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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.

Network30.128.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
30.128.0.0
Broadcast address
30.191.255.255
First usable
30.128.0.1
Last usable
30.191.255.254
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 1E800000 · Integer 511705088 to 515899391
Reverse DNS zones
128.30.in-addr.arpa
129.30.in-addr.arpa
130.30.in-addr.arpa
131.30.in-addr.arpa
132.30.in-addr.arpa
133.30.in-addr.arpa
134.30.in-addr.arpa
135.30.in-addr.arpa
136.30.in-addr.arpa
137.30.in-addr.arpa
138.30.in-addr.arpa
139.30.in-addr.arpa
140.30.in-addr.arpa
141.30.in-addr.arpa
142.30.in-addr.arpa
143.30.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
Address00011110.10000000.00000000.0000000030.128.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00011110.10000000.00000000.0000000030.128.0.0
Broadcast00011110.10111111.11111111.1111111130.191.255.255
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)

30.128.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
130.128.0.0/1730.128.0.1 to 30.128.127.25430.128.127.25532,766
230.128.128.0/1730.128.128.1 to 30.128.255.25430.128.255.25532,766
330.129.0.0/1730.129.0.1 to 30.129.127.25430.129.127.25532,766
430.129.128.0/1730.129.128.1 to 30.129.255.25430.129.255.25532,766
530.130.0.0/1730.130.0.1 to 30.130.127.25430.130.127.25532,766
630.130.128.0/1730.130.128.1 to 30.130.255.25430.130.255.25532,766
730.131.0.0/1730.131.0.1 to 30.131.127.25430.131.127.25532,766
830.131.128.0/1730.131.128.1 to 30.131.255.25430.131.255.25532,766
930.132.0.0/1730.132.0.1 to 30.132.127.25430.132.127.25532,766
1030.132.128.0/1730.132.128.1 to 30.132.255.25430.132.255.25532,766
1130.133.0.0/1730.133.0.1 to 30.133.127.25430.133.127.25532,766
1230.133.128.0/1730.133.128.1 to 30.133.255.25430.133.255.25532,766
1330.134.0.0/1730.134.0.1 to 30.134.127.25430.134.127.25532,766
1430.134.128.0/1730.134.128.1 to 30.134.255.25430.134.255.25532,766
1530.135.0.0/1730.135.0.1 to 30.135.127.25430.135.127.25532,766
1630.135.128.0/1730.135.128.1 to 30.135.255.25430.135.255.25532,766
1730.136.0.0/1730.136.0.1 to 30.136.127.25430.136.127.25532,766
1830.136.128.0/1730.136.128.1 to 30.136.255.25430.136.255.25532,766
1930.137.0.0/1730.137.0.1 to 30.137.127.25430.137.127.25532,766
2030.137.128.0/1730.137.128.1 to 30.137.255.25430.137.255.25532,766
2130.138.0.0/1730.138.0.1 to 30.138.127.25430.138.127.25532,766
2230.138.128.0/1730.138.128.1 to 30.138.255.25430.138.255.25532,766
2330.139.0.0/1730.139.0.1 to 30.139.127.25430.139.127.25532,766
2430.139.128.0/1730.139.128.1 to 30.139.255.25430.139.255.25532,766
2530.140.0.0/1730.140.0.1 to 30.140.127.25430.140.127.25532,766
2630.140.128.0/1730.140.128.1 to 30.140.255.25430.140.255.25532,766
2730.141.0.0/1730.141.0.1 to 30.141.127.25430.141.127.25532,766
2830.141.128.0/1730.141.128.1 to 30.141.255.25430.141.255.25532,766
2930.142.0.0/1730.142.0.1 to 30.142.127.25430.142.127.25532,766
3030.142.128.0/1730.142.128.1 to 30.142.255.25430.142.255.25532,766
3130.143.0.0/1730.143.0.1 to 30.143.127.25430.143.127.25532,766
3230.143.128.0/1730.143.128.1 to 30.143.255.25430.143.255.25532,766
3330.144.0.0/1730.144.0.1 to 30.144.127.25430.144.127.25532,766
3430.144.128.0/1730.144.128.1 to 30.144.255.25430.144.255.25532,766
3530.145.0.0/1730.145.0.1 to 30.145.127.25430.145.127.25532,766
3630.145.128.0/1730.145.128.1 to 30.145.255.25430.145.255.25532,766
3730.146.0.0/1730.146.0.1 to 30.146.127.25430.146.127.25532,766
3830.146.128.0/1730.146.128.1 to 30.146.255.25430.146.255.25532,766
3930.147.0.0/1730.147.0.1 to 30.147.127.25430.147.127.25532,766
4030.147.128.0/1730.147.128.1 to 30.147.255.25430.147.255.25532,766
4130.148.0.0/1730.148.0.1 to 30.148.127.25430.148.127.25532,766
4230.148.128.0/1730.148.128.1 to 30.148.255.25430.148.255.25532,766
4330.149.0.0/1730.149.0.1 to 30.149.127.25430.149.127.25532,766
4430.149.128.0/1730.149.128.1 to 30.149.255.25430.149.255.25532,766
4530.150.0.0/1730.150.0.1 to 30.150.127.25430.150.127.25532,766
4630.150.128.0/1730.150.128.1 to 30.150.255.25430.150.255.25532,766
4730.151.0.0/1730.151.0.1 to 30.151.127.25430.151.127.25532,766
4830.151.128.0/1730.151.128.1 to 30.151.255.25430.151.255.25532,766
4930.152.0.0/1730.152.0.1 to 30.152.127.25430.152.127.25532,766
5030.152.128.0/1730.152.128.1 to 30.152.255.25430.152.255.25532,766
5130.153.0.0/1730.153.0.1 to 30.153.127.25430.153.127.25532,766
5230.153.128.0/1730.153.128.1 to 30.153.255.25430.153.255.25532,766
5330.154.0.0/1730.154.0.1 to 30.154.127.25430.154.127.25532,766
5430.154.128.0/1730.154.128.1 to 30.154.255.25430.154.255.25532,766
5530.155.0.0/1730.155.0.1 to 30.155.127.25430.155.127.25532,766
5630.155.128.0/1730.155.128.1 to 30.155.255.25430.155.255.25532,766
5730.156.0.0/1730.156.0.1 to 30.156.127.25430.156.127.25532,766
5830.156.128.0/1730.156.128.1 to 30.156.255.25430.156.255.25532,766
5930.157.0.0/1730.157.0.1 to 30.157.127.25430.157.127.25532,766
6030.157.128.0/1730.157.128.1 to 30.157.255.25430.157.255.25532,766
6130.158.0.0/1730.158.0.1 to 30.158.127.25430.158.127.25532,766
6230.158.128.0/1730.158.128.1 to 30.158.255.25430.158.255.25532,766
6330.159.0.0/1730.159.0.1 to 30.159.127.25430.159.127.25532,766
6430.159.128.0/1730.159.128.1 to 30.159.255.25430.159.255.25532,766
6530.160.0.0/1730.160.0.1 to 30.160.127.25430.160.127.25532,766
6630.160.128.0/1730.160.128.1 to 30.160.255.25430.160.255.25532,766
6730.161.0.0/1730.161.0.1 to 30.161.127.25430.161.127.25532,766
6830.161.128.0/1730.161.128.1 to 30.161.255.25430.161.255.25532,766
6930.162.0.0/1730.162.0.1 to 30.162.127.25430.162.127.25532,766
7030.162.128.0/1730.162.128.1 to 30.162.255.25430.162.255.25532,766
7130.163.0.0/1730.163.0.1 to 30.163.127.25430.163.127.25532,766
7230.163.128.0/1730.163.128.1 to 30.163.255.25430.163.255.25532,766
7330.164.0.0/1730.164.0.1 to 30.164.127.25430.164.127.25532,766
7430.164.128.0/1730.164.128.1 to 30.164.255.25430.164.255.25532,766
7530.165.0.0/1730.165.0.1 to 30.165.127.25430.165.127.25532,766
7630.165.128.0/1730.165.128.1 to 30.165.255.25430.165.255.25532,766
7730.166.0.0/1730.166.0.1 to 30.166.127.25430.166.127.25532,766
7830.166.128.0/1730.166.128.1 to 30.166.255.25430.166.255.25532,766
7930.167.0.0/1730.167.0.1 to 30.167.127.25430.167.127.25532,766
8030.167.128.0/1730.167.128.1 to 30.167.255.25430.167.255.25532,766
8130.168.0.0/1730.168.0.1 to 30.168.127.25430.168.127.25532,766
8230.168.128.0/1730.168.128.1 to 30.168.255.25430.168.255.25532,766
8330.169.0.0/1730.169.0.1 to 30.169.127.25430.169.127.25532,766
8430.169.128.0/1730.169.128.1 to 30.169.255.25430.169.255.25532,766
8530.170.0.0/1730.170.0.1 to 30.170.127.25430.170.127.25532,766
8630.170.128.0/1730.170.128.1 to 30.170.255.25430.170.255.25532,766
8730.171.0.0/1730.171.0.1 to 30.171.127.25430.171.127.25532,766
8830.171.128.0/1730.171.128.1 to 30.171.255.25430.171.255.25532,766
8930.172.0.0/1730.172.0.1 to 30.172.127.25430.172.127.25532,766
9030.172.128.0/1730.172.128.1 to 30.172.255.25430.172.255.25532,766
9130.173.0.0/1730.173.0.1 to 30.173.127.25430.173.127.25532,766
9230.173.128.0/1730.173.128.1 to 30.173.255.25430.173.255.25532,766
9330.174.0.0/1730.174.0.1 to 30.174.127.25430.174.127.25532,766
9430.174.128.0/1730.174.128.1 to 30.174.255.25430.174.255.25532,766
9530.175.0.0/1730.175.0.1 to 30.175.127.25430.175.127.25532,766
9630.175.128.0/1730.175.128.1 to 30.175.255.25430.175.255.25532,766
9730.176.0.0/1730.176.0.1 to 30.176.127.25430.176.127.25532,766
9830.176.128.0/1730.176.128.1 to 30.176.255.25430.176.255.25532,766
9930.177.0.0/1730.177.0.1 to 30.177.127.25430.177.127.25532,766
10030.177.128.0/1730.177.128.1 to 30.177.255.25430.177.255.25532,766
10130.178.0.0/1730.178.0.1 to 30.178.127.25430.178.127.25532,766
10230.178.128.0/1730.178.128.1 to 30.178.255.25430.178.255.25532,766
10330.179.0.0/1730.179.0.1 to 30.179.127.25430.179.127.25532,766
10430.179.128.0/1730.179.128.1 to 30.179.255.25430.179.255.25532,766
10530.180.0.0/1730.180.0.1 to 30.180.127.25430.180.127.25532,766
10630.180.128.0/1730.180.128.1 to 30.180.255.25430.180.255.25532,766
10730.181.0.0/1730.181.0.1 to 30.181.127.25430.181.127.25532,766
10830.181.128.0/1730.181.128.1 to 30.181.255.25430.181.255.25532,766
10930.182.0.0/1730.182.0.1 to 30.182.127.25430.182.127.25532,766
11030.182.128.0/1730.182.128.1 to 30.182.255.25430.182.255.25532,766
11130.183.0.0/1730.183.0.1 to 30.183.127.25430.183.127.25532,766
11230.183.128.0/1730.183.128.1 to 30.183.255.25430.183.255.25532,766
11330.184.0.0/1730.184.0.1 to 30.184.127.25430.184.127.25532,766
11430.184.128.0/1730.184.128.1 to 30.184.255.25430.184.255.25532,766
11530.185.0.0/1730.185.0.1 to 30.185.127.25430.185.127.25532,766
11630.185.128.0/1730.185.128.1 to 30.185.255.25430.185.255.25532,766
11730.186.0.0/1730.186.0.1 to 30.186.127.25430.186.127.25532,766
11830.186.128.0/1730.186.128.1 to 30.186.255.25430.186.255.25532,766
11930.187.0.0/1730.187.0.1 to 30.187.127.25430.187.127.25532,766
12030.187.128.0/1730.187.128.1 to 30.187.255.25430.187.255.25532,766
12130.188.0.0/1730.188.0.1 to 30.188.127.25430.188.127.25532,766
12230.188.128.0/1730.188.128.1 to 30.188.255.25430.188.255.25532,766
12330.189.0.0/1730.189.0.1 to 30.189.127.25430.189.127.25532,766
12430.189.128.0/1730.189.128.1 to 30.189.255.25430.189.255.25532,766
12530.190.0.0/1730.190.0.1 to 30.190.127.25430.190.127.25532,766
12630.190.128.0/1730.190.128.1 to 30.190.255.25430.190.255.25532,766
12730.191.0.0/1730.191.0.1 to 30.191.127.25430.191.127.25532,766
12830.191.128.0/1730.191.128.1 to 30.191.255.25430.191.255.25532,766

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.