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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.

Network47.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
47.0.0.0
Broadcast address
47.127.255.255
First usable
47.0.0.1
Last usable
47.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 2F000000 · Integer 788529152 to 796917759
Reverse DNS zones
0.47.in-addr.arpa
1.47.in-addr.arpa
2.47.in-addr.arpa
3.47.in-addr.arpa
4.47.in-addr.arpa
5.47.in-addr.arpa
6.47.in-addr.arpa
7.47.in-addr.arpa
8.47.in-addr.arpa
9.47.in-addr.arpa
10.47.in-addr.arpa
11.47.in-addr.arpa
12.47.in-addr.arpa
13.47.in-addr.arpa
14.47.in-addr.arpa
15.47.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00101111.00000000.00000000.0000000047.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00101111.00000000.00000000.0000000047.0.0.0
Broadcast00101111.01111111.11111111.1111111147.127.255.255
Split into smaller subnets/16
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

47.0.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
147.0.0.0/1647.0.0.1 to 47.0.255.25447.0.255.25565,534
247.1.0.0/1647.1.0.1 to 47.1.255.25447.1.255.25565,534
347.2.0.0/1647.2.0.1 to 47.2.255.25447.2.255.25565,534
447.3.0.0/1647.3.0.1 to 47.3.255.25447.3.255.25565,534
547.4.0.0/1647.4.0.1 to 47.4.255.25447.4.255.25565,534
647.5.0.0/1647.5.0.1 to 47.5.255.25447.5.255.25565,534
747.6.0.0/1647.6.0.1 to 47.6.255.25447.6.255.25565,534
847.7.0.0/1647.7.0.1 to 47.7.255.25447.7.255.25565,534
947.8.0.0/1647.8.0.1 to 47.8.255.25447.8.255.25565,534
1047.9.0.0/1647.9.0.1 to 47.9.255.25447.9.255.25565,534
1147.10.0.0/1647.10.0.1 to 47.10.255.25447.10.255.25565,534
1247.11.0.0/1647.11.0.1 to 47.11.255.25447.11.255.25565,534
1347.12.0.0/1647.12.0.1 to 47.12.255.25447.12.255.25565,534
1447.13.0.0/1647.13.0.1 to 47.13.255.25447.13.255.25565,534
1547.14.0.0/1647.14.0.1 to 47.14.255.25447.14.255.25565,534
1647.15.0.0/1647.15.0.1 to 47.15.255.25447.15.255.25565,534
1747.16.0.0/1647.16.0.1 to 47.16.255.25447.16.255.25565,534
1847.17.0.0/1647.17.0.1 to 47.17.255.25447.17.255.25565,534
1947.18.0.0/1647.18.0.1 to 47.18.255.25447.18.255.25565,534
2047.19.0.0/1647.19.0.1 to 47.19.255.25447.19.255.25565,534
2147.20.0.0/1647.20.0.1 to 47.20.255.25447.20.255.25565,534
2247.21.0.0/1647.21.0.1 to 47.21.255.25447.21.255.25565,534
2347.22.0.0/1647.22.0.1 to 47.22.255.25447.22.255.25565,534
2447.23.0.0/1647.23.0.1 to 47.23.255.25447.23.255.25565,534
2547.24.0.0/1647.24.0.1 to 47.24.255.25447.24.255.25565,534
2647.25.0.0/1647.25.0.1 to 47.25.255.25447.25.255.25565,534
2747.26.0.0/1647.26.0.1 to 47.26.255.25447.26.255.25565,534
2847.27.0.0/1647.27.0.1 to 47.27.255.25447.27.255.25565,534
2947.28.0.0/1647.28.0.1 to 47.28.255.25447.28.255.25565,534
3047.29.0.0/1647.29.0.1 to 47.29.255.25447.29.255.25565,534
3147.30.0.0/1647.30.0.1 to 47.30.255.25447.30.255.25565,534
3247.31.0.0/1647.31.0.1 to 47.31.255.25447.31.255.25565,534
3347.32.0.0/1647.32.0.1 to 47.32.255.25447.32.255.25565,534
3447.33.0.0/1647.33.0.1 to 47.33.255.25447.33.255.25565,534
3547.34.0.0/1647.34.0.1 to 47.34.255.25447.34.255.25565,534
3647.35.0.0/1647.35.0.1 to 47.35.255.25447.35.255.25565,534
3747.36.0.0/1647.36.0.1 to 47.36.255.25447.36.255.25565,534
3847.37.0.0/1647.37.0.1 to 47.37.255.25447.37.255.25565,534
3947.38.0.0/1647.38.0.1 to 47.38.255.25447.38.255.25565,534
4047.39.0.0/1647.39.0.1 to 47.39.255.25447.39.255.25565,534
4147.40.0.0/1647.40.0.1 to 47.40.255.25447.40.255.25565,534
4247.41.0.0/1647.41.0.1 to 47.41.255.25447.41.255.25565,534
4347.42.0.0/1647.42.0.1 to 47.42.255.25447.42.255.25565,534
4447.43.0.0/1647.43.0.1 to 47.43.255.25447.43.255.25565,534
4547.44.0.0/1647.44.0.1 to 47.44.255.25447.44.255.25565,534
4647.45.0.0/1647.45.0.1 to 47.45.255.25447.45.255.25565,534
4747.46.0.0/1647.46.0.1 to 47.46.255.25447.46.255.25565,534
4847.47.0.0/1647.47.0.1 to 47.47.255.25447.47.255.25565,534
4947.48.0.0/1647.48.0.1 to 47.48.255.25447.48.255.25565,534
5047.49.0.0/1647.49.0.1 to 47.49.255.25447.49.255.25565,534
5147.50.0.0/1647.50.0.1 to 47.50.255.25447.50.255.25565,534
5247.51.0.0/1647.51.0.1 to 47.51.255.25447.51.255.25565,534
5347.52.0.0/1647.52.0.1 to 47.52.255.25447.52.255.25565,534
5447.53.0.0/1647.53.0.1 to 47.53.255.25447.53.255.25565,534
5547.54.0.0/1647.54.0.1 to 47.54.255.25447.54.255.25565,534
5647.55.0.0/1647.55.0.1 to 47.55.255.25447.55.255.25565,534
5747.56.0.0/1647.56.0.1 to 47.56.255.25447.56.255.25565,534
5847.57.0.0/1647.57.0.1 to 47.57.255.25447.57.255.25565,534
5947.58.0.0/1647.58.0.1 to 47.58.255.25447.58.255.25565,534
6047.59.0.0/1647.59.0.1 to 47.59.255.25447.59.255.25565,534
6147.60.0.0/1647.60.0.1 to 47.60.255.25447.60.255.25565,534
6247.61.0.0/1647.61.0.1 to 47.61.255.25447.61.255.25565,534
6347.62.0.0/1647.62.0.1 to 47.62.255.25447.62.255.25565,534
6447.63.0.0/1647.63.0.1 to 47.63.255.25447.63.255.25565,534
6547.64.0.0/1647.64.0.1 to 47.64.255.25447.64.255.25565,534
6647.65.0.0/1647.65.0.1 to 47.65.255.25447.65.255.25565,534
6747.66.0.0/1647.66.0.1 to 47.66.255.25447.66.255.25565,534
6847.67.0.0/1647.67.0.1 to 47.67.255.25447.67.255.25565,534
6947.68.0.0/1647.68.0.1 to 47.68.255.25447.68.255.25565,534
7047.69.0.0/1647.69.0.1 to 47.69.255.25447.69.255.25565,534
7147.70.0.0/1647.70.0.1 to 47.70.255.25447.70.255.25565,534
7247.71.0.0/1647.71.0.1 to 47.71.255.25447.71.255.25565,534
7347.72.0.0/1647.72.0.1 to 47.72.255.25447.72.255.25565,534
7447.73.0.0/1647.73.0.1 to 47.73.255.25447.73.255.25565,534
7547.74.0.0/1647.74.0.1 to 47.74.255.25447.74.255.25565,534
7647.75.0.0/1647.75.0.1 to 47.75.255.25447.75.255.25565,534
7747.76.0.0/1647.76.0.1 to 47.76.255.25447.76.255.25565,534
7847.77.0.0/1647.77.0.1 to 47.77.255.25447.77.255.25565,534
7947.78.0.0/1647.78.0.1 to 47.78.255.25447.78.255.25565,534
8047.79.0.0/1647.79.0.1 to 47.79.255.25447.79.255.25565,534
8147.80.0.0/1647.80.0.1 to 47.80.255.25447.80.255.25565,534
8247.81.0.0/1647.81.0.1 to 47.81.255.25447.81.255.25565,534
8347.82.0.0/1647.82.0.1 to 47.82.255.25447.82.255.25565,534
8447.83.0.0/1647.83.0.1 to 47.83.255.25447.83.255.25565,534
8547.84.0.0/1647.84.0.1 to 47.84.255.25447.84.255.25565,534
8647.85.0.0/1647.85.0.1 to 47.85.255.25447.85.255.25565,534
8747.86.0.0/1647.86.0.1 to 47.86.255.25447.86.255.25565,534
8847.87.0.0/1647.87.0.1 to 47.87.255.25447.87.255.25565,534
8947.88.0.0/1647.88.0.1 to 47.88.255.25447.88.255.25565,534
9047.89.0.0/1647.89.0.1 to 47.89.255.25447.89.255.25565,534
9147.90.0.0/1647.90.0.1 to 47.90.255.25447.90.255.25565,534
9247.91.0.0/1647.91.0.1 to 47.91.255.25447.91.255.25565,534
9347.92.0.0/1647.92.0.1 to 47.92.255.25447.92.255.25565,534
9447.93.0.0/1647.93.0.1 to 47.93.255.25447.93.255.25565,534
9547.94.0.0/1647.94.0.1 to 47.94.255.25447.94.255.25565,534
9647.95.0.0/1647.95.0.1 to 47.95.255.25447.95.255.25565,534
9747.96.0.0/1647.96.0.1 to 47.96.255.25447.96.255.25565,534
9847.97.0.0/1647.97.0.1 to 47.97.255.25447.97.255.25565,534
9947.98.0.0/1647.98.0.1 to 47.98.255.25447.98.255.25565,534
10047.99.0.0/1647.99.0.1 to 47.99.255.25447.99.255.25565,534
10147.100.0.0/1647.100.0.1 to 47.100.255.25447.100.255.25565,534
10247.101.0.0/1647.101.0.1 to 47.101.255.25447.101.255.25565,534
10347.102.0.0/1647.102.0.1 to 47.102.255.25447.102.255.25565,534
10447.103.0.0/1647.103.0.1 to 47.103.255.25447.103.255.25565,534
10547.104.0.0/1647.104.0.1 to 47.104.255.25447.104.255.25565,534
10647.105.0.0/1647.105.0.1 to 47.105.255.25447.105.255.25565,534
10747.106.0.0/1647.106.0.1 to 47.106.255.25447.106.255.25565,534
10847.107.0.0/1647.107.0.1 to 47.107.255.25447.107.255.25565,534
10947.108.0.0/1647.108.0.1 to 47.108.255.25447.108.255.25565,534
11047.109.0.0/1647.109.0.1 to 47.109.255.25447.109.255.25565,534
11147.110.0.0/1647.110.0.1 to 47.110.255.25447.110.255.25565,534
11247.111.0.0/1647.111.0.1 to 47.111.255.25447.111.255.25565,534
11347.112.0.0/1647.112.0.1 to 47.112.255.25447.112.255.25565,534
11447.113.0.0/1647.113.0.1 to 47.113.255.25447.113.255.25565,534
11547.114.0.0/1647.114.0.1 to 47.114.255.25447.114.255.25565,534
11647.115.0.0/1647.115.0.1 to 47.115.255.25447.115.255.25565,534
11747.116.0.0/1647.116.0.1 to 47.116.255.25447.116.255.25565,534
11847.117.0.0/1647.117.0.1 to 47.117.255.25447.117.255.25565,534
11947.118.0.0/1647.118.0.1 to 47.118.255.25447.118.255.25565,534
12047.119.0.0/1647.119.0.1 to 47.119.255.25447.119.255.25565,534
12147.120.0.0/1647.120.0.1 to 47.120.255.25447.120.255.25565,534
12247.121.0.0/1647.121.0.1 to 47.121.255.25447.121.255.25565,534
12347.122.0.0/1647.122.0.1 to 47.122.255.25447.122.255.25565,534
12447.123.0.0/1647.123.0.1 to 47.123.255.25447.123.255.25565,534
12547.124.0.0/1647.124.0.1 to 47.124.255.25447.124.255.25565,534
12647.125.0.0/1647.125.0.1 to 47.125.255.25447.125.255.25565,534
12747.126.0.0/1647.126.0.1 to 47.126.255.25447.126.255.25565,534
12847.127.0.0/1647.127.0.1 to 47.127.255.25447.127.255.25565,534

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.