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IPv4 Subnet Calculator

Enter an IP with a CIDR prefix or a subnet mask to see its network, broadcast, host range, and host count. You can also split the network into smaller subnets.

$ ipcalc
Try:192.168.1.10/2410.0.0.0/8172.16.5.4/20203.0.113.9/29
IPv6 calculator →
private IP (RFC 1918)10.12.128.0/20
network10.12.128.0/20
broadcast10.12.143.255
first host10.12.128.1
last host10.12.143.254
subnet mask255.255.240.0
wildcard0.0.15.255
addresses4,096
usable hosts4,094
classA
ipcalc 10.12.128.0/20
address00001010.00001100.10000000.00000000
subnet mask11111111.11111111.11110000.00000000
network00001010.00001100.10000000.00000000
broadcast00001010.00001100.10001111.11111111
green = network part, grey = host part
hex0x0a0c8000
decimal168591360
reverse dns0.128.12.10.in-addr.arpa
ipv4-mapped::ffff:a0c:8000

/20 split into /25 · 32 subnets

close ×
#networkhost rangebroadcast
110.12.128.0/2510.12.128.1 – 10.12.128.12610.12.128.127
210.12.128.128/2510.12.128.129 – 10.12.128.25410.12.128.255
310.12.129.0/2510.12.129.1 – 10.12.129.12610.12.129.127
410.12.129.128/2510.12.129.129 – 10.12.129.25410.12.129.255
510.12.130.0/2510.12.130.1 – 10.12.130.12610.12.130.127
610.12.130.128/2510.12.130.129 – 10.12.130.25410.12.130.255
710.12.131.0/2510.12.131.1 – 10.12.131.12610.12.131.127
810.12.131.128/2510.12.131.129 – 10.12.131.25410.12.131.255
910.12.132.0/2510.12.132.1 – 10.12.132.12610.12.132.127
1010.12.132.128/2510.12.132.129 – 10.12.132.25410.12.132.255
1110.12.133.0/2510.12.133.1 – 10.12.133.12610.12.133.127
1210.12.133.128/2510.12.133.129 – 10.12.133.25410.12.133.255
1310.12.134.0/2510.12.134.1 – 10.12.134.12610.12.134.127
1410.12.134.128/2510.12.134.129 – 10.12.134.25410.12.134.255
1510.12.135.0/2510.12.135.1 – 10.12.135.12610.12.135.127
1610.12.135.128/2510.12.135.129 – 10.12.135.25410.12.135.255
1710.12.136.0/2510.12.136.1 – 10.12.136.12610.12.136.127
1810.12.136.128/2510.12.136.129 – 10.12.136.25410.12.136.255
1910.12.137.0/2510.12.137.1 – 10.12.137.12610.12.137.127
2010.12.137.128/2510.12.137.129 – 10.12.137.25410.12.137.255
2110.12.138.0/2510.12.138.1 – 10.12.138.12610.12.138.127
2210.12.138.128/2510.12.138.129 – 10.12.138.25410.12.138.255
2310.12.139.0/2510.12.139.1 – 10.12.139.12610.12.139.127
2410.12.139.128/2510.12.139.129 – 10.12.139.25410.12.139.255
2510.12.140.0/2510.12.140.1 – 10.12.140.12610.12.140.127
2610.12.140.128/2510.12.140.129 – 10.12.140.25410.12.140.255
2710.12.141.0/2510.12.141.1 – 10.12.141.12610.12.141.127
2810.12.141.128/2510.12.141.129 – 10.12.141.25410.12.141.255
2910.12.142.0/2510.12.142.1 – 10.12.142.12610.12.142.127
3010.12.142.128/2510.12.142.129 – 10.12.142.25410.12.142.255
3110.12.143.0/2510.12.143.1 – 10.12.143.12610.12.143.127
3210.12.143.128/2510.12.143.129 – 10.12.143.25410.12.143.255
01 / table

IPv4 CIDR prefix table.

Click a prefix longer than your network to split it into subnets.

prefixsubnet maskaddresseshostsin your /20
/00.0.0.04,294,967,2964,294,967,294-
/1128.0.0.02,147,483,6482,147,483,646-
/2192.0.0.01,073,741,8241,073,741,822-
/3224.0.0.0536,870,912536,870,910-
/4240.0.0.0268,435,456268,435,454-
/5248.0.0.0134,217,728134,217,726-
/6252.0.0.067,108,86467,108,862-
/7254.0.0.033,554,43233,554,430-
/8255.0.0.016,777,21616,777,214-
/9255.128.0.08,388,6088,388,606-
/10255.192.0.04,194,3044,194,302-
/11255.224.0.02,097,1522,097,150-
/12255.240.0.01,048,5761,048,574-
/13255.248.0.0524,288524,286-
/14255.252.0.0262,144262,142-
/15255.254.0.0131,072131,070-
/16255.255.0.065,53665,534-
/17255.255.128.032,76832,766-
/18255.255.192.016,38416,382-
/19255.255.224.08,1928,190-
/20255.255.240.04,0964,0941
/21255.255.248.02,0482,0462 split →
/22255.255.252.01,0241,0224 split →
/23255.255.254.05125108 split →
/24255.255.255.025625416 split →
/25255.255.255.12812812632 split →
/26255.255.255.192646264 split →
/27255.255.255.2243230128 split →
/28255.255.255.2401614256 split →
/29255.255.255.24886512 split →
/30255.255.255.252421,024 split →
/31255.255.255.254222,048 split →
/32255.255.255.255114,096 split →
02 / faq

About this calculator.

How do I use this subnet calculator?

▼

Type an IP address followed by a prefix, like 192.168.1.10/24, or by a subnet mask, like 192.168.1.10 255.255.255.0. Without a prefix it uses /24. Click a row in the table to split the network into smaller subnets.

Why are usable hosts always 2 fewer?

▼

The first address in a subnet is the network address and the last is the broadcast address, so neither can go to a device. The exceptions are /31 (point-to-point links, RFC 3021) and /32 (a single address), which use every address.

Can I use it from a terminal?

▼

Yes. curl 'ipku.in/en/tools/ipv4-subnet-calculator?q=192.168.1.10/24' returns the result as plain text.

Learn how to work it out →