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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)10.1.192.0/21
network10.1.192.0/21
broadcast10.1.199.255
first host10.1.192.1
last host10.1.199.254
subnet mask255.255.248.0
wildcard0.0.7.255
addresses2,048
usable hosts2,046
classA
ipcalc 10.1.192.0/21
address00001010.00000001.11000000.00000000
subnet mask11111111.11111111.11111000.00000000
network00001010.00000001.11000000.00000000
broadcast00001010.00000001.11000111.11111111
green = network part, grey = host part
hex0x0a01c000
decimal167886848
reverse dns0.192.1.10.in-addr.arpa
ipv4-mapped::ffff:a01:c000

/21 split into /26 · 32 subnets

close ×
#networkhost rangebroadcast
110.1.192.0/2610.1.192.1 – 10.1.192.6210.1.192.63
210.1.192.64/2610.1.192.65 – 10.1.192.12610.1.192.127
310.1.192.128/2610.1.192.129 – 10.1.192.19010.1.192.191
410.1.192.192/2610.1.192.193 – 10.1.192.25410.1.192.255
510.1.193.0/2610.1.193.1 – 10.1.193.6210.1.193.63
610.1.193.64/2610.1.193.65 – 10.1.193.12610.1.193.127
710.1.193.128/2610.1.193.129 – 10.1.193.19010.1.193.191
810.1.193.192/2610.1.193.193 – 10.1.193.25410.1.193.255
910.1.194.0/2610.1.194.1 – 10.1.194.6210.1.194.63
1010.1.194.64/2610.1.194.65 – 10.1.194.12610.1.194.127
1110.1.194.128/2610.1.194.129 – 10.1.194.19010.1.194.191
1210.1.194.192/2610.1.194.193 – 10.1.194.25410.1.194.255
1310.1.195.0/2610.1.195.1 – 10.1.195.6210.1.195.63
1410.1.195.64/2610.1.195.65 – 10.1.195.12610.1.195.127
1510.1.195.128/2610.1.195.129 – 10.1.195.19010.1.195.191
1610.1.195.192/2610.1.195.193 – 10.1.195.25410.1.195.255
1710.1.196.0/2610.1.196.1 – 10.1.196.6210.1.196.63
1810.1.196.64/2610.1.196.65 – 10.1.196.12610.1.196.127
1910.1.196.128/2610.1.196.129 – 10.1.196.19010.1.196.191
2010.1.196.192/2610.1.196.193 – 10.1.196.25410.1.196.255
2110.1.197.0/2610.1.197.1 – 10.1.197.6210.1.197.63
2210.1.197.64/2610.1.197.65 – 10.1.197.12610.1.197.127
2310.1.197.128/2610.1.197.129 – 10.1.197.19010.1.197.191
2410.1.197.192/2610.1.197.193 – 10.1.197.25410.1.197.255
2510.1.198.0/2610.1.198.1 – 10.1.198.6210.1.198.63
2610.1.198.64/2610.1.198.65 – 10.1.198.12610.1.198.127
2710.1.198.128/2610.1.198.129 – 10.1.198.19010.1.198.191
2810.1.198.192/2610.1.198.193 – 10.1.198.25410.1.198.255
2910.1.199.0/2610.1.199.1 – 10.1.199.6210.1.199.63
3010.1.199.64/2610.1.199.65 – 10.1.199.12610.1.199.127
3110.1.199.128/2610.1.199.129 – 10.1.199.19010.1.199.191
3210.1.199.192/2610.1.199.193 – 10.1.199.25410.1.199.255
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 →