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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.

Network63.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
63.0.0.0
Broadcast address
63.63.255.255
First usable
63.0.0.1
Last usable
63.63.255.254
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 3F000000 · Integer 1056964608 to 1061158911
Reverse DNS zones
0.63.in-addr.arpa
1.63.in-addr.arpa
2.63.in-addr.arpa
3.63.in-addr.arpa
4.63.in-addr.arpa
5.63.in-addr.arpa
6.63.in-addr.arpa
7.63.in-addr.arpa
8.63.in-addr.arpa
9.63.in-addr.arpa
10.63.in-addr.arpa
11.63.in-addr.arpa
12.63.in-addr.arpa
13.63.in-addr.arpa
14.63.in-addr.arpa
15.63.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
Address00111111.00000000.00000000.0000000063.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00111111.00000000.00000000.0000000063.0.0.0
Broadcast00111111.00111111.11111111.1111111163.63.255.255
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)

63.0.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
163.0.0.0/1763.0.0.1 to 63.0.127.25463.0.127.25532,766
263.0.128.0/1763.0.128.1 to 63.0.255.25463.0.255.25532,766
363.1.0.0/1763.1.0.1 to 63.1.127.25463.1.127.25532,766
463.1.128.0/1763.1.128.1 to 63.1.255.25463.1.255.25532,766
563.2.0.0/1763.2.0.1 to 63.2.127.25463.2.127.25532,766
663.2.128.0/1763.2.128.1 to 63.2.255.25463.2.255.25532,766
763.3.0.0/1763.3.0.1 to 63.3.127.25463.3.127.25532,766
863.3.128.0/1763.3.128.1 to 63.3.255.25463.3.255.25532,766
963.4.0.0/1763.4.0.1 to 63.4.127.25463.4.127.25532,766
1063.4.128.0/1763.4.128.1 to 63.4.255.25463.4.255.25532,766
1163.5.0.0/1763.5.0.1 to 63.5.127.25463.5.127.25532,766
1263.5.128.0/1763.5.128.1 to 63.5.255.25463.5.255.25532,766
1363.6.0.0/1763.6.0.1 to 63.6.127.25463.6.127.25532,766
1463.6.128.0/1763.6.128.1 to 63.6.255.25463.6.255.25532,766
1563.7.0.0/1763.7.0.1 to 63.7.127.25463.7.127.25532,766
1663.7.128.0/1763.7.128.1 to 63.7.255.25463.7.255.25532,766
1763.8.0.0/1763.8.0.1 to 63.8.127.25463.8.127.25532,766
1863.8.128.0/1763.8.128.1 to 63.8.255.25463.8.255.25532,766
1963.9.0.0/1763.9.0.1 to 63.9.127.25463.9.127.25532,766
2063.9.128.0/1763.9.128.1 to 63.9.255.25463.9.255.25532,766
2163.10.0.0/1763.10.0.1 to 63.10.127.25463.10.127.25532,766
2263.10.128.0/1763.10.128.1 to 63.10.255.25463.10.255.25532,766
2363.11.0.0/1763.11.0.1 to 63.11.127.25463.11.127.25532,766
2463.11.128.0/1763.11.128.1 to 63.11.255.25463.11.255.25532,766
2563.12.0.0/1763.12.0.1 to 63.12.127.25463.12.127.25532,766
2663.12.128.0/1763.12.128.1 to 63.12.255.25463.12.255.25532,766
2763.13.0.0/1763.13.0.1 to 63.13.127.25463.13.127.25532,766
2863.13.128.0/1763.13.128.1 to 63.13.255.25463.13.255.25532,766
2963.14.0.0/1763.14.0.1 to 63.14.127.25463.14.127.25532,766
3063.14.128.0/1763.14.128.1 to 63.14.255.25463.14.255.25532,766
3163.15.0.0/1763.15.0.1 to 63.15.127.25463.15.127.25532,766
3263.15.128.0/1763.15.128.1 to 63.15.255.25463.15.255.25532,766
3363.16.0.0/1763.16.0.1 to 63.16.127.25463.16.127.25532,766
3463.16.128.0/1763.16.128.1 to 63.16.255.25463.16.255.25532,766
3563.17.0.0/1763.17.0.1 to 63.17.127.25463.17.127.25532,766
3663.17.128.0/1763.17.128.1 to 63.17.255.25463.17.255.25532,766
3763.18.0.0/1763.18.0.1 to 63.18.127.25463.18.127.25532,766
3863.18.128.0/1763.18.128.1 to 63.18.255.25463.18.255.25532,766
3963.19.0.0/1763.19.0.1 to 63.19.127.25463.19.127.25532,766
4063.19.128.0/1763.19.128.1 to 63.19.255.25463.19.255.25532,766
4163.20.0.0/1763.20.0.1 to 63.20.127.25463.20.127.25532,766
4263.20.128.0/1763.20.128.1 to 63.20.255.25463.20.255.25532,766
4363.21.0.0/1763.21.0.1 to 63.21.127.25463.21.127.25532,766
4463.21.128.0/1763.21.128.1 to 63.21.255.25463.21.255.25532,766
4563.22.0.0/1763.22.0.1 to 63.22.127.25463.22.127.25532,766
4663.22.128.0/1763.22.128.1 to 63.22.255.25463.22.255.25532,766
4763.23.0.0/1763.23.0.1 to 63.23.127.25463.23.127.25532,766
4863.23.128.0/1763.23.128.1 to 63.23.255.25463.23.255.25532,766
4963.24.0.0/1763.24.0.1 to 63.24.127.25463.24.127.25532,766
5063.24.128.0/1763.24.128.1 to 63.24.255.25463.24.255.25532,766
5163.25.0.0/1763.25.0.1 to 63.25.127.25463.25.127.25532,766
5263.25.128.0/1763.25.128.1 to 63.25.255.25463.25.255.25532,766
5363.26.0.0/1763.26.0.1 to 63.26.127.25463.26.127.25532,766
5463.26.128.0/1763.26.128.1 to 63.26.255.25463.26.255.25532,766
5563.27.0.0/1763.27.0.1 to 63.27.127.25463.27.127.25532,766
5663.27.128.0/1763.27.128.1 to 63.27.255.25463.27.255.25532,766
5763.28.0.0/1763.28.0.1 to 63.28.127.25463.28.127.25532,766
5863.28.128.0/1763.28.128.1 to 63.28.255.25463.28.255.25532,766
5963.29.0.0/1763.29.0.1 to 63.29.127.25463.29.127.25532,766
6063.29.128.0/1763.29.128.1 to 63.29.255.25463.29.255.25532,766
6163.30.0.0/1763.30.0.1 to 63.30.127.25463.30.127.25532,766
6263.30.128.0/1763.30.128.1 to 63.30.255.25463.30.255.25532,766
6363.31.0.0/1763.31.0.1 to 63.31.127.25463.31.127.25532,766
6463.31.128.0/1763.31.128.1 to 63.31.255.25463.31.255.25532,766
6563.32.0.0/1763.32.0.1 to 63.32.127.25463.32.127.25532,766
6663.32.128.0/1763.32.128.1 to 63.32.255.25463.32.255.25532,766
6763.33.0.0/1763.33.0.1 to 63.33.127.25463.33.127.25532,766
6863.33.128.0/1763.33.128.1 to 63.33.255.25463.33.255.25532,766
6963.34.0.0/1763.34.0.1 to 63.34.127.25463.34.127.25532,766
7063.34.128.0/1763.34.128.1 to 63.34.255.25463.34.255.25532,766
7163.35.0.0/1763.35.0.1 to 63.35.127.25463.35.127.25532,766
7263.35.128.0/1763.35.128.1 to 63.35.255.25463.35.255.25532,766
7363.36.0.0/1763.36.0.1 to 63.36.127.25463.36.127.25532,766
7463.36.128.0/1763.36.128.1 to 63.36.255.25463.36.255.25532,766
7563.37.0.0/1763.37.0.1 to 63.37.127.25463.37.127.25532,766
7663.37.128.0/1763.37.128.1 to 63.37.255.25463.37.255.25532,766
7763.38.0.0/1763.38.0.1 to 63.38.127.25463.38.127.25532,766
7863.38.128.0/1763.38.128.1 to 63.38.255.25463.38.255.25532,766
7963.39.0.0/1763.39.0.1 to 63.39.127.25463.39.127.25532,766
8063.39.128.0/1763.39.128.1 to 63.39.255.25463.39.255.25532,766
8163.40.0.0/1763.40.0.1 to 63.40.127.25463.40.127.25532,766
8263.40.128.0/1763.40.128.1 to 63.40.255.25463.40.255.25532,766
8363.41.0.0/1763.41.0.1 to 63.41.127.25463.41.127.25532,766
8463.41.128.0/1763.41.128.1 to 63.41.255.25463.41.255.25532,766
8563.42.0.0/1763.42.0.1 to 63.42.127.25463.42.127.25532,766
8663.42.128.0/1763.42.128.1 to 63.42.255.25463.42.255.25532,766
8763.43.0.0/1763.43.0.1 to 63.43.127.25463.43.127.25532,766
8863.43.128.0/1763.43.128.1 to 63.43.255.25463.43.255.25532,766
8963.44.0.0/1763.44.0.1 to 63.44.127.25463.44.127.25532,766
9063.44.128.0/1763.44.128.1 to 63.44.255.25463.44.255.25532,766
9163.45.0.0/1763.45.0.1 to 63.45.127.25463.45.127.25532,766
9263.45.128.0/1763.45.128.1 to 63.45.255.25463.45.255.25532,766
9363.46.0.0/1763.46.0.1 to 63.46.127.25463.46.127.25532,766
9463.46.128.0/1763.46.128.1 to 63.46.255.25463.46.255.25532,766
9563.47.0.0/1763.47.0.1 to 63.47.127.25463.47.127.25532,766
9663.47.128.0/1763.47.128.1 to 63.47.255.25463.47.255.25532,766
9763.48.0.0/1763.48.0.1 to 63.48.127.25463.48.127.25532,766
9863.48.128.0/1763.48.128.1 to 63.48.255.25463.48.255.25532,766
9963.49.0.0/1763.49.0.1 to 63.49.127.25463.49.127.25532,766
10063.49.128.0/1763.49.128.1 to 63.49.255.25463.49.255.25532,766
10163.50.0.0/1763.50.0.1 to 63.50.127.25463.50.127.25532,766
10263.50.128.0/1763.50.128.1 to 63.50.255.25463.50.255.25532,766
10363.51.0.0/1763.51.0.1 to 63.51.127.25463.51.127.25532,766
10463.51.128.0/1763.51.128.1 to 63.51.255.25463.51.255.25532,766
10563.52.0.0/1763.52.0.1 to 63.52.127.25463.52.127.25532,766
10663.52.128.0/1763.52.128.1 to 63.52.255.25463.52.255.25532,766
10763.53.0.0/1763.53.0.1 to 63.53.127.25463.53.127.25532,766
10863.53.128.0/1763.53.128.1 to 63.53.255.25463.53.255.25532,766
10963.54.0.0/1763.54.0.1 to 63.54.127.25463.54.127.25532,766
11063.54.128.0/1763.54.128.1 to 63.54.255.25463.54.255.25532,766
11163.55.0.0/1763.55.0.1 to 63.55.127.25463.55.127.25532,766
11263.55.128.0/1763.55.128.1 to 63.55.255.25463.55.255.25532,766
11363.56.0.0/1763.56.0.1 to 63.56.127.25463.56.127.25532,766
11463.56.128.0/1763.56.128.1 to 63.56.255.25463.56.255.25532,766
11563.57.0.0/1763.57.0.1 to 63.57.127.25463.57.127.25532,766
11663.57.128.0/1763.57.128.1 to 63.57.255.25463.57.255.25532,766
11763.58.0.0/1763.58.0.1 to 63.58.127.25463.58.127.25532,766
11863.58.128.0/1763.58.128.1 to 63.58.255.25463.58.255.25532,766
11963.59.0.0/1763.59.0.1 to 63.59.127.25463.59.127.25532,766
12063.59.128.0/1763.59.128.1 to 63.59.255.25463.59.255.25532,766
12163.60.0.0/1763.60.0.1 to 63.60.127.25463.60.127.25532,766
12263.60.128.0/1763.60.128.1 to 63.60.255.25463.60.255.25532,766
12363.61.0.0/1763.61.0.1 to 63.61.127.25463.61.127.25532,766
12463.61.128.0/1763.61.128.1 to 63.61.255.25463.61.255.25532,766
12563.62.0.0/1763.62.0.1 to 63.62.127.25463.62.127.25532,766
12663.62.128.0/1763.62.128.1 to 63.62.255.25463.62.255.25532,766
12763.63.0.0/1763.63.0.1 to 63.63.127.25463.63.127.25532,766
12863.63.128.0/1763.63.128.1 to 63.63.255.25463.63.255.25532,766

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.