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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.

Network38.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
38.0.0.0
Broadcast address
38.63.255.255
First usable
38.0.0.1
Last usable
38.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
A (default /8)
As numbers
Hex 26000000 · Integer 637534208 to 641728511
Reverse DNS zones
0.38.in-addr.arpa
1.38.in-addr.arpa
2.38.in-addr.arpa
3.38.in-addr.arpa
4.38.in-addr.arpa
5.38.in-addr.arpa
6.38.in-addr.arpa
7.38.in-addr.arpa
8.38.in-addr.arpa
9.38.in-addr.arpa
10.38.in-addr.arpa
11.38.in-addr.arpa
12.38.in-addr.arpa
13.38.in-addr.arpa
14.38.in-addr.arpa
15.38.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00100110.00000000.00000000.0000000038.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00100110.00000000.00000000.0000000038.0.0.0
Broadcast00100110.00111111.11111111.1111111138.63.255.255
Split into smaller subnets/17
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

38.0.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
138.0.0.0/1738.0.0.1 to 38.0.127.25438.0.127.25532,766
238.0.128.0/1738.0.128.1 to 38.0.255.25438.0.255.25532,766
338.1.0.0/1738.1.0.1 to 38.1.127.25438.1.127.25532,766
438.1.128.0/1738.1.128.1 to 38.1.255.25438.1.255.25532,766
538.2.0.0/1738.2.0.1 to 38.2.127.25438.2.127.25532,766
638.2.128.0/1738.2.128.1 to 38.2.255.25438.2.255.25532,766
738.3.0.0/1738.3.0.1 to 38.3.127.25438.3.127.25532,766
838.3.128.0/1738.3.128.1 to 38.3.255.25438.3.255.25532,766
938.4.0.0/1738.4.0.1 to 38.4.127.25438.4.127.25532,766
1038.4.128.0/1738.4.128.1 to 38.4.255.25438.4.255.25532,766
1138.5.0.0/1738.5.0.1 to 38.5.127.25438.5.127.25532,766
1238.5.128.0/1738.5.128.1 to 38.5.255.25438.5.255.25532,766
1338.6.0.0/1738.6.0.1 to 38.6.127.25438.6.127.25532,766
1438.6.128.0/1738.6.128.1 to 38.6.255.25438.6.255.25532,766
1538.7.0.0/1738.7.0.1 to 38.7.127.25438.7.127.25532,766
1638.7.128.0/1738.7.128.1 to 38.7.255.25438.7.255.25532,766
1738.8.0.0/1738.8.0.1 to 38.8.127.25438.8.127.25532,766
1838.8.128.0/1738.8.128.1 to 38.8.255.25438.8.255.25532,766
1938.9.0.0/1738.9.0.1 to 38.9.127.25438.9.127.25532,766
2038.9.128.0/1738.9.128.1 to 38.9.255.25438.9.255.25532,766
2138.10.0.0/1738.10.0.1 to 38.10.127.25438.10.127.25532,766
2238.10.128.0/1738.10.128.1 to 38.10.255.25438.10.255.25532,766
2338.11.0.0/1738.11.0.1 to 38.11.127.25438.11.127.25532,766
2438.11.128.0/1738.11.128.1 to 38.11.255.25438.11.255.25532,766
2538.12.0.0/1738.12.0.1 to 38.12.127.25438.12.127.25532,766
2638.12.128.0/1738.12.128.1 to 38.12.255.25438.12.255.25532,766
2738.13.0.0/1738.13.0.1 to 38.13.127.25438.13.127.25532,766
2838.13.128.0/1738.13.128.1 to 38.13.255.25438.13.255.25532,766
2938.14.0.0/1738.14.0.1 to 38.14.127.25438.14.127.25532,766
3038.14.128.0/1738.14.128.1 to 38.14.255.25438.14.255.25532,766
3138.15.0.0/1738.15.0.1 to 38.15.127.25438.15.127.25532,766
3238.15.128.0/1738.15.128.1 to 38.15.255.25438.15.255.25532,766
3338.16.0.0/1738.16.0.1 to 38.16.127.25438.16.127.25532,766
3438.16.128.0/1738.16.128.1 to 38.16.255.25438.16.255.25532,766
3538.17.0.0/1738.17.0.1 to 38.17.127.25438.17.127.25532,766
3638.17.128.0/1738.17.128.1 to 38.17.255.25438.17.255.25532,766
3738.18.0.0/1738.18.0.1 to 38.18.127.25438.18.127.25532,766
3838.18.128.0/1738.18.128.1 to 38.18.255.25438.18.255.25532,766
3938.19.0.0/1738.19.0.1 to 38.19.127.25438.19.127.25532,766
4038.19.128.0/1738.19.128.1 to 38.19.255.25438.19.255.25532,766
4138.20.0.0/1738.20.0.1 to 38.20.127.25438.20.127.25532,766
4238.20.128.0/1738.20.128.1 to 38.20.255.25438.20.255.25532,766
4338.21.0.0/1738.21.0.1 to 38.21.127.25438.21.127.25532,766
4438.21.128.0/1738.21.128.1 to 38.21.255.25438.21.255.25532,766
4538.22.0.0/1738.22.0.1 to 38.22.127.25438.22.127.25532,766
4638.22.128.0/1738.22.128.1 to 38.22.255.25438.22.255.25532,766
4738.23.0.0/1738.23.0.1 to 38.23.127.25438.23.127.25532,766
4838.23.128.0/1738.23.128.1 to 38.23.255.25438.23.255.25532,766
4938.24.0.0/1738.24.0.1 to 38.24.127.25438.24.127.25532,766
5038.24.128.0/1738.24.128.1 to 38.24.255.25438.24.255.25532,766
5138.25.0.0/1738.25.0.1 to 38.25.127.25438.25.127.25532,766
5238.25.128.0/1738.25.128.1 to 38.25.255.25438.25.255.25532,766
5338.26.0.0/1738.26.0.1 to 38.26.127.25438.26.127.25532,766
5438.26.128.0/1738.26.128.1 to 38.26.255.25438.26.255.25532,766
5538.27.0.0/1738.27.0.1 to 38.27.127.25438.27.127.25532,766
5638.27.128.0/1738.27.128.1 to 38.27.255.25438.27.255.25532,766
5738.28.0.0/1738.28.0.1 to 38.28.127.25438.28.127.25532,766
5838.28.128.0/1738.28.128.1 to 38.28.255.25438.28.255.25532,766
5938.29.0.0/1738.29.0.1 to 38.29.127.25438.29.127.25532,766
6038.29.128.0/1738.29.128.1 to 38.29.255.25438.29.255.25532,766
6138.30.0.0/1738.30.0.1 to 38.30.127.25438.30.127.25532,766
6238.30.128.0/1738.30.128.1 to 38.30.255.25438.30.255.25532,766
6338.31.0.0/1738.31.0.1 to 38.31.127.25438.31.127.25532,766
6438.31.128.0/1738.31.128.1 to 38.31.255.25438.31.255.25532,766
6538.32.0.0/1738.32.0.1 to 38.32.127.25438.32.127.25532,766
6638.32.128.0/1738.32.128.1 to 38.32.255.25438.32.255.25532,766
6738.33.0.0/1738.33.0.1 to 38.33.127.25438.33.127.25532,766
6838.33.128.0/1738.33.128.1 to 38.33.255.25438.33.255.25532,766
6938.34.0.0/1738.34.0.1 to 38.34.127.25438.34.127.25532,766
7038.34.128.0/1738.34.128.1 to 38.34.255.25438.34.255.25532,766
7138.35.0.0/1738.35.0.1 to 38.35.127.25438.35.127.25532,766
7238.35.128.0/1738.35.128.1 to 38.35.255.25438.35.255.25532,766
7338.36.0.0/1738.36.0.1 to 38.36.127.25438.36.127.25532,766
7438.36.128.0/1738.36.128.1 to 38.36.255.25438.36.255.25532,766
7538.37.0.0/1738.37.0.1 to 38.37.127.25438.37.127.25532,766
7638.37.128.0/1738.37.128.1 to 38.37.255.25438.37.255.25532,766
7738.38.0.0/1738.38.0.1 to 38.38.127.25438.38.127.25532,766
7838.38.128.0/1738.38.128.1 to 38.38.255.25438.38.255.25532,766
7938.39.0.0/1738.39.0.1 to 38.39.127.25438.39.127.25532,766
8038.39.128.0/1738.39.128.1 to 38.39.255.25438.39.255.25532,766
8138.40.0.0/1738.40.0.1 to 38.40.127.25438.40.127.25532,766
8238.40.128.0/1738.40.128.1 to 38.40.255.25438.40.255.25532,766
8338.41.0.0/1738.41.0.1 to 38.41.127.25438.41.127.25532,766
8438.41.128.0/1738.41.128.1 to 38.41.255.25438.41.255.25532,766
8538.42.0.0/1738.42.0.1 to 38.42.127.25438.42.127.25532,766
8638.42.128.0/1738.42.128.1 to 38.42.255.25438.42.255.25532,766
8738.43.0.0/1738.43.0.1 to 38.43.127.25438.43.127.25532,766
8838.43.128.0/1738.43.128.1 to 38.43.255.25438.43.255.25532,766
8938.44.0.0/1738.44.0.1 to 38.44.127.25438.44.127.25532,766
9038.44.128.0/1738.44.128.1 to 38.44.255.25438.44.255.25532,766
9138.45.0.0/1738.45.0.1 to 38.45.127.25438.45.127.25532,766
9238.45.128.0/1738.45.128.1 to 38.45.255.25438.45.255.25532,766
9338.46.0.0/1738.46.0.1 to 38.46.127.25438.46.127.25532,766
9438.46.128.0/1738.46.128.1 to 38.46.255.25438.46.255.25532,766
9538.47.0.0/1738.47.0.1 to 38.47.127.25438.47.127.25532,766
9638.47.128.0/1738.47.128.1 to 38.47.255.25438.47.255.25532,766
9738.48.0.0/1738.48.0.1 to 38.48.127.25438.48.127.25532,766
9838.48.128.0/1738.48.128.1 to 38.48.255.25438.48.255.25532,766
9938.49.0.0/1738.49.0.1 to 38.49.127.25438.49.127.25532,766
10038.49.128.0/1738.49.128.1 to 38.49.255.25438.49.255.25532,766
10138.50.0.0/1738.50.0.1 to 38.50.127.25438.50.127.25532,766
10238.50.128.0/1738.50.128.1 to 38.50.255.25438.50.255.25532,766
10338.51.0.0/1738.51.0.1 to 38.51.127.25438.51.127.25532,766
10438.51.128.0/1738.51.128.1 to 38.51.255.25438.51.255.25532,766
10538.52.0.0/1738.52.0.1 to 38.52.127.25438.52.127.25532,766
10638.52.128.0/1738.52.128.1 to 38.52.255.25438.52.255.25532,766
10738.53.0.0/1738.53.0.1 to 38.53.127.25438.53.127.25532,766
10838.53.128.0/1738.53.128.1 to 38.53.255.25438.53.255.25532,766
10938.54.0.0/1738.54.0.1 to 38.54.127.25438.54.127.25532,766
11038.54.128.0/1738.54.128.1 to 38.54.255.25438.54.255.25532,766
11138.55.0.0/1738.55.0.1 to 38.55.127.25438.55.127.25532,766
11238.55.128.0/1738.55.128.1 to 38.55.255.25438.55.255.25532,766
11338.56.0.0/1738.56.0.1 to 38.56.127.25438.56.127.25532,766
11438.56.128.0/1738.56.128.1 to 38.56.255.25438.56.255.25532,766
11538.57.0.0/1738.57.0.1 to 38.57.127.25438.57.127.25532,766
11638.57.128.0/1738.57.128.1 to 38.57.255.25438.57.255.25532,766
11738.58.0.0/1738.58.0.1 to 38.58.127.25438.58.127.25532,766
11838.58.128.0/1738.58.128.1 to 38.58.255.25438.58.255.25532,766
11938.59.0.0/1738.59.0.1 to 38.59.127.25438.59.127.25532,766
12038.59.128.0/1738.59.128.1 to 38.59.255.25438.59.255.25532,766
12138.60.0.0/1738.60.0.1 to 38.60.127.25438.60.127.25532,766
12238.60.128.0/1738.60.128.1 to 38.60.255.25438.60.255.25532,766
12338.61.0.0/1738.61.0.1 to 38.61.127.25438.61.127.25532,766
12438.61.128.0/1738.61.128.1 to 38.61.255.25438.61.255.25532,766
12538.62.0.0/1738.62.0.1 to 38.62.127.25438.62.127.25532,766
12638.62.128.0/1738.62.128.1 to 38.62.255.25438.62.255.25532,766
12738.63.0.0/1738.63.0.1 to 38.63.127.25438.63.127.25532,766
12838.63.128.0/1738.63.128.1 to 38.63.255.25438.63.255.25532,766

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.