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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)10.1.112.0/21
network10.1.112.0/21
broadcast10.1.119.255
first host10.1.112.1
last host10.1.119.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.1.112.0/21
address00001010.00000001.01110000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000001.01110000.00000000
broadcast00001010.00000001.01110111.11111111
green = network part, grey = host part
hex0x0a017000
decimal167866368
reverse dns0.112.1.10.in-addr.arpa
ipv4-mapped::ffff:a01:7000

/21 split into /25 · 16 subnets

close ×
#networkhost rangebroadcast
110.1.112.0/2510.1.112.1 – 10.1.112.12610.1.112.127
210.1.112.128/2510.1.112.129 – 10.1.112.25410.1.112.255
310.1.113.0/2510.1.113.1 – 10.1.113.12610.1.113.127
410.1.113.128/2510.1.113.129 – 10.1.113.25410.1.113.255
510.1.114.0/2510.1.114.1 – 10.1.114.12610.1.114.127
610.1.114.128/2510.1.114.129 – 10.1.114.25410.1.114.255
710.1.115.0/2510.1.115.1 – 10.1.115.12610.1.115.127
810.1.115.128/2510.1.115.129 – 10.1.115.25410.1.115.255
910.1.116.0/2510.1.116.1 – 10.1.116.12610.1.116.127
1010.1.116.128/2510.1.116.129 – 10.1.116.25410.1.116.255
1110.1.117.0/2510.1.117.1 – 10.1.117.12610.1.117.127
1210.1.117.128/2510.1.117.129 – 10.1.117.25410.1.117.255
1310.1.118.0/2510.1.118.1 – 10.1.118.12610.1.118.127
1410.1.118.128/2510.1.118.129 – 10.1.118.25410.1.118.255
1510.1.119.0/2510.1.119.1 – 10.1.119.12610.1.119.127
1610.1.119.128/2510.1.119.129 – 10.1.119.25410.1.119.255
01 / table

IPv4 CIDR prefix table.

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

prefixsubnet maskaddresseshostsin your /21
/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-
/20255.255.240.04,0964,094-
/21255.255.248.02,0482,0461
/22255.255.252.01,0241,0222 split →
/23255.255.254.05125104 split →
/24255.255.255.02562548 split →
/25255.255.255.12812812616 split →
/26255.255.255.192646232 split →
/27255.255.255.224323064 split →
/28255.255.255.2401614128 split →
/29255.255.255.24886256 split →
/30255.255.255.25242512 split →
/31255.255.255.254221,024 split →
/32255.255.255.255112,048 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 →