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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.

Network10.0.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
10.0.0.0
Broadcast address
10.31.255.255
First usable
10.0.0.1
Last usable
10.31.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Private (RFC 1918) 10.0.0.0/8
Office and home networks; not routed on the internet
Old class
A (default /8)
As numbers
Hex 0A000000 · Integer 167772160 to 169869311
Reverse DNS zones
0.10.in-addr.arpa
1.10.in-addr.arpa
2.10.in-addr.arpa
3.10.in-addr.arpa
4.10.in-addr.arpa
5.10.in-addr.arpa
6.10.in-addr.arpa
7.10.in-addr.arpa
8.10.in-addr.arpa
9.10.in-addr.arpa
10.10.in-addr.arpa
11.10.in-addr.arpa
12.10.in-addr.arpa
13.10.in-addr.arpa
14.10.in-addr.arpa
15.10.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001010.00000000.00000000.0000000010.0.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network00001010.00000000.00000000.0000000010.0.0.0
Broadcast00001010.00011111.11111111.1111111110.31.255.255
Split into smaller subnets/18
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

10.0.0.0/11 makes 128 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
110.0.0.0/1810.0.0.1 to 10.0.63.25410.0.63.25516,382
210.0.64.0/1810.0.64.1 to 10.0.127.25410.0.127.25516,382
310.0.128.0/1810.0.128.1 to 10.0.191.25410.0.191.25516,382
410.0.192.0/1810.0.192.1 to 10.0.255.25410.0.255.25516,382
510.1.0.0/1810.1.0.1 to 10.1.63.25410.1.63.25516,382
610.1.64.0/1810.1.64.1 to 10.1.127.25410.1.127.25516,382
710.1.128.0/1810.1.128.1 to 10.1.191.25410.1.191.25516,382
810.1.192.0/1810.1.192.1 to 10.1.255.25410.1.255.25516,382
910.2.0.0/1810.2.0.1 to 10.2.63.25410.2.63.25516,382
1010.2.64.0/1810.2.64.1 to 10.2.127.25410.2.127.25516,382
1110.2.128.0/1810.2.128.1 to 10.2.191.25410.2.191.25516,382
1210.2.192.0/1810.2.192.1 to 10.2.255.25410.2.255.25516,382
1310.3.0.0/1810.3.0.1 to 10.3.63.25410.3.63.25516,382
1410.3.64.0/1810.3.64.1 to 10.3.127.25410.3.127.25516,382
1510.3.128.0/1810.3.128.1 to 10.3.191.25410.3.191.25516,382
1610.3.192.0/1810.3.192.1 to 10.3.255.25410.3.255.25516,382
1710.4.0.0/1810.4.0.1 to 10.4.63.25410.4.63.25516,382
1810.4.64.0/1810.4.64.1 to 10.4.127.25410.4.127.25516,382
1910.4.128.0/1810.4.128.1 to 10.4.191.25410.4.191.25516,382
2010.4.192.0/1810.4.192.1 to 10.4.255.25410.4.255.25516,382
2110.5.0.0/1810.5.0.1 to 10.5.63.25410.5.63.25516,382
2210.5.64.0/1810.5.64.1 to 10.5.127.25410.5.127.25516,382
2310.5.128.0/1810.5.128.1 to 10.5.191.25410.5.191.25516,382
2410.5.192.0/1810.5.192.1 to 10.5.255.25410.5.255.25516,382
2510.6.0.0/1810.6.0.1 to 10.6.63.25410.6.63.25516,382
2610.6.64.0/1810.6.64.1 to 10.6.127.25410.6.127.25516,382
2710.6.128.0/1810.6.128.1 to 10.6.191.25410.6.191.25516,382
2810.6.192.0/1810.6.192.1 to 10.6.255.25410.6.255.25516,382
2910.7.0.0/1810.7.0.1 to 10.7.63.25410.7.63.25516,382
3010.7.64.0/1810.7.64.1 to 10.7.127.25410.7.127.25516,382
3110.7.128.0/1810.7.128.1 to 10.7.191.25410.7.191.25516,382
3210.7.192.0/1810.7.192.1 to 10.7.255.25410.7.255.25516,382
3310.8.0.0/1810.8.0.1 to 10.8.63.25410.8.63.25516,382
3410.8.64.0/1810.8.64.1 to 10.8.127.25410.8.127.25516,382
3510.8.128.0/1810.8.128.1 to 10.8.191.25410.8.191.25516,382
3610.8.192.0/1810.8.192.1 to 10.8.255.25410.8.255.25516,382
3710.9.0.0/1810.9.0.1 to 10.9.63.25410.9.63.25516,382
3810.9.64.0/1810.9.64.1 to 10.9.127.25410.9.127.25516,382
3910.9.128.0/1810.9.128.1 to 10.9.191.25410.9.191.25516,382
4010.9.192.0/1810.9.192.1 to 10.9.255.25410.9.255.25516,382
4110.10.0.0/1810.10.0.1 to 10.10.63.25410.10.63.25516,382
4210.10.64.0/1810.10.64.1 to 10.10.127.25410.10.127.25516,382
4310.10.128.0/1810.10.128.1 to 10.10.191.25410.10.191.25516,382
4410.10.192.0/1810.10.192.1 to 10.10.255.25410.10.255.25516,382
4510.11.0.0/1810.11.0.1 to 10.11.63.25410.11.63.25516,382
4610.11.64.0/1810.11.64.1 to 10.11.127.25410.11.127.25516,382
4710.11.128.0/1810.11.128.1 to 10.11.191.25410.11.191.25516,382
4810.11.192.0/1810.11.192.1 to 10.11.255.25410.11.255.25516,382
4910.12.0.0/1810.12.0.1 to 10.12.63.25410.12.63.25516,382
5010.12.64.0/1810.12.64.1 to 10.12.127.25410.12.127.25516,382
5110.12.128.0/1810.12.128.1 to 10.12.191.25410.12.191.25516,382
5210.12.192.0/1810.12.192.1 to 10.12.255.25410.12.255.25516,382
5310.13.0.0/1810.13.0.1 to 10.13.63.25410.13.63.25516,382
5410.13.64.0/1810.13.64.1 to 10.13.127.25410.13.127.25516,382
5510.13.128.0/1810.13.128.1 to 10.13.191.25410.13.191.25516,382
5610.13.192.0/1810.13.192.1 to 10.13.255.25410.13.255.25516,382
5710.14.0.0/1810.14.0.1 to 10.14.63.25410.14.63.25516,382
5810.14.64.0/1810.14.64.1 to 10.14.127.25410.14.127.25516,382
5910.14.128.0/1810.14.128.1 to 10.14.191.25410.14.191.25516,382
6010.14.192.0/1810.14.192.1 to 10.14.255.25410.14.255.25516,382
6110.15.0.0/1810.15.0.1 to 10.15.63.25410.15.63.25516,382
6210.15.64.0/1810.15.64.1 to 10.15.127.25410.15.127.25516,382
6310.15.128.0/1810.15.128.1 to 10.15.191.25410.15.191.25516,382
6410.15.192.0/1810.15.192.1 to 10.15.255.25410.15.255.25516,382
6510.16.0.0/1810.16.0.1 to 10.16.63.25410.16.63.25516,382
6610.16.64.0/1810.16.64.1 to 10.16.127.25410.16.127.25516,382
6710.16.128.0/1810.16.128.1 to 10.16.191.25410.16.191.25516,382
6810.16.192.0/1810.16.192.1 to 10.16.255.25410.16.255.25516,382
6910.17.0.0/1810.17.0.1 to 10.17.63.25410.17.63.25516,382
7010.17.64.0/1810.17.64.1 to 10.17.127.25410.17.127.25516,382
7110.17.128.0/1810.17.128.1 to 10.17.191.25410.17.191.25516,382
7210.17.192.0/1810.17.192.1 to 10.17.255.25410.17.255.25516,382
7310.18.0.0/1810.18.0.1 to 10.18.63.25410.18.63.25516,382
7410.18.64.0/1810.18.64.1 to 10.18.127.25410.18.127.25516,382
7510.18.128.0/1810.18.128.1 to 10.18.191.25410.18.191.25516,382
7610.18.192.0/1810.18.192.1 to 10.18.255.25410.18.255.25516,382
7710.19.0.0/1810.19.0.1 to 10.19.63.25410.19.63.25516,382
7810.19.64.0/1810.19.64.1 to 10.19.127.25410.19.127.25516,382
7910.19.128.0/1810.19.128.1 to 10.19.191.25410.19.191.25516,382
8010.19.192.0/1810.19.192.1 to 10.19.255.25410.19.255.25516,382
8110.20.0.0/1810.20.0.1 to 10.20.63.25410.20.63.25516,382
8210.20.64.0/1810.20.64.1 to 10.20.127.25410.20.127.25516,382
8310.20.128.0/1810.20.128.1 to 10.20.191.25410.20.191.25516,382
8410.20.192.0/1810.20.192.1 to 10.20.255.25410.20.255.25516,382
8510.21.0.0/1810.21.0.1 to 10.21.63.25410.21.63.25516,382
8610.21.64.0/1810.21.64.1 to 10.21.127.25410.21.127.25516,382
8710.21.128.0/1810.21.128.1 to 10.21.191.25410.21.191.25516,382
8810.21.192.0/1810.21.192.1 to 10.21.255.25410.21.255.25516,382
8910.22.0.0/1810.22.0.1 to 10.22.63.25410.22.63.25516,382
9010.22.64.0/1810.22.64.1 to 10.22.127.25410.22.127.25516,382
9110.22.128.0/1810.22.128.1 to 10.22.191.25410.22.191.25516,382
9210.22.192.0/1810.22.192.1 to 10.22.255.25410.22.255.25516,382
9310.23.0.0/1810.23.0.1 to 10.23.63.25410.23.63.25516,382
9410.23.64.0/1810.23.64.1 to 10.23.127.25410.23.127.25516,382
9510.23.128.0/1810.23.128.1 to 10.23.191.25410.23.191.25516,382
9610.23.192.0/1810.23.192.1 to 10.23.255.25410.23.255.25516,382
9710.24.0.0/1810.24.0.1 to 10.24.63.25410.24.63.25516,382
9810.24.64.0/1810.24.64.1 to 10.24.127.25410.24.127.25516,382
9910.24.128.0/1810.24.128.1 to 10.24.191.25410.24.191.25516,382
10010.24.192.0/1810.24.192.1 to 10.24.255.25410.24.255.25516,382
10110.25.0.0/1810.25.0.1 to 10.25.63.25410.25.63.25516,382
10210.25.64.0/1810.25.64.1 to 10.25.127.25410.25.127.25516,382
10310.25.128.0/1810.25.128.1 to 10.25.191.25410.25.191.25516,382
10410.25.192.0/1810.25.192.1 to 10.25.255.25410.25.255.25516,382
10510.26.0.0/1810.26.0.1 to 10.26.63.25410.26.63.25516,382
10610.26.64.0/1810.26.64.1 to 10.26.127.25410.26.127.25516,382
10710.26.128.0/1810.26.128.1 to 10.26.191.25410.26.191.25516,382
10810.26.192.0/1810.26.192.1 to 10.26.255.25410.26.255.25516,382
10910.27.0.0/1810.27.0.1 to 10.27.63.25410.27.63.25516,382
11010.27.64.0/1810.27.64.1 to 10.27.127.25410.27.127.25516,382
11110.27.128.0/1810.27.128.1 to 10.27.191.25410.27.191.25516,382
11210.27.192.0/1810.27.192.1 to 10.27.255.25410.27.255.25516,382
11310.28.0.0/1810.28.0.1 to 10.28.63.25410.28.63.25516,382
11410.28.64.0/1810.28.64.1 to 10.28.127.25410.28.127.25516,382
11510.28.128.0/1810.28.128.1 to 10.28.191.25410.28.191.25516,382
11610.28.192.0/1810.28.192.1 to 10.28.255.25410.28.255.25516,382
11710.29.0.0/1810.29.0.1 to 10.29.63.25410.29.63.25516,382
11810.29.64.0/1810.29.64.1 to 10.29.127.25410.29.127.25516,382
11910.29.128.0/1810.29.128.1 to 10.29.191.25410.29.191.25516,382
12010.29.192.0/1810.29.192.1 to 10.29.255.25410.29.255.25516,382
12110.30.0.0/1810.30.0.1 to 10.30.63.25410.30.63.25516,382
12210.30.64.0/1810.30.64.1 to 10.30.127.25410.30.127.25516,382
12310.30.128.0/1810.30.128.1 to 10.30.191.25410.30.191.25516,382
12410.30.192.0/1810.30.192.1 to 10.30.255.25410.30.255.25516,382
12510.31.0.0/1810.31.0.1 to 10.31.63.25410.31.63.25516,382
12610.31.64.0/1810.31.64.1 to 10.31.127.25410.31.127.25516,382
12710.31.128.0/1810.31.128.1 to 10.31.191.25410.31.191.25516,382
12810.31.192.0/1810.31.192.1 to 10.31.255.25410.31.255.25516,382

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.