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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.

Network74.7.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
74.7.0.0
Broadcast address
74.7.127.255
First usable
74.7.0.1
Last usable
74.7.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
A (default /8)
As numbers
Hex 4A070000 · Integer 1241972736 to 1242005503
Reverse DNS zones
0.7.74.in-addr.arpa
1.7.74.in-addr.arpa
2.7.74.in-addr.arpa
3.7.74.in-addr.arpa
4.7.74.in-addr.arpa
5.7.74.in-addr.arpa
6.7.74.in-addr.arpa
7.7.74.in-addr.arpa
8.7.74.in-addr.arpa
9.7.74.in-addr.arpa
10.7.74.in-addr.arpa
11.7.74.in-addr.arpa
12.7.74.in-addr.arpa
13.7.74.in-addr.arpa
14.7.74.in-addr.arpa
15.7.74.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01001010.00000111.00000000.0000000074.7.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network01001010.00000111.00000000.0000000074.7.0.0
Broadcast01001010.00000111.01111111.1111111174.7.127.255
Split into smaller subnets/24
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

74.7.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
174.7.0.0/2474.7.0.1 to 74.7.0.25474.7.0.255254
274.7.1.0/2474.7.1.1 to 74.7.1.25474.7.1.255254
374.7.2.0/2474.7.2.1 to 74.7.2.25474.7.2.255254
474.7.3.0/2474.7.3.1 to 74.7.3.25474.7.3.255254
574.7.4.0/2474.7.4.1 to 74.7.4.25474.7.4.255254
674.7.5.0/2474.7.5.1 to 74.7.5.25474.7.5.255254
774.7.6.0/2474.7.6.1 to 74.7.6.25474.7.6.255254
874.7.7.0/2474.7.7.1 to 74.7.7.25474.7.7.255254
974.7.8.0/2474.7.8.1 to 74.7.8.25474.7.8.255254
1074.7.9.0/2474.7.9.1 to 74.7.9.25474.7.9.255254
1174.7.10.0/2474.7.10.1 to 74.7.10.25474.7.10.255254
1274.7.11.0/2474.7.11.1 to 74.7.11.25474.7.11.255254
1374.7.12.0/2474.7.12.1 to 74.7.12.25474.7.12.255254
1474.7.13.0/2474.7.13.1 to 74.7.13.25474.7.13.255254
1574.7.14.0/2474.7.14.1 to 74.7.14.25474.7.14.255254
1674.7.15.0/2474.7.15.1 to 74.7.15.25474.7.15.255254
1774.7.16.0/2474.7.16.1 to 74.7.16.25474.7.16.255254
1874.7.17.0/2474.7.17.1 to 74.7.17.25474.7.17.255254
1974.7.18.0/2474.7.18.1 to 74.7.18.25474.7.18.255254
2074.7.19.0/2474.7.19.1 to 74.7.19.25474.7.19.255254
2174.7.20.0/2474.7.20.1 to 74.7.20.25474.7.20.255254
2274.7.21.0/2474.7.21.1 to 74.7.21.25474.7.21.255254
2374.7.22.0/2474.7.22.1 to 74.7.22.25474.7.22.255254
2474.7.23.0/2474.7.23.1 to 74.7.23.25474.7.23.255254
2574.7.24.0/2474.7.24.1 to 74.7.24.25474.7.24.255254
2674.7.25.0/2474.7.25.1 to 74.7.25.25474.7.25.255254
2774.7.26.0/2474.7.26.1 to 74.7.26.25474.7.26.255254
2874.7.27.0/2474.7.27.1 to 74.7.27.25474.7.27.255254
2974.7.28.0/2474.7.28.1 to 74.7.28.25474.7.28.255254
3074.7.29.0/2474.7.29.1 to 74.7.29.25474.7.29.255254
3174.7.30.0/2474.7.30.1 to 74.7.30.25474.7.30.255254
3274.7.31.0/2474.7.31.1 to 74.7.31.25474.7.31.255254
3374.7.32.0/2474.7.32.1 to 74.7.32.25474.7.32.255254
3474.7.33.0/2474.7.33.1 to 74.7.33.25474.7.33.255254
3574.7.34.0/2474.7.34.1 to 74.7.34.25474.7.34.255254
3674.7.35.0/2474.7.35.1 to 74.7.35.25474.7.35.255254
3774.7.36.0/2474.7.36.1 to 74.7.36.25474.7.36.255254
3874.7.37.0/2474.7.37.1 to 74.7.37.25474.7.37.255254
3974.7.38.0/2474.7.38.1 to 74.7.38.25474.7.38.255254
4074.7.39.0/2474.7.39.1 to 74.7.39.25474.7.39.255254
4174.7.40.0/2474.7.40.1 to 74.7.40.25474.7.40.255254
4274.7.41.0/2474.7.41.1 to 74.7.41.25474.7.41.255254
4374.7.42.0/2474.7.42.1 to 74.7.42.25474.7.42.255254
4474.7.43.0/2474.7.43.1 to 74.7.43.25474.7.43.255254
4574.7.44.0/2474.7.44.1 to 74.7.44.25474.7.44.255254
4674.7.45.0/2474.7.45.1 to 74.7.45.25474.7.45.255254
4774.7.46.0/2474.7.46.1 to 74.7.46.25474.7.46.255254
4874.7.47.0/2474.7.47.1 to 74.7.47.25474.7.47.255254
4974.7.48.0/2474.7.48.1 to 74.7.48.25474.7.48.255254
5074.7.49.0/2474.7.49.1 to 74.7.49.25474.7.49.255254
5174.7.50.0/2474.7.50.1 to 74.7.50.25474.7.50.255254
5274.7.51.0/2474.7.51.1 to 74.7.51.25474.7.51.255254
5374.7.52.0/2474.7.52.1 to 74.7.52.25474.7.52.255254
5474.7.53.0/2474.7.53.1 to 74.7.53.25474.7.53.255254
5574.7.54.0/2474.7.54.1 to 74.7.54.25474.7.54.255254
5674.7.55.0/2474.7.55.1 to 74.7.55.25474.7.55.255254
5774.7.56.0/2474.7.56.1 to 74.7.56.25474.7.56.255254
5874.7.57.0/2474.7.57.1 to 74.7.57.25474.7.57.255254
5974.7.58.0/2474.7.58.1 to 74.7.58.25474.7.58.255254
6074.7.59.0/2474.7.59.1 to 74.7.59.25474.7.59.255254
6174.7.60.0/2474.7.60.1 to 74.7.60.25474.7.60.255254
6274.7.61.0/2474.7.61.1 to 74.7.61.25474.7.61.255254
6374.7.62.0/2474.7.62.1 to 74.7.62.25474.7.62.255254
6474.7.63.0/2474.7.63.1 to 74.7.63.25474.7.63.255254
6574.7.64.0/2474.7.64.1 to 74.7.64.25474.7.64.255254
6674.7.65.0/2474.7.65.1 to 74.7.65.25474.7.65.255254
6774.7.66.0/2474.7.66.1 to 74.7.66.25474.7.66.255254
6874.7.67.0/2474.7.67.1 to 74.7.67.25474.7.67.255254
6974.7.68.0/2474.7.68.1 to 74.7.68.25474.7.68.255254
7074.7.69.0/2474.7.69.1 to 74.7.69.25474.7.69.255254
7174.7.70.0/2474.7.70.1 to 74.7.70.25474.7.70.255254
7274.7.71.0/2474.7.71.1 to 74.7.71.25474.7.71.255254
7374.7.72.0/2474.7.72.1 to 74.7.72.25474.7.72.255254
7474.7.73.0/2474.7.73.1 to 74.7.73.25474.7.73.255254
7574.7.74.0/2474.7.74.1 to 74.7.74.25474.7.74.255254
7674.7.75.0/2474.7.75.1 to 74.7.75.25474.7.75.255254
7774.7.76.0/2474.7.76.1 to 74.7.76.25474.7.76.255254
7874.7.77.0/2474.7.77.1 to 74.7.77.25474.7.77.255254
7974.7.78.0/2474.7.78.1 to 74.7.78.25474.7.78.255254
8074.7.79.0/2474.7.79.1 to 74.7.79.25474.7.79.255254
8174.7.80.0/2474.7.80.1 to 74.7.80.25474.7.80.255254
8274.7.81.0/2474.7.81.1 to 74.7.81.25474.7.81.255254
8374.7.82.0/2474.7.82.1 to 74.7.82.25474.7.82.255254
8474.7.83.0/2474.7.83.1 to 74.7.83.25474.7.83.255254
8574.7.84.0/2474.7.84.1 to 74.7.84.25474.7.84.255254
8674.7.85.0/2474.7.85.1 to 74.7.85.25474.7.85.255254
8774.7.86.0/2474.7.86.1 to 74.7.86.25474.7.86.255254
8874.7.87.0/2474.7.87.1 to 74.7.87.25474.7.87.255254
8974.7.88.0/2474.7.88.1 to 74.7.88.25474.7.88.255254
9074.7.89.0/2474.7.89.1 to 74.7.89.25474.7.89.255254
9174.7.90.0/2474.7.90.1 to 74.7.90.25474.7.90.255254
9274.7.91.0/2474.7.91.1 to 74.7.91.25474.7.91.255254
9374.7.92.0/2474.7.92.1 to 74.7.92.25474.7.92.255254
9474.7.93.0/2474.7.93.1 to 74.7.93.25474.7.93.255254
9574.7.94.0/2474.7.94.1 to 74.7.94.25474.7.94.255254
9674.7.95.0/2474.7.95.1 to 74.7.95.25474.7.95.255254
9774.7.96.0/2474.7.96.1 to 74.7.96.25474.7.96.255254
9874.7.97.0/2474.7.97.1 to 74.7.97.25474.7.97.255254
9974.7.98.0/2474.7.98.1 to 74.7.98.25474.7.98.255254
10074.7.99.0/2474.7.99.1 to 74.7.99.25474.7.99.255254
10174.7.100.0/2474.7.100.1 to 74.7.100.25474.7.100.255254
10274.7.101.0/2474.7.101.1 to 74.7.101.25474.7.101.255254
10374.7.102.0/2474.7.102.1 to 74.7.102.25474.7.102.255254
10474.7.103.0/2474.7.103.1 to 74.7.103.25474.7.103.255254
10574.7.104.0/2474.7.104.1 to 74.7.104.25474.7.104.255254
10674.7.105.0/2474.7.105.1 to 74.7.105.25474.7.105.255254
10774.7.106.0/2474.7.106.1 to 74.7.106.25474.7.106.255254
10874.7.107.0/2474.7.107.1 to 74.7.107.25474.7.107.255254
10974.7.108.0/2474.7.108.1 to 74.7.108.25474.7.108.255254
11074.7.109.0/2474.7.109.1 to 74.7.109.25474.7.109.255254
11174.7.110.0/2474.7.110.1 to 74.7.110.25474.7.110.255254
11274.7.111.0/2474.7.111.1 to 74.7.111.25474.7.111.255254
11374.7.112.0/2474.7.112.1 to 74.7.112.25474.7.112.255254
11474.7.113.0/2474.7.113.1 to 74.7.113.25474.7.113.255254
11574.7.114.0/2474.7.114.1 to 74.7.114.25474.7.114.255254
11674.7.115.0/2474.7.115.1 to 74.7.115.25474.7.115.255254
11774.7.116.0/2474.7.116.1 to 74.7.116.25474.7.116.255254
11874.7.117.0/2474.7.117.1 to 74.7.117.25474.7.117.255254
11974.7.118.0/2474.7.118.1 to 74.7.118.25474.7.118.255254
12074.7.119.0/2474.7.119.1 to 74.7.119.25474.7.119.255254
12174.7.120.0/2474.7.120.1 to 74.7.120.25474.7.120.255254
12274.7.121.0/2474.7.121.1 to 74.7.121.25474.7.121.255254
12374.7.122.0/2474.7.122.1 to 74.7.122.25474.7.122.255254
12474.7.123.0/2474.7.123.1 to 74.7.123.25474.7.123.255254
12574.7.124.0/2474.7.124.1 to 74.7.124.25474.7.124.255254
12674.7.125.0/2474.7.125.1 to 74.7.125.25474.7.125.255254
12774.7.126.0/2474.7.126.1 to 74.7.126.25474.7.126.255254
12874.7.127.0/2474.7.127.1 to 74.7.127.25474.7.127.255254

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.