.71.192/2674.4.71.193 to 74.4.71.25474.4.71.25562
3374.4.72.0/2674.4.72.1 to 74.4.72.6274.4.72.6362
3474.4.72.64/2674.4.72.65 to 74.4.72.12674.4.72.12762
3574.4.72.128/2674.4.72.129 to 74.4.72.19074.4.72.19162
3674.4.72.192/2674.4.72.193 to 74.4.72.25474.4.72.25562
3774.4.73.0/2674.4.73.1 to 74.4.73.6274.4.73.6362
3874.4.73.64/2674.4.73.65 to 74.4.73.12674.4.73.12762
3974.4.73.128/2674.4.73.129 to 74.4.73.19074.4.73.19162
4074.4.73.192/2674.4.73.193 to 74.4.73.25474.4.73.25562
4174.4.74.0/2674.4.74.1 to 74.4.74.6274.4.74.6362
4274.4.74.64/2674.4.74.65 to 74.4.74.12674.4.74.12762
4374.4.74.128/2674.4.74.129 to 74.4.74.19074.4.74.19162
4474.4.74.192/2674.4.74.193 to 74.4.74.25474.4.74.25562
4574.4.75.0/2674.4.75.1 to 74.4.75.6274.4.75.6362
4674.4.75.64/2674.4.75.65 to 74.4.75.12674.4.75.12762
4774.4.75.128/2674.4.75.129 to 74.4.75.19074.4.75.19162
4874.4.75.192/2674.4.75.193 to 74.4.75.25474.4.75.25562
4974.4.76.0/2674.4.76.1 to 74.4.76.6274.4.76.6362
5074.4.76.64/2674.4.76.65 to 74.4.76.12674.4.76.12762
5174.4.76.128/2674.4.76.129 to 74.4.76.19074.4.76.19162
5274.4.76.192/2674.4.76.193 to 74.4.76.25474.4.76.25562
5374.4.77.0/2674.4.77.1 to 74.4.77.6274.4.77.6362
5474.4.77.64/2674.4.77.65 to 74.4.77.12674.4.77.12762
5574.4.77.128/2674.4.77.129 to 74.4.77.19074.4.77.19162
5674.4.77.192/2674.4.77.193 to 74.4.77.25474.4.77.25562
5774.4.78.0/2674.4.78.1 to 74.4.78.6274.4.78.6362
5874.4.78.64/2674.4.78.65 to 74.4.78.12674.4.78.12762
5974.4.78.128/2674.4.78.129 to 74.4.78.19074.4.78.19162
6074.4.78.192/2674.4.78.193 to 74.4.78.25474.4.78.25562
6174.4.79.0/2674.4.79.1 to 74.4.79.6274.4.79.6362
6274.4.79.64/2674.4.79.65 to 74.4.79.12674.4.79.12762
6374.4.79.128/2674.4.79.129 to 74.4.79.19074.4.79.19162
6474.4.79.192/2674.4.79.193 to 74.4.79.25474.4.79.25562
6574.4.80.0/2674.4.80.1 to 74.4.80.6274.4.80.6362
6674.4.80.64/2674.4.80.65 to 74.4.80.12674.4.80.12762
6774.4.80.128/2674.4.80.129 to 74.4.80.19074.4.80.19162
6874.4.80.192/2674.4.80.193 to 74.4.80.25474.4.80.25562
6974.4.81.0/2674.4.81.1 to 74.4.81.6274.4.81.6362
7074.4.81.64/2674.4.81.65 to 74.4.81.12674.4.81.12762
7174.4.81.128/2674.4.81.129 to 74.4.81.19074.4.81.19162
7274.4.81.192/2674.4.81.193 to 74.4.81.25474.4.81.25562
7374.4.82.0/2674.4.82.1 to 74.4.82.6274.4.82.6362
7474.4.82.64/2674.4.82.65 to 74.4.82.12674.4.82.12762
7574.4.82.128/2674.4.82.129 to 74.4.82.19074.4.82.19162
7674.4.82.192/2674.4.82.193 to 74.4.82.25474.4.82.25562
7774.4.83.0/2674.4.83.1 to 74.4.83.6274.4.83.6362
7874.4.83.64/2674.4.83.65 to 74.4.83.12674.4.83.12762
7974.4.83.128/2674.4.83.129 to 74.4.83.19074.4.83.19162
8074.4.83.192/2674.4.83.193 to 74.4.83.25474.4.83.25562
8174.4.84.0/2674.4.84.1 to 74.4.84.6274.4.84.6362
8274.4.84.64/2674.4.84.65 to 74.4.84.12674.4.84.12762
8374.4.84.128/2674.4.84.129 to 74.4.84.19074.4.84.19162
8474.4.84.192/2674.4.84.193 to 74.4.84.25474.4.84.25562
8574.4.85.0/2674.4.85.1 to 74.4.85.6274.4.85.6362
8674.4.85.64/2674.4.85.65 to 74.4.85.12674.4.85.12762
8774.4.85.128/2674.4.85.129 to 74.4.85.19074.4.85.19162
8874.4.85.192/2674.4.85.193 to 74.4.85.25474.4.85.25562
8974.4.86.0/2674.4.86.1 to 74.4.86.6274.4.86.6362
9074.4.86.64/2674.4.86.65 to 74.4.86.12674.4.86.12762
9174.4.86.128/2674.4.86.129 to 74.4.86.19074.4.86.19162
9274.4.86.192/2674.4.86.193 to 74.4.86.25474.4.86.25562
9374.4.87.0/2674.4.87.1 to 74.4.87.6274.4.87.6362
9474.4.87.64/2674.4.87.65 to 74.4.87.12674.4.87.12762
9574.4.87.128/2674.4.87.129 to 74.4.87.19074.4.87.19162
9674.4.87.192/2674.4.87.193 to 74.4.87.25474.4.87.25562
9774.4.88.0/2674.4.88.1 to 74.4.88.6274.4.88.6362
9874.4.88.64/2674.4.88.65 to 74.4.88.12674.4.88.12762
9974.4.88.128/2674.4.88.129 to 74.4.88.19074.4.88.19162
10074.4.88.192/2674.4.88.193 to 74.4.88.25474.4.88.25562
10174.4.89.0/2674.4.89.1 to 74.4.89.6274.4.89.6362
10274.4.89.64/2674.4.89.65 to 74.4.89.12674.4.89.12762
10374.4.89.128/2674.4.89.129 to 74.4.89.19074.4.89.19162
10474.4.89.192/2674.4.89.193 to 74.4.89.25474.4.89.25562
10574.4.90.0/2674.4.90.1 to 74.4.90.6274.4.90.6362
10674.4.90.64/2674.4.90.65 to 74.4.90.12674.4.90.12762
10774.4.90.128/2674.4.90.129 to 74.4.90.19074.4.90.19162
10874.4.90.192/2674.4.90.193 to 74.4.90.25474.4.90.25562
10974.4.91.0/2674.4.91.1 to 74.4.91.6274.4.91.6362
11074.4.91.64/2674.4.91.65 to 74.4.91.12674.4.91.12762
11174.4.91.128/2674.4.91.129 to 74.4.91.19074.4.91.19162
11274.4.91.192/2674.4.91.193 to 74.4.91.25474.4.91.25562
11374.4.92.0/2674.4.92.1 to 74.4.92.6274.4.92.6362
11474.4.92.64/2674.4.92.65 to 74.4.92.12674.4.92.12762
11574.4.92.128/2674.4.92.129 to 74.4.92.19074.4.92.19162
11674.4.92.192/2674.4.92.193 to 74.4.92.25474.4.92.25562
11774.4.93.0/2674.4.93.1 to 74.4.93.6274.4.93.6362
11874.4.93.64/2674.4.93.65 to 74.4.93.12674.4.93.12762
11974.4.93.128/2674.4.93.129 to 74.4.93.19074.4.93.19162
12074.4.93.192/2674.4.93.193 to 74.4.93.25474.4.93.25562
12174.4.94.0/2674.4.94.1 to 74.4.94.6274.4.94.6362
12274.4.94.64/2674.4.94.65 to 74.4.94.12674.4.94.12762
12374.4.94.128/2674.4.94.129 to 74.4.94.19074.4.94.19162
12474.4.94.192/2674.4.94.193 to 74.4.94.25474.4.94.25562
12574.4.95.0/2674.4.95.1 to 74.4.95.6274.4.95.6362
12674.4.95.64/2674.4.95.65 to 74.4.95.12674.4.95.12762
12774.4.95.128/2674.4.95.129 to 74.4.95.19074.4.95.19162
12874.4.95.192/2674.4.95.193 to 74.4.95.25474.4.95.25562

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.